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Why did Neanderthals become extinct?

Mirror image? Not quite, but traces of Neanderthal DNA exist in the modern human gene pool.
Mirror image? Not quite, but traces of Neanderthal DNA exist in the modern human gene pool.
Markus Matzel/ullstein bild via Getty Images

You've probably heard the word "Neanderthal" used to insult someone, typically a person acting boorishly or one with a prominent brow ridge. New evidence shows that calling someone a Neanderthal might not be too far from the truth. Neanderthals became extinct earlier than previously thought, but before going extinct, they mated with modern humans' ancestors — the same ones who aided in their extinction.

Neanderthals are an early species of human that lived primarily in Europe and southwest Asia from about 130,000 years ago until their extinction approximately 40,000 years ago. The first Neanderthal bones were found in the Neander River Valley in Germany in 1856, and at the time people thought they were the bones of strange modern humans. Neanderthals were generally more massive but shorter than modern humans. They also had a more prominent brow ridge and sloping forehead [Source: O'Neil].

Since that first discovery, Neanderthal bones have been found across Europe and Asia, from Spain to Russia to Iraq. So what happened to this early species that seems to have been all over the map? It's a question that has plagued scientists for years, but new testing has revealed information that may help explain the Neanderthals' demise.

It appears that we — or at least our ancestors — were at least partially responsible for their extinction. About 45,000 years ago, Neanderthal numbers were dwindling. They had become isolated, living in patchy groups across Europe by the time modern humans (Homo sapiens) were making inroads. The two groups would have competed for food, for shelter, for everything they needed to live -- but Homo sapiens was more technologically advanced. It is also thought that a volcanic eruption in Italy and a cooling climate event about 40,000 years ago delivered the last blow to a species that was already on the way out [source: Vergano].

But before Neanderthals left, some mated with modern humans. Traces of Neanderthal DNA show up in humans to this day.