This argument has been going on, probably, since we found out that Neanderthals existed. Did Cro-Magnons and Neanderthals interbreed?
The latest article on the subject at National Geographic’s website: Odd Skull Boosts Human, Neandertal Interbreeding Theory.
A human skull from Romania shows Neanderthal features (i.e. a skull groove), pointing to hybridization. However,
“Recent DNA research has cast doubt on this theory, suggesting that although humans and Neandertals share some 99.5 percent of their genetic blueprint, their last common ancestor lived some 400,000 years ago.”
Okay, modern people don’t have Neanderthal physical characteristics, or carry Neanderthal DNA. I don’t see how these pieces of evidence cancel each other out.
Think mules, people. Horse mates with donkey, we get a mule. Mules are sterile. So, why couldn’t Cro-Magnons and Neanderthals have done the same, producing sterile offspring?