Parents sacrifice offspring for sex

Apparently humans aren't the only animals that let their vices interfere with good parenting. A new study shows that Penduline Tits actually increase their fitness by abandoning 1/3 of their offspring in order to spend time seeking copulations.

In this highly promiscuous species, birds can have up to seven mates at a time, and they swap around to different nests caring for various offspring. They are not, however, perfectly coordinated, and the result is that sometimes offspring get left with no one to care for them, and they die of "neglect."

This may seem counterintuitive, considering that offspring are the vehicles that carry an individual's genes into the future; it seems that abandoning 1/3 of your children is a waste of valuable descendants. Not so, says Dr. Tamas Székely from the University of Bath, the researcher behind this study. The benefits of the extra copulations that birds gain from "playing the field" outweigh the losses of sacrificing some of their offspring; if they dutifully stayed at the nest every time, while they would have a higher success rate per clutch, they would produce less clutches in the long run.