Promiscuity Maybe Not So Bad After All

**FILE** A bee is seen in the blossom of an almond tree near Modesto, Calif., in this Friday, Feb. 20, 2004, file photo. The bees fertile touch is behind one-third of what we eat. The berries, fruits and nuts that lend flavor to about 28 of Haagen-Dasz's ice cream flavors depend on the insects for pollination. The company, owned by Vevey, Switzerland-based Nestle SA, uses one million pounds of almonds alone in their products. (AP Photo/Rich Pedroncelli)
AP Photo/Rich Pedroncelli
Good news for fans of polyandry, which is the practice of females mating with multiple males in species from mammals to insects: You may hold in your hands - or loins, maybe - the key for the survival of humanity.

A study of fruit flies by the Natural Environment Research Council in the U.K. has found that promiscuous females of a species may be the key to that species' survival.

The reason is that when females partner with fewer mates, the likelihood that they'll have all-female broods rises. A so-called "sex ratio distortion" (SR) chromosome exists that kills Y chromosome (male) sperm before fertilization. Female offspring carry the SR, which will be passed on to their male children until there are all-female broods born.

Short version: Do it more, widen your brood-load and reduce the risk of getting all-female broods. Species saved!

Read more about the study and polyandry here.