They are just crazy claims to flog a book. The findings are not exactly scientific in any way so it's hard to say it's anything more than an interesting idea. The whole article is mostly based on anecdotes and inferences. Take the footprint thing for example. There are a whole bunch of assumptions in that measurement: they could have been taking longer strides or bounding at that particular time, or the hunter could have been taller than 6'5'' (there is always an error associated with estimating physical dimensions from fossils). Any of which would throw the estimations way out, so it's hard to take his claim that they'd beat Bolt seriously on such little evidence. The historical anecdotes about the rowers could have been wildly exaggerated, there's no way of knowing how fast they really went.
It annoys me too when anthropologists think they are also evolutionary biologists as well and make stupid statements like the one about "highly aggressive men" go to jail or get killed earlier and exclude themselves from the gene pool. That's not an example of a selective pressure. A selective pressure would be if the majority of "highly aggressive men" were wiped out before reaching reproductive age. Then you would definitely see a noticeable change in the gene pool. But I doubt it's the case that the majority of "highly aggressive men" are being killed in gang wars or in Iraq. It's just a vague hypothesis with no evidence to back it up.
