When Polyandry is Natural

Many monogamists and some polygynists and even a few polyamorists will assert that polyandry isn't natural. It is Discredited Argument #5 and at thealmagest.com I found another example of polyandry in nature.

Researchers at Bielefeld University and the Technische Universität Braunschweig are the first to confirm the benefit of multiple paternities for a vertebrate under completely natural conditions. Together with their team, Dr. Barbara Caspers and Dr. Sebastian Steinfartz have shown that female fire salamanders mate with several males under natural conditions (so-called polyandry). This grants them fitness-relevant benefits by increasing their number of offspring. The results of their study are being published this Friday (29 November) in the Early View version of Molecular Ecology.

Since humans have sex for many reasons, not just reproduction, it can have other benefits in humans.

For a long time, it was assumed that females in the animal world are monogamous, that is, they mate with only one male. Males, in contrast, can increase their reproductive success by mating with several females. Nowadays, however, polyandry is assumed to be the rule in the animal world and monogamy to be more of an exception.

Interesting.

By subjecting these tissue samples to genetic paternity analyses, the researchers could precisely reconstruct how many males each female had mated with and whether or not the sperm of the different males had been mixed – female salamanders can store the sperm of different males for several months in internal receptive organs called spermathecae. The eggs of the female will only be fertilized with the stored sperm, if environmental conditions are optimal and after eggs have developed into full larvae these are deposited in streams and ponds.

Fascinating.

Through paternity analyses, the researchers were able to show that some females had mated with as many as four different males. The mixing of the sperm from various males in the spermatheca of the female seems to have quite positive effects, leading to more eggs being fertilized and, as a result, more larvae were finally deposited. Accordingly, polyandry and sperm competition seems to be an important mechanism to increase reproductive success and therefore fitness of a female in this terrestrial vertebrate species.

If you're interested in the details of the data, you can find more information in these places...
http://www.uni-bielefeld.de/biologie/vhf/SF/b_caspers.html
http://ekvv.uni-bielefeld.de/blog/uninews/entry/the_more_the_better

This blog supports the rights of all adults, including those in, or who want, polyandrous relationships, or polygynous relationships, or polyamorous relationships of any sort.