New research reveals longevity gains slowing, life expectancy of 100 unlikely

Genetics required. Natural evolution has zero interest in old people, so there has been no evolutionary pressure to extend lifespan. Possibly even the opposite.

We could apply that pressure, either through selective breeding over generations, or through direct genetic modification. Maybe we aren't quite there yet, but it won't be long.

Experiments on insects with selective breeding have easily tripled lifespans. How well that would transfer to mammals is hard to say, but a substantial increase is certainly possible.

In modern society there is little evolutionary pressure to extend lifespan, but that's a very recent phenomenon. If my parents watch my kids and do the cooking so I have more time to hunt or work the field that improves the survival chances of my children, and my children share 25% of their DNA with their grandparents. The grandparents living a long productive life is good for the survival of their grandchildren, and thus for the reproduction of their DNA, causing evolutionary pressure. It's mostly the unproductive years (dementia, debilitating illness, severely limited mobility) that are a detriment.

You could argue the same forces are still at play at societal levels. People around the age of 50 have a vast economic impact, having accumulated experience and relationships over many decades. And the average age of soldiers in Ukraine is somewhere around 40-45. If one country had a population that stayed at the mental and physical fitness of a 50 year old for another 20 years that would be a drastic advantage, both in terms of skilled workforce and in terms of military capability. Even just another 5 productive years are a big deal in a world where the time you spend productively working is about twice the time you spend "growing up" and getting an education. And my nation doing well means my children can afford more children, spreading my DNA, making it favored by evolution