john hawks weblog

The New York Times reports a new study in JAMA on the mortality risk associated with different BMI classes. The study found that obesity and underweight classes faced a higher mortality risk, but that overweight people were just as well off as normal weight.

In our analysis, we did not find overweight (BMI 25 to

The authors speculate that there may have been a recent reduction in mortality associated with obesity and overweight because of increasingly successful treatment of chronic high blood pressure and high cholesterol. Likewise people with extra weight may have an advantage in maintaining bone density and muscle strength into old age compared to normal or underweight people.

References:

Flegal KM, Graubard BI, Williamson DF, Gail MH. 2005. Excess deaths associated with underweight, overweight, and obesity. JAMA 293:1861-1867. JAMA Online

Chris Ruff and colleagues (2005) provide additional statistics on body mass in high latitude populations, including Inupiat and Finns. The importance of the paper is that previous regressions to estimate body mass in fossil humans have been based on lower-latitude populations. High latitude populations with broader pelves might be expected to have a slightly different mass than would be predicted for lower latitude populations, so adding the new samples ought to improve accuracy of estimation. Ruff and colleagues found that the new samples did result in slightly higher estimates of body mass for fossil Neandertals and other high latitude samples (including earlier and later Europeans and the Jinniushan skeleton from northern China). These estimates were not very far from the original estimates based on the earlier comparative sample, though, so the effect is minor.

Whenever I see estimates like these, they serve as a reality check of sorts about the common knowledge that Neandertals were massive and stocky in body form. The new body mass estimates for Neandertals are 75.8 kg (166 lb) for La Chapelle-aux-Saints and 82.3 kg (181 lb) for Kebara. When I was in high school, I was pretty lean myself and I wrestled in the 185 pound weight class. In other words, these massive Neandertals were nothing like the people we consider to be massive today.

On the other hand, they were hunter-gatherers, so we are in a whole different world in terms of fatness. Ethnographic hunter-gatherers are relatively small in terms of both mass and stature. But then, ethnographic hunter-gatherers tend to live in relatively marginal environments with more or less severe scarcity of resources. To give a bit of scale, Katzmarzyk and Leonard (1998) report on body mass in populations with different mean temperature. The sample is not huge, but it is illustrative:

Body mass against climate, from Katzmarzyk and Leonard 1998.

The red line on the chart I inserted at the body mass of La Chapelle. It is slightly large for an Eskimo, and slightly larger for an African (although notably not for a Polynesian). The important point is that the Neandertals were really not all that large compared to today's humans, whether we look at industrialized societies or not. If we accept the large size of a few specimens as indications of a large average mass in the population, this population is still not striking. Ruff (2002) provides a good review of the variation in body size in recent and living human populations. Considering the evidence that human body size has decreased over the terminal Pleistocene and Holocene, Neandertals would appear to be even closer to us and to contemporary populations.

Neandertals mainly appear to stand apart because of the contrast between them and later Europeans. This contrast mainly stems from the taller stature of later people, but in addition to an increase in height there was also a reduction in pelvic breadth. Overall, this appears to indicate a smaller mass for Upper Paleolithic Europeans, although the sample of individuals with both stature and bi-iliac measurements is very small (n = 6 in Ruff et al. 2005).

Ruff (2002:217) presents the following hypothesis:

One possible explanation for these observations is that the Late Pleistocene reduction in body size was due primarily to genetic factors, possibly reduced selection for large body size in association with technological improvements (Frayer 1984), whereas the succeeding fluctuations (decrease, then, in higher latitudes, increase) in body size in the Holocene were due to environmental effects on growth, e.g., nutrition.

The first part of this hypothesis begs for testing. An alternative is that the dietary changes that led to nutritional deficits in growing people were established long before the Holocene when agricultural subsistence patterns appeared. With their constant technological improvements, Upper Paleolithic people appear to be working much harder for their subsistence than Neandertals. Or social stratification may have led to inequities in food access that likewise had developmental consequences. One might even imagine that delayed maturation was an adaptation to restriction in calories or micronutrients during development -- which might make sense considering that undernourished populations today exhibit slower developmental times and delayed maturation compared to Westernized populations.

Of course if there was no mass reduction in Upper Paleolithic people, the first part of the hypothesis is moot.

As a bottom line, Neandertals were pretty clearly distinctive in their body proportions, by having broad pelves, short distal limb segments, and relatively short statures. But this distinctiveness did not necessarily extend to greater body mass, especially in comparison to contemporary and earlier humans, and present-day Europeans. If you have an image of Neandertals as hulking, muscle-bound brutes (or hulking, muscle-bound hunks, depending on your taste), then please consider that in Olympic boxing terms, La Chapelle's mass of 75.8 kg is just above the border between middleweight and light heavyweight, two classes below the maximum. The real heavyweights (i.e. super heavyweight class) start at full 14 stone, or 91.6 kg. That includes the pelvis from Atapuerca, but so far no other fossil humans.

References:

Katzmarzyk PT and Leonard WR. 1998. Climatic influences on human body size and proportions: Ecological adaptations and secular trends. Am J Phys Anthropol 106:483-503. Wiley InterScience

Ruff C. 2002. Variation in human body size and shape. Ann Rev Anthropol 31:211-232. Annual Reviews

Ruff C, Niskanen M, Junno J-A, Jamison P. 2005. Body mass prediction from stature and bi-iliac breadth in two high latitude populations, with application to earlier higher latitude humans. J Hum Evol 48:381-392.

Several papers at the AAPA meetings presented evidence for deep Asian-specific lineages in the present human gene pool. For example, from Mike Hammer's abstract:

Preliminary data from two loci that show evidence of ancient admixture will be discussed. A gene tree constructed from sequence data at the first locus roots in East Asia and has a most recent common ancestor ~2 million YBP. The pattern of nucleotide variation at the second locus reveals two major lineages that have not undergone recombination for over 2 million years, and statistically rejects the null hypothesis of panmixia during the early ancestry of modern humans (Hammer et al. 2005:115).

And from Shimada and Hey (2005:195):

Most sequences [from a 10.1 kb region of the X] are quite similar to one another, however three sequences differed from the others at an average of 28.6 substitutions. Assuming a molecular clock, and a human/chimpanzee divergence time of 6 million years, the estimated age of the base of the human sequences is 1.1 million years ago, whereas the estimated base of the tree excluding these divergent human sequences is 290,000 years ago. These divergent sequences were found in samples from the Middle East (Druze and Bedouin populations) and North Africa (Mozabite population). The pattern is suggestive of admixture between non-African archaic humans and Modern Humans [sic].

There were also more analytical papers by Hey and separately by Alan Rogers and colleagues (2005:182):

The "ancestral allele" at a given locus is the allele thought to have been carried by the last common ancestor (LCA) of all humans. These are only estimates, of course, but they are often relatively good ones. Thus, it is interesting that human ancestral alleles are usually most common in Africa. Some claim that the ancestral allele should be most common in Africa, because it is the ancestral population. We argue otherwise. In the absence of selection or ascertainment bias, the expected frequency of the ancestral allele is the same in each modern population, regardless of the history of population size, subdivision, or gene flow. The observed tendency of ancestral alleles to cluster in Africa argues either for some form of ascertainment bias or for some form of selection.

We attribute the pattern to two forms of ascertainment bias, which affect different sorts of locus. These biases, together with a history of expansion out of Africa, are capable of producing the observed pattern. The only loci that are certainly free of bias are those that sequence arbitrary stretches of DNA far from known genes. In these bias-free systems, there is no tendency for ancestral alleles to be most common in Africa.

Out of these papers I found the last to be the most interesting. What the paper essentially said was that earlier work that had found the "ancestral allele" of most genes to lie in Africa was entirely irrelevant to the issue of modern human origins. This is because there is no reason to expect this ancestral allele should preferentially appear in any population, regardless of their demographic history. Rogers reported in the presentation that the last paragraph of the abstract was wrong: they now have good reason to believe that ascertainment bias is not responsible for the observed pattern. That would leave natural selection as apparently the only explanation, although what pattern of selection would create the excess of ancestral alleles in Africa is up for grabs. I have an idea, but I'm not sharing it just yet.

The study is a powerful blow against the case for a recent, exclusively African origin of modern humans. It doesn't demolish the case, since the arguments for a recent African origin extend to other aspects of the genetic record, but it is damaging and suggests that a lot of work should be reevaluated.

But if work supporting Out-of-Africa should be reevaluated, the study suggests that work refuting it should be reconsidered also. The genes examined by Hammer and colleagues and by Shimada and Hey both rely upon the finding of ancient genetic variation outside of Africa -- in essence, placing the "ancestral allele" for these genes in Eurasia. Rogers' and colleagues' analysis shows this logic to be misleading.

The key is, that as we look at an increasing proportion of the genome, we are more likely to see a complex set of relationships. From my standpoint, that indicates that the pattern of human relationships was also likely complex, and that multiple forces (especially selection) were important in generating the current pattern of diversity. But for someone supporting a pure Out-of-Africa model, it means a retrenchment to a "consistency"-based argument: if you can't show the data are inconsistent with (i.e. absolutely falsify) a recent African origin, then you're just whistling in the wind. Despite the complete sequence of the human genome and a growing sample of individuals for many genomic regions, we can't seem to settle on whether the boundary case (no archaic input into human populations) has been falsified.

Hammer and Jeff Wall are working on the problem; looking for analytical methods to definitively falsify an exclusive Out-of-Africa model. In short, they're looking for smoking gun evidence of archaic genes in the recent human gene pool, and they think they have two. One of these was described in Garrigan et al. (2005), discussed in an earlier post. Another shows a similar pattern of diversity outside of Africa. Together with the work by Shimada and Hey, and the earlier work of Alan Templeton (2002), these loci would appear to show very strong evidence of ancient genetic exchanges among human populations, beyond the timeframe predicted by the Out-of-Africa model.

In my opinion, much of this logic is misleading. Many people studying the problem have a tendency to think that "archaic" genes should be hugely divergent from the genes of most living people. The search pattern to find them is to look for something very rare and different outside of Africa, or to place the root of the genealogy unambiguously in Asia or Europe. This is the premise behind Wall's 2000 study for example:

To model archaic admixture, I use an infinite-sites coalescent model with recombination. I assume there is no selection and a constant rate of recombination per base pair per generation. Consider a panmictic population with diploid effective population size N. Going backward in time, suppose that at time T₀ the remaining ancestors are placed randomly into one of two subpopulations with probabilities c and 1 - c. From time T₀ to time T₁, these subpopulations are assumed to be completely isolated from each other and panmictic with diploid effective population sizes of cN and N, respectively. Then, at time T₁, all remaining lineages are placed into a single panmictic population with diploid effective size N (Wall 2000:1272-1273).

To translate a bit; the study assumed that archaic humans were arranged into completely isolated populations for a long period of time. This long period of isolation (described as a "deviation from panmixia") resulted in genetic sequences that were artificially elevated in their divergence from the mainstream of modern human origins, and these might be recognized by examining the genetic variation in living Eurasians. In Hammer and colleagues' abstract, the concept of "statistically rejects the null hypothesis of panmixia during the early ancestry of modern humans" comes straight from this sort of logic.

But the hypothesis that archaic humans were completely (or even largely) isolated from each other is artificially extreme. It is a Pleistocene version of polygenism, except with a recent frenzy of interbreeding in the Upper Paleolithic. I don't believe it, and I don't know anybody who seriously would.

Far more likely is the idea that archaic humans were always connected to each other by some level of gene flow. I would take as a null hypothesis that the level was consistent with the current F_ST of 0.1 to 0.15, which would mean an average of around two individuals moving between each pair of continents per generation. At this level, selected alleles can move relatively quickly across the human range. With the small effective size estimated for human populations, no ancient human group should have been very genetically divergent from another. This means that we shouldn't expect to find "archaic" alleles that are very different from most living people. And if we could have sequenced their DNA when they were alive, we would find that archaic people weren't very different from each other, either.

DNA sequences from Neandertals confirm this expectation. The most recent common ancestor of the Neandertal mtDNA sequences and living humans may have lived as recently as 250,000 years ago. The initial estimate was around 600,000 years, which is elevated because of the anomolously high divergence of the Feldhofer 1 sequence. But even at this high date, the MRCA is significantly more recent than the earliest habitation of Europe, and far more recent than the initial dispersal of people from Africa. In other words, these archaic populations were connected to each other, and were exchanging genes. If there was any isolation of later Middle Pleistocene populations, such as the Neandertals, it was short compared to their shared ancestry. Their genes weren't very different from ours, and they were probably cycling toward greater similarity with us.

If this is true, then we shouldn't expect to find many genes that indicate a strikingly divergent pattern for non-Africans. We should expect most genes to be more or less the same, although many will show greater African diversity for ecological and demographic reasons. Only those genes with exceptional histories of local adaptation will show highly divergent alleles in one place or another. These genes might well be interesting because some of them will be related to the morphological features of archaic humans. But they will probably be exceptionally rare.

So maybe that's why we are only now beginning to find them.

References:

Garrigan D, Mobasher Z, Severson T, Wilder JA, and Hammer MF. 2005. Evidence for archaic Asian ancestry on the human X chromosome. Mol Biol Evol 22:189-192.

Hammer MF, Garrigan D, Wilder JA, Mobasher Z, Severson T, and Kingan SB. 2005. Sequence data from the autosomes and X chromosome: evidence for ancient admixture in the history of H. sapiens? (abstract). Am J Phys Anthropol suppl 40:115.

Shimada MK, and Hey J. 2005. History of modern human population structure inferred from the worldwide survey on Xp11.22 sequences. Am J Phys Anthropol suppl 40:195.

Templeton AR. 2002. Out of Africa again and again. Nature 416:45-51.

Wall JD. 2000. Detecting ancient admixture in humans using sequence polymorphism data. Genetics 154:1271-1279.

Mark Weiss from NSF appeared at the AAPA business meeting to discuss recent changes in the funding guidelines from the Physical Anthropology program. The most significant change, effective in the upcoming (July 2005) funding cycle, is the requirement to file and follow a data access plan with every grant. This change is the NSF response to the questionaire circulated last year among physical anthropologists and archaeologists. It follows policy changes at the top levels of NSF, ultimately initiated by the Clinton and Bush administrations toward greater openness of publicly funded research data and protocols.

From the
Physical Anthropology grant information page:

NSF is committed to the principle that research supported with public funds should be made widely available. Under NSF's data sharing policy, the Foundation expects investigators to share with other researchers, at no more than incremental cost and within a reasonable time, the data, samples, physical collections, and other supporting materials created or gathered in the course of the work. To implement that policy in ways appropriate to Physical Anthropology and Archaeology, beginning July 1, 2005 these Programs will require that all proposals include a one-page detailed description of the applicant's data access plan in the "Supplementary Documents" section. This page will be in addition to the standard 15-page project description. Applications lacking this statement will not be reviewed. The Programs realize that individual cases may differ widely and recognize that any absolute timeline or rigid set of rules is not possible. They also recognize that revision and adjustment may often be required as the work proceeds. The data access plan, however, will be considered an integral part of the project and therefore subject to reviewer and panel evaluation. Major departure from it will constitute a significant project change and require NSF approval. Successful applicants will be required to address this issue in every progress and final report. PIs on all awards made under these guidelines will be expected to discuss implementation of their plans in the "Results of Prior Research" section when they submit subsequent applications.

To me, this appears to be a good compromise between the different positions on data access. Some researchers would prefer to have casts, photographs, and measurements of specimens become publicly available (without restrictions) immediately after they are published. Others (including a subset of primary excavators) would prefer to limit access to photos and data until after a full monographic treatment of the specimens is published. There are good arguments on both sides.

In favor of limiting access, specimens are rare and fragile, and access to them should be carefully limited to preserve them. The skills required to prepare fossil specimens are rare, and they must be cultivated in long-term research projects. The only way that such projects can survive is if they can maximize the impact of their most important finds, and this means controlling the publication of pictures, limiting the creation and distribution of casts, and promoting students of the principal invesigators as groundbreakers making new and important discoveries. If such research projects had to make their data public immediately, there would be no incentive for them to continue their work.

But even those who are in favor of limiting access to fossil specimens must recognize that the situation in paleoanthropology today does not benefit them. There are very few publicly accessible datasets. Even pure electronic data for which analysis has been published and for which the cost of transmission is negligible, such as CT data, generally cannot be had. There are exceptions, who either provide data for sale or for free, and from the bottom of my heart I thank them for their choice to better the science. Their choice is all the more laudable, because the situation at present has created absolute disincentives to share data. At present, closing access is the only way to punish freeriders who fail to share data themselves. And commoditizing data and casts can be the only way to get valuable data out of other researchers.

And in my opinion, the issue of access to new fossil hominids has received an unwarranted share of the attention. Ann Gibbons' 2002 article, "Glasnost for hominids," is an excellent treatment, but it only scratches the periosteum of the problem. If the only problem with access to specimens was that only a few people could see something until ten years after it was unearthed, that would be bad, but still much better than the situation as it stands.

The real problem is that twenty to thirty years after many fossils are uncovered, there is no cast availability, little public data access, few financial accommodations to make such access possible. Specialists like me often find ways around these barriers. But I do not think it would be overstating the problem to suggest that perhaps half the people teaching human evolution in four-year universities have never touched a cast of a Hadar fossil. I would be delighted to be proved wrong, but I don't think I am. Our field is educating students into a world in which A. afarensis is unknown in the laboratory and poorly represented in our textbooks. I'm not talking about new specimens, here, I'm talking about fossils that were found in the mid-1970's and monographed in 1982. Nor is this problem limited to early hominids. What proportion of people teaching about the modern human origins problem do you suppose have seen a cast of any "early modern" fossil other than Skhul 5?

One may object that this kind of teaching effort really isn't the same thing as primary research, and one would be right. But I am one who thinks that teaching is essential to my research. And I see it the same way as my high school band teacher: you can't have a good high school band without a good junior high and grade school band program. We can't train competent professionals without a strong undergraduate training, and the undergraduate training of our professional paleoanthropologists is a lot more varied than the graduate programs. Unless we strengthen the broad base of the field, we have little hope of strengthening its research depth.

And the fact is that primary paleoanthropological research is no longer the province of a few dozen professionals. The field is increasingly interdisciplinary, involving hundreds of people with no expertise in anatomy at all. The fossil record is an afterthought to many of these people, and it is our task to continue to show its relevance. We can't do this without the tools.

Righting the paleoanthropology ecosystem

In this sense, the current ecosystem in paleoanthropology is dysfunctional, and the problem of data access has had a negative impact on the quality of science in the field.

New specimens are a bottleneck in paleoanthropological research. The pace of research is positively limited by the rarity of fossils. This bottleneck has several consequences, including the complete absence of research on some topics that are poorly addressed by fossils, the high citation rates of initial announcements of fossil discoveries, and a funding structure that privileges field research leading to new discoveries. Because this bottleneck is so acute, a naive observer may confuse it for the entire field.

But except for this one part, paleoanthropology as a whole is a normal part of evolutionary biology. Like other parts of biology, ours is a comparative science in which all competent work depends on thorough procedural knowledge of evolutionary theory and factual knowledge of comparative samples, such as extant apes, humans, and other primates.

Even most paleoanthropologists do not themselves recognize the breadth of their field. There is a tendency to see the field as an unstable ecosystem, in which a very small number of primary producers (who find new sites and excavate and prepare fossils) support a huge number of consumers:

The classical ecological pyramid has a broad base of primary produces, with increasingly smaller numbers of secondary and tertiary consumers. Modern paleoanthropology, however, is like an inverted ecological pyramid. Armchair commentators abound. Actual producers of fossil data are increasingly rare. But boosting the number of producers is not feasible because so few professionals have the requisite specialized skills. Even fewer are qualified to teach them. The production of primary paleoanthropological data requires physical search, discovery, extraction, dating, contextualizing, preparation, photography, molding, analysis, writeup, and publication. The process now takes years of work by large coordinated teams (White 2000:289).

Tim White is one of the premier fieldworkers in the discipline, and it is not surprising that he should display a fossil-centric view of the field. But is it really true that we have nothing of value besides the fossils; that they are the only "product" we deal in? Are the rest of us really nothing more than jackals nipping at his heels?

I would propose an alternative model of our ecosystem. Rather than privileging the mere objects that fossils actually are, I would privilege the knowledge that we gain about human origins from them. Fossils are far from the only source of this knowledge. Indeed, all the knowledge that we obtain from fossils ultimately comes from comparing those ancient fragmentary remains with the more complete comparative samples of extant species, not to mention their rich genetic, behavioral, and soft-tissue morphological record. Even modelers and mathematicians, like myself, wring data out of fossils that ultimately do not inhere in the bones themselves but in their relationship with other specimens and species.

Left to itself, this work is steady and vegetative. We produce observations, comparisons, hypotheses, and ultimately evolutionary theory. We travel, we study specimens, we present our work to public audiences and to groups of our peers for scrutiny and comment. And this open process helps us to make our knowledge better. Without a single fossil, this body of theory would be left sorely wanting for accuracy, but it would exist nonetheless and would be nonetheless be the most valuable evidence for our evolution that we have. Just as Darwin's Descent of Man preceded all but the Neandertals, our work today precedes the next hundred years of fossil discoveries and awaits testing in light of them.

Those of us familiar with this kind of work tend to call it not "armchair commentating" but instead "critical thinking." We train our students in it, and work to make them knowledge producers as well. We socialize them that the best way to succeed in the real world is to share data and to play well with others. And we hope they won't get burned in their first encounter with a real predator.

Our field has its T. rex and the like. The activity of these top predators is spastic and episodic. When they roar, presenting us with a new precious relic, much of the field cowers and prays that we don't have to relearn everything from our graduate training that the new fossil makes obsolete. These carnivores devour comparative biology, for their fossils have little relevance outside its context. Newton called it "standing on the shoulders of giants," but sometimes it seems more like Spinal Tap dwarves trodding on a tiny Stonehenge.

Most of us recognize that new fossils are more than bludgeons to beat away the jackals. They are the only tests that many of our hypotheses can ever hope to have. And I don't see anything to be gained in classing part of our science as highly important and another part as irrelevant or worse. The fact is that all of us work with each other's data and conclusions. Some of us have established barriers to make that process more difficult. All of us deal with the same bottleneck of fossil evidence, but for many of us that bottleneck is a mere inconvenience, while for others it is the crook used to lever an entire career.

It is fitting and just that the acquisition of new fossils should be a high funding priority; if not the highest. This bottleneck prevents progress, and we should do anything in our power to alleviate it. But high funding for new field research does not imply that access should not be more open.

Closed access unnecessarily impedes progress in other areas that might otherwise be made. The present situation is unstable, and I see these critical problems:

1. The slow reporting of specimens and failure to share casts and data slows research on some important topics, limiting them to a small cadre of researchers. As an extreme example, no study of the energetics of the earliest bipeds is now possible, because many major specimens currently exist without having been reported, and none of the people working on them specialize in energetics. But more practically, only two years ago it was reported that only a single person had seen all of the then-extant evidence for Miocene hominids (Gibbons 2002). How can a field progress when so few people are in a position to review its data? If these people review each other's papers (because they are the only recognized experts), then how can any of us have confidence in their rigor?
2. Studies published on inaccessible fossils are not replicable. Suppose that someone publishes the energetics of the earliest bipeds, using measurements from new specimens. Certainly anyone reading this research can run the same measurements through the equations, but how can they be sure that the measurements are accurate or relevant, without examining the fossils or reconstructions themselves? This is the current situation with Sahelanthropus and its CT reconstruction, for instance: the publication exists, but is not replicable because access does not exist.
3. Students who can study inaccessible fossils can trade on this knowledge to promote themselves. Now, I don't think there's anything wrong with self-promotion; after all, jobs are scarce. But quality of access has increasingly become confused with quality of training. Ideally, a student will have both. Paleoanthropology is a comparative science, and extensive experience with comparative samples such as extant apes is needed for any competent research. To the extent that some students exploit the fossil bottleneck to leverage greater visibility, the quality of training expected of new hires is diminished.
4. Casts are generally inaccessible. Despite the current ubiquity of CT scanning of fossils and creation of stereolith casts, even these cannot be purchased. All of the problems above would be less pressing if there were some assurance that eventually all qualified researchers would have access to casts and scans. But when an initial description, peer-reviewed by only friendly colleagues, stands for decades without reanalysis because of the lack of access, a mistake that shouldn't occupy more than five pages in a dissertation ultimately bends the course of the discipline for years.
5. Most important, public support for our discipline depends on its perception in a country where a majority of people don't believe that humans evolved. Those arrayed against us argue that new fossils are hidden away and not studied by the scientific process of peer review. They argue that many human fossils are manufactured, and that there are no guarantees that they are not the product of a small group of scientists with an anti-creationist agenda. As long as we do not open access to the primary evidence of human evolution, these criticisms are not only damaging, as far as the nonspecialist public is concerned they are also valid. We do nothing but damage the profession when we fail to share the products of our research as freely as possible, not only with each other, but with humanity.

Will the policy work?

To the extent that new grants will make data more available, will encourage the spread of CT scans of fossils, and will help to spread photos and observations of new discoveries to the public, I think the data access policy will be helpful. I think there may be nothing to be done about the availability of casts, as long as museums control their reproduction. I respect and value the work of all museums who conserve fossil remains, but they are not set up for widespread public sale of fossil replicas. And a commercial solution will have little incentive to reproduce rare fossils that are not part of the central story of evolution. In my opinion, the most important aspect of data access is to increase the effectiveness of peer review and to guarantee replicability of research. For these goals, I think the new policy has a maximal chance of success.

Of course the real test of the value of the new policy is to see whether grants start to be declined on the basis of data access restrictions. As I read it, this new policy basically sets the clock at zero. There is no condition that specifies that previously funded work should be made public, and no effective means of pressure to create a situation favoring the sharing of old data and specimens. There are now specimens that have been out of the ground for thirty years that cannot be studied. There are hominid specimens that have been out of the ground for ten years or longer that remain undescribed. This situation will not change.

If the new policy is to be a success, then the proof of it cannot wait for ten to thirty years. It needs teeth. It needs two or three high-profile grants to be declined because of data access issues. And it needs those cases to be made public, so that everyone can have confidence in the openness of the process. This doesn't mean that the names of the applicants and their alleged sharing violations should be dragged through the press. It does mean that NSF should publish the number of grants (and their proposed funding amounts) declined for failings in the data access plan.

But more importantly, it needs replication among other granting agencies. A large set of molecular anthropologists have just shown their willingness to completely forego public funding, in order to maintain certain kinds of controls (in this case ethical ones) over their research (See Genographic Project). Will paleoanthropologists do the same? It would be helpful if some of the important private foundations, such as the National Geographic Society, the Leakey Foundation, Wenner-Gren, and others would establish data access provisions also.

Another helpful idea would be for one of these foundations to establish a data bank. Notice what is missing in the NSF policy is any discussion of a data archive. Other areas of NSF and NIH have such archives and maintain policies of mandatory deposition of data. This is most prominent for genetics, with the GenBank archive and journal publication of most results conditional on mandatory submission of data to the archive. Thus, there is no logical impediment to the creation of such a resource by a federal agency. The fact that they chose not to implement such a policy, I find significant.

Among other considerations, this choice probably depended upon discussions with museums and governmental agencies in other countries, who are the conservators and permit-granters for most fossil research. There are good reasons for the U.S. government not to compromise the activities of international museums by making public images, casts, and CT data of their fossils. On the other hand, much money and effort could be saved if such an archive were available, and it would increase the quality of published science by increasing sample sizes, consistency of measurements and estimates. It would also help conserve the fossils by protecting them from the investigators themselves. Non-governmental agencies are probably the best sources for such a centralized archive because they may have more ability to work directly with multinational sources to broker a solution. In my opinion, such an archive would be more important and would have a more positive scientific effect than five years of ordinary research funding for such an organization.

Not so long ago, Wenner-Gren was the principal international sponsor of cast production. There is no logical reason why it or some other foundation could not be again.

Final thoughts

This turned into more of an essay than I really intended, but it is a subject that I think all of us are strongly invested in. The issues at stake are what kind of science we want to have, and how do we want to limit access to its findings. I believe that our research should be as public as possible. I think that openness leads to better science, and I think that restrictions to access only make us suffer at the hands of those who wish us ill. I hope that this new policy will lead to more conversations about the future of the field. I will be most pleased if I can play some role in moving those conversations forward.

References:

Gibbons A. 2002. Glasnost for hominids: seeking access to fossils. Science 297:1464-1468.

White TD. 2000. A view on the science: physical anthropology at the millennium. Am J Phys Anthropol 113:287-292.

BBC News story

New Scientist story

Information about the project from the Waitt Family Foundation

National Geographic Genographic Project site

As reported in the news stories above, the Genographic Project is a collaborative research undertaking by the National Geographic Society, the Waitt Family Foundation, IBM, and a number of independent research labs around the world. The goal of the project is to sample over 100,000 individuals from diverse global populations in order to achieve a fine-grained understanding of migrations recent in human prehistory.

MSNBC is reporting that the project is funded to the tune of 40 million dollars. For some perspective, this would fund all the research projects under the Physical Anthropology section of NSF for roughly 15 years.

The project leader is Spencer Wells. Wells is best known for his documentary program, "Journey of Man," in which he trekked around the world to illustrate the evidence for human migrations from the Y chromosome. The most memorable scene is one in which he corners a bewildered man in a Kazakh village to tell him he has a sequence inferred to be ancestral to a billion Asians. The poor man thought that Wells had come to tell him he was going to die. In a nutshell, this is the effect that anthropological genetic work has come to have on indigenous peoples around the world.

The current project is audacious in its scope. It bears clear echoes of an earlier proposed project, called the Human Genome Diversity Project, but with even more extensive sample sizes. If it met all of its goals, the Genographic Project would clarify the course of human movements and population growth since the development of agriculture 10,000 years ago, and possibly even earlier.

Who will do the work?

Here's what Wells says in the
FAQ at the Waitt Foundation site:

We assembled a team of top human population geneticists from around the world - 10 principal investigators focusing on indigenous peoples around the world, plus one focusing on ancient DNA, from the USA, Brazil, UK, France, Lebanon, South Africa, Russia, India, China and Australia. They are all experts in their respective fields, very thoughtful scientists, and passionate about the work they do. I'm lucky to be collaborating with them - it's like having the "dream team" of human population genetics.

It is fairly unclear to me just what IBM is going to contribute aside from bioinformatics. I don't know, for example, if they have someone who can model population movement to generate simulated samples to test migration hypotheses against. I think it is unlikely that they have anyone who is modeling natural selection, which is the force most likely to affect the geographic distribution of many human genes, the Y chromosome included.

Should you send in your DNA?

You may be thinking, "It sounds great; I just wish I could participate myself!" Well, if you want to, you can! For only $99.95, you can purchase a Genographic Participation Kit from the National Geographic Store:

With a simple and painless cheek swab you can sample your own DNA. You'll submit the sample through our secure, private, and completely anonymous system, then log on to the project Web site to track your personal results online.

This is not a genealogy test and you won't learn about your great grandparents. You will learn, however, of your deep ancestry, the ancient genetic journeys and physical travels of your distant relatives.

But is it safe? Won't they take your DNA to make tiny clones of you and fetal pig implant organs to support them?

Here is what National Geographic says in their
FAQ about the DNA sequences sent in by people who purchase their "kits":

We will keep your cheek scraping sample only for the Genographic Project. Your sample will not be used for any other purpose without your written permission. The genetic tests we will perform are designed only to research early human origins and movements. The tests do not tell us anything about your health, or about any health problems you (or your family) may have. This is an anthropological study only. Unless you instruct us otherwise, your cells will be destroyed at the conclusion of the Project....During the project, you will have the opportunity to contact Family Tree DNA, the company licensed to perform testing for Genographic Project participants, to request follow up testing if you choose. Unless you do so before the conclusion of our project, your cells will be destroyed and will not be available for follow up testing.

Sounds like a great marketing opportunity. Which isn't, I think, exactly what anthropologists ought to be promoting.

My advice is, don't send in a swab. Not to say I don't trust the National Geographic Society; in fact I think that this part of the project is pretty innocuous. My main concern is that $100 is a lot to pay for something that is very likely to tell you what you already know: "Gee, I come from Europe, and my ancestors got there 15,000 years ago from the Near East." Or something that is very likely to be patently false: "Gee, I have a sequence found in Greece and also found in one village in northwestern Pakistan. My ancestors must have ridden with Alexander the Great!" Please don't waste your money. It is much more useful to learn about your grandparents.

Of course, the kit does come with the video featuring Spencer Wells. If you're into that kind of thing. He does have a high Q-rating.

If anyone does order these, let me know. I would really like to be able to report on the contents, and especially the kind of results that they send. I am imagining this is only a step removed from those genealogy companies that send you your "family crest" and a story to accompany it, but I would be happy to be proved wrong.

Is this the Human Genome Diversity Project?

The short answer is, "Not exactly, but it comes from some of the same people who brought us that one."

Three things set the project apart, as I understand it. One is the apparent lack of public funding sources. This is in part a function of increased efficiency of genetic research: this can be done much more cheaply today than would have been possible in 1995. Also, the National Geographic Society has done very well for itself recently by pushing projects that generate publicity like this one. In a way, it is a perfect match, since it is literally "geographic" and since it involves the possibility of direct public participation. Of course the lack of public funding means that the project is not subject to public oversight, which places it beyond some of the critics of the HGDP. To me, this is a matter of some concern. The advisory board of the project is chaired by Luca Cavalli-Sforza (Stanford University) who was the main figure behind the HGDP.

Second, there is no guarantee of complete coverage of indigenous peoples. With the HGDP, there was the ostensible goal of sampling intensively among language families and other ways of determining "ancient" groups that were worth sampling. Merritt Ruhlen (Stanford University) was one of the principal linguists advocating this approach for the HGDP; he is on the advisory board of this project, so there may be some attempt to do a similar thing. The New Scientist story says, "Collecting genetic information from relatively isolated populations will be a priority because this will provide the clearest picture of humankind's evolutionary past." Of course it was this kind of logic that got the HGDP in trouble in the first place. At this point, the project does not explicitly describe how such sampling will be done, so I assume that its sample of indigenous people will include mainly those groups who have participated in such research before.

Third, there is the ostensible limit of data acquisition to Y chromosome and mtDNA markers related to migration history. This may also be a consequence of technological change since the mid-1990's. Today, researchers can design "gene chips" to very rapidly type an individual's genome for particular markers of interest, without going through the effort of obtaining an entire sequence. This is very efficient and low in cost, and I would expect that this is the technology they are using on most of the samples, including all those from the DNA kits.

On the other hand, this methodology throws away much of the interesting data on diversity. Going without complete sequencing introduces an ascertainment bias that can make it difficult to determine interesting demographic characteristics about the population. This may make it more challenging to determine whether the population expanded at particular times in the past, for example. These biases may partially be overcome by sequencing thousands of individuals, so there is clearly a strategy at work here. But I would be very surprised if a large subset of the individuals -- the ones for which a larger tissue sample is available, or for whom a cell line has been produced -- were not subjected to sequencing of long genomic regions. I expect there will be microsatellite and SNP data coming out of these samples from other genomic regions in addition to the Y and mtDNA analyses.

With these caveats, the Genographic Project clearly carries on the legacy of the HGDP. This means that we should consider the criticisms of the HGDP to see if they apply to this project. The most important criticism was the human rights issue, and in particular the opinion that the human subjects had not been sufficiently protected. In large part this was because informed consent from members of indigenous groups might never have been possible without undergoing specialized training in genetics and medicine, and because the project therefore depended upon approval from "tribal elders" or other individuals chosen to speak for their groups. This procedure was viewed by many critics as fundamentally outside the normal protections of liberal democracies, and such criticisms were never satisfactorily answered.

But this was far from the only criticism of the HGDP, and there were a number of scientific issues that questioned the fundamental worth of the project. One criticism was the sampling strategy. The idea of capturing DNA from small tribes and linguistic groups that are dwindling in numbers doesn't seem like such a bad one at first glance. But the fact is that the changes in process in such groups are not biological ones, they are cultural ones. For the most part, although there are exceptions, the people are not becoming extinct, nor are their genes. They are just adopting new lifestyles and joining new groups.

This cultural change certainly complicates the attempt to find patterns of ancient history and migrations. But sampling the dwindling small groups speaking languages that are nearly gone probably won't help. These groups themselves were the product of similar movements and group losses in the past. To be sure, some of these movements are precisely those that the Genographic Project is attempting to recover. But sampling groups rather than locations confounds the effects of cultural and geographic factors leading to human variation. A better sampling strategy would be designed around geographic coordinates instead of linguistic ones.

The issue of sampling strategy is related to the separate issue of analytical method. There was never a clear methodology that satisfied critics that the results would be valid. The sampling strategy that promoted groups or language families as fundamental elements of analysis invites a cluster or dendrographic-based analytical method. Since human populations do not fit a tree well, this statistical method is guaranteed to mislead about relationships. But geography-based methods, such as Cavalli-Sforza's famous PC plots of genetic variation over space, also yield misleading results.

Today, most analyses of Y chromosome and mtDNA variation use "founder analysis," which is an attempt to delinate the earliest movement of people to a region based on the most recent common genetic ancestors found in both the region and its presumed source. This kind of analysis is also limited in the information that it can generate, and its results are also subject to challenges. Especially, the method is sensitive to the age and distribution of discrete markers (the very markers that this research is designed to look for), which really cannot be aged very precisely, and which may have different distributions today than at the relevant time in the past.

And of course, there is the overarching assumption of no selection, which for the Y chromosome and mtDNA has become increasingly problematic.

Will companies be profiting from this research?

Apparently for the public kits, there will be no research other than the Y chromosome and mtDNA markers useful for a narrow study of migration history.

For the larger samples acquired as part of the "diversity sampling," no such guarantees have been given. Nor should we expect to see any such guarantees, because these samples include thousands of tissue samples from people that have already been taken with no conditions attached.

The news stories about the Genographic Project say that commercialization is not the goal. For example, New Scientist
reports:

In the 1990s, Luca Cavalli-Sforza at Stanford University in California, US, attempted to set up an even more ambitious project called the Human Genome Diversity Project, to map genetic diversity around the world. But it foundered after opposition from groups representing indigenous peoples, who saw it as an attempt by western companies to profit from their genes.

IBM says the Genographic Project is different as no medical studies will be done, and none of the data will be commercialised. An independent advisory board, including indigenous advocate Tammy Williams of Cape York, Australia, will oversee sampling and research.

I think this is very misleading. For the research to be minimally useful, it must include markers beyond those on the Y chromosome and mtDNA. Although it has usually been argued otherwise, the fact is that single loci cannot give good information about migration. The evolution of any single locus is stochastic, so that the overwhelming majority of information that it might hold about migration depends on how it compares to other genetic loci. But even excluding the obvious necessity to look at other areas of the genome, both the Y chromosome and mtDNA are of increasing biomedical interest. Several recent research articles have examined the possibility that normal geographic variants of the mtDNA are associated with increased disease risk. So regardless of the intentions of the project, any public information resulting from the project will be applied in biomedical contexts.

The question really is whether anyone will profit from it. For this, a purely private research enterprise can offer nothing but its word, and that of its advisory board. I don't have any reason to think that these people have any motives to profit directly from biomedical information, but I would rather have some very solid guarantees about the way information will be used. Again, I do not doubt their good intentions, but I would be cautious. At this stage, after the project has just been announced, that information has not yet been provided to the public. The participant with the most to lose is the National Geographic Society, which risks squandering much of the goodwill it has in developing nations if it fails to make explicit how research subjects will be protected.

What unforeseen consequences will this research have?

Of course if I can foresee them, then they are by definition foreseen rather than unforeseen! Nevertheless, there are some consequences that you are not going to hear anyone talking about.

Here's something that won't be reported anywhere but seems fairly obvious. If National Geographic and IBM are working with around ten research centers on a project involving 100,000 genetic samples, then the scale of anthropological genetics has irreversibly changed. Labs that are not now capable of dealing with samples of thousands of individuals fairly quickly are in danger of being shut out of empirical research entirely.

That is not to say that smaller projects are irrelevant. Ancient DNA research will never involve more than a few individuals at a time, and the study of genetic structure within small-scale human societies and primate groups will never involve thousands of samples. But the point is coming, if we have not already reached it, when these small projects will be tackled more easily by graduate students at a large lab than by independent scientists with a small lab. It makes little sense to maintain small labs when the economy of scale on DNA sequencing makes it much cheaper to obtain more data from larger setups. And as DNA data becomes cheaper, more reviewers will expect that things are verified by resequencing; so that most small labs may end up sending things out for this reason anyway. Only if technology ultimately provides small, portable solutions to yield sequences in the field will the balance shift to smaller setups. But then one hardly needs to be a molecular specialist to get DNA data, especially if one is using the same computer programs for analysis anyway.

What we will see with the project is probably not greatly different than we would have seen without it. The findings of the project will appear to confirm some arbitrary number of interesting historical population movements. We have already seen this with the Phoenician research project led by Wells, Brian Sykes' research on early Europeans, the "Genghis Khan" sequence, the Cohanim and Lemba connection, and any number of others. Together, they will create an impressive perception of progress toward understanding human history. Individually, each of them will be a flimsy case based on weak evidence.

But they will make for some interesting National Geographic specials.

One study reported at the meetings brought to mind a growing literature on the sophistication of Pliocene archaeological assemblages, grouped as "Oldowan" or "pre-Oldowan." Most Oldowan tools lack a standardized form, and the assemblages are dominated by flakes, core tools with one sharp edge or point, and unmodified manuports or hammerstones. The lack of standardized tools (such as handaxes) lead easily to the conclusion that Oldowan technical assemblages are simple, so that anyone could make one who could chip rock.

But a number of recent sources illustrate that this perception isn't accurate. The Oldowan encompasses a variation of manufacturing complexity and other elements, but cannot be said to be merely rocks that have been carried or bashed together. The most interesting studies have examined the issue of raw material exploitation and the actual processes used to reduce stone into useful tools.

David Braun gave a presentation that relates to this topic at the 2005 Paleoanthropology Society meetings. In an analysis of the lithic remains at the Kanjera South site (Kenya), the group found that the intensity of the reduction sequence varied with source material.

Kanjera South, dating to around 2.2 million years, preserves one of the largest early records of material culture. According to Plummer et al. (2001:810):

Hominins at Kanjera South utilized a wider variety of lithic raw materials than found at most Oldowan sites, some of which (chert, quartz, quartzite) must have been transported from outside the immediate vicinity of the deposits since they are not present in the local clast population.

In the study by Braun et al. (2005), fine-grained quartzite, which had a nearest source outcrop a long distance away from the site, was reduced more intensively than locally available rock. This reduction involved more flakes taken per core, and occasional retouch. They hypothesized that this difference was due to the hardness of the quartzite and its ability to hold an edge, which makes tools made on quartzite potentially more useful. The hominids apparently recognized these qualities in the raw materials and exploited the quartzite. We can probably infer that the transport distance was a result of this recognition as well.

Stout and colleagues (2005) report on the use of raw materials at Gona, which is at present the earliest site at which stone tools are found, dating to around 2.6 million years. This study sampled unmodified stone taken from conglomerates that represent natural accumulations. If stone were taken merely from local sources without selectivity, the modified stone assemblages from the site would be expected to match these conglomerates. As described by Stout et al. (2005:366-367), the past understanding of Oldowan toolmakers has suggested that they may not have exhibited a clear understanding of the technical qualities of their raw materials:

At Koobi Fora, the high frequency of basalt in local conglomerates (i.e. ancient stream channels) is closely mirrored by its predominance in the artifact assemblages (Toth, 1985; Schick, 1987; Isaac et al., 1997). Although quartz, chert and glassy volcanics are "reasonably easily available" in the conglomerates, these material types do not appear to have been specifically selected for (Isaac et al., 1997:268).

This paper gives an excellent review of the history of raw material choice. In brief, the literature review indicates that early toolmakers at Koobi Fora may have exercised some degree of selectivity by avoiding certain kinds of stone (vesicular lavas and weathered cobbles). By Olduvai Bed II (after 1.7 million years ago), some toolmakers were clearly going out of their way to acquire certain stone materials:

The increased use of chert at Olduvai around 1.65 Myr was clearly occasioned by the temporary exposure of rich sources of this material by the retreating waters of the paleo-lake (Hay 1976). Hominid toolmakers at this time readily appreciated the superior flaking properties of chert, leading to the formation of the earliest known special-purpose quarry site at MNK CFS (Stiles et al. 1974; Stiles 1998) (Stout et al. 2005:367).

So when did this technical knowledge really originate? Was it a skill that developed gradually over the million years between Gona and Olduvai Bed II?

Stout and colleagues find that the materials used for tools at Gona do not match the natural cobbles that were avaiable in a number of respects. In essence, the hominids ignored many kinds of stone that had fracture patterns or other properties that made them less suitable as raw materials. They (2005:368) state the conclusion most clearly at the end of their introduction:

The strong pattern of raw material selection seen at Gona demonstrates that low levels of selectivity are not universal in the Oldowan. The fact that the assemblages from Gona are the oldest known in the world also argues against an overarching temporal trend toward increasing selectivity within the Oldowan.

The flaking skill of early hominids is the subject of a paper by Roche and colleagues (1999) in Science. At the two localities of Lokalalei 1 and 2C, both dating to 2.34 million years ago on the west shore of Lake Turkana, this study accomplished refits of stone flakes and cores to directly inspect the reduction sequence. They found that this sequence was quite complicated in many of the instances of manufacture at the two localities:

At LA2C, the dominant reduction sequence consists of these more reduced cores. Unidirectional or multidirectional removals are flaked on a single debitage surface, from natural or prepared platforms. This knapping system allows the production of a long series of removals without changing the volumetric structure of the core. The repeated application by the knappers of the same technical principles to a whole series of cores, and during the reduction of each core, indicates an elaborate debitage scheme, implying motor precision and coordination. These principles include an appreciation of the quality of the collected raw materials, a judicious exploitation of the natural morphology of the blocks and the maintenance of adequate flaking angles during the entire debitage sequence. These show that the notion of production was already assimilated by a group of hominids in this particular area. This notion is integrated within a real debitage strategy, here well-mastered and unprecedented for this time period (Roche et al. 1999:59).

Upon this description and analysis of the debitage, the study bases the following conclusion:

Overall simplicity and similarities between assemblages are the two main arguments recently put forward to substantiate a technological stasis hypothesis between the 2.6 and 1.6 Myr time periods, and to merge the related assemblages into a single vast 'Oldowan' technocomplex. The stasis hypothesis cannot hold out against the detailed technological analysis of the LA2C lithic assemblage. There can be no doubt about the elaborate character of the LA2C debitage schemes, which are far more sophisticated than at any other Pliocene site (Roche et al. 1999:59).

In total, these studies attest to the technological expertise of some early toolmakers. It is perhaps important to remember that the archaeological record should be expected to reflect an average technical competence much less than that possible (or possibly even typical) of early hominids. For example, every instance of stone flaking by an expert toolmaker certainly was preceded by novice flaking by the same individual earlier in his life. Considering the early mortality evidenced by australopithecine (and early human) remains, many potential toolmakers must have died before reaching proficiency. And toolmaking expertise was probably not uniformly distributed among social groups, so that some individuals had the opportunity to learn by observation some relatively complex reduction sequences and material properties, while others would have had to acquire the same knowledge by long trial and error, if at all.

In this framework, later changes in the archaeological record may reflect social and life history changes as much as ecological changes or brain evolution. Toolmaking intensifies later in the Oldowan, raw material selectivity increases, and some standard forms and more technically sophisticated artifacts, such as bifaces, routinely occur. The increased mental complexity of Pleistocene hominids may be a cause, but the behavioral changes have no obvious anatomical, life history, or other correlate. The apparent sophistication of the earliest toolmakers argue against the hypothesis that the later Oldowan represents a fundamentally more intelligent hominid species, with specialized adaptations to tool manufacture lacking in earlier hominids. Instead, I would suggest that later Oldowan hominids had on average a greater retention of cultural knowledge as a function of more stable groups and a longer life history than australopithecines. This shift might or might not have been accompanied by an increase in the capacity to learn, as might be evidenced by a greater length of the juvenile growth period.

From a conceptual perspective, there is necessarily a real limit on the standardization that is possible within any "technocomplex," and particularly one that spans a million years or longer. The kind of information that is ultimately transmissible (either horizontally or vertically) among hominids over this extreme time period is of the most rarified form imaginable. A model of early archaeological assemblages that incorporated the probable manner and form of information transfer among groups (along with their global demography) would predict both a global lack of complexity and a great extent of variability within that simple context. The evidence of technical skills therefore may inform directly about the demography of groups and their relationships with each other. The extent to which such variability may be consistent with cultural diffentiation among groups in other primate species (such as chimpanzees) I take to be a testable hypothesis.

References:

Most references within the featured articles below:

Plummer T, Ferraro J, Ditchfield P, Bishop L, Potts R. 2001. Late Pliocene Oldowan excavations at Kanjera South, Kenya. Antiquity 75:809-810.

Roche H, Delagnes A, Burgal JP, Feibel C, Kibunjia M, Mourre V, Texler PJ. 1999. Early hominid stone tool production and technical skill 2.34 Myr ago in West Turkana, Kenya. Science 399:57-60.

Stout D, Quade J, Semaw S, Rogers MJ, Levin NE. 2005. Raw material selectivity of the earliest stone toolmakers at Gona, Afar, Ethiopia. J Hum Evol 48:365-380.

...wherein I disavow any suggestion that LB1 or any of the Flores fossils are australopithecines.

Along with four of the best anatomists that I know, I had the opportunity to see detailed pictures of the LB1 postcrania.

The specimen is beyond any doubt or question pathological.

This is very clearly shown by many details that are either not depicted or are not clear in the photos in the original Nature paper. It is not my place to provide more information about these details; my understanding is that a thorough presentation of them is forthcoming. I will say that this specimen has morphological characters that would indicate severe developmental abnormalities even if the skull had never been found. This is in no way a close call.

It remains to be shown whether the pathology in the specimen explains its brain size. Examination of the endocast shows features that are highly unusual. It would seem to me remarkable if the occurrence of these features was purely coincidental with the postcranial and cranial pathology.

My suggestion of australopithecine affinity was based strongly on the anatomy of the pelvis and the size of the brain. Since the specimen is pathological, I no longer trust that either feature characterized the Flores population rather than this single individual.

I also saw the other skeletal specimens. These have not been described, so I will not talk about them, although their existence has been widely cited as evidence that LB1 was typical of its population. A look at the rest of the sample lends little credence to this idea.

The bottom line is that this specimen cannot be assumed to be representative of the population from which it came. Any interpretation that starts with the assumption that LB1 is normal should be viewed with extreme skepticism.

One of the highlights of the scientific program of the meetings was Fred Spoor's paper on the new cranial vault from Ileret, KNM-ER 42700. It is difficult to describe without a picture (which I don't have), but at a glance, the skull is very similar to another small, subadult skull that may be similar in geological age, Mojokerto. From the abstract:

Renewed fieldwork at Ileret, east of Lake Turkana, resulted in the discovery of a well-preserved calvaria KNM-ER 42700). The specimen derives from strata dated to an age between 1.5 and 1.6 Ma. The state of closure of the sutures, and of the spheno-occipital synchondrosis in particular, suggests that the individual was a subadult or young adult at death. Initial assessment of KNM-ER 42700 indicates affinities with Homo erectus (including H. ergaster). However, in its absolute vault dimensions it is closer to specimens assigned to H. habilis than to the traditional hypodigm of H. erectus. It also lacks some characteristic H. erectus features, including well-developed supraorbital tori and supratoral hollowing (Spoor et al. 2005:201).

Spoor did a very nice job presenting the anatomy of the skull and its metric comparisons with the known erectine and habiline sample. With a date of around 1.55 million years, it overlaps temporally with African early humans, and also potentially with habilines (although it would likely be the latest example of these, it would not be by too much).

This overlap is important to consider because of the very small size of the specimen. Spoor reported that its endocranial volume is estimated as 691 ml. Depending on its chronological age, the brain may not have quite reached its adult size; although Spoor argued for a older age estimate (and therefore smaller adult brain), he estimated that at a maximum, the brain may have reached 720 ml.

Anywhere in this range, around 700 ml, makes this specimen the smallest of the African erectines. It is in the size range of the Dmanisi erectines. But it is also within the size range of the habilines (KNM-ER 1470 has a volume of 752 ml), and unlike Dmanisi, this specimen has no face to set it apart from a large habiline. So its vault features and measurements must be examined to make clear what kind of hominid it is.

The specimen shares several nonmetric features with erectines, including a frontal sagittal keel, a high petrotympanic angle, and a flattened profile of the parietals in lateral profile. One of the most interesting aspects of Spoor's talk was that he found no compelling metric differences that would distinguish between the habilines and erectines. Although the habilines were consistently smaller in their measurements, they had basically the same relation of cranial measurements. Personally, I would say that disregarding the face, some of the habiline vaults are really similar in shape to erectines, expecially OH 16 and KNM-ER 1813.

Spoor argued on the basis of his bivariate metric comparisons that vault thickness, occipital curvature, and supraorbital torus size are not good H. erectus characters, and instead he accentuates nonmetric characters like keeling. To me, this is another dent in our understanding of what drove the evolution of speciation in early Homo.

References:

Spoor F, Leakey MG, Leakey LN. 2005. A comparative analysis of the KNM-ER 42700 hominin calvaria from Ileret (Kenya). Am J Phys Anthrol Supplement 40:200-201.

A number of readers have been asking what the deal is with the "Goliath" specimen discussed by Lee Berger (and reconstructed by him and Steve Churchill) in the National Geographic program, "Searching for the Ultimate Survivor." The femoral fragment found by Berger himself was apparently from Hoedjiespunt, around 300,000 years old. The specimen itself has not yet been reported.

The reconstruction shown on the program is based on the Kabwe cranial and postcranial remains. The Kabwe skull is the best known specimen from the site, but there are also another maxilla and postcrania representing three or more individuals. One (E719) of two innominate bones (os coxae) and one femur (E 907) are quite large, although they probably do not belong to the same individual as the skull (Wolpoff 1999). I would assume that the full-body reconstruction on the program used these to estimate and model a very large body size.

Kabwe (E 686) cranium, lateral view

"Ultimate Survivor" discusses the "Goliaths" living in Europe, which means that they are talking about Homo heidelbergensis. There is a clear division of opinion about this species in the field. Some researchers, myself included, think it is a superfluous name that doesn't describe a real ancient reproductive community, and so we tend not to use it at all. But among those who believe that H. heidelbergensis is valid, there are essentially two viewpoints. Some would limit its application to European fossils only, which is where the type specimen, the Mauer mandible, was found. Others would apply H. heidelbergensis much more broadly to essentially all Middle Pleistocene European and African fossils, and some specimens from China as well. In this usage, H. heidelbergensis is basically inclusive of all specimens that have been called "archaic Homo sapiens, on the basis of enlarged brain size compared to earlier humans combined with the lack of most of the distinctive features of Neandertals.

So the question is, were Middle Pleistocene humans a race of giants? There is no question that there were some individuals with large mass. The large Kabwe specimen is one; the individual represented by the very broad Sima de los Huesos pelvis is another -- probably the most massive individual in the Middle Pleistocene record. These large specimens had masses upward of 80 to 90 kg, and are more massive than any Early Pleistocene humans, who averaged only between 60 and 70 kg.

But these large specimens provide only a small part of the overall picture of body size. The multiple skeletal remains from the single site of Kabwe alone indicate a range of body sizes. Not only in Africa but elsewhere there is clear evidence of a mixture of smaller and larger specimens. As shown by Ruff et al. (1997), this range of variation is not more extensive than in living human populations. Part of the variation is related to climate (higher latitude populations are more massive), part is probably due to sex (the largest specimens are undoubtedly males, meaning that there must have been a range of smaller female individuals also). But whetever the sources of variation they were substantial and did not greatly change after the beginning of the Middle Pleistocene.

Body mass vs. time, from Ruff et al. 1997. Note the large body sizes of a few individuals after 600,000 years ago, and the subsequent stasis.

The large body size of some Middle Pleistocene fossil individuals, as well as the Late Pleistocene Neandertals, has led to considerable speculation about their adaptation. Much of this centers around the assertion that early humans were greatly powerful and muscular compared to recent people. This assertion is supported by the increased shaft thickness of the long bones of many early humans. These shafts generally have quite thick cortical bone and reduced medullary cavities; not only compared to recent people but also to early Holocene skeletal remains. Since early farmers certainly worked hard and did not lead lives of luxury, the archaic humans stand out as robust.

Perhaps world-class athletes -- at least those before the widespread use of anabolic steroids -- offer a closer approximation to the body build and mass of archaic Homo sapiens. Tanner (1964) reported on the mass and proportions of athletes in the 1958 British Empire and Commonwealth Games in Cardiff, and the 1960 Olympic Games in Rome. The competitors who most closely approximate the build of Neanderthals were the throwers, weight-lifters and wrestlers. Some of these men weighed as much as 91 kg, even though they were narrower across the hips than most Neanderthals. Using a larger, more muscular living human reference sample could produce even larger and perhaps more realistic body-mass estimates (Kappelman 1997:127).

Of course, I weigh as much as 91 kg, and without making any claims about how narrow I am at the hips, my body proportions are not especially Neandertal-like. I doubt that an Olympic weightlifter would make a better model of a Neandertal than I do. The specialized muscle building regimen necessary for performance athletes is not part of the standard mode of human growth and development. Almost certainly a Neandertal with the lean body mass of a performance athlete would be at a huge energetic disadvantage without a substantial fat store, since the availability of food for hunter-gatherers is neither uniform nor uninterrupted. Today's hunter-gatherers are not particularly muscle-bound -- although they are strong and lean, they are not "cut," and when healthy they have noticeable fat stores. So while I would not suggest that archaic humans were by any means portly, I would suggest that if they had high mass estimates, then a substantial part of that must be modeled as fat rather than pure muscle.

The relatively rapid decrease in modern human body mass during the past 90,000 yr is a dramatic contrast to the large body mass of archaic Homo during the preceding two million years. What selection pressures could have resulted in both smaller body mass and larger relative brain size in modern humans? These changes do not seem to be tightly linked to technological innovation, although the less sturdily constructed skeleton implicates different behaviours, suggesting that modern humans adopted increasingly less active lifestyles. Now, rather than focusing solely on models that favour selection for ever-larger brains, we should examine the possibility that the pattern in modern humans was driven by selection for smaller bodies, perhaps favoured by a social structure that relied on more cooperative foraging and better communication skills (Kappelman 1997:127).

We can add an additional possibility: that increased dietary constraints resulted from population size increases, and that Late Pleistocene humans decreased in body size as a secular trend. It is almost certainly true that a secular trend toward lower mass occurred during the Holocene with the advent of agricultural subsistence. The lower protein and other nutritional content of early agricultural diets combined with the increased incidence of epidemic diseases during childhood both resulted in smaller adult body sizes. Since the industrial revolution, this secular trend has reversed in societies with increasingly Westernized diets.

Moreover evidence from the past 40 years has indicated that the body size differences among human populations have begun to decrease as nutrition has improved in developing nations:

Current analyses indicate that body mass varies inversely with mean annual temperature in males (r=-0.27, P

This means that mass is approaching the same situation as stature, where any prediction of Allen's rule appears to be partly cancelled by the tall present-day stature of Northern Europeans, which is in large part a recent, post-industrial development.

So in my view, the body size of Middle Pleistocene humans was influenced by not only their activity pattern and adaptation to locomotion, but also their diet and body composition. They cannot be described as giants, or "Goliaths" compared to recent humans. In particular, the mean body sizes of people living today in industrialized societies are very similar to those of Middle Pleistocene humans.

The body size in Western countries today is a function of genes acting in an environment with nearly maximal nutrition and minimal disease and parasite load. In archaic humans, evidence suggests a diet very high in animal protein, and the small population sizes and low densities would likely maintain a low rate of acute communicable diseases and parasites. Unlike recent hunter-gatherers who occupy lands historically unused by agriculturalists, archaic humans could live and forage in the most productive habitats with the most abundant food sources. In short, archaic humans were probably healthier and better-fed than their later Upper Paleolithic and Holocene counterparts.

The Middle Pleistocene saw the most extensive increases in human brain sizes during all of human evolution. It is interesting to consider the role of diet and population density in creating the circumstances during which this increase happened.

References:

Kappelman J. 1997. They might be giants. Nature 387:126-127.

Katzmarzyk PT and Leonard WR. 1998. Climatic influences on human body size and proportions: ecological adaptations and secular trends. Am J Phys Anthropol 106(4):483-503.

Ruff CB, Trinkaus E, Holliday TW. 1997. Body mass and encephalization in Pleistocene Homo. Nature 387:173-176.

Wolpoff MH. 1999. Paleoanthropology. McGraw-Hill, New York.

One of the features of the National Geographic (April 2005) article on Dmanisi is the discussion of the necessity of other people to aid and care for the old and infirm. The skull D3444 is an old adult individual, with no teeth remaining and the alveolar surfaces of the jaws nearly completely resorbed. This means that the individual lived without functional teeth for a period of time extending well beyond a year, and possibly to several years.

The article quotes some of the researchers working on the fossils about the importance of the condition of this individual:

In the survival of the old man, "we're looking at perhaps the first sign of truly human behavior in one of our ancestors," says [David] Lordkipanidze. It could be a glimpse of a new level of planning and sharing, adds Philip Rightmire, an anthropologist at Binghamton University in New York State who is one the Dmanisi research team. "Seeing this at the very dawn of Homo, our own genus," he says, "may be the most exciting thing of all." (Fischman 2005:19)

The idea is that a person who could not chew could not survive on his or her own. So he or she (I'm sticking to "he or she" until I see more information about D3444; it is more robust than the two females, but not extremely so) needed help from other people, in this story. The interesting aspect of this specimen is that it is so much older than the next oldest specimens with comparably extensive tooth loss, which are all Neandertals. Dmanisi does appear to considerably extend the time period over which we have evidence for human survival in the face of extensive disability; at least in terms of dental function.

There has been some criticism of the idea that tooth loss is a necessary indicator of care from other individuals.

The observation of old, edentulous individuals in a number of species of primates has formed the basis of a disagreement about the importance of such individuals for inferring the behavioral capacities of early hominids. This literature is reviewed by Cuozzo and Sauther (2004), and includes two examinations of the Aubesier 11 Neandertal by Lebel and Trinkaus and two critiques by David DeGusta. The gist of the argument is a discussion of whether any wild primates are observed to be missing as many teeth as certain Neandertal specimens (particularly Aubesier 11, but one may also include Monte Circeo, La Chapelle-aux-Saints, and possibly others who retain a higher proportion than Aubesier 11).

In my view, the actual proportion of missing teeth is much less important than the overall view of the function of the dentition. A chimpanzee with no functional occlusion is certainly almost as poorly off as a Neandertal with no teeth at all, even if many teeth are still present.

As an example, here is a shot of a female chimpanzee palate in the CMNH collection:

This is one out of around fifty wild-shot chimpanzees, a collection that is biased toward younger individuals than would have died natural deaths. The mandible retains the premolars and molars, although only one incisor, so the individual had essentially no functional dental occlusion. All chewing capacity was tooth against gum. As such, this chimpanzee wasn't quite as poorly off as the D3444 individual, but was certainly comparable in terms of dental dysfunction. There are several chimpanzee crania in this collection that are missing a few teeth, although none as extensive as this one (1).

But I don't think this line of argument is particularly productive, because it evades the central issue: do rare individuals ever allow any inferences about the social attributes of ancient humans? The edentulous hominids are evidence of the extreme end of a range of variation in life history traits. DeGusta (2002, 2003) essentially argues that the extreme end for Middle Pleistocene humans is not greatly different, if at all, from that in other primate species. I am sympathetic with that view, but I don't think it goes far enough to answer the problem. For one thing, the data as they stand indicate that Neandertals actually did survive with worse health status than other primates. This is not only true of tooth loss (where the difference is quite minor) but also bone breakage, arthritis, cranial injuries, and other assessments of both trauma and chronic health conditions. For earlier humans, the data are sparser, but these people had their problems also, as evidenced by D3444 and specimens like KNM-ER 1808. I suspect that the sample of Early Pleistocene hominids as it stands is not significantly different from Neandertals in health (although it is significantly different in longevity). So we cannot let the matter rest on the idea that other primates are like early humans in end-of-life health status; it is quite likely that early humans were not very much like any other primate.

DeGusta (2003) includes another objection to the assumption that edentulous individuals indicate care from other individuals:

Lebel and Trinkaus (2003) and Lebel et al. (2001) fail to suggest any reason why Aubesier 11 would have been unable to obtain or manually process soft foods on his/her own, rather than relying on conspecifics to do so. There is no evidence of any condition, or even advanced age, that would have precluded Aubesier 11 from doing so. So even granting the rest of their argument, Aubesier 11 cannot be used as evidence of conspecific care (92).

To take the position that these individuals are strong evidence of social behavior is to make several assumptions:

1. That a change in the average pattern of behavior highly affects the extreme end of the range of life history.
2. That it is social interaction and not some other behavioral or life history change (e.g. diet, disease, day range, secondary altriciality) that is responsible for the difference.
3. That the end of the range is sampled adequately to make such inferences.

I think all these assumptions are unwarranted.

In the case of life history variation, I think that the survival of a small number of individuals under extraordinary circumstances says little about the habitual capabilities of a species. The difference between extraordinary and ordinary is one of sampling density. One individual out of a sample of five may be entirely normal, or a one-in-hundreds freak occurrence. Ten individuals out of fifty, while the same proportion of a sample, clearly are not exceptional.

In any population, some individuals are likely to survive under circumstances that would usually be fatal. For example, food availability varies greatly both from place to place and from year to year. Although the odds of mortality are higher for older adults, in practical terms these odds fluctuate along with ecological conditions. There are likely to be periods of years when a very low proportion of older individuals die, and some survive with infirmities that are extreme for their population. Older edentulous individuals who are otherwise healthy have a number of advantages. These range from a relatively high social status (and thereby a claim on food noticed by others) to extensive knowledge of food sources and other ecological needs, to a greater ability to evade or resist predators.

We can ask a more basic question. Is antemortem tooth loss in humans evidence of aid from other individuals? A high proportion of older adult humans today lack functional dentitions. In industrialized societies and to a great extent elsewhere, these people make use of artificial dentitions, which we can presume were not part of the technological repertoire of Early Pleistocene humans. But dentures and other dental appliances are unavailable to a substantial proportion of edentulous humans today, for economic and other cultural reasons. These people do not starve; instead they use extensive extraoral processing to enable the consumption of a relatively normal diet. This does not require, although it sometimes involves, the assistance of other people.

Certainly the present-day situation is different from that experienced by the Dmanisi hominids, or even Neandertals for that matter. Edentulous people today are greatly aided by the consumption of a high-starch diet of grains, tubers, or other stored vegetables that can be reduced with long cooking to a paste or mush. But among living people such a diet is routine, and long survival after the loss of a functional dentition is very common. In Pleistocene humans, such survival was almost certainly exceptional, as argued by the low proportion of edentulous remains.

It is no great stretch to think that an occasional older person might have put together a diet for several years that would allow survival without teeth. Such a diet need not have been steady or nutritionally complete. We can imagine the life of such a person, possibly with long stretches of hunger punctuated by a rare full meal on soft plant foods, honey, organ meat from an animal, or chunks of flesh painstakingly sliced thin with a stone flake. We do not even need to imagine that such foods would have been cooked, as supported by the survival of edentulous, non-cooking primates.

Tooth loss and selection

There is another, possibly more interesting, question arising from this specimen. Presumably the dentition is adapted to the life history of a species. Long-lived species have teeth that last a long time; short-lived species need not have teeth that last as long. Under some circumstances, there is value to having teeth that have thinner enamel (and therefore wear more rapidly), are smaller (and therefore wear more rapidly), or otherwise do not last as long. Smaller teeth may allow the application of greater masticatory force to certain kinds of food items (such as pliable plant or animal muscle fibers). Thinner enamel allows an enamel/dentine wear gradient that maintains greater occlusal topography for more effective shearing of food. But such teeth are not well-suited to a long lifespan unless the rate of attrition can be reduced by diet choice. These contrary influences on tooth form lead to different stable equilibria in different species, depending upon their life history and diet.

The interesting question is the strength of selection resulting from loss of dental function in old individuals. These people survive for some length of time with compromised teeth. Although the causes of tooth loss and extreme dental wear are not always the same, both factors lead to a reduction in dental function. This is especially true for old people who have had lives leading to high degrees of attrition or dental disease; which may occur more or less depending on the prevailing environmental conditions, social status of the individual, and possibly dietary preferences.

Notes:

1. As an interesting aside, I scored dental wear in over 100 male gorillas from this collection, and I do not remember that any of them had any significant number of teeth missing. This recollection accords with the data presented by Cuozzo and Sauther (2004), where they find no gorillas out of 65 that have more than 40 percent of their teeth missing. [UPDATE 4/26/05: A reader points out that these observations come from Nancy Lovell's (1990) work, cited by Cuozzo and Sauther (2004).] To be honest, I don't remember there being a single specimen missing that many teeth, although I deliberately excluded specimens with missing teeth from my own wear sample so I surely don't remember them as well as the ones I used.

References:

Cuozzo FP, Sauther ML. 2004. Tooth loss, survival, and resource use in wild ring-tailed lemurs (Lemur catta): Implications for inferring conspecific care in fossil hominids. J Hum Evol 46:623-631.

DeGusta D. 2002. Comparative skeletal pathology and the case for conspecific care in middle Pleistocene hominids. J Archaeol Sci 29:1435-1438.

DeGusta D. 2003. Aubesier 11 is not evidence of Neanderthal conspecific care. J Hum Evol 45:91-94.

Fischman J. 2005. Family ties: Dmanisi find. National Geographic April, 2005:17-27.

Lovell NC. 1990. Patterns of Injury and Illness in Great Apes: A Skeletal Analysis. Smithsonian Institution Press, Washington DC.

Lebel S, Trinkaus E. 2002. Middle Pleistocene human remains from the Bau de l'Aubesier. J Hum Evol 43:659-685.

Lebel S, Trinkaus E, Faure M, Fernandez P, Guérin C, Richter D, Mercier N, Valladas H, Wagner G. 2001. Comparative morphology and paleobiology of middle Pleistocene human remains from the Bau de l'Aubesier, Vaucluse, France. Proc Natl Acad Sci U S A 98:11097-11102.