2018-11-07 18:50:23 UTC
The Cognitive Advantages of Growing Older
The later decades of our lives are there for a good evolutionary
By Alison Gopnik, Nov. 2, 2018, Wall St. Journal
If, like me, youre on the wrong side of sixty, youve probably
noticed those increasingly frequent and sinister senior moments.
What was I looking for when I came into the kitchen? Did I already
take out the trash? Whats old whats-his-names name again?
One possible reaction to aging is resignation: Youre just past your
expiration date. You may have heard that centuries ago the average
life expectancy was only around 40 years. So you might think that
modern medicine and nutrition are keeping us going past our
evolutionary limit. No wonder the machine starts to break down.
In fact, recent research suggests a very different picture. The
shorter average life expectancy of the past mainly reflects the fact
that many more children died young. If you made it past childhood,
however, you might well live into your 60s or beyond. In todays
hunter-gatherer cultures, whose way of life is closer to that of our
prehistoric ancestors, its fairly common for people to live into
their 70s. That is in striking contrast to our closest primate
relatives, chimpanzees, who very rarely live past their 50s.
There seem to be uniquely human genetic adaptations that keep us going
into old age and help to guard against cognitive decline. This
suggests that the later decades of our lives are there for a reason.
Human beings are uniquely cultural animals; we crucially depend on the
discoveries of earlier generations. And older people are well suited
to passing on their accumulated knowledge and wisdom to the next
Building Bridges Across the Generational Divide
Michael Gurven, an anthropologist at the University of California,
Santa Barbara, and his colleagues have been studying aging among the
Tsimane, a group in the Bolivian Amazon. The Tsimane live in a way
that is more like the way we all lived in the past, through hunting,
gathering and small-scale farming of local foods, with relatively
little schooling or contact with markets and cities. Many Tsimane are
in their 60s or 70s, and some even make it to their 80s.
In a 2017 paper in the journal Developmental Psychology, Prof. Gurven
and colleagues gave over 900 Tsimane people a battery of cognitive
tasks. Older members of the group had a lot of trouble doing things
like remembering a list of new words. But the researchers also asked
their subjects to quickly name as many different kinds of fish or
plants as they could. This ability improved as the Tsimane got older,
peaking around age 40 and staying high even in old age.
Research on Western urban societies has produced similar findings.
This suggests that our cognitive strengths and weaknesses change as we
age, rather than just undergoing a general decline. Things like
short-term memory and processing speedwhats called fluid
intelligencepeak in our 20s and decline precipitously in older age.
But crystallized intelligencehow much we actually know, and how
well we can access that knowledgeimproves up to middle age, and then
declines much more slowly, if at all.
So when I forget what happened yesterday but can tell my grandchildren
and students vivid stories about what happened 40 years ago, I may not
be falling apart after all. Instead, I may be doing just what