Reproduction through the Ages
Martin, Mike, Science & Spirit
For centuries, "Go forth and multiply" has been a mantra of human survival, but according to a recent study, having a lot of children may not be the best way to grow and nurture your family tree. Dustin Penn, of the Konrad Lorenz Institute for Ethology in Austria, or KLIVV, and Ken Smith, of the University of Utah, studied the "Darwinian reproductive fitness" of 21,684 Utah couples married between 1860 and 1895, and found that having a greater number of children significantly affected the lifespan of the mother and the survival rate of later-born siblings.
"Natural selection does not necessarily favor maximal reproduction," Penn and Smith claim in a paper published in the Proceedings of the National Academy of Sciences at the end of last year. "Reproduction imposes fitness costs, reducing parental survival and offspring quality."
Penn, an evolutionary biologist and director of KLIVV, explained that "social scientists often assume that natural selection favors maximizing offspring production," but animal studies have long suggested otherwise. "Birds that rear too many young can lose their entire clutch," Penn said. …