In the natural world, litters are large because overall survival is low. Offspring that make it to adulthood are tough and long-lived.

It takes a bit of traveling and living in countries where childhood mortality remains high to understand what pharmacological intervention can mean.

And global travel also means that diseases still taking a high toll on life and vigor abroad will always be brought here too.

Civilization has its fault but going back to the paleo lifestyle and thinking it's the Garden of Eden is greatly delusional in the scheme of things.