Why do grandmothers exist?
It is Chet’s turn to muse — about the recent research on grandmothers and their role in child rearing:
So the question is: What is the adaptive value of grandmotherhood?
Which is another way of asking why there is such a gap between the age of menopause and the age of senescence in women.
Menopause is the permanent cessation of ovulation, and it affects most women sometime in the fifth decade of life. Senescence is the decline of bodily vigor that precedes death, which generally occurs decades later.
If you are wondering, Grandpas are easy to explain, it seems:
Grandpas are easy to explain; they can potentially propagate their genes until they fall out of their rocking chairs. It’s those fit-as-a-fiddle but infertile grandmas who are the evolutionary riddle.
The answer, of course, it not new to the readers of this blog:
According to the Utah researchers, human females live for a long time beyond menopause to ensure that their grandchildren eat and their daughters have more babies. Grandmothers are favored by evolution because they help ensure success for the family gene pool.
The useful grandmother hypothesis has recently found more support by researchers working with Gambians and populations of Canadians and Finns.
This idea that natural selection might favor a group rather than individuals is controversial in biology. So too is the idea that human evolution should be dramatically different from that of our close mammalian and primate relations.
A nice piece.
BoingBoing informs us of the attack of the ninjas on Stallman in an attempt to reenact an xkcd comic; I was wondering if there were also wikipedian protestors in the crowd.
Birth order effects
Vaughan at Mind Hacks points to an article in the Time magazine on the effect of birth order on IQ and also indicates that culture and cultural expectations may have a role to play in highlighting or diminishing these effects:
We featured some studies previously on Mind Hacks that suggested that first born children have marginally higher IQ scores, although a similar study in Thai medical students found the reverse effect, younger siblings tended to be more intelligent.
This highlights the role of culture in these effects, and the Time article illustrates a similar point with regards to girls. Perhaps fifty years ago when girls were less expected to go to college and have careers, the birth order effect may have been much less clear because of the cultural limitations on female work and education.
Now the cultural expectations have changed, the effect of birth order on psychological development may also be different.
Rajeev at his Almanack has a nice and detailed (albeit a bit mathematical) essay on quantum tunneling:
Perhaps the most spectacular early prediction of quantum mechanics was tunneling: that particles can do things that are forbidden in Newton’s mechanics, although with a small probability.
Tyler Cowen at MR:
It was an amazing week for reading (the best since I’ve started doing MR) mostly because it was an amazing week for flying.
As a first installment, Cowen recommends a couple of novels, a couple of books on economics and a book on music — and, almost all of them come with very strong recommendations. Of the music book, for example, Cowen has to say this:
If you are only going to buy (and read) ten books on music, ever, this should be one of them.