The Journal of Human Evolution has released a new article in press announcing the discovery of a new archaic Homo sapiens specimen from Lake Eyasi, Tanzania. It is a rather modest paper, with no real ulterior motive underwritten… which I’ve come to appreciate. In the paper, the authors describe the geochronology and the morphology of the new fossil frontal bone (EH06).
This ain’t the first big paleoanthropological discovery from Lake Eyasi. The lake has yielded other hominid remains, the most famous of which is Eyasi 1. Prior to this new paper, these fossils could not be dated accurately. They resemble archaic Homo sapiens which places them somewhere in the later Middle Pleistocene and have some unique traits that are shared with Neandertals, like a suprainiac fossa. But, without a definitive chronological control, these fossils have been disregarded in regards to the temporal and spatial distribution of Homo sapiens.
So how old is this new frontal bone? Well the authors didn’t date the frontal bone itself, instead they sampled 5 wildebeest teeth from the same bone assemblage that the hominid frontal bone was found from. The authors used several dating techniques, like electron spin resonance and 230Th/234U — a method that calculates the time since uranium was deposited into the sample. Some of the samples had too much thorium in them to get an accurate date, but for some of them the authors were able to extract a date. Correlating these dates with the ones from ESR the authors were able to figure out that the wildebeest teeth and most likely the hominid frontal bone are 88,000 to 132,000 years old. This date coordinates with other archaic Homo sapiens fossils ages.
I won’t repeat the description of the fossil, because I don’t consider it as impactful as the actual geochronology. I will however post this gorgeous image of the fossil from the original paper.
With a date on this frontal bone, we now know a little bit more about the timing and spread of early humans within Africa.
- DOMINGUEZRODRIGO, M., MABULLA, A., LUQUE, L., THOMPSON, J., RINK, J., BUSHOZI, P., DIEZMARTIN, F., ALCALA, L. (2008). A new archaic Homo sapiens fossil from Lake Eyasi, Tanzania. Journal of Human Evolution DOI: 10.1016/j.jhevol.2008.02.002