We have covered an enormous time interval during the past weeks, from 7 million year old Sahelanthropus to the appearance of Homo erectus/ergaster/georgicus some 1.8 million years ago. We are getting closer to Homo heidelbergensis, Homo neanderthalensis, the Denisovans and Homo sapiens!
Homo erectus was first found in Asia more than 100 years ago, and much later in Africa, where it was named Homo ergaster. However, the African Homo erectus/ergaster finds are around 1.6-1.7 million years old, and thus much older than the finds in Asia, suggesting that Homo erectus was the first to leave Africa and to populate Asia. Interestingly, discoveries that have been made at the site of Dmanisi in Georgia suggest that this early exodus must have taken place pretty early too. Finds of what the researchers call early Homo date to around 1.7-1.8 million years, and thus seem older than the African finds. However, the dating uncertainties for all the hominid layers are also large, which means that the ages of the African erectus finds and of the finds from Georgia possibly overlap.
What makes Dmanisi such an interesting site is that the five skulls that have been found there and attributed to early Homo (or Homo eegaster/erectus/georgicus) show larger variations in respect to brain volume and cranial anatomy and morphology, suggesting that the evolution of early Homo may have been more complicated than so far assumed. For those of you who would like to read a balanced view on the Dmanisi finds, I suggest the blog of John Hawks and also Adam Benton’s blog.
Below are a few other further reading suggestions on Homo erectus/ergaster/georgicus:
About stone tools and what they tell us about hominid behaviour.
About Homo erectus:
http://natgeo.se/daka-pa-var-sida-av-skiljelinjen (in Swedish)
About the most recent Dmanisi finds
Kunskapskanalen showed recently an interesting program about the tectonic history of Asia and part of the program dealt with Homo erectus and Homo floresiensis in Indonesia: where they were found and theories about how they reached Java and Flores. If you are not interested in how the Himalayas formed, or what causes earthquakes, the just start watching at 37 min 52 seconds!