Humans vs. our 3.7 million year old ancestor: Not so different after all?
I love my degree (Zoology), but if I had to choose a different degree which I think I would enjoy equally it would be Biological Anthropology, otherwise known as the physical development of the human species or more generally human evolution. I am not alone in my fascination for this subject. It is shared with many people from our own species, all trying to understand who, what, where and when we came from. The modern technological revolution has resulted in a huge leap forward in genetics and computer simulation which has increased our knowledge in this area astronomically. This allows scientists to refine, and/or recreate previously used methods in a hope to increase the accuracy of their conclusions.
A paper recently published in the Journal of the Royal Society has used new methodology to show that the first known fully bipedal hominin footprints are 3.7 million years old – 1.8 million years older than previously thought. The research was carried out by scientists at the Universities of Liverpool, Manchester and Bournemouth. The footprints, (discovered in Laetoli, Africa) are much more similar to a modern human than expected. Using computer simulation the gait of these hominins can be recreated, and that too is very similar to modern humans.
The method of using footprints as a way to visualise the individual that left them is relatively new one but has revolutionised our understanding of early bipedalism in hominins. First, computer software creates a 3D image of the foot which left the footprint, which is then compared to modern human footprints. The software can also show where the most pressure is applied when making the print. This relates to the posture of the individual and so can also be useful in visualising the print maker. All this information is then brought together to identify the most likely printmaker based on what we already know about the morphology of past hominins. In this case the 3.7 million year old footprints were made by a member of Australopithecus afarensis. It was previously thought that A. afarensis used the side of its foot to walk but the pressure points identified show that was not the case. This research shows that A. afarensis actually used it’s big toe to push off from the ground, much like a modern human. Furthermore the early hominin had a much more upright posture than previously thought and had a gait very similar to modern day humans.
It is widely accepted that A. afarensis is a direct ancestor of the Homo lineage, and therefore a direct ancestor of modern humans too. As I discussed in my previous blog, research is been carried out to try and decipher what it is that makes humans unique. It was long thought the answer was our big brains, which resulted in our upright posture, which was our great advantage. However this research shows that at the time when the hominin lineage developed a big brain (2.4-1.5 million years ago), hominins had already been walking upright for at least 1.5 million years. As a result this quest to know what it is that makes us unique is still left wide open. What is clear is that modern humans have a passion to know things, in particular to know about ourselves and what we came from. The advances in technology are allowing us to take further conclusions from the evidence available to us and to learn from it. There is after all that old cliché: how can you know yourself without first knowing where you came from.