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Sunday, July 24, 2011

Granny power: Why grandparents ensured human survival

Older people are important in establishing kinships and would have been essential to survival

Last updated at 4:02 PM on 24th July 2011

Reaching 30 may not seem old by today's standards but a sudden rise in the number of people hitting that age some 30,000 years ago had a profound impact on mankind.

The 30-year-olds created a generation of grandparents who now offered a level of knowledge which could now be passed on to the younger generation.

This led to a dramatic cultural shift which resulted in better food production, the creation of more complex tools and weapons as well as artistic expression.

Survival: Grandparents passed on skills such as tool-making and water supplies allowing their offspring to survive for longer

Anthropologists say grandparents passed on tips about poisonous food and skills such as tool-making and water supplies allowing their offspring to survive for longer.

After studying the Hadza hunter-gatherers of Tanzania, Kirstin Hawkes of the University of Utah proposed that grandmothers played a significant role in the evolution of homo- sapiens.

According to the Observer she said: 'Good foraging grannies mean healthy Hadza kids - and that was also true of our ancestors.'

She argues that when a female occasionally lived longer, she would would help her daughter with their children, to dig and forage for food.

This would enable the daughter and children to thrive and the genes for longevity were passed on.

Gran knows best:Good foraging grannies played a significant role in the evolution of homo- sapiens

Professor Rachel Caspari of Central Michigan University said grandfathers also played a vital role and the surge in the numbers of elderly humans triggered a cultural explosion.

In the current issue of Scientific American she said: 'Living to an older age had profound effects on the populations sizes, social interactions and genetics of early modern human groups.

'And may explain why they are more successful than other archaic humans, such as Neanderthals.'

By analysing teeth, scientists could determine the age at which ancient humans died.

A significant difference was discovered between Homo-sapiens - who evolved in Africa and migrated to Europe 30,000 years ago -and Neanderthals who were in Europe before them.

Caspari states: 'For every 10 young Neanderthals who died between the ages of 10 and 30, there were only four older adults who survived past the age of 30.'

But for every 10 young adult members of Homo-sapiens who died, there were 20 who had reached 30 or older, a fivefold increase.

Professor Chris Stringer of London's Natural History Museum said this effect would have been profound.

He said; 'Older people are important in establishing kinships.

'When it came to disputes over access to water holes or to land rich in game, the elders there were able to remember distant relations in other tribe, the easier it would have been to negotiate and share resources.

'Older people would have been essential to survival.