"In four of the biggest climatic-vegetational events of the last 50 million years, the mammals and birds show no noticeable change in response to changing climates. No matter how many presentations I give where I show these data, no one (including myself) has a good explanation yet for such widespread stasis despite the obvious selective pressures of changing climate. Rather than answers, we have more questions—and that's a good thing! Science advances when we discover what we don't know, or we discover that simple answers we'd been following for years no longer work."-http://www.skeptic.com/eskeptic/12-02-15/#feature-
But human development continued following climate we think.