‘Grandparent genes’ discovered by scientists: Grandparents are genetically programmed to care for their grandchildren

By Sarah Knapton, The Telegraph

Genes which ensure the survival of grandparents so that they can care for grandchildren and pass on wisdom to future generations, have been found by scientists.

Special gene variants, which appear in large numbers in humans, appear to protect against dementia and heart problems which means people do not normally suffer health problems until they are much older than other animals.

Scientists at the University of California, San Diego, believe that the genes ensure that grandparents survive so they can help out with childcare and pass down important knowledge.

Most animals do not live long after the age of reproduction ends because natural selection will always favour genes which boost reproductive success. Yet humans live decades beyond reproductive age, forming large family networks and taking on important roles.

Researchers have discovered that ‘grandparent’ genes evolved specifically to protect older adults against neurodegenerative and cardiovascular disease, and preserve their contribution to society.

"We unexpectedly discovered that humans have evolved gene variants that can help protect the elderly from dementia," said Dr Ajit Varki, Professor of Medicine and Cellular and Molecular Medicine at UC San Diego School of Medicine.

"Such genes likely evolved to preserve valuable and wise grandmothers and other elders, as well as to delay or prevent the emergence of dependent individuals who could divert resources and effort away from the care of the young."

To find out which genes were essential to longer life in humans, scientists compared genes in chimpanzees, our nearest relative, with those of humans.

They found that levels of a CD33 gene variant were four times higher in humans than in chimps. CD33 is essential for keeping the immune system functioning correctly and is known to suppress the sticky amyloid-beta which builds up in the brain, stopping neurons from functioning, in Alzheimer’s patients.

Researchers also found human-specific variations in many other genes involved in the prevention of cognitive decline, such as APOE.

"When elderly people succumb to dementia, the community not only loses important sources of wisdom, accumulated knowledge and culture, but elders with even mild cognitive decline who have influential positions can harm their social groups by making flawed decisions," said co-author Dr Pascal Gagneux, of the Salk Center for Academic Research and Training in Anthropogeny.

"Such genes likely evolved to preserve valuable and wise grandmothers and other elders, as well as to delay or prevent the emergence of dependent individuals who could divert resources and effort away from the care of the young.

“Our study does not directly prove that these factors were involved in the selection of protective variants of CD33, APOE and other genes, but it is reasonable to speculate about the possibility. After all, inter-generational care of the young and information transfer is an important factor for the survival of younger kin in the group and across wider social networks or tribes."

The research was published in the journal Proceedings of the National Academy of Sciences.

Read the article: Knapton, S. (2015, November). ‘Grandparent genes’ discovered by scientists: Grandparents are genetically programmed to care for their grandchildren. The Telegraph.

 Photo courtesy of Alamy.



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