Human evolution: how as family we differ (Introduction)

by David Turell , Monday, November 09, 2020, 14:18 (1475 days ago) @ David Turell

The relationship of infant and elderly need for help:

https://aeon.co/essays/why-childhood-and-old-age-are-key-to-our-human-capacities?utm_so...

"Human beings need special care while we are young and when we become old. The 2020 pandemic has made this vivid: millions of people across the world have taken care of children at home, and millions more have tried to care for grandparents, even when they couldn’t be physically close to them. COVID-19 has reminded us how much we need to take care of the young and the old. But it’s also reminded us how much we care for and about them, and how important the relations between the generations are. I have missed restaurants and theatres and haircuts, but I would easily give them all up to be able to hug my grandchildren without fear. And there is something remarkably moving about the way that young people transformed their lives to protect older ones.

"But this raises a puzzling scientific paradox. We know that biological creatures are shaped by the forces of evolution, which selects organisms based on their fitness – that is, their ability to survive and reproduce in a particular environment. So why has it allowed us to be so vulnerable and helpless for long stretches of our lives? Why do the strong, able humans in their prime of life put so much time and energy into caring for those who are not yet, or no longer, so productive? New research argues that those vulnerabilities are intimately related to some of our greatest human strengths – our capacities for learning, cooperation and culture.

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"On an evolutionary timescale, Homo sapiens emerged only quite recently. Yet in that short time, we have evolved a particularly weird life history, with a much longer childhood and old age than other animals. In particular, we’re very different from our closest primate relatives. By at least age seven, chimpanzees provide as much food as they consume, and they rarely live past 50 – there’s no chimp equivalent of human menopause. Even in forager cultures, where growing up is accelerated, children aren’t self-sufficient until they’re at least 15. What’s more, even in communities without access to modern medicine, if you make it past childhood you might well live into your 70s. We live some 20 years longer than chimpanzees and, except for a few whale species, particularly orcas, we are the only mammals who systematically outlive our fertility.

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"These changes in life history evolved at the same time as dramatic changes in human brains and minds. We have many more neurons than other primates. And we developed striking abilities to learn and invent, communicate and cooperate, and create and transmit culture. New analyses of fossil records show that humans evolved their large brains and distinctive capacities in parallel with their longer childhood and old age. Our unique human vulnerabilities somehow emerged in concert with our unique human strengths. Just how are these two kinds of changes related? Researchers from biology, psychology and anthropology have recently begun to work together in order to answer these questions – answers that help to explain what makes us distinctively human.

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"For humans, the elders at the other end of the lifespan appear to be a particularly important source of care, and might have played a crucial role in human evolution. The anthropologist Kristen Hawkes has called this ‘the grandmother hypothesis’, and has shown that, in forager cultures, post-menopausal grandmothers are a crucial resource, especially for toddlers. Since human mothers have babies at relatively short intervals, a mum might be nursing a new infant even while the older sibling still needs lots of attention – grandmothers can take over after a nursing infant becomes an equally vulnerable but even more demanding toddler.

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"Traditionally, anthropologists argued that humans cooperated in order to hunt more effectively. But recent studies of forager cultures suggest that the benefits of hunting might be exaggerated – actually the grandmothers quietly digging up roots and tubers potentially provided many more calories than those mighty hunters.

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"Orcas are among the only other mammals with post-menopausal grandmothers. Orca children
and grandchildren stay close to the older females, even after they mature themselves.

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"...childhood and old age – those vulnerable, unproductive periods of our lives – turn out, biologically, to be the key to many of our most valuable, deeply human capacities. They nurture and facilitate our exploration and creativity, cooperation, coordination and culture, learning and teaching."

Comment: We are very different, and the author blames Natural Selection for our arrival with no mention of why the brain expanded like it did. Orcas and us, my bold. Why?