November 20th, 2012


Investing with your tits

SciAm mentions an interesting study on breast milk. Economically stable mothers produce richer (fattier) milk for sons than daughters. Poor mothers produce richer milk for daughters.

Apparently, this jibes with evolutionary predictions on parental investment: "The Trivers-Willard hypothesis states that natural selection favors parental investment in daughters when times are hard and in sons when times are easy. ... Well-off parents who can afford to invest in sons should do so because their gamble could give them many grandchildren. Conversely, poor parents should not heavily invest in sons because it is unlikely to pay off -- their offspring start at the bottom of the socioeconomic ladder. For those families, daughers are a safer bet becase as long as they survive to adulthood, they are likely to produce young."