meetings

More than most will admit, scientists today depend on good science writing. What they read is coming from other scientists, from bloggers and students, and from traditional journalists embedded in a range of publication models.

Most of us abandon our textbooks long before earning our Ph.D., digging deeper and deeper into the narrow research tracks that will support a career on the cutting edge. Merely reading research in that narrow field is not enough. We have to master it -- knowing the methods and results with such detail that we can take them up or find their flaws. It takes me days to really digest an important piece of science.

Who loves science more than those who have devoted careers to it? We're far from the majority of consumers of mainstream science magazines (as pointed out by Ed Yong). But we consume them above our weight because good reporting fills an important need. Scientists are teachers, we interact with the public and many of us conduct research with importance to a broad audience. To do those things well, our knowledge must have equal breadth. Reading abstracts and conclusions is hardly enough, we need context. Some of that context comes from our training, but most of us rely on good science writing to bring us information outside our narrow specialties.

Science writing emerges today from an ecosystem that includes traditional, "mainstream" publications, online news outlets and blogs. Many people have commented on the ways these information sources have converged as traditional science writers have come to depend on blogs, while bloggers link and comment on news and perspective pieces, and bring expert criticism to many scientific papers. Individually, these actors aren't doing anything very new, but collectively they have connected storytelling and critique in a way that can be instantly telegraphed to influential readers and a broader public.

ScienceOnline2011 was a great meeting of many of the trailblazers in this new ecosystem. The halls were packed with people jazzed about science. A lot of the participants were working journalists, many aspiring science writers, and a good proportion of working scientists -- like the melba toasts in a bowl of Chex Mix.

This melba is here to tell you how essential the ecosystem has become to working scientists. I read blogs, write a blog, read broadly across science. I want to know the story behind the research, and I want to know what critics think -- especially the ones who have done other work I like. I can't read every new paper outside my area, but if I'm interested enough to follow up, I want immediate links to the originals.

I need the ecosystem. It enables me to be a publicly engaged scientist and an effective teacher. Besides that, this community helps with my research. Working at the borderline between genetics and paleontology isn't easy, and I find that many important insights come from even farther afield. The ecosystem lets me stretch my antennae across a much bigger cross-section of today's science.

I may be an outlier in my engagement with blogs and social media, but I know my colleagues. Many in human genetics have learned essentially everything they know about modern human origins from reading the press. Especially the postdocs and grad students coming in from other fields, who may never have taken an anthropology course. Likewise, many paleoanthropologists only know the genetics that they've heard at conferences or read in the news. That's why it has been so essential for us engaged in the field to educate and engage with science journalists. Without accurate coverage of human evolution, we can hardly keep interdisciplinary research going. Like biological ecosystems, the science writing ecosystem provides us services that are often unpaid and unrecognized.

Some readers may think I'm exaggerating the value of science writing. Surely I'm glossing over its many problems. Surely scientists should be getting their information from peer-reviewed research, not second-hand accounts.

I'm no Pollyanna about these problems, but they're hardly new. Universities have always overinflated their press releases, and know-nothing writers have always embellished them. Sensationalism, even outright misleading headlines or stories, are still out there attracting eyes, but then they always were. There have always been scientists who failed even to read abstracts of papers, much less working to understand their methods.

What's new is the diversity of reporting, along with a growing number of people in a position to -- as David Dobbs says -- "call bullshit" on bad writing. Blogs, mainstream science reporting, emerging writers, podcasts -- all provide overlapping channels of information at multiple levels to overlapping audiences. The resulting community is much smaller than the pooled readership of its printed or online output, but vastly larger than the combined Rolodexes of top science journalists 10 years ago.

I don't need to recount the way blogs have changed reporting, but I hope to highlight how they make science better. Reporting and commentary are not pre-publication peer review, but no firewall separates these functions. Both require honesty and candor about science's methods and limits. Our ecosystem today accords less privilege to "top" journals, and more to the scientists and writers who take initiative.

Ann Gibbons reports on the AAPA meetings with a story about all the Homo erectus pelvis and stature papers ("Human ancestor caught in the midst of a makeover," subscription required). Research on the proportions of early Homo was the main event of the meetings, and Gibbons really caught the highlights of the story.

I wrote about body size in Homo erectus a few months ago, and much of the story follows from the basics I outlined there ("The changing height of Homo erectus"). But there I emphasized that the estimated adult height of KNM-WT 15000 was an outlier in a relatively small body size distribution.

What I didn't anticipate is that some interesting work might come along to question the tall adult stature estimate for that skeleton. Gibbons describes the work of Ronda Graves and colleagues, presented at the meetings:

Using intermediate growth rates, graduate student Ronda Graves of Stony Brook University in New York state calculated that Nariokotome Boy would have had less time than originally predicted to reach his adult height when he died. She estimated at the meeting that he would have reached 163 cm in height and 56 kg in weight as an adult—"shorter and wider" than previously thought.

This seems very short, at least when I first saw it. On reflection, Ohman and colleagues (2002) had provided a stature estimate at death of KNM-WT 15000, as only 147 cm, and they suggested it might have been as short as 141 cm. That's an awful lot shorter than had previously been estimated on the basis of regressions.

If Graves and colleagues are right about the lack of a human-like growth spurt, an additional 20 cm (8 inches) wouldn't be unusually small for an adult stature. Those stature estimates would put KNM-WT 15000 between the 50th and 90th percentiles for American 10-year-old boys, or between the 25th and 75th percentiles for 11-year-olds. By contrast, an adult stature of 163 would be around the 3rd percentile for adult American men. The assumptions about growth totally determine the outcome for adult height.

The credibility of the growth assumptions can only be tested by looking at other adult and juvenile remains. There is much more to say on this topic, but I'll point out one relevant comparison: The estimated stature of the adult skeleton from Dmanisi, including the complete D4167 femur and D3901 tibia, is between 145 and 166 cm. Graves' KNM-WT 15000 stature estimate is right within this range.

Meanwhile, there was a lot of disagreement about hips.

[Scott] Simpson and Linda Spurlock of the Cleveland Museum of Natural History realigned the pieces of Nariokotome Boy's pelvis, guided by a female H. erectus pelvis from Gona, Ethiopia, that Simpson reported 2 years ago (Science, 14 November 2008, p. 1089). They found that the widest measure from side to side on the boy's pelvis is 255 to 260 millimeters rather than 225 to 230 mm. This would give the boy an adult hip breadth of 295 to 301 mm rather than the 266 mm originally proposed, and would match those of the short, wide-hipped female from Gona, whose pelvic breadth was 288 mm. "H. erectus was not simply a small-brained modern human," says Simpson.

Simpson's reconstruction seemed reasonable, and it's actually not that big a difference -- roughly an inch and a half (3 cm) in bi-iliac breadth. The main differences were in the overall shape of the pelvis, being shorter with a more flaring iliac blade.

Gibbons describes the disputation that happened after Chris Ruff's presentation. Ruff has suggested that the Gona pelvis may not represent Homo -- that its broad proportions and small acetabula (hip sockets) suggest it may have belonged to an australopithecine (presumably, A. boisei).

Much of the disagreement comes down to the estimation of femur head diameter from acetabulum breadth -- Ruff (2010) gave an estimate of 32.6 mm, Simpson and colleagues estimated between 35 and 36 mm, based on a different method. What you would want is enough acetabula of both genera to be able to examine their variation directly. We don't have such a sample; what we have are a few acetabula and several femur heads. We have the additional problem that living people seem to have a different relation of femur head and acetabulum diameters than in other anthropoids, and it's not obvious which should be applied to early hominins.

I guess (in the relative absence of data) that this acetabulum diameter of the Gona pelvis was in the zone of overlap between Homo and Australopithecus. There's no question that later Homo -- say after 1 million years ago -- is substantially larger in acetabulum diameter, from every specimen so far described. But there are occasional small specimens of Homo even in the Middle Pleistocene. At 1.15 million years old, the Gona specimen is more than 300,000 years later than the last known occurrence of Australopithecus. The femur head that would fit the Gona acetabulum would be smaller than KNM-ER 1472 or D4167 from Dmanisi, both around 40 mm. At least one australopithecine femur head (AL 333-3) is that large, so the femur head diameter distributions do overlap. The STW 431 acetabulum diameter is a sliver larger than that of the Gona pelvis (Ruff 2010 makes it 3 mm bigger, but other workers have given a smaller estimate). SK 3155 may well be Homo and has a smaller acetabulum.

Of course, if we go as far as SK 3155, we have to consider the topic of the Malapa innominate. Can we tell small-bodied Homo from Australopithecus on the basis of pelvic morphology? Several people writing about the Gona pelvis have made it sound like a bigger version of Lucy's. But that's not really true. The australopithecine-like appearance comes from its breadth and consequent features, including the long pubes and flaring anterior ilia. The rest? Maybe there's something here for a clever anatomist.

UPDATE (2010-04-27): I have some e-mail about the last occurrence of A. boisei, which I wrote above was more than 300,000 years older than the Gona pelvis.

The most potent counterargument is Swartkrans Member 1, which has uranium-lead dates around 830,000 years ago, and has been placed by many workers around a million years ago. I actually hadn't been thinking of South Africa. But it is relevant, as the East African record between 1.4 and a million years ago may not be strong enough to argue that the last occurrence of A. boisei is really very close to the extinction time.

Meanwhile, there is OH 36, an ulna from Olduvai Gorge that may represent A. boisei. Since it's (obviously) not cranial, and is quite large and robust compared to postcranial remains that are associated with A. boisei, I've always been very skeptical of that assessment. If there's one feature of the ulna that actually has some phylogenetic importance in the Early Pleistocene, I figure it's size.

But given the current question about body size, that reason for skepticism may have receded in importance. On the other hand, OH 36 seems to represent a substantially bigger individual than the Gona pelvis, so maybe introducing robust australopithecines into the mix doesn't help anything.

Several things puzzle me. Even into Member 1 times, Swartkrans is dominated by A. robustus, with very little Homo. In East Africa, A. boisei is never quite so predominant in the hominin assemblage as the case in South Africa, but was nevertheless very common up to 1.5 million years ago. Did it persist much later? Was it cryptic from the point of view of the fossil record? Are the Swartkrans dates older than we think?

References:

Gibbons A. 2010. Human ancestor caught in the midst of a makeover. Science 328:413. doi:10.1126/science.328.5977.413

Ohman JC, Wood C, Wood B, Crompton RH, Günther MM, Yu L, Savage R, Wang W. 2002. Stature-at-death of KNM-WT 15000. Hum Evol 17:129-141. doi:10.1007/BF02436366

Ruff C. 2010. Body size and body shape in early hominins -- implications of the Gona pelvis. J Hum Evol (in press) doi:10.1016/j.jhevol.20 09.10.0 03

I'm just back from the physical anthropology meetings. What a lot of interesting things there were -- a few in the sessions, and many outside of them!

A few people asked me what I saw or heard that I would be writing up for the blog. I had to explain that a long time ago I decided not to blog about stuff I saw at conferences. It makes life easier in several ways -- I don't have to sit around taking notes, and people don't have to worry what they tell me.

Naturally, there are exceptions to every rule. Sometimes people have already published their stuff, or they're hoping to publicize work that won't be appearing in "embargo" journals. And sometimes there's stuff that isn't science, at least not directly, but deserves a record of some kind.

About these meetings, I want to write one thing -- these were outstanding for sharing casts of new things with the field at large. Darryl de Ruiter brought casts of many of the Malapa specimens, and made many opportunities to share them with everybody interested. Scott Simpson had brought a cast of his new reconstruction of the pelvis of the Nariokotome skeleton, and was showing it along with his poster about it.

For readers who don't usually study anatomy, I have to emphasize just how important it is to be able to look at a physical object. Descriptions and photos are, of course, necessary for publication, and they give a formalized account of anatomy. But the sheer size and three-dimensional appearance of a physical object carries tremendous information, not easily conveyed in words. I have worked with bone and fossils for many years, so that handling a cast allows me to place it next to thousands of objects in my tactile mental catalog. I have a much better understanding of those fossils now that I've gotten a chance to handle the casts, and that memory will stay with me.

I haven't seen such an availability of new casts at the meetings since 2001, when Maeve Leakey had casts of Kenyanthropus.

So I want to recognize how open and accessible those objects were at these meetings. These guys are real class acts, and their willingness to share and talk about the new fossils will advance the science. The quality of the reviews for their upcoming research papers will certainly be higher, since many of the potential reviewers will have a much greater familiarity with the fossils. Besides that, the mere opportunity to look at things along with a wide range of experts is really unique. I congratulate them.