These Monkeys Always Give Birth to Twins – How Do They Do It?

Unlike all other primates, clawed New World Monkeys almost always give birth to twins. But why? It turns out these animals have a unique set of adaptations that make it possible — and could prove useful to humans as well. » 12/31/13 7:30am 12/31/13 7:30am

The Mystery of How Identical Twins Develop Different Personalities

Despite having the same genetic makeup, identical twins have their own distinctive personalities. Just how their individuality emerges has remained a bit of a mystery. But now, researchers have found that life experiences affect brain development — and this may help us understand how personalities form. » 5/09/13 11:11am 5/09/13 11:11am

Twins carry a secret evolutionary benefit

At first glance, there's no good reason why humans would evolve the ability to give birth to twins. Indeed, human reproductive systems make having even one child difficult. But twins are doing a big favor for their siblings' survival chances. » 8/10/11 7:30am 8/10/11 7:30am