March 27, 2012
Were European Neanderthals Long Gone Before Humans Arrived?
New research suggests Western European Neanderthals were likely to have been extinct long before humans arrived on the evolutionary scene.
Long thought to be the birth place of Neanderthal evolution, Western Europe has been studied and researched by scientists and anthropologists to better understand our ancient forefathers. As these Neanderthals began to disappear around 30,000 years ago, anthropologists had estimated either climate changes or competition from early humans caused the disappearance of these creatures. However, a study of ancient DNA shows the Neanderthals may have been on the verge of extinction long before modern humans arrived.An international research team conducted the study. Rolf Quam, Binghamton University anthropologist co-authored the study led by Anders GÃ¶therstrÃ¶m at Uppsala University and Love DalÃ©n at the Swedish Museum of Natural History. They published their findings in the journal Molecular Biology and Evolution.
“The Neanderthals are our closest fossil relatives and abundant evidence of their life-ways and skeletal remains have been found at many sites across Europe and western Asia,” said Quam, assistant professor of anthropology. “Until modern humans arrived on the scene, it was widely thought that Europe had been populated by a relatively stable Neanderthal population for hundreds of thousands of years. Our research suggests otherwise and in light of these new results, this long-held theory now faces scrutiny.”
The team focused on mitochondrial DNA sequences from 13 Neanderthal individuals, as well as a new DNA sequence from a Spanish cave, Valdegoba. The team´s findings were surprising; Neanderthals from western Europe older than 50,000 years showed a high degree of genetic variation from those Neanderthals from Western Asia and the Middle East. This kind of genetic variation suggests the species was abundant in the area for a long period of time. The Neanderthals 50,000 years or younger showed an extremely reduced amount of genetic variation. This suggests the Western European Neanderthals went through some sort of demographic crisis or tragedy to greatly reduce the amount of humans in the area for a long period of time. The anthropologists suggest this period of time could coincide with an extremely cold point of time in Western Europe.
“The fact that Neanderthals in western Europe were nearly extinct, but then recovered long before they came into contact with modern humans came as a complete surprise to us,” said DalÃ©n, associate professor at the Swedish Museum of Natural History in Stockholm. “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.”
According to the press release announcing the results of this new study, Quam agrees with DalÃ©n and suggests scientists should reconsider the idea of cold adaptation for the Neanderthals.
“At the very least, this tells us that without the aid of material culture or technology, there is a limit to our biological adaptation,” said Quam. “It may very well have been the case that the European Neanderthal populations were already demographically stressed when modern humans showed up on the scene.”
The results of these tests cannot be listed as entirely conclusive, however. The DNA being sequenced by the team is severely degraded and, as such, experts on modern DNA sequencing and paleoanthropologists from Denmark, Spain, Sweden, and the United States have been asked to be involved in the study.
Image 2: Focusing on mitochondrial DNA sequences from 13 Neanderthal individuals, including a new sequence from the site of Valdegoba cave in northern Spain, the research team of Rolf Quam, a Binghamton University anthropologist, Anders GÃ¶therstrÃ¶m at Uppsala University and Love DalÃ©n at the Swedish Museum of Natural History, found some surprising results. Credit: Rolf Quam
Image 3: This image shows Rolf Quam, a Binghamton University anthropologist, in the Valdegoba cave indicating where the Neanderthal mandible came from in the stratigraphy. Credit: Rolf Quam