Yes, we might have different stresses as a species now, but I'm not sure we have any more stress than we had thousands of years ago.
The less snarky remark would be that Robert Sapolsky has done plenty of research on stress responses in primates and found that the single largest predictor of high stress responses is inequality, which our modern times do seem to generate in abundance.
> anthropologists have found that hunter-gatherers tend to have significantly more leisure time than people in more complex societies.
Perhaps being able to think doesn't help much when it comes to happiness. Thinking is useful practically but it's as if you have to suppress it in order to experience happiness.
You should read a bit about their sex lives...