Humanity would fare just as well without its elders as it does with them, according to scientists.
The claims come as part of a study which found no obvious evolutionary need to live beyond the age of 50 in humans.
The discovery disputes the ‘grandmother hypothesis’, which suggests humans live long beyond their reproductive age because they care for grandchildren.
The theory also suggests that older members of our communities pass down important cultural knowledge that helps us survive.
Humanity would fare just as well without its elders as it does with them, according to scientists. The claims come as part of a study which found no obvious evolutionary need for genes that help us live beyond reproductive age (stock image)
GRANDMOTHER HYPOTHESIS
The new discovery disputes the ‘grandmother hypothesis’.
This suggests humans live long beyond their reproductive age because they care for grandchildren and hand down important cultural knowledge.
But researchers found no evidence that humans living beyond reproductive age benefits our species.
The scientists found no genetic evidence men evolve to live longer by virtue of being able to father children late in life.
They also found no indication that genes that promote women’s survival past the age of 50 are favoured by evolution.
But the latest findings suggest the scientific explanation for human longevity, which has been debated for decades, remains a mystery.
Dr Jacob Moorad, of Edinburgh University’s School of Biological Sciences, said: ‘Why we live beyond 50 has long puzzled scientists.
‘There are no obvious evolutionary benefits to genes that promote living in infertile individuals.’
In their study, the researchers analysed detailed family records of people born in Utah from 1860-1899.
This community, recently descended from the area’s pioneering settlers, had no birth control, meaning their data reflects natural fertility.
Researchers used the records to investigate three possible explanations for longevity in men and women.
They examined whether genes that aid survival or reproduction in early life might also bring benefits in later life.
They also looked at whether genes linked to elderly fertility in men might increase lifespan in women.
Finally, they examined whether having grandparents on hand to care for children might validate living into old age, developing the world’s first mathematical genetic model to describe this idea.
The discovery disputes the ‘grandmother hypothesis’, which suggests humans live long beyond their reproductive age because they care for grandchildren and hand down important cultural knowledge (stock image)
The scientists were surprised to find no genetic evidence men evolve to live longer by virtue of being able to father children late in life.
Instead, they found that genes which are beneficial to both early and late life are most likely the reason why men live past reproductive age.
The team found no indication that genes that promote women’s survival past the age of 50 are favoured by evolution.
Dr Moorad said the post-reproductive lifespan in women remains puzzling, as his team has thoroughly investigated all proposed evolutionary pathways.
He said: ‘We believe the most likely explanation for this absence is that one or more genetic correlations involving late-life female survival were positive in the past.’
Further studies, with additional population records, may help to shed light on the mystery of why women live to old age.
