As I said previously, most of my time in sessions at this year’s AAPA meetings were at talks focused on hominid evolution. So while I am sure there were great presentations on bioarchaeology, primate behavior, human biology, genetics and other topics, I was listening to talks about fossils and fossil-related research. A few highlights from my seat:
Yohannes Haile-Selassie gave a talk on the Burtele foot to one of the more packed audiences of the meeting. The talk primarily summarized the argument of their recent Nature paper, although Haile-Sellasie did mention that they have dentognathic material from the site that, apparently, does not look like Ar. ramidus. He also said that the original foot specimens were found several years ago and they have subsequently re-visited the site repeatedly in the hopes of recovering more of the specimen, but with no luck. It is hard to interpret the specimen at the moment, except to say again that it could be a very important specimen for understanding locomotor evolution and diversity during the early part of hominin evolution. However, in the absence of additional associated material, particularly some of the tarsal elements, interpretations of it may be extremely difficult and lend themselves to multiple, divergent explanations.
Matt Cartmill gave a very entertaining talk on an under-appreciated aspect of human uniqueness – the large proportion of our fat that is distributed subcutaneously (as opposed to being disbursed within our abdominal viscera). Cartmill made a compelling case that the human pattern of subcutaneous fat is associated with bipedality, and thus that some of the human-specific aspects of skin may actually go all the way back to the origin of the hominin lineage.
In other foot news, Jeremy DeSilva talked more about the enigmatic foot and ankle bones of the Australopithecus sediba material from Malapa, South Africa. In Jerry’s view, the anatomy of the ankle and foot of this specimen is most consistent with the idea that this specimen (and possibly the species) was a biped prone to hyper-pronation.
Paul Constantino gave a paper (co-authored by Matt Skinner) attempting to determine the dynamics of maximum hominin bite force based on dental fracture properties. An interesting approach to the question that generated a lot of questions for me (in a good way).
Friday morning’s paleoanthropology session saw a whole series of talks about fossil footprints. Sarita Morse gave a really wonderful talk on the challenges associated with reconstructing morphology and gait from footprints by looking at experimentally derived intra-individual variation in footprints across a variety of substrates. Her talk was followed by Kevin Hatala and Heather Dingwall, in separate presentations, talking about the early Pleistocene footprints from Ileret, Kenya.
Lauren Schroeder, a graduate student at the University of Cape Town, gave a presentation on a topic near and dear to my heart, mandibular variation in early Homo. Only she looked at this variation from the perspective of the new fossils from Malapa, South Africa, designated provisionally as Australopithecus sediba.
Martin Haeusler suggested that the primary sign of pathology in the spine of the Nariokotome skeleton is evidence of a severely ruptured lumbar disc. If true, the Turkana Boy probably had severe and potentially debilitating back pain for at least his final six months of life.
In my presentation I presented a comparison of growth patterns between the Nariokotome speciman and the two Dmanisi partial skeletons. I focused particularly on the difference in crural index between the two samples. Despite putting together the talk for some time, it was only when I sat down, and immediately upon sitting down, that I realized how I should have humorously summed up my results – Dmanisi has a short lower leg because of some combination of being old, cold, underfed and overworked. Oh well…maybe next time I’ll focus on the humerus.
Tonya Smith attempted to sort a whole set of enigmatic late Pleistocene teeth from SE Asia on the basis of the internal and life history dental characteristics. Paleoanthropologists face a unique challenge in this part of the world because of the co-occurrence and similarity between human and orangutan molars.
In the final talk of our session, Linda Van Blerkom talked about reconsidering traditional perspectives on human infectious disease. Often, such diseases are thought to be of recent evolutionary origin, coinciding with population expansion associated with the advent of agriculture. Using genetic data from humans and these infectious agents, Van Blerkom pointed out that most of these infectious diseases actually have a much longer evolutionary history with humans, though they existed as persistent rather than acute illnesses prior to human population expansion at the end of the Pleistocene.
In one of the few non-Paleo talks I attended, Diane Doran-Sheehy talked about some of the misconceptions that exist about gorilla demographics owing to the fact that most of our data come from long-term studies of Eastern mountain gorillas. Long term studies of these gorillas has given the impression that gorillas progress through life history stages relatively rapidly for an ape, including short inter-birth intervals and low levels of infant mortality. More recent field studies of Western gorillas, though lacking the same study duration, suggest the Eastern mountain gorillas might be outliers and that other gorilla groups have higher mortality, longer inter-birth intervals and a slower life history progression.
There were many many other fine presentations and events, but I will leave those for other conference attendees. Thank you, Portland!
