Orangutans are pretty amazing animals. They’re one of the few great apes alive today and among humankind's closest cousins. But we may not have realized just how amazing they are until now.

The discovery started with a scene out of something like "CSI." Raya, an older adult male orangutan, had been killed by humans back in 2013. Researchers knew Raya had come from an unusual population of orangutans and had preserved his skeleton for study. And as they pored over the remains, a couple of weird things started to stick out.

"We were surprised that the skull was quite different in some characteristics from anything we had seen before," said Matt Nowak, an anthropologist. The teeth looked different too.