Human
Thank Grandma for Your Romantic Bond with Someone Special, and Your Lifespan
Catherine Griffin
First Posted: Sep 09, 2015 10:32 AM EDT
If you are in a loving relationship with someone, you may have grandma to blame. Scientists have taken a closer look at the grandma hypothesis, which suggests that grandmothers help feed weaned children, allowing mothers to have the next babies sooner.
The grandmother hypothesis credits prehistoric grandmothering for our long human lifespan. Now, though, researchers have turned to computer simulations to link grandmothering and longevity to a surplus of older fertile men and, in turn, to the male tendency to guard a female mate from the competition and form a "pair bond" with her instead of mating with numerous partners.
"It looks like grandmothering was crucial to the development of pair bonds in humans," said Kristen Hawkes, senior author of the new study, in a news release. "Pair bonds are universal in human societies and distinguish us from our closest living relatives. Our hypothesis is that human pair bonds evolved with increasing payoffs for mate guarding, which resulted from the evolution of grandmothering life history."
Female chimps rarely live past childbearing years, usually into their 30s or sometimes their 40s. However, human females often live decades past their child-bearing years. This may have begun with our early human ancestors 2 million years ago.
Before then, the hypothesis goes that few females lived past their fertile years. But changing environments led to the use of food like buried tubers that weaned children couldn't dig themselves. The older females thus helped feed the kids, allowing their daughters to have the next baby sooner. This means that grandmothers' longevity genes became increasingly common in the population and human lifespan increased.
In fact, computer simulations supported this hypothesis, finding that without grandmothering, simulated lifespans reach equilibrium when they match those of great apes.
The researchers also found that as human lifespans grew longer, the ratio of fertile men to fertile women increased over time. This made it advantageous for males to develop a pair bond with a female.
The findings reveal a bit more about human evolution and show that, thanks to grandmas, we live longer and have "pair bonds."
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First Posted: Sep 09, 2015 10:32 AM EDT
If you are in a loving relationship with someone, you may have grandma to blame. Scientists have taken a closer look at the grandma hypothesis, which suggests that grandmothers help feed weaned children, allowing mothers to have the next babies sooner.
The grandmother hypothesis credits prehistoric grandmothering for our long human lifespan. Now, though, researchers have turned to computer simulations to link grandmothering and longevity to a surplus of older fertile men and, in turn, to the male tendency to guard a female mate from the competition and form a "pair bond" with her instead of mating with numerous partners.
"It looks like grandmothering was crucial to the development of pair bonds in humans," said Kristen Hawkes, senior author of the new study, in a news release. "Pair bonds are universal in human societies and distinguish us from our closest living relatives. Our hypothesis is that human pair bonds evolved with increasing payoffs for mate guarding, which resulted from the evolution of grandmothering life history."
Female chimps rarely live past childbearing years, usually into their 30s or sometimes their 40s. However, human females often live decades past their child-bearing years. This may have begun with our early human ancestors 2 million years ago.
Before then, the hypothesis goes that few females lived past their fertile years. But changing environments led to the use of food like buried tubers that weaned children couldn't dig themselves. The older females thus helped feed the kids, allowing their daughters to have the next baby sooner. This means that grandmothers' longevity genes became increasingly common in the population and human lifespan increased.
In fact, computer simulations supported this hypothesis, finding that without grandmothering, simulated lifespans reach equilibrium when they match those of great apes.
The researchers also found that as human lifespans grew longer, the ratio of fertile men to fertile women increased over time. This made it advantageous for males to develop a pair bond with a female.
The findings reveal a bit more about human evolution and show that, thanks to grandmas, we live longer and have "pair bonds."
Related Stories
The Ancient Shoulder Fossil of an Ape-like Ancestor Solves the Mystery of Human Evolution
Million-Year-Old Monkey from the Caribbean Sheds Light on Human Evolution
For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).
See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone