Virginia Hughes, writing for National Geographic News:
“What’s most likely to happen is you’re going to get really sick or lethal mutations. You’re going to get a lot of dead proto-Neanderthals,” Noonan says.
Even if a clone did survive, the ethical dilemmas of raising a Neanderthal would be complicated. In some ways, Neanderthals were similar to modern humans. They used tools and created art, and they likely had the mental capacity for language and abstract thinking.
In other respects, though, Neanderthals were quite different. They went extinct before the agricultural revolution, so they would probably have difficulty stomaching our modern diet, heavy in grains and dairy. Their physical appearance—short and stocky, with big heads and strong muscles—would make them stick out, too.
What would it be like to see a Neanderthal in a modern city? Take a look.