Who were the Neanderthals? The Neanderthals were archaic people who colonized Europe and some parts of the Middle East as long as 400,000 years ago. They co-existed with the first anatomically modern humans from about 80,000 to 30,000 years ago when they became extinct.
Why did Neanderthals become extinct? Although they had survived for hundreds of thousands of years and mastered the cold climates of the last Ice Age, Neanderthals became over-specialized and were never very populous to begin with. They were eventually edged out by Homo sapiens sapiens, but not before hybridization had occurred. Hybrid vigor due to Neanderthal admixture undoubtedly played a role in what human populations best succeeded in the changing climate of Europe. In a sense, Neanderthals never became totally extinct. Their genes live on in hybrid populations.
Are the Neanderthals a different species? No, the fact that they interbred with modern humans shows they were not a separate species. Modern humans are classified as Homo sapiens sapiens. Most scientists today view Neanderthals as a sub-species or hominid sister group of all present-day humans. Homo sapiens sapiens and Neanderthals are believed to have a common ancestor who lived about 500,000 years ago in Africa.
Where and when did modern humans mix with Neanderthals? The international research team that reconstructed the Neanderthal genome, Svääbo et al at the Max Planck Institute in Germany, suggests that interbreeding took place in Arabia, Israel or elsewhere in the Middle East or Western Asia when the first small group of modern human ancestors of all non-African peoples left the African Continent about 80,000 years ago. Taking the beachcomber route, these forefathers and foremothers of all non-African peoples spread and expanded to India, Southeast Asia, Australia, China, Siberia, the Caucasus and eventually Europe, with back migrations to the Middle East and North Africa. Because of what is known as a “founder effect,” they carried Neanderthals genes into all descendant populations.
So Africans have no Neanderthal in them? African Americans have Neanderthal genes to the extent they are part Caucasian in their ancestry (as much as 30% on average).
What about Native Americans? Since Native Americans were also part of the out-of-Africa primitive groups of humans who partly interbred with Neanderthals, they also have some degree of Neanderthal genes. Moreover, Native Americans with high quotients of Middle Eastern or European admixture, accordingly, have high probabilities of having Neanderthal admixture.
Does this test tell me how many Neanderthal genes I have? No. First, it is not a test but an index. It shows how you compare with others on a scale of 1.1 to 5.0, with 5.0 being the highest score. Only a costly procedure like the Human Genome Project can directly determine what genes you have. The Neanderthal Index measures how your individual DNA profile (DNA fingerprint) inherited from all your ancestors measures up against other human populations. Certain of these are “archaic.” They are thought to have higher rather than lower amounts of Neanderthal genes based on their individual genetic histories.
How reliable is the Neanderthal Index? The index is based on probabilistic predictions of the occurrence of your individual autosomal profile in archaic populations retaining Neanderthal genes. Because of the laws governing large numbers, this test can suggest strength or weakness of Neanderthal admixture in your overall genetic composition and, correspondingly, traits associated with Neanderthal ancestry. The statistics come from about 400 studies published in the field of forensic science, all publicly available. Each population was defined by a valid representative sample of living subjects in that location, usually about 200 tested individuals. There are no known biases in the statistics. For instance, they are not taken from purposive medical or genetic studies or criminal files like the FBI but academic and sound, objective sources.
What is an archaic population? This is a statistical model formed from a sample of contemporary DNA test subjects representing a population whose DNA patterns were set and preserved in the oldest of prehistoric times with relatively little genetic inflow from outside the group. This definition excludes African populations, which are believed to be even earlier and contain the highest diversity and deep ancestry of all humankind. Archaic populations reflect varying high degrees of Neanderthal ancestry and hybridization. They include the following out-of-Africa populations:
What were Neanderthals like? They were much like “us.” They lived in family groups, had names, hunted game, usually at night in groups, baked acorn meal bread, and had language, religion, cuisine, medicine, trade, tools, crafts and art, including music, dance and body paint. The growing list of physical features known from study of their burials includes: large amount of body hair, red hair, blue or green eyes, fair skin, large eyes, greater fertility, early maturation into adulthood, short legs and forearms, weak knees and shoulders, a strong grip of the hand and fingers, barrel chest, wide pelvis, rugged brow ridge, large, sometimes odd-shaped noses, and prominent occipital bun. Ongoing research promises to reveal even more about past human admixture with Neanderthals, particularly the division into Northern and Southern types.
What data are our notions of Neanderthals based on? Discovered in a quarry in Germany in 1856, 40,000-year-old Neanderthal man became the first recognized early human fossil. Neanderthals are named after the Neander Valley (German thal or tal) in which they first came to light. More and more of them turned up over the years: in Belgium (1886), a nearly complete skeleton in southern France (1908), Israel (then-Palestine, 1930) and Iraq (1953). The first ambitious genetic work was a partial sequencing of their mitochondrial DNA based on highly degraded specimens: Krings et al., Cell 90, 19 (1997). A second mtDNA sequence was achieved in 2000. The complete mtDNA sequence came in 2008: Green et al., Cell 134, 416 (2008).
What is the correct spelling of the word? Although first spelled Neanderthal, German language orthographic reforms rendered the spelling of the name Neandertal in the twentieth century, although most people even today prefer to stick with the th of the original word.
How can I learn more? The blockbuster scientific study proving Neanderthal admixture with humans by Green et al was published in May 2010. There are probably just one or two good books about our Neanderthal cousins, although several new studies are scheduled to appear this fall. Here is a short list of references you can explore now.
What does my Neanderthal Index score mean? To understand your score of 1.1 to 5.0, please refer to these rubrics.
Very High (4.0-5.0). You have numerous high matches to Archaic Populations, including a strong match in your European ancestry to Finno-Uralic peoples.
High (3.0-3.9). You have prominent matches to Archaic Populations, not necessarily including Finno-Uralic peoples.
Average (2.0-2.9). You have matches to Archaic Peoples on a par with other people’s results.
Low (1.0-1.9). Your matches to Archaic Populations are generally below other people’s results.
Very Low (0.1-0.9). You have no significant matches to Archaic Populations.
What populations have the smallest amounts of Neanderthal admixture? There are probably no populations that are completely free of Neanderthal admixture, although Central Africans may have the least. Here is a list of populations that generally score lowest on admixture with the Neanderthal Index: Japanese, Swedish, British, Russian, Slavic, Chinese, Sub-Saharan African (especially Central and Mozambican and Angolan) and Indian (when dominant).
How much of this is science and how much theory? Since the publication of the Draft Sequence of the Neanderthal Genome in May 2010, it has become an accepted scientific fact that most humans are part Neanderthal. Europeans have between 1 and 4 percent Neanderthal genes on a conservative estimate. As more Neanderthal fossils are studied and new sources of admixture identified in hybrid fossils, it is likely that this figure will be revised upward. Many theories abound on the timing and extent of Neanderthal admixture, but no scientists question the evidence.
Read the original press release from the Max Planck Institute for Evolutionary Anthropology in Leipzig.