A complete 1.8 million year old skull found from Dmanisi, Georgia could be evidence that early hominids are actually all members of a single species. Researchers published their analysis in Science today and argue that the skull’s combination of primitive and more evolved features, such as a small braincase (546 cubic cm) with a large prognathic face.., Similar morphological affinities with the earliest known Homo fossils from Africa, which make it difficult to classify by now accepted definitions of early hominid species.
This month in the Journal of Human Evolution, a new study on the teeth of the Dmanisi Homo erectus has been published. A site in the Republic of Georgia, Dmanisi has yielded a vast quantity of hominin fossils dating to approximately 1.8 million years ago—even an elderly individual without teeth. The discovered crania are remarkably well-preserved, and have given scientists the ability to look at our evolutionary history with higher resolution.
Based on the skeletal remains, how can we ascertain specifics about hominin diet? For this particular study, researchers used microwear analysis on two molars from Dmanisi. Microwear analysis observes the patterning left on teeth by components of specific diets. As one example, tough silicates in plants leave identifiable traces, as do other silica-based sands that end up being chewed.
Comparisons in wear patterns were made with Dmanisi H. erectus and African H. erectus as well as the genus Australopithecus and earlier Homo, to get an idea of where the Dmanisi hominins fit in on the spectrum of microwear diagnostic traits. These diagnostic traits include heterogeneity of the tooth surface, as well as complexity in the roughness of the tooth surface. To give you an idea of general evolutionary trends, Australopithecines typically had larger teeth and thicker enamel to break down tougher, lower quality foods. As later Homo emerged, teeth tended to get smaller and enamel thinner.
The results indicated that the molars of Dmanisi Homo erectus were very similar to African Homo erectus in general. However, there were also characteristics found to be consistent with other earlier hominin species. Overall the authors cautioned against drawing conclusions with such a small number of teeth, saying that meaningful statistical results are unattainable based on the sample size.
According to authors, the wear patterns on the Dmanisi teeth are indicative of hominins that exploited a range of foods. It seems then that versatility and not specialization is what defines H. erectus in both Africa and Europe. The ability to take advantage of a larger resource base is no doubt one of the factors that allowed the first hominins to spread out across such an expansive area.
By Matthew Magnani
Pontzer, H., Scott, J.R., Lordkipanidze, D., Ungar, P.S. 2011.“Dental microwear texture analysis and diet in the Dmanisi hominins.” Journal of Human Evolution 61:683-687.
National Geographic is running news that Erik Trinkhaus and others have published the findings of the oldest modern human outside of Africa, specifically in China. Not much is given on the locality and specifics of the fossil, but the article does state that the fossil mandible fragment and teeth are 60,000 years older than any other modern human fossil. That leads to some curious questions of interbreeding with other Homo species and curiosities about the presence of modern humans that did not ‘act’ modern… In other words, the archaeological record isn’t quite on the same page.
Hawks hasn’t posted on the paper and find yet, but he is quoted in the National Geographic article saying the mandible dimensions are within range of both Neandertals and modern human. Unsurprisingly, the Out of Africa theory is challenged. I still don’t know what to think of it all, the chin does look very robust.
The PNAS article is not yet published at the time of the National Geographic writing and me blogging this post. Seems like people are still jumping publication embargoes. I shouldn’t have to call out what a cheap shot it is to have sensationalist news getting out before the first hand reports do. I guess things will never change. So until I get my hands on the real paper, I’m just calling it as others are reporting it.
The controversies over the hobbits or Homo floresiensis just refuse to end. It seems that the hobbits might not be a Homo after all. I guess they found the index and ring fingers of the hobbits (Sorry, inside joke. Read this post if you want).
Homo floresiensis (LB1) skull. Photo from Science Museum.
Homo floresiensis, LB1, skull (left) and human skull (right). Photo from BBC.
Anyway, Peter Brown from the University of New England who first described Homo floresiensis said that he is considering of stripping the hobbits from the genus Homo. Brown and his colleague, Tomoko Maeda, said that the Homo floresiensis lineage possibly left Africa before the evolution of the genus Homo. Their paper had been accepted and will be published in an upcoming special Homo floresiensis edition of the Journal of Human Evolution.
I can’t wait for the paper to come out. In the meantime, you can read this article from The Australian.
Originally posted on The Prancing Papio.
A new genetic survey by Dr. Sarah A. Tishkoff of the University of Pennsylvania and her team has found that modern humans originated in an area between Namibia and Angola, on the coast of southwest Africa. Read the New York Times Article: Eden? Maybe. But Where’s the Apple Tree?
However, this harsh and inhospitable area is nothing Eden-like, they said. The origin of a species, like modern humans, is generally pinpointed to a place where its individuals show the highest genetic diversity. After comparing genetic data from populations around the world, the researchers pinpointed the population with the highest genetic diversity – somewhere on the coast of southwest Africa near the Kalahari Desert. The Bushmen or San people currently call this area their home.
The researchers have also calculated the exit point of modern humans that left Africa about 50,000 years ago. The exit point lies in an area of the African coast of the Red Sea. If the “Out Of Africa” theory holds true, this tribal group of about 150 people that left Africa at that exit point displaced other archaic Homo sapiens populations from different continents, giving rise to the current modern human populations.
Originally posted on The Prancing Papio.
The 7th Human Evolution Symposium, Hobbits in the Haystack: Homo floresiensis and Human Evolution was held yesterday at Stony Brook. Turnouts were great despite damp and rainy weather. Convened by Richard Leakey, the symposium was an all day event where researchers share their findings on Homo floresiensis. The highlight of the symposium is the first ever complete cast of LB1, or Flo and a host of Homo floresiensis researchers.
The symposium ended with questions and issues for discussion by Richard Leakey. Then, the floor was opened for general Q&A session with the panel.
“Accepting it (Homo floresiensis) will require us to rewrite the textbooks.” – William Jungers, Stony Brook University.
Here is a list of topic presented by speakers during the symposium:
- “Hobbits in context: life, times and death of Homo floresiensis” by Michael J. Morwood, University of Wollongong, Australia.
- “Digging up Hobbits: The Excavations at Liang Bua” by Thomas Sutikna, National Research and Development Centre for Archaeology, Indonesia.
- “Stone Tools and Hominins on Flores” by Mark Moore, University of New England, Australia.
- “Whence Homo floresiensis? Clues from the brain.” by Dean Falk, Florida State University.
- “Her Teeth Were Sharp, Her Gums Were Raw, and Spit Was Dripping From Her Jaw: The Little Things That Make Us Human” by Peter Brown, University of New England, Australia.
- “Why the Tiny Wrist Bones of a Hobbit Tell Us So Much About a Big Chapter in Human Evolutionary Theory” by Matthew Tocheri, Smithsonian Institution.
- “The Hobbit Shrugged: The Shoulder of Homo floresiensis and its Implications For Human Evolution.” by Susan Larson, Stony Brook University.
- “Can Island Dwarfing Explain Hobbit Body Size and Shape?” by William Jungers, Stony Brook University.
- “Virtual Hobbits and Health in Homo floresiensis” by Charles Hildebolt, Washington University in St. Louis.
A list of what Richard Leakey commented and asked during the symposium:
- We should be careful when using Lucy as model for comparison because Lucy is not representative of the genus Australopithecine in general.
- We don’t have Homo erectus feet in our fossil record. The fossilized foot prints that were found in Ileret, Kenya has been suggested that it was left behind by Homo ergaster, an earlier version of Homo erectus.
- There should be more discussion on the types of dating methods used on Homo floresiensis and the artifacts found in association with it.
- There should be more discussion and research to link lithic materials to the Hobbits, or Homo floresiensis.
- What were the geographic isolation of Flore? How did the Hobbits ended up in Flores?
- Were there large carnivores in Flores or lack thereof? Hobbits have ape-like feet that were built for walking but not for running. Did they survive despite that because they have no need for speed to get away from predators?
Originally posted on The Prancing Papio.