Who doesn’t enjoy a good mystery? The CSI franchise of television crime dramas ranks among the most popular TV programs in the world. Another scientific whodunit could be even more intriguing than any episode of CSI: What caused Neanderthals to become extinct? Researchers have run into unexpected twists and turns in the drama as they’ve applied increasingly sophisticated scientific methods to solve this mystery.1
Neanderthals appear in the fossil record around 200,000 to 150,000 years ago and lived in the Middle East, Europe, and western Asia. Many paleoanthropologists believe these hominids went extinct around 28,000 to 30,000 years ago. Since humans made their way into Europe around 40,000 years ago, they must have coexisted there with Neanderthals for perhaps as long as 10,000 years.
Nobody knows what caused Neanderthals’ extinction. Some researchers believe humans killed them off. Others think humans outcompeted Neanderthals. And yet another theory posits that Neanderthals may have died off because they lacked the cognitive ability to survive the harsh climate of Europe. Genetic data that suggests humans and Neanderthals interbred, thereby introducing Neanderthal genes into the human genome, further deepens the mystery. (Although other studies raise questions about the likelihood of human-Neanderthal interbreeding.)
Using sophisticated forensic techniques, an international team of researchers tried to solve the case by analyzing tiny fragments of mitochondrial DNA painstakingly isolated from the remains of thirteen Neanderthals. Based on their work, the team concluded that Neanderthals from western Europe younger than 48,000 years in age possessed limited genetic diversity. On the other hand, older Neanderthals and those from eastern Europe displayed a much more extensive genetic diversity. Investigators interpreted these results from the “scene of the crime” to indicate that Neanderthals in Europe nearly went extinct around 50,000 years ago, well before modern humans arrived. Then, after the near extinction, Neanderthals recovered to recolonize central and western Europe.
According to Love Dalén, one of the ancient crime scene investigators, “The fact that Neanderthals in Europe were nearly extinct, but then recovered, and that all this took place long before they came into contact with modern humans came as a complete surprise to us. This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought.”2
This new insight means that humans probably didn’t drive Neanderthals to extinction. Instead, it suggests that Neanderthals likely disappeared for other reasons—perhaps as a consequence of their limited cognitive ability. In contrast, when the first modern humans made their way into the colder climates of Europe and Asia they thrived.
Some researchers have asserted that the thinking capacity of Neanderthals and humans would have been similar. The latest work suggests otherwise. The implied cognitive differences uncovered by investigators between the two species help solve the Neanderthal extinction mystery and provide solid evidence for RTB’s human origins model.
- Love Dalén et al., “Partial Genetic Turnover in Neanderthals: Continuity in the East and Population Replacement in the West,” Molecular Biology and Evolution (February 23, 2012), doi: 10.1093/molbev/mss074.
- “European Neanderthals Were on the Verge of Extinction even before the Arrival of Modern Humans,” (February 25, 2012) Sciencedaily.com.