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How a New Species of Ancestors is Changing our Theory of Human Evolution: Juliet Brophy

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Juliet Brophy

Juliet Brophy – TED Talk TRANSCRIPT

Human origins. Who are we? Where do we come from, and how do we know?

In my field, paleoanthropology, we explore human origins — the “who” and “where” questions — by analyzing fossils that date back thousands and even millions of years.

In 2015, a team of colleagues and I named a new species in the genus Homo — our genus — Homo naledi. Let’s take a step back and put that into context.

The last common ancestors between humans and chimps date somewhere between 6 million and 8 million years. The earliest hominins, or earliest human ancestors, evolved into a group known as the australopithecines. The australopithecines evolved into the genus Homo and eventually modern humans — us.

With each new fossil discovery, we get a little bit closer to better understanding who we are and where we came from. With these new fossil finds, we realize we now have to make changes to this tree.

Until this discovery, we thought we had a pretty good idea about the patterns of evolutionary change. Current fossil evidence suggests that the earliest populations of the genus Homo evolved in Africa somewhere between 2 million and 3 million years.

Fast-forward to approximately 300,000 years to where we see the origins of the first modern humans. While the fossil record between these time frames in Africa is relatively sparse, the fossils nonetheless demonstrated certain trends from our earliest ancestors to modern humans.

For example, our brains were becoming larger relative the rest of our body. Our pelves were becoming more bowl-shaped, and our hand-wrist morphology, or form, suggested a change in our grip as we began to make and use stone tools and spend less time in the trees.

These new fossils disrupt everything we thought we knew about these trends and force us to change the way that we think about human evolution. South Africa in general, but the Cradle of Humankind in particular, contains numerous sites where hundreds of thousands of fossils have been found.

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As an undergraduate student, I fell in love with one of them. Mrs Ples. The skull of a 21-million-year-old early human ancestor. From that point on, I was determined to go to South Africa and study human evolution.

I first traveled there in 2003, and I did get to see my beloved Mrs Ples. But words can hardly convey my excitement when I was chosen as an early career scientist by Lee Berger, a world-renowned paleoanthropologist, to be one of the primary analysts of recently excavated unpublished fossils.

This treasure trove of fossils was being recovered from a new site called the Dinaledi Chamber in the Rising Star cave system. Species are often named based on a skull, a lower jaw, or, very rarely, a handful of postcranial, or below-the-neck, elements.

The fossils from Dinaledi were another story altogether. An unprecedented approximately 1800 specimens — so far — have been excavated from the Rising Star system, representing at least 15 individual skeletons.

The research team that I was invited to join was tasked with describing, comparing and analyzing the fossils, with the difficult goal of identifying to what species the fossils belonged. We were divided up into our different areas of expertise. We were divided up in different areas of the lab, too.

So there was “Hand Land,” for the fossil hand people, “Hip Heaven” for the pelvis. I was in the “Tooth Booth.” And after long, intense days in the lab, the different teams would meet up at night and discuss our findings, still consumed by questions from our analyses. It was incredible how different the interpretations were. Each body part seemed to come from a different species, based on what we knew from the fossil record.

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