Are any animals truly monogamous?

As Henry Reich explains in this installment of Minute Earth, yes, monogamy does exist in the animal kingdom – though fewer creatures practice it than you probably realize. » 2/19/14 4:00pm 2/19/14 4:00pm

Do boys get better breast milk?

In many mammals, humans included, the composition of a mother's breast milk varies with the sex of her offspring, with sons receiving nutritionally richer milk than daughters. Interestingly, the opposite has been found to be true in impoverished mothers. » 12/16/13 11:30am 12/16/13 11:30am

How did monogamy evolve?

From an evolutionary standpoint, monogamy doesn't seem to make much sense – especially for males. And yet, it's practiced by a significant number of mammalian species, including humans. Now, in a fantastic example of science in progress, two newly published studies with divergent conclusions seek to explain why. » 7/30/13 12:07pm 7/30/13 12:07pm

This Is Why Spider Monogamy Is Terrifying

In certain species of spiders and insects, females kill and eat their mates after sex. But the dark fishing spider experiences a very odd twist on this gruesome tale. » 6/19/13 1:02pm 6/19/13 1:02pm

Oxytocin keeps committed men away from attractive women

Often referred to as the "trust hormone," oxytocin is typically associated with helping couples establish a greater sense of intimacy and attachment. Lesser known, however, is its potential role, if any, in preventing couples from cheating. But as a new study from the University of Bonn suggests, it may in fact… » 11/14/12 6:30am 11/14/12 6:30am

Sexual promiscuity among deer mice rewrites DNA and boosts the immune…

The California mouse and the deer mouse are very similar, except California mice find one partner and mate with them for life, while deer mice take on as many mates as possible. That lifestyle difference has a major biological impact. » 9/03/12 12:00pm 9/03/12 12:00pm

Cheaters More Likely to Pass on Infections Than People in Open…

People often think that open relationships increase your risk of catching a disease — but actually, openly seeing other people is much safer than sneaking around, a new study proves. According to a study published in the Journal of Sexual Medicine suggests that people in open relationships actually have less of a… » 6/14/12 3:40pm 6/14/12 3:40pm

Cichlid fish are secretly monogamous

When animals practice monogamy, we can generally tell right away. After all, couples like to hang out together, whether they're humans or squirrels or hawks. But one fish keeps its monogamy so top-secret that researchers actually called their pairings "invisible." » 11/23/11 2:40pm 11/23/11 2:40pm

For some shrimp, monogamy requires sacrifices. Blood sacrifices.

The cleaner shrimp is perfectly happy to live out its life in peace and tranquility with its monogamous partner. But add any more shrimp to the mix — even another happy couple — and the whole thing turns into a bloodbath. » 11/14/11 5:00pm 11/14/11 5:00pm