News in Brief Genetics

Pregnancy in mammals evolved with help from roving DNA

'Jumping genes' changed uterus to stop laying eggs

Puppies

HOLD THE EGGS  Roving DNA helped program mammals like this dog to give birth to live young instead of laying eggs.

VladimirFLoyd/iStockphoto

By Kate Baggaley

- More than 2 years ago

Roving pieces of DNA helped early mammals ditch egg-laying in favor of giving birth to live young.