A side view of the new ant species <em>Eurhopalothrix zipacna</em>. Mounting glue and paper appear beneath the ant, one of 33 new species discovered in Central America by Jack Longino, a biologist at the University of Utah.
Fewer than 10 percent of all mammal species are monogamous. In fact, biologists have long disagreed over why monogamy exists at all. That's the subject of two studies published this week — and they come to different conclusions.
Animals that leave the most offspring win the race to spread their genes and to perpetuate their lineage. So for most mammals, males have a simple strategy: Mate with as many females as possible.
"Monogamy is a problem," says Dieter Lukas, a biologist at Cambridge University. "Why should a male keep to one female?"