Evolutionary tree, Darwin’s notebook

Whether you like it or not, you are, in fact, my cousin. We can verify this through a couple of complementary lines of argument, one working forward in time, the other working backward. First, we know that all human beings comprise a single species, Homo sapiens. In 2005, Ian McDougall and colleagues reported in the journal ‘Nature’ that the oldest fossils belonging to our species were dated at 195,000 years old, and were discovered in Omo, Ethiopia. We all share this common point of origin as our lineages have intertwined and diverged over the last 8,000 to 9,000 generations or so.

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