> The author may have hit on the answer without realizing it. He's in the gym doing pull-ups. Is his lat strength necessary for some important part of his survival? Highly unlikely. Pre-20th century, when most work was highly physical, would he have gone out after work to research and test out efficient lat exercises? Probably not either.

Yeah but don't you kinda proof his point though? When we all created machines to do all the manual labor for us we got fat and unhealthy. Only recently we've really began to understand how important excercise (manual labor) is for us.

I fear that the obvious result of a laissez-faire attitude is that in 20-30 years we find out that there was actual benefit of using our mind, reading, writing, etc.

In the case of our muscles, we were lucky that we didn't need those to identify the health benefits of excercise and we could come up with a solution. In the case of our brains, we might not be as lucky, so maybe be prudent and assume it's something that's beneficial?