Neanderthals were a species of early humans that lived in Europe and parts of Asia around 400,000 to 40,000 years ago. They are known for their robust build, large skulls, and distinctive brow ridges. Neanderthals used tools, hunted animals, and gathered plants for food, showing they had complex survival skills. Recent studies suggest that Neanderthals may have had a form of language and engaged in cultural practices, such as burying their dead. They coexisted with early Homo sapiens and interbred with them, contributing to the genetic makeup of modern humans.