More People in Love Than Previously Thought

[Blind groper]

[Given that for most of human history, humans typically died within 10-15 years after first being able to impregnate each other, the idea of "long lasting love" was probably not as applicable. You fuck and get pregnant at 14, have the baby, and die of rotten teeth at 27, just in time for the child to about reach maturity. They fuck, procreate, and die 13 or 14 years later of an infected wound from the bite of some random animal.

Not true.

Many primitive human societies have short average life spans. Emphasize the word 'average'. The reason is due to high mortality of babies, and high mortality of children. The longer those primitive people lived, the longer they could expect to live.

If a person made it to reproductive age, there was a very big chance they would make grandparents.

[Coito ergo sum]

[Given that for most of human history, humans typically died within 10-15 years after first being able to impregnate each other, the idea of "long lasting love" was probably not as applicable. You fuck and get pregnant at 14, have the baby, and die of rotten teeth at 27, just in time for the child to about reach maturity. They fuck, procreate, and die 13 or 14 years later of an infected wound from the bite of some random animal.

Not true.

Many primitive human societies have short average life spans. Emphasize the word 'average'. The reason is due to high mortality of babies, and high mortality of children. The longer those primitive people lived, the longer they could expect to live.

If a person made it to reproductive age, there was a very big chance they would make grandparents.

Err, very true, because it wasn't only infant mortality rates that were high (although they were staggeringly high). There was also very high child mortality rates, very high adolescent mortality rates and very high adult mortality rates. And, there were many more things that killed even young adults that we take for granted now -- teeth, for example, were huge killers, and folks who now get routine root canals and impacted teeth removed would very often just die back then. Small wounds would get infected and kill people at very high rates. A broken ankle would often be a killer. A bad cut was often a death sentence.

While some folks would no doubt make to what we consider to be old age now, the numbers would be far, far fewer then than they are now..

[Blind groper]

Coito

Of course the ones who make it to old age are fewer than today.
However, once a person reached reproductive age in that society, the worst dangers were behind them, and there was a high chance of reaching a reasonable age.

You failed to mention two of the major killers in maturity. Women dying in childbirth and men dying in intertribal warfare. Yet even with all those, after reaching reproductive age, the chances of reaching grandparent age are a lot more than 50% in most primitive societies.