Though the <i>average</i> life expectancy in medieval Europe (which is what he seems to mean by "in history") was about 40, people didn't only expect to live to be 40. Everyone considered the natural human lifespan to be the canonical 3 score years and 10. I.e. 70. They knew there was a good chance some accident or disease would nab them before that, but they didn't feel as if they were in a rush because they only had half as much time.<p>It's also an urban legend that "centuries ago" women matured earlier and had children in their teens. In the Amazon rainforest perhaps. In Europe the average age of marriage for women has been in the mid twenties for many, many centuries. Possibly back to pre-Roman times. The worse things were economically, the later the age tended to be.