From ScienceDaily:
Dr. Barr used computer simulation to model what the fossil record might look like over time in the absence of any climate change and found clusters of species originations that were of similar magnitude to the clusters observed in the fossil record. This means random patterns are likely under-credited for their role in speciation fluctuation, he said.
Dr. Barr’s findings mean scientists may need to rethink widely-accepted ideas about why human ancestors became smarter and more sophisticated.
“The idea that our genus originated more than 2.5 million years ago as part of a turnover pulse in direct response to climate change has a deep history in paleonthropology,” Dr. Barr said. “My study shows that the magnitude of that pulse could be caused by random fluctuations in speciation rates. One implication is that we may need to broaden our search for why our genus arose at that time and place.”
…
This research challenges scientists to be careful about the stories they tell about the history of human adaption, Dr. Barr said. Traits that make humans different from our ancestors, like larger brains and greater technological sophistication, could have arisen for a variety of reasons, he said.
“We can sit in the present and tell stories of the past that make sense of our modern day adaptations,” he said. “But these could have evolved for reasons we don’t know.” Paper. (paywall) – W. Andrew Barr. Signal or noise? A null model method for evaluating the significance of turnover pulses. Paleobiology, 2017; 1 DOI: 10.1017/pab.2017.21 More.
We’ll see. The advantage of just-so stories (“stories of the past that make sense of our modern day adaptations”) is that they allow us to imagine that we know things we really don’t.
See also: “The evolutionary psychologist knows why you vote — and shop, and tip at restaurants”
and
What we do and don’t know about human evolution