First you have to believe that the guy is not totally fos. He doesn't help his case there, by comparing present day man to Neanderthal women. Neanderthal is generally accepted to be a separate species.

I am unconvinced that aborigines have ever been as fast as he claims

There is no doubt there is a big difference in life styles and how we develop these days but the risk is probably more that we become a caste species since a certain percent of males today are driven to develop themselves physically while others are admittedly inactive. I have seen other opinions that the original ancient Greek athletes don't hold a candle to today's athletes.

Evolution is not as simple as he seems to think.