HUMAN lifespan took a sudden leap about 32,000 years ago, allowing people to grow older and wiser, scientists revealed yesterday.
The five-fold jump in longevity may have been the key factor that shaped modern civilisation.
Before then, lifespan had steadily increased alongside thousands of years of human evolution, the study found.
But it took off dramatically in the early Upper Paleolithic Period, around 30,000 BC, when Homo sapiens was becoming established in Europe.
The American scientists believe there had to be a distinct evolutionary advantage to large numbers of people growing older.
On the one hand, it would have led to more disease and disability. On the other, it would have not only encouraged social relationships and kinship bonds, but also the passing of information from old and experienced individuals to younger generations.
This is the so-called "grandmother hypothesis". Experts have argued that grandmothers are useful because of the knowledge they hand on to their reproductive-age daughters, and their daughters’ children.
Longer survival would also have increased the number of years available for reproduction.
Together, these factors could have promoted the expansion of populations, creating social pressures that led to the growth of trade networks, increased mobility, and more complex systems of co-operation and competition.
One of the researchers, anthropologist Rachel Caspari, from the University of Michigan at Ann Arbor, said: "There has been a lot of speculation about what gave modern humans their evolutionary advantage. This research provides a simple explanation for which there is now concrete evidence: modern humans were older and wiser."
The findings, published in the journal Proceedings of the National Academy of Sciences, were based on a comparison of more than 750 tooth fossils from successive time periods.