100%. I carried this misconception after high school and college and was surprised to learn it’s completely wrong. There’s a name for the old-age end of the bimodal distribution: longevity. Longevity is the natural lifespan of people who don’t die of any early mortality factors. Most people who have the misconception are accidentally conflating life expectancy with longevity. A few unscrupulous peddlers of false hope, like Ray Kurzweil for example, intentionally conflate life expectancy with longevity to reinforce the misconception. As I was learning about longevity I started talking to my anthropologist brother about it, and he was like, oh yeah, people who don’t die from war or disease or infection have always lived to be about 80 years old for all of known history. He mentioned there’s plenty of written evidence from, e.g. Socrates’ day, and also lots of human remains that support it from ten thousand years ago.
This is why life expectancy has gone up, while longevity has mostly remained unchanged (for at least thousands of years). Longevity represents the best we can do, and life expectancy can’t exceed longevity. Life expectancy will asymptotically approach longevity as medicine improves.
I think it's worth noting that we (in the west) have a lot less of most diseases and infections now, stuff like polio, plague, malaria.
I don't suffer from delusions that we have accurate data on conditions like obesity and T2D going back to the middle ages, but we have seen incidence rates of these kinds of disease explode upwards over the last century.
I'd be interested in more detailed data broken down by disease over time.
