Who Were Neanderthals and Did They Interbreed with Modern Humans?

Transcription

1 Anthropology 1020 Sharon Vidriales-Estrada Who Were Neanderthals and Did They Interbreed with Modern Humans? References 1. Wikipedia (Internet) Neanderthals search 2. Scientific American (Article) Our Inner Neanderthal Published in July Odyssey (Journal Article) What s New with Neanderthals. Published in October Essentials of Physical Anthropology (Book) Published in 2011, University of Cambridge (Internet) Doubts about whether Modern Humans and Neanderthals Interbred Published Aug Modern Humans May Have Interbred with Neanderthals and Denisovans (Internet) YouTube posted, September 21, Neanderthal-Human Hybrids (Internet) Hypothesis Journal My e-portfolio: URL/

2 Perhaps as early as 850,000 years ago to about 200,000 years ago homo heidelbergensis began to appear in Africa and Europe. Then Neanderthals traits began to appear around 600, ,000 years ago. These early Hominins originated in Africa and then migrated to Asia and Europe. After they migrated an Ice Age was occurring through Europe, Asia, North America and Antarctica, but mostly Europe and Northern Asia. These Hominins were greatly affected by the extreme temperatures, causing migration to be blocked between Europe and Northern Africa. Because glaciations were occurring, traveling to other continents was also blocked or difficult at best. The Hominins living in Africa became geographically isolated from other hominins that were living in Europe. Due to the isolation the hominins in Europe could only exchange genes with one another causing genetic drift, which later evolved their own separate species which is known as Neanderthals. Other hominins in Africa also evolved to modern Homo sapiens. Neanderthals lived and adapted to the frigid, bitter climates. They lived in caves as well as open air sites. They became hunters and ate fruits, vegetables, seeds, nuts and bird eggs. They also exploited marine life. We also know that Neanderthals had their own tool technology which is known as Acheulian Technology and also invented a method called the Levallois technique. Neanderthals were very robust, barrel-chested, and very muscled. Their brain size was 1,520 cm3 while the average Modern humans measured between 1,300 to 1,400 cm3.

3 Modern Humans first appeared in Africa 130,000 years ago and started moving into Europe about 45,000 years ago and they probably first encountered Neanderthals and interbred with them in the Middle East. We know this information because starting in the early 1829, paleoanthropologist started to discover fossils of Neanderthal bones in Europe. Using these fossils, scientists wanted to use these fossils bones to sequence their DNA. By 1997, a Professor named Svante Pääbo and his colleagues were the first to sequence the mitochondrial DNA at the Max Planck Institute for Evolutionary Anthropology. They used DNA obtained from three Neanderthal bones that come from Vindija cave in Croatia. These bones are more than 38,000 years old. Another similar gene that modern humans and Neanderthals had was a gene called FOXP2. This gene has been linked to how we process speech and language. It is estimated that 1-4% of Europeans and Asians DNA is Neanderthal. Based on genetic evidence, Neanderthals probably interbred with modern humans between 80,000 to 50,000 years ago. Scientists figured that since no Neanderthal DNA is found in modern Africans and that Neanderthals must have interbred with archaic Homo sapiens. How else would those genetic markers have appeared in modern Asians and Europeans? Neanderthals fossils have only been found in Europe and the Middle East. Neanderthals fossils were found from La Chapelle-aux Saints, France to El Sidron, Spain to Israel to Iraq as well as Uzbekistan. Today Neanderthals no longer exist and disappeared from the fossil record about 25,000 years ago, somewhere on the remote island of Gibraltar, by southern Spain. Scientists don t know exactly how Neanderthals became extinct but theories such as due to harsh weather

4 conditions and/or competition with modern humans for food abound. Data may suggest that the small numbers of Neanderthals, since they would have had smaller populations, mated with much larger populations of archaic H. sapiens and that over time they simply disappeared into their populations. Evidently, it also appears that only archaic H. sapiens females may have been able to have viable hybrid offspring. Since humans and Neanderthals share a small percentage of nuclear DNA but they do not share the same type of mtdna that means that hybrids that contained the mtdna may have not been viable or survived in modern humans. mtdna can only be transmitted from mothers so that alludes to that H. sapiens male and Neanderthal women could not produce fertile and/or offspring. This causes a perplexing issue with how only specific segments of DNA were able to be transmitted or that they simply disappeared, probably with Neanderthals themselves. To me this raises the question as to how closely related H. sapiens are to Neanderthals and whether they were a different species entirely, since producing viable fertile offspring is how one also defines differing species. However, it has been shown that speciehybrids may be viable from cross breeds from one gender to another but not so visa-versa. There is also some doubt and a current study found an alternative explanation for the genetic similarities between Neanderthals and H. sapiens other than hybridization. The study found, using modeling, that the similarities between Neanderthals and H. sapiens was probably due to common ancestry without hybridization. That the DNA that modern humans and Neanderthals share can all be attributed to their common origin without recent influx of Neanderthal DNA into modern humans. DNA analysis, in many ways, has posed more questions than answers and while the debate is still raging on some fronts, which assures me that science is alive and well. Science in its infinite question and answer forum/debate still has room for dissention and thought provoking

5 quandaries. Things are rarely black and white and that is fine by me, as long as the gray has a reasonable argument. Do I believe that Neanderthals and H. sapiens interbreed? Ask me in a few a years, once more data is gathered. There is always room to question.