Anthropology.net

EurekAlert is running a very interesting press release on the discovery of a 500,000 year old Homo erectus fossil recovered from Turkey. Apparently the fossil, a fragment of skull bone, shows lesions that the individual had tuberculosis.

Tuberculosis is a deadly infectious disease caused by multiple strains of mycobacteria. Because the mycobacteria have lost numerous coding and non-coding regions in its genome, it is hard to retrace the genetic differences that would tell us of the origins, relationships, and movement of the disease causing pathogen. But through analyzing relatively modern human skeletal remains (I’m talking thousands of years modern) from Egypt and Peru, we know that tuberculosis was taking a big toll on humans relatively recently in our evolutionary history.

If this Homo erectus really did have tuberculosis, then that means he probably, and other hominids, got sick because his body produced less vitamin D due to darker skin and had a less vigilant immune system, hundreds of thousands of years ago. From what’s reported in the press release, I don’t buy it. And neither does John Hawks. I think it is over analyzed and sensationalized science to make big headlines.

I really don’t understand why a Homo erectus from Turkey isn’t enough of a killer headline. To my knowledge this is the first hominid found in Turkey and it fills a big spatial gap in understanding human evolution. Of course, I really don’t know enough about the tuberculosis evidence in this individual to make a solid judgment… we’ll have to wait until we get the paper…

Speaking of which, paper should be out anytime soon in the American Journal of Physical Anthropology, so the entire details of the fossil aren’t known to us until the AJPA decides to give the green light and publish the paper. I have, however, discussed this press release with several colleagues and they are all skeptical.

The first thing they are curious about is the date. We speculate that dating was established using faunal evidence. The problem with that is the faunal composition of Turkey during the Pleistocene isn’t well known. Sure, the late Miocene is, and that’s cause there are a lot of Miocene sites… but at 500,000 years ago it is hard to correlate a date to what organisms were around at the time.

I also got word that John Kappelman, and his team damaged the fossil. I don’t know if it was during excavation, transportation, or curation/research, but having rumors run around that your team damaged the first ever Turkish hominid isn’t something the bolsters ones reputation in the field. But again, take this with a grain of salt… it is a rumor. There aren’t any official reports that his team actually broke the fossil, and if Kappelman’s not really liked, I can see how people will start up these things. Physical anthropologists are a catty bunch. But to be really honest, I can’t help but think the tuberculosis is a smokescreen to distract attention from this broken specimen.

Anyways, just reporting on this new paleoanthropology paper… be sure to keep checking the AJPA for the paper, and check out Razib’s post as well.

Lucy that little australopithecine which we also know as AL 288-1 is quite possibly the most popular fossil hominid known. Her remains have sparked lots of controversy lately, which shows how important and impactful this 3 million year old is to the field of paleoanthropology as well as popular culture. To feed into the pop culture craze, Norbert and Liberatore have created a graphic novel titled, “Lucy.” The site is in French and I don’t know French, so I can’t really give you more information other than that.

Judging from the sample pages the authors put up, the illustrations look very well done. The story line and page layouts remind me less of a graphic novel like Maus or Persepolis and more of the Marvell comics I read as a child. Curious to see an example? Check this one out.

The 29th edition of the anthropology blog carnival Four Stone Hearth is now up at Remote Central, so thanks very much to everyone who submitted content for it, and I hope there is plenty of interest for everyone to read.

The next edition of 4SH will be at The Greenbelt, two weeks from now on December 19th, which would make it the equivalent of the Christmas 2007 edition, as well as being the last one for this year, so if you wish to submit content you can do so by following this link: submit@fourstonehearth.net, or indeed by submitting direct to the host site.

I have been really anticipating the following study. The first press releases came out in March and in October, I introduced it here. It seems like the paper is finally ready to be published, but we still gotta wait until PNAS puts it up on their early edition section. It should be soon but I really can’t wait any more! It is almost torturous how PNAS teases us with press releases for such a long time prior to the actual publication being released. So in the mean time, I’m gonna have to make you suffer thru an extension of my October introduction.

The study ultimately originates from Jean-Jacques Hublin, director of the Human Evolution Department at Max Planck Institute for Evolutionary Anthropology in Leipzig. But the team of co-authors are an international group who studied growth patterns in Neandertal teeth. Similar to the rings around a tree are these unique growth lines both inside and on the surfaces of teeth that can be counted to estimate age and developmental stage at death. This form of tooth analysis is called dental anthropology.

As an undergraduate, I was friends with several graduate students at my anthropology department were studying this aspect of physical anthropology. My friend Josh studied animal teeth, specifically deer teeth, from archaeological sites to estimate the time of year that hunting took place. If I remember correctly, Vicki Wedel and Chelsey Juarez have also both used this form of analysis to estimate the age of human remains found in a forensic context.

The new study applies dental anthropology in a paleoanthropological context; Neandertals were analyzed to study their growth developmental patterns in comparison to humans. In October, only four hominids were reported in the analysis the Nean dertals from Le Moustier and Krapina and the early Homo sapiens from Qafzeh and Jebel Irhoud. In a press release issued today, the Scladina Neandertal child is also included in the study.

Here’s an excerpt of the most important result so far,

“The Scladina juvenile, which appears to be developmentally similar to a 10-12 year old human, was estimated to be in fact about 8 years old at death… The Scladina Neanderthal grew teeth over a shorter period of time, and has more teeth erupted… than similarly-aged fossil or living humans (Homo sapiens). This suggests that other aspects of physical development were likely more rapidly achieved as well, implying significant differences in the behaviour or social organization of these ancient humans. This pattern of development appears to be intermediate between early members of our genus (e.g., Homo erectus) and living people, suggesting that the characteristically slow development and long childhood is a recent condition unique to our own species.”

So Neandertal growth and development was much more accelerated than modern day humans. Very interesting conclusion. The following two tables document standard patterns of tooth development in modern humans, they were reconstructed from pages 32, 45, and 53 of Ash & Nelson, Wheeler’s Dental Anatomy, Physiology, and Occlusion. Note, this is not a fixed pattern for all humans, but rather a compilation of average times of tooth development. For example, my third molars (wisdom) teeth were completely developed and erupting when I just turned 14. This table says the norm for wisdom tooth eruption is 17-21 years of age.

So clearly my developmental pattern was ahead of the game as far as my wisdom teeth goes. What if that was the case then for this Scladina Neandertal? What if it was like me and developed its teeth faster? This here in lies the problem with limited samples. Sure, I don’t yet have the publication to see exactly how large the sample size was, but without large numbers (n = to 100 or larger) it is hard to get an accurate representation on what’s the normal accepted values for tooth variation. I know there ain’t that many juvenile Neandertal fossils as of yet.

If Neandertals were anything like us, and the genetic, archaeological, and skeletal evidence shows they were more similar than not, surely they a lot of variation that would affect the rates of development and life history… Just something to think about before the paper comes out.

One last thing, here’s the running title and citation to the paper,

“Rapid Dental Development in a Middle Paleolithic Belgian Neanderthal”
Tanya M. Smith, Michel Toussaint, Donald J. Reid, Anthony J. Olejniczak, Jean-Jacques Hublin
Proceedings of the National Academy of Sciences USA December 2007

This week, we saw a short paper in Science on Paranthropus robustus sexual dimorphism and the implications the differences between sexes had on this early hominid social behavior. Here’s the title and a link to the original publication, “Extended Male Growth in a Fossil Hominin Species.”

Sexual dimporphism is what scientists use to define the differences between male and female body sizes and anatomical variation. In great apes like gorillas and orangutans, there is a large degree of sexual dimporphism. Males are physically much larger, for example, some male silverback gorillas are twice the size of female gorillas. Male gorillas also have pronounced sagittal crests and other skeletal features that support larger bodies. Chimpanzees and bonobos do not exhibit sexual dimporhism to the degree gorillas and orangutans do. They fall more in line with humans. Most modern day human skeletons have finite differences that aren’t really cut and dry, but almost all male ape primates have two periods of growth and development during adolescence, one prior to females and one after female adolescence development wraps up. This is understood as an adaptation to complete growth after all the competition has passed its prime.

As the binomial name implies, the specimen analyzed in this last week’s issue of Science, Paranthropus robustus is a robust australopithecine. Robust means it has a lot of pronounced features, and this species makes for a great example to study robusticity because there’s a lot of Paranthropus fossils.

There is some really ignorant press that confused Paranthropus robustus as a human ancestor, such as this National Geographic News headline, “Early Human Ancestors May Have Had “Harem” Societies.” This headline is not particularly true. True, these australopithecines were bipedal and succeed after Australopithecus afarensis and africanus. A branch off of the Australopithecene lineage most likely gave rise to early Homo, but the current consensus among plaoeanthropology is that the Paranthropus lineage did not. Another separate australopithecine lineage gave rise to the Paranthropus genus.

Furthermore, all known P. robustus fossils are not older than 2 to 2.5 million years ago, which means they succeeded A. africanus and appeared after the Homo lineage already diverged. I’d like to clarify that not everything hominid is directly related to humans. For all we know now, we can only say that
the Paranthropus genusshared a commn ancestor with humans. So keep that in mind as I review this publication.

This study used 35 P. robustus specimens from Swartkranns, Kromdraai, and Drimolen sites in South Africa. Like I mentioned in the paragraph above, the deposits these fossils came out from are no older than 2 million years ago and no younger than 1.5 million years ago. The authors limited their pool of specimens to analyze into three criteria. The fossils had to show evidence that the last molar tooth had erupted. M3, the last molar, usually coincides with adolescence, a time during life history where sexual differences manifest while the primate undergoes puberty and sexual maturity. Other logistical criteria included having sufficient parts of the fossil fragments to make a complete analysis. Ultimately 19 face fragments, most of which came from Swartkrans and most of the 16 jaw fragments also from Swartkrans were studied. In the sample there were about 29 males and 6 females P. robustus represented, which they account for because males were less shielded from predation than females.

The amount of wear on each specimen’s teeth was studied to estimate the ages of the individuals at the time of death. The authors state that they had a sample that represented ‘nearly every stage of dental wear from young adulthood to old age.’ The authors make note of an observation that the P. robustus males exhibited a bimaturation pattern, and older males were much larger than the younger males.

They authors go onto infer how the differences in the pattern of development in P. robustus males and females represent gorillas and not really other australopithecines. The pressed loved this, eating it up and spitting it out to the public that early hominids had harems much like a male silverback does. I’m not too certain about that, it is a strong possibility that’s the case. The adaptionists understand this is an excellent reproductive and evolutionary strategy, larger the male the more he can dominate females as well as thwart out competition from other males. That’s how silverbacks do it, and other animals such as lions, elephant seals, etc.

But I’m not completely sold. I’m uncertain about this all because one of my undergraduate professors, Dr. Adrienne Zihlman, instilled a lot of uncertainty in me about sexual versus species differences, especially in australopithecines. She argued that lots of the robust australopithecines, such as P. robustus can represent only the males of the species while the gracile ones represent the females. Ultimately, she was saying what we maybe calling different species could be just the differences between males and females. If you ever seen male and female orangutan or gorilla skeletons, and didn’t know who was who, you could divide them up into 4 different species. For this reason, I’m not sold that P. robustus was harem like, I do agree that the authors made an astute observation that there is a bimaturation processes in the 29 of the specimens analyzed. That’s about all I feel comfortable with settling on.

Thanks to the evolution of the eye, the invention of the written word, and a nifty application called the Internet, there will be a new edition of the blog carnival Four Stone Hearth appearing at Remote Central, some time on Wednesday morning, December 5th.

There’s still plenty of room in the in-tray for submissions of content, so please feel free to send material along to either submit@fourstonehearth.net, or directly to me at Remote Central.

Material can either be that which has manifested itself upon your screen via tapping away at your keyboard, or simply something you’ve seen elsewhere and consider a worthwhile contribution to the blog carnival.