> primitive cultures live[d] as long as we do

BTW, an extremely minor point: I intentionally used present-tense because primitive cultures still exist.

Well, any culture existing today is by definition a modern culture. But, more substantively:

There are no cultures today which are comparable to primitive cultures of the past. One nice point I've seen made is that when hunter-gatherers were the rule, they could live on arable land. After the advent of agriculture, obviously, that became impossible.

> This means that life expectancy was short.

Surely you know what I meant. If you made it to middle-age you lived just as long.

The highest age was about the same, but they were more likely to die at every age than we are today. A 40 year old still could expect a shorter average life than a 40 year old today.

> The highest age was about the same

That's not what I took away from the article, but I could be wrong. That wouldn't be anything interesting to discuss or write about.