they might have been healthy and tall
Gosh, I’d sure like to see some actual statistics on that.
According to Kevin Kelly in The World Without Technology, the reason why everyone in a HG tribe is healthy is because their life expectancy is so low that all their older and less healthy people are already dead.
I suspect that the informal nature of a talk might mean that one can describe things at an intermediate level of detail (“and so do this and that”) that would look strange in a more formal paper, and so writers feel that they’re stuck with either going into a full level of detail (which would be too much work to do for everything) or else saying “I’ll leave this as an exercise to the reader”… even though going into some detail would be more useful to the reader.