The title is tongue in cheek, some researchers now are suggesting that speciation may be proportional to a particular energetic value. R.A. Fisher wanted an "ideal gas law" for evolutionary genetics, but this is ridiculous! In any case, one issue that many of us who are interested in paleoanthropology will have noted is that Africa seems to have been the repeated mother of hominid species. That is, "erectus" left around 2 million years ago, only to be swept aside by moderns around 50,000 years ago. Why Africa twice? This might be part of the answer, and is a flip to WIlliam H. Calvin's Ice Age driven hypothesis in A Brain for all Seasons.