I think it's unwise to assume, as this article does, that selection pressures are always exogenous. In fact, for group species, selection pressures are often endogenous. The human brain, for example, has been shaped by eons of competition with peers as much as it has been shaped by external environmental factors such as predators and food options. Today we see something rather interesting: for the first time in human history, mate selection does not primarily depend on proximity. This is resulting in people increasingly selecting on the basis of intelligence and shared interests. If this trend were to continue for a couple of thousand years (unlikely, as we will almost certainly accidentally self-inflict mass extermination due to our inescapable folly) it would result in speciation. Intelligence is highly heritable, and phenotypical differences are even today very obvious: people with lower IQs tend to be overweight and suffer the various obesity-related diseases we all know so much about; more intelligent people on average make better lifestyle choices. So fast-forward and we'd expect to see genetic differences between those who descend from lower-IQ parentage (for example, higher resistance to high levels of blood sugar) as well as increasing differences in genes that code for proteins associated with higher IQ. This is evolution in action.

Anyone who enjoys my articles here on Medium may be interested in my books Why Democracy Failed and The Praying Ape, both available from Amazon.