'Sexual Suicide' Pushed These Marsupials Onto Australia's Endangered List

It was the Bloodhound Gang that decreed: “You and me baby ain’t nothing but mammals/So let’s do it like they do it on the Discovery Channel.” Some mammals do it so much that they are now on the brink of extinction. According to statement from the Queensland University of Technology released Friday, the Australian government has officially listed the black-tailed dusky antechinus and the silver-headed antechinus as endangered species. A host of factors have brought about their demise, the researchers write, but their obsession with doing it certainly isn’t helping.

“Australia has the worst mammal extinction rate anywhere on Earth,” explained QUT professor Andrew Baker, Ph.D. in the statement. “We can now turn the country’s attention to the important job of saving these threatened species. If we take immediate action, hopefully in time we will see the antechinus removed from the endangered list.”

What we likely can’t do, however, is save the antechinuses from themselves. A small, carnivorous marsupial indigenous to Australia, Tasmania, and New Guinea, the antechinus is one of the few mammals that exhibit a phenomenon called “semelparous reproduction.” This means that, after the end of a truly frantic annual mating period, all of the males die.

Each year, there’s a two- to three-week period of speed-mating during which males, all hyped up on testosterone, hook up with as many females as possible. Their sex spurts can last up to 14 hours at a time, which sounds impressive but is also an impressively inefficient use of precious testosterone. The spike in the hormone triggers a malfunction in what Baker calls a “stress hormone shut-off switch” and the accompanying rise in stress hormones cause the male’s immune systems to collapse. Each of them die before any of their brood are born.

“This yearly male suicide mission, which halves each antechinus population, means the mums have enough spiders and insects to eat while they raise the next precious generation,” Baker explained in 2015, after the discovery of two new species of antechinus. “But the future of each species is entrusted to the mothers alone.”

While sex is obviously essential for survival, life is all about balance. An overemphasis focus on sex, unfortunately, throws that off. In April, scientists revealed another creature whose focus on sweet, sweet lovin’ doomed them: ostracods — specifically those that lived a million years ago and were endowed with very large genitals. In a survey of 93 species of ancient ostracods, the scientists realized that those with larger genitals were the most likely to die, demonstrating that their evolutionary over-investment in genitalia robbed them of the energy they needed for their overall existence.

Overall, there are 15 separate species of antechinus in Australia, and while only two are officially on the endangered list now, Baker warns that they are all at risk. Besides their suicidal mating, a warming climate, habitat loss, and feral animals all contribute major challenges to their survival. Climate change affects the black-tailed dusky antechinus and the silver-headed antechinus in particular. These shrew-like critters live in remote, misty mountain tops, which puts them in considerable danger as their situation shifts. Since boning to the point of sexual suicide is a preexisting habit that the antechinus aren’t likely to drop any time soon, it’s up to us to cut greenhouse gases (and make sure cats don’t gobble them) to make sure they survive.