An exhibit shows the life of a neanderthal family in a cave in the new Neanderthal Museum in the northern town of Krapina in this February 25, 2010, file photo.

Scientists said on March 18, 2016, an analysis of genetic information on about 1,500 people from locations around the world confirmed at least four interbreeding episodes tens of thousands of years ago, three with our close cousins the Neanderthals and one with the mysterious extinct human species known as Denisovans.