Evolution of legs in the trees

2 Feb 2013

Coming hot on the heels of the news that Lucy lived in the trees is another spike in the hide of the consensus hymn sheet. A new study questions some cherished beliefs central to the hypothetical, and uniformitarian, concept of how humans evolved from apes - from swinging in trees to walking on two legs. It took a lot of time. It involved small changes over loads of time. It involved habitat change and enforced adaptation ... and so forth. Basically, hominids are thought to have stood up on two legs in a savannah environ - peering over the long grass somewhat like a cheetah on the look out for lions. It is also a given and accepted factoid that humans evolved in the Rift Valley of Africa - the so called cradle of humanity. Now, a study of sediment cores and pollen analysis of the dregs and droppings comprising the sediments have produced some contrary evidence- upsetting the well oiled Out of Africa model. The shift to bipedalism is currently dated between 6 and 4 million years ago, a deduction derived from a variety of evidences. However, the shift from thick forest, the usual view of the primal condition of any landscape, appears to have happened much earlier - something like 12 million years ago. The sediments seem to imply East Africa was mostly a savannah environment with dry and light woodland here and there, seasonally important. It is at this point we note where the sediments were taken - the Gulf of Aden. Nowadays, winds dump sediment here from the surrounding regions, including the area in which the Rift Valley cuts its path. This research paper appears, from the news release, to run somewhat counter to earlier ecological studies in East Africa where it was posited a somewhat up and down climate had ensued - swinging between wet and dry periods and depending on the monsoon track. Perhaps too much is being drawn from the sediments - or the wind systems of today differ from the wind directions in the past. Actual evidence of a dry climate over 12 million years will now be hunted - and who knows if the micro climate deep inside the Rift Valley was perhaps quite different from that above and around the geological scar. See http://phys.org/print278859744.html