Here we see yet another case of researchers viewing reality through evolutionary glasses, leading to bold interpolations well beyond the actual evidence.
Nothing in Darwin's mechanism guarantees humans will think rationally. Fitness might actually favor stupidity. For proof, look at the reasoning of people who believe in natural selection.
Is evolutionary theory just a very malleable and ductile idea, able to adapt to changing observations, or should it be described as a strong theory, powerful in its explanatory breadth?