October 15, 2013
Going Out With A Bang: Sexual Suicide
The animal kingdom is pretty kinky. For example, practices such as sexual cannibalism, where the female eats the male after intercourse, are common in praying mantises and some spiders. However, we mammals like to think that we are somewhat classier. We may believe that we are above this madness and not complete slaves to our sexual desires.
That, simply, is not the case. An extreme example is found in a species of small marsupials. These mouse-like creatures practice suicidal reproduction, or semelparity. This little critter, referred to as Antechinus stuartii, is a native Aussie that prefers wet forest environments. He is gray-brown in color, with large ears and dark eyes. Do not be fooled by his muted colors. He is a sex machine.
During the breeding season, the male receives a burst of hormones with very simple instructions: “Hump all of the things.” He rarely eats or sleeps, operating on sexual desire alone. (Talk about thinking with the wrong head…)
This poor little guy will seek out every female that he can get his paws on. He is determined to pass on his genes to the next generation. Sadly, he will die in the attempt.
He becomes so stressed throughout this endeavor, that his immune system begins to collapse. Ed Yong further explains the toll that this takes on the Antechinus male. “His fur falls off. He bleeds internally.” But, don’t let the slow deterioration scare you. This little guy can keep at it for 14 hours at a time. Yong describes these romantic evenings as “violent, frenetic encounters.”
Oftentimes, males die due to infection and blood parasites because they did not meet their basic needs in order to survive. Contrary to popular belief, sex cannot fill all of the holes in one’s life. Antechinus males reach sexual maturity at nine months, but they will likely die within the year. In contrast, females live an average of three years.
Yong’s article, entitled “Why A Little Mammal Has So Much Sex That It Disintegrates,” also mentions that females start avoiding the sickly males near the end of mating season. I don’t blame them. Who wants to have sex with somebody who is diseased, missing patches of hair, and stressed beyond reason?
This whole ordeal seems a bit unreasonable. Why does it happen? Some biologists have argued that the Antechinus males are being altruistic. By dying, there are more resources for the females and future offspring. However, researchers at the University of New Mexico argue: “individual sexual selection leads to apparent self-sacrifice.”
They think that semelparity occurs because of the short mating season and increased promiscuity. Because there is such a small mating window, the male is driven to insanity to ensure that he passes on his genetic material. He has developed biological mechanisms that require sexual suicide.
Do you know what this says to me? Males are once again blaming the females for their obsession with intercourse. What else is new?
Image Credit: Glen Fergus