Basing quality-of-life estimates on average life expectancy at birth warps our view of pre-modern life:
For Neanderthals and other pre-modern humans life was short and brutal primarily because they had to kill animals with handheld weapons at close range. Neanderthals who survived into their thirties looked like they had been pulled out of a Humvee that was hit by an IED. One fellow was missing an eye, an arm, a thumb and a foot! These guys suffered from no known diseases. However, their main food [according to chemical analysis of their bones] was the auroch — basically a rodeo bull — which they had to kill be wrestling with it, stabbing it, and smashing it with rocks!
For a Neanderthal 35 years old was as old as it is for an NFL running back or a lightweight boxer. If one imagines a world where such athletes were executed at retirement, and that all men were such athletes, you get a good idea of the climate for thirty-something folks in the Old Stone Age.
Mature Stone Age hunting and gathering societies, which had not yet invented alcohol, and which did not live with disease bearing domesticate animals, and did not engage in repetitive chores that wear away their connective tissue, produced healthier warriors and women than more technologically advanced societies until the 20th Century. Although few men survived to old age due to constant small scale warfare, male leaders and women living into their 70s was common. As with other apex predators, like lions, most of a primitive’s day consisted of leisure activities.
Agriculture caused people to live in one place, which encouraged disease. With the addition of domestic animals living in close proximity, humanity acquired the measles, all the pox diseases, and venereal disease [don’t ask how]. The result was that few children lived to age five. This is reflected in the fact that many societies did not name children at birth, and that children were seen as a burden until they were able to engage in the horrid economy which the adults were shackled to.
An agrarian man typically worked from sunrise to sundown doing a small cluster of repetitive motions, resulting in a terribly worn body by about age 30. The woman had it no better, on her knees grinding grain all day long, and becoming arthritic before age 30.
This was a nasty way to live, so conquerors lived according to the more ancient primitive tradition. The apex of the population — the nobility and royalty, being the top 5% — continued to live as primitives, hunting and fighting and enjoying leisure time, and making all of those great scientific, literary, artistic, and military advances.
The common agrarian person was a machine, a brute who ate, worked, shat and died in misery, and was regarded as subhuman by his masters, who lived, essentially, as a primitive warrior class.
Note that the age of majority has always been based on man’s prime as an athlete or war fighter. Ancient Greek warrior-athletes, Roman soldiers and medieval knights were not considered fit for combat until age 21, and were regarded as pretty well shot by 40. This has not changed, with modern boxers and football players considered subpar until age 22 and over the hill by age 35. Likewise, various social rights, such as firearms licenses, drinking privileges, voting rights, and military service, have typically not been granted until the 18–22 year age range. It has also remained nigh unthinkable for a head of state to be younger than 35 years of age. This athletic life span corresponds with the hunting life span of the Neanderthal auroch hunter.