media

NPR has been doing a special series of reports during their "Morning Edition" program called "The Human Edge", all about various aspects of human evolution. I think it's just wonderful that they're doing this, and the stories are available on the NPR website, which is also great.

I've been out of town and so haven't been following closely. So I'm just noticing that some of these stories actually drive me up the wall. Every one of them is presented as what Stephen Jay Gould called a "just-so story".

I'll take one of the latest articles as an example: "Food For Thought: Meat-Based Diet Made Us Smarter". The story begins with a short resume of the "expensive tissue hypothesis", with quotes from one of expensive tissue's main exponents, Leslie Aiello. This hypothesis is a serious one, which paleoanthropologists take seriously, and which has some empirical support in the comparative biology of primates. But here's how the story poses the hypothesis:

"You can't have a large brain and big guts at the same time," explains Leslie Aiello, an anthropologist and director of the Wenner-Gren Foundation in New York City, which funds research on evolution. Digestion, she says, was the energy-hog of our primate ancestor's body. The brain was the poor stepsister who got the leftovers.

...

Meat is packed with lots of calories and fat. Our brain — which uses about 20 times as much energy as the equivalent amount of muscle — piped up and said, "Please, sir, I want some more."

As we got more, our guts shrank because we didn't need a giant vegetable processor any more. Our bodies could spend more energy on other things like building a bigger brain. Sorry, vegetarians, but eating meat apparently made our ancestors smarter — smart enough to make better tools, which in turn led to other changes, says Aiello.

That's a "just-so story." How did meat make us smarter? Is it a magical meat property? If I fed enough meat to the local deer, would they get smarter? The expensive tissue hypothesis proposes an energetic trade-off, but doesn't provide any mechanism by which the evolution of smarter brains (or diet shift) would occur. A trade-off is simply "you can't have your cake and eat it too." It needn't say anything at all about how you bake a cake, or what happens if you can't eat it.

I'm not anti-expensive tissue, I just want to recognize the limits of these explanatory hypotheses. Energy cannot explain everything about human cognitive evolution. It's an important constraint, but it cannot be the only one. Without some countervailing force, energy expenditure would always favor smaller brains. So we deserve some account of mechanism, not just energy budget.

The story about endurance running attempts to tackle the issue of mechanism: "For Humans, Slow and Steady Running Won the Race". This story relies on interviews with Dan Lieberman, who favors the idea that Homo erectus adopted a form of long-distance running.

"Most animals are designed for speed, for power, not for endurance," Lieberman explains, as we make a turn onto the bridge. "And we are a special species in having been selected for endurance, not speed."

So we grew longer legs and lighter feet; the joints in the legs and pelvis got bigger to absorb a lot of impact; and we grew a bigger butt muscle.

Lieberman says these and other changes allowed us to run down and exhaust prey, like antelopes. He notes that "persistence hunters" in Africa have been known to do that. And the payoff would've been big for early humans: lots of high-calorie meat to feed a bigger brain.

Again, this is presented as a just-so story. It's a plausible narrative, but the article doesn't situate it in an evolutionary context. How exactly would you test this hypothesis? You could look at prey species profiles for early Homo (favoring low-endurance species), you could consider other cognitive and physiological requirements of persistence hunting (tracking ability, knowledge of water sources), you could look for evidence of gateway strategies (use of slow-acting poisons that require long-distance tracking). You could also try to refute alternative explanations for the anatomical features in question, such as their usefulness for long-distance walking, walking on irregular substrates, or simple allometry with body size or lifespan.

These are serious hypotheses with literature and evidence supporting them. I just wish that they could be reported in a way that made it sound like paleoanthropologists are skeptical scientists!

I got to return to bloggingheads.tv this week for Science Saturday, with a conversation between me and Christina Agapakis, of the Oscillator blog.

Here's a non-embedded link to the diavlog. Christina's work is in synthetic biology, and we talked a lot about the recent announcement from the J. Craig Venter Institute, with some background on what synthetic biology is, and how the newsmaking work fits into the field as a whole. I learned a lot from our conversation. We got to the Neandertal genome in the second half of our conversation, and we found several common links -- and neither of us mentioned synthetic Neandertals once!

Last year, I complained that paleoanthropology had been exceptionally boring. One piece of evidence was the year-end retrospective in Discover about the top 100 science stories, of which only three were paleoanthropology-related.

Now, I would never have claimed that this year has been boring for paleoanthropology. But reading through the current Discover, there actually weren't all that many big stories. Sure, enough to make it an interesting year, especially considering the October onslaught. But except for Ardi, it was a year of empirical news and little fundamental movement in our knowledge about human evolution.

Here's a list of the paleoanthro stories in this year's top 100:

3. Ardipithecus. This of course raises the question about which science stories were bigger -- number 1 was vaccines, number 2 the Augustine report on NASA's future. Ardi also made a second appearance as part of number 43, the Darwin-centric entry.

35. Neandertal DNA. This was more media event than story in 2009, but worth including in any year.

51. Hohle Fels flutes.

80. We get a target-rich environment starting here: Chimpanzees plan ahead -- this is the meat-for-sex story.

81. "Human gene changes mouse talk" -- transgenic FOXP2 mice.

82. "Early humans tended the disabled" -- the Atapuerca craniosynostosis case.

There are a few more that touch on issues discussed here on the blog, but except for the Paleoindian drive lines discovered under Lake Huron (number 95), they don't really hit paleoanthropology.

However, one paleoanthropologist does make another appearance: I was unaware until I read item number 93 that Dean Falk was working on Einstein's brain.

UPDATE (2009-12-11): Several readers wrote to request the reference to Falk's Einstein brain work. A copy is free online from PubMed.

I've just returned from a week in Leiden, the old university city of the Netherlands. I was a guest of the archaeology faculty, in particular Wil Roebroeks and his stable of students and postdocs, and they were fantastic hosts. I can't say enough about the new friends I have in Leiden.

Except maybe that they set an awfully high bar for the next place I get to visit!

There was excitement in the whole country as the Naturalis museum opened the first exhibition outside Georgia of the D2700 skull from Dmanisi. The TV news covered David Lordkipanidze arriving with the skull, and followed his entourage from the airport. The daily newspapers carried huge broadsheet stories about the fossils and the exhibition. It was pretty cool.

I only wish Lucy had gotten anything like that kind of reception in the States.

I played a small part opening the exhibit by participating in the public lectures at Naturalis on Saturday. There was a very energetic crowd of ticketholders, eager to hear about the science of early humans and to attend the exhibit.

The skull and its mandible D3735 are displayed in the "Treasure Room" of the museum:

The museum houses the original Dubois fossil collections from Trinil, Java, including the Pithecanthropus skull and femur. If you visit, you can see the originals on display:

I sat down alone with them for a while during the gala reception and did what comes naturally:

Unfortunately, spending a week in the Netherlands meant that I had to miss our Thanksgiving at home. Gretchen thinks we should have turkey in the next week or two to make up for it, and I'm not complaining. On the date, however, I got a real authentic Pilgrim experience, as I stayed just above the American Pilgrim Museum in Leiden:

Such a unique place, with incredibly nice proprietors!

So, blogging has been slow as I was soaking in the surroundings, and giving my hosts a preview of some of the research that will be coming out in the next year or two. They've told me that they'll feel paid amply if I keep doing what I do here. So let's get back to it!

I want to point to an interview between conservative radio host Hugh Hewitt and Richard Dawkins, on the subject of Dawkins' new book, The Greatest Show on Earth: The Evidence for Evolution. Hewitt is a practicing Catholic and lawyer, as well as a Stephen Jay Gould undergraduate student, and by no means hostile to the idea of evolution. He has clearly spent more thought preparing for the Dawkins interview than Dawkins had done.

Hewitt, like many interviewers, spends a lot of time trying to pin down Dawkins on issues related to his previous book, The God Delusion. But what I thought worth discussion was this section of the interview:

HH: So after Lucy, what’s the next most forward one closest to us?
RD: After Lucy, that would be, I would think, Australopithecus Africanus, or Homo Habilus.
HH: And about how many years separate those two?
RD: About, well, actually, Homo Habilus would be only a few hundred thousand years from Lucy.
HH: And after Homo Habilus, what’s next?
RD: I would think Homo Erectus, which would be maybe about another million years, and then Homo Sapiens.
HH: And so do you expect, Richard Dawkins, that as the continued search for fossils goes on, that those gaps in the record will be filled in?
RD: Well, I don’t call them gaps. I mean…
HH: I know that, but…
RD: They’re pretty close.
HH: But do you expect any intermediate fossils to be discovered for those periods?
RD: Yes, I do, but I don’t think we even need them, because they’re already so close, that the terminology, I mean, for example, Homo Habilus is sometimes called Australopithecus Habilus, they’re so close, that the terminology becomes disputed.
HH: And do you expect they will all be in Africa?
RD: Yes.
HH: And none of them in Asia, none of them…
RD: Well, humans first moved out into Asia about one and a half million years ago as Homo Erectus, so there are specimens in Asia which were independently there, and they came from Africa.
HH: And so a hundred years from now, when this conversation is underway, what do you expect most of the argument to be about, if indeed there is an argument left?
RD: Well, there already isn’t an argument left, because if you actually look at the evidence, it is completely conclusive.

I think this is a really bad job of laying out the case for human evolution. He's got the basic facts, at a superficial level, but there's no flavor here, no joy of discovery.

As a result, Dawkins leaves the impression that there are a handful of fossils and large gaps between them. Thousands of listeners, many receptive to science, are hearing that the evidence for human evolution consists of three species put together by a lot of hand-waving. And one of them, that "Homo that could be Australopithecus", we don't even know well enough to give it a name!

Now Dawkins is not a paleoanthropologist. So, one might think we should cut him some slack. But human evolution is the stumbling block for a lot of people, and you have to get this right. There are hundreds and hundreds of specimens that underlie our knowledge of Plio-Pleistocene human evolution. Those specimens are contextualized both by date and by their paleoecology. We know a damned lot about them. Some aspects of the science are subject to debate, sure, but most is rock solid. That's what you need to be ready to get out of your mouth in a hundred words or less.

How should you do it? Have a short story -- I mean, literally, a 100-word story -- that conveys the flavor and reality of fossil humans. I'd say nowadays, you start with Dmanisi. Here's a site, found under the foundation of a medieval monastery, with five fossil humans who are the earliest known people out of Africa. In size and looks they're clearly in between those of earlier ape-like australopithecines and today's humans. There was an old woman who was the first-known person to outlive her teeth -- but unlike your grandma, her brain was half the size, and "old" might have meant forty. Two teen-agers, a boy and a big, big man whose teeth were twice as big as mine. Since they lived, one point eight million years ago, the earth's poles have reversed not once, but six times.

OK, that was 110 words -- it's not easy. But you have to be ready. Why is Homo erectus not just a human, in the biblical sense? What's the next story up in time (I'd go with Atapuerca)? What about backward (Ardipithecus is a good one, but you'll want to do better than Dawkins' name-dropping mention)?

Lay listeners don't care about species names -- that's fancy obfuscatory science-lingo. Yes, we use species names for special purposes. But evolutionary biology is not typology. Species are not or unit of study -- individuals and populations are. We have more than a hundred specimens from Sterkfontein or Koobi Fora; more than thirty-five bodies in the caves of Atapuerca. Calling them Australopithecus africanus, or Homo erectus, or Homo heidelbergensis -- those names trivialize the evidence.

People wonder why I'm passionate about open access -- this is one of the reasons. What a great opportunity we're missing, by not being able to direct folks to the rich record of basic evidence for our origins. TalkOrigins is awesome, but we need visuals, more links to research, a directory of paleoanthropologists, the reality of human genetic evolution.

I've cited a small part of a very long interview, with many interesting parts. I don't fault Dawkins or Hewitt at all for the focus on atheism versus religion -- the fact is, that is why many interviewers are willing to have Dawkins come on, they know the ratings potential of that issue. I just think it's a poor piece of communication, to be unprepared with evocative examples that will give people a vivid picture of the reality of evolution. Because that's the point of the new book, right?

It's one thing to come off well during a brief appearance on The Colbert Report. But an hour-long radio show -- there's no format better to bring out the real evidence. But you've got to be snappy.

Today, Science Saturday on bloggingheads.tv is a conversation between Razib Khan and me. We had a fun conversation about Ardipithecus and the recent study of the population genetics of India.

Here's a non-embedded link to the bloggingheads site

Razib pointed out the similarity of eyeglasses in our last diavlog.

Obviously, we've taken the pills that make us smarter:

I think we did pretty well staying on topic in this one, and getting into some paleoanthropology deeper than your average radio interview.

If you're finding my blog from the bloggingheads site, please look around! My Ardipithecus topic link. That goes way back, long before the current discoveries, and there are some interesting posts in there, from today's perspective.

I especially like the two posts about bushes, ladders, and whether Ardipithecus is our direct ancestor or not: "Spacecraft all over the Pliocene", and "A ladder not a bush?"

Oh, and I almost forgot this 2006 post linking to Tim White's kvetching over the Orrorin femur: "Orrorin opera." If you want a background picture of the competitiveness of research in early hominin field paleontology, that's a case worth examining -- or for a broader view, Ann Gibbons' book, "The First Human," has many stories as well.

UPDATE (2009-10-22): I wrote this post before the film premiered, but it's gotten a lot of Google traffic. My notes on watching the film might be more interesting. I haven't yet gotten to see the whole thing, but together with some correspondents, I think I've put together some useful notes.

ORIGINAL POST (2009-10-01):

OK, so if you thought Ardipithecus was going to be different from the Darwinius media fiasco... this one is for you:

A DISCOVERY CHANNEL EXCLUSIVE, WORLD PREMIERE SPECIAL
BRINGS YOU THE STORY OF THE LATEST NEWS ABOUT HUMAN EVOLUTION

DISCOVERING ARDI airs Sunday, October 11 at 9 PM (ET/PT)

Following publication in the journal Science on the discovery and study of a 4.4 million-year-old female partial skeleton nicknamed "Ardi," Discovery Channel will present a world premiere special, DISCOVERING ARDI, Sunday October 11 at 9 PM (ET/PT) documenting the sustained, intensive investigation leading up to this landmark publication of the Ardipithecus ramidus fossils.

...

"The novel anatomy that we describe in these papers fundamentally alters our understanding of human origins and early evolution," said project anatomist and evolutionary biologist, Professor C. Owen Lovejoy, Kent State University.

Project co-director and paleontologist Professor Tim White of the Human Evolution Research Center at the University of California Berkeley adds, "Ardipithecus is not a chimp. It's not a human. It's what we used to be."

Oh, my. Well it stands to reason that something this coordinated wasn't just science. I wonder whether anyone will ask the questions about the timing of Science's publication and the documentary release only a week later.

I have to tell you, I've been wondering about all the bogus-looking Darwin paraphrases these guys have been throwing out -- you know, the ones about how Darwin taught us about how chimpanzees changed from their common ancestors, and how fossil humans would tell us about the apes. I can't find anything like that in any of Darwin's publications -- please e-mail if it's there and I'm missing it.

But now I see where they're coming from. It's the tagline from the Discovery show!

DISCOVERING ARDI

DARWIN COULD ONLY DREAM OF FINDING THIS

Really? I'm soooooo tempted to make that the blog's tagline right now.... OOOH OOOH, better yet --

DARWIN COULD ONLY DREAM OF BEING THIS HANDSOME

Primate paleontologist Elwyn Simons and (many) colleagues cosigned a letter in the current Nature protesting the high price paid for the "Ida" fossil, Darwinius masillae ("Outrage at high price paid for a fossil"). Reportedly, the "A" side of the fossil was sold for around $750,000, which Simons and colleagues suggest "amplified" the "publicity barrage surrounding this fossil." The letter is worth reading in its entirety, but many of my readers do not have access to the journal so I will reproduce the final paragraph:

In our view, such objectionable pricing and publicity can only increase the difficulty of scientific collecting by encouraging the commercial exploitation of sites and the disappearance of fossils into private collections. We believe that payments on this scale are detrimental to scientific investigation, and respectable institutions should not be responsible for making or publicizing them. We strongly believe that fossils should not have any commercial value.

I hope the letter can spur some constructive discussion. Not every fossil is rare -- but even common ones have scientific value, as we can understand the dynamics of ancient populations only by examining large samples of individuals with known provenience. Nowadays, it has become more and more possible to study ancient communities of organisms, not merely single species. Even at a site like Messel, with large numbers of specimens, there will be rare taxa represented by only one or two specimens. Rare things are inevitable, and the question is how to fairly allocate access to them by both researchers and the public.

References:

Simons EL, Ankel-Simons F, Chatrath PS, Kay RS, Williams B, Fleagle JG, Gebo DL, Beard CK, Dawson M, Tattersall I, Rose KD. 2009. Outrage at high price paid for a fossil. Nature 460:456 doi:10.1038/460456a

So I told you I was going to be beating the press. The Guardian's Robin McKee picks up the story of the Les Rois "Neandertal":

How Neanderthals met a grisly fate: devoured by humans

One of science's most puzzling mysteries - the disappearance of the Neanderthals - may have been solved. Modern humans ate them, says a leading fossil expert.

Now, I suppose it's no surprise to see The Guardian running with the most sensationalized possible angle. Of course, if you are reading the blog, you got the story five days ago with a balanced account of the paper, all the uncertainties about whether the specimen in question is a Neandertal, and a paraphrase of paper's own interpretation of the cutmark evidence:

The authors point out that many of the faunal remains are also cutmarked, including mandibles apparently smashed open. I suppose this may be construed as evidence for cannibalism -- at the extreme, that the fearsome modern humans were hunting down the last Neandertals. And there's no particular reason to think that this isn't cannibalism at Les Rois, but given the scarcity of the sample, it's not nearly so strong as the evidence at some other sites.

The authors suggest that this may fit in with a pattern evident at other Upper Paleolithic sites, in which human remains were deliberately altered or processed for symbolic purposes. There is a perforated human tooth at the site, evidently created for use as a pendant. Some kind of mortuary practice is probably just as consistent with the scanty information we have as cannibalism.

All in all, I didn't think the story was all that sensationalistic to begin with -- you have to assume a lot to put a human's teeth around a Neandertal bone here. If anything, McKee buries the lede -- assuming that this mandible was a Neandertal, it and the unassociated Neandertal-like teeth in the same level are quite possibly the earliest diagnostic specimens associated with the Aurignacian!

Believe me -- I know from sensational angles. Just wait until the next story....

From an otherwise-horrifying story about the plight of albinos in East Africa:

Ideally, they would like guarded camps, like one Burundi has started, where albinos can take refuge. But because Tanzania has an estimated 170,000 albinos, it would be a huge undertaking. Albinism is common among East Africans; 1 birth in 3,000 is albino, versus 1 in 20,000 in the United States.

So...that makes 510 million people in Tanzania, right? Wrong. That's more than 10 times bigger than it ought to be.

The frequency of albinism really is high in sub-Saharan Africa. Most instances are OCA2-type albinism. Variation around OCA2 also generates blue eyes, but that's a different allele. Albinism is a consequence of knockout mutations that stop the normal action of the gene.

Why is this type of albinism so common in Africa? That's not entirely clear. The incidence is as high as 1/3900 births in southern Africa, but substantially less in West-Central Africa. This type of albinism is only around 1/36000 in Americans of European descent, and only 1/15000 in African-Americans. That 1/3900 frequency doesn't sound like much, but since only homozygotes express albinism, it equates to an allele frequency of around 1.6 percent. That means that over 3 percent of people carry the allele in populations where it is most common.

Alleles that are bad and relatively common deserve some explanation. People born with this type of albinism have certain disadvantages, more severe in the cultural and physical environments of the past. These are not limited to traditional fear of albinos, but also include risks of cancer and blindness. The African variety of OCA2 albinism (partially redundant since "OCA2" stands for oculocutaneous albinism, type 2) is almost all attributable to a single deletion mutation, which occurred sometime before 3000 years ago.

There are two possible explanations. Genetic drift might have elevated the frequency of this allele as early Bantu agriculturalists dispersed from West-Central Africa into East and South Africa. In that scenario, there's nothing special about albinism; it's just a marker that happened to surf up to a high frequency along with population movement.

Or, heterozygotes who carry the allele might have some fitness advantage. The nature of this advantage isn't obvious, but OCA2 knockouts do commonly occur in other species, hinting that the gene might have pleiotropic effects on other phenotypes. Even the blue-eyed allele of OCA2-HERC2 seems unlikely to have been selected for its effect on eye color, considering that effect is usually recessive.

It's a case where the common error -- that each phenotype is "caused" by a single gene, and vice versa -- may easily lead people astray.

Our work on recent selection was featured in Discover magazine this month. I'll link to that later. In the meantime, I've been getting some thoughtful letters from readers of the article. I thought I would post some of these letters with answers, because they really illustrate a cross-section of interest in the work. Here's the first:

I am just a private citizen, but I have thought about something for some time. Let's take 1,000 sets of identical twins and divide them into two groups. The groups will be put far apart and never come in contact with each for 1000 years. The two areas the two groups go to are identical and the number of them stays at 1,000.

After the 1000 years they are brought back together. I will wager $10,000 the two groups will have evolved differently, even though they lived in identical climates. Is anyone willing to take me up on the bet?

I am guessing if we took one set of identical twins who could live for 1000 years, separate them for the 1000 years in identical climates, the same thing would happen.

My thinking is that climate is part of the evolution process, but the more complicated life gets means the body has to adjust to the changes. If one group's environment doesn't change, then they only have to adjust to the environment once. If the other group starts to invent things and are constantly improving on things, then they have to keep evolving to the constant changes. I say living in one area that keeps changing for 1,000 years will change the person.

There's a bit more to this letter, which I may include later. In the meantime, here's what I wrote in response:

Thank you for your letter. In fact you are entirely correct; if you separate two sets of identical people for 1000 years, the two populations will evolve differently. This will be much more so if you separate 100 people instead of 1000, as the chance element of evolution is the largest factor in these small populations.

Now, on the other hand, if you separate two groups of 100,000 or 1,000,000 people for 1000 years, we will see very little genetic change at all in either group. Except to the extent that their genes are subject to selection.

But as you mention, the genes of these large populations may evolve differently even if their phenotypes are subject to the same environment. For example, Europeans and north Asians have both evolved lighter skin color in the last 20,000 years. But in these two populations we see very different genetic changes. Europeans have a high frequency of new genetic changes in genes like SLC24A5, OCA2, and Mc1r; Asians also have a change in Mc1r but lack the others; instead they have changes in other genes like DCT.

Again and again in recent human evolution, we see that chance element influencing the variation that selection has to work with. In maybe the most famous example, different populations have come to suffer from falciparum malaria in the last 5000 years. In these populations, we see diverse mutations that help to resist the malaria parasite. The sickle cell trait became common in West Africa and north India; West Africa also got hemoglobin C and G6PD deficiency. Hemoglobin E arose in southeast Asia; alpha- and beta-thalassemia appeared in the eastern Mediterranean and elsewhere; ovalocytosis in New Guinea. These different genetic adaptations have different values and different costs. If humans had always lived in a single population exposed to malaria, some of these adaptations may not have proliferated. But the long distances and slow movement between these populations means that new adaptations can grow in numbers faster than they spread to different parts of the globe.

I certainly wouldn't take up his wager. But who knows, there may be a profit opportunity here -- there are a lot of folks studying human genetics who don't think evolution in recent humans is possible!

This Sunday evening, at 9:00 EDT/ 8:00 CDT, the National Geographic Channel will show "The Neanderthal Code" in the US. I appear in this film, and you can see some clips already at the documentary's website.

The film focuses on the current genomic DNA recovery from Neandertals; many of the major players in the DNA sequencing effort appear. My research is covered, as well as other contemporary approaches to Neandertal biology and behavior. It's not complete, but it's a good documentary and at 2 hours, it's double the length of most.

Of course, the film shows a lot of people running around in Neandertal makeup, which I usually don't like -- but this time, they dress one in modern clothes and put him on the subway to see what happens. Was Carleton Coon right? Will people notice something odd? Tune in and see!

"Hmmm....MANscaping...."

UPDATE (2008/09/20): Zach Zorich of Archaeology gives it a positive review:

This program covers a vast amount of science, both old and new, and serves as a thorough and entertaining summary of the latest interpretations and data on our species's closest fossilized relatives. The show addresses several important questions: Did Neanderthal's make art? Were they tougher than professional bull-riders? Did they have religion? If so, were they such a bunch of Puritans that they wouldn't mate with the Homo sapiens who invaded their territory in Europe roughly 40,000 years ago?

Puritans. Hmm....that gives me an idea for a picture...

Meanwhile, several e-mailers have noticed this:

Now, I'm sure it was unintentional, but this cracked me up: as the narrator announces "Today, it’s obvious who dominates the planet" and pauses, the video cues to a shot of John standing in the middle of Times Square(?), looking straight into the camera!

Ahhh, yes. We've been laughing about that one for a few weeks!