October 23, 2014
http://www.cnn.com/2014/10/23/health/genome-45000-year-old-bone/index.html?hpt=he_c2
To understand the article, knowledge of Neanderthals is needed. Neanderthals are a species of humans that are now extinct, and their DNA differs from modern humans' DNA by less than 1%, and 2% of non-African genomes come from Neanderthals. "Modern humans" are the ones who left Africa around 60,000 years ago and went to Asia/Europe, where they encountered the Neanderthals and other now extinct species of humans. Up until this point, scientists believed that Neanderthals disappeared 30,000 years ago because they simply became absorbed into the population of the modern humans, but they hadn't decided the exact date when Neanderthals began breeding with modern humans.
Six years ago, a thigh bone was found in Siberia by a river. It turned out to be older than any other modern human dated. DNA sequencing reveals that 2.3% of the genome comes from Neanderthals. From this new data, scientists put the date of the start of interspecies breeding at roughly 50,000 to 60,000 years ago.
This relates to radiometric dating and evolution evidence. In class, we previously studied how carbon isotopes are used for radiometric dating. The bone was dated using radioactive isotopes by measuring the amount of the isotope left in the bone, and then comparing the numbers to the length of it's half-life, which would give an approximate age for the bone. We recently also discussed evidence needed for evolution of life, and one of the examples that came up was fossils. This bone is an example of a fossil that explains the disappearance of Neanderthals and the reason that part of our DNA is the same as the Neanderthals although they are currently extinct.
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ReplyDeleteIf neanderthals had continued to breed with neanderthals and early humans had not strayed away from breeding with their own kind, how would the evolutionary process have been different? What are some characteristics we would lack in comparison to our current state?
ReplyDeleteThe evolutionary process definitely would have been different. We have Neanderthal DNA, so if they didn't interbreed, we wouldn't have their DNA right now. I believe that the Neanderthals most likely would have died out, since scientists think that the modern humans were more sophisticated than the Neanderthals. Evidence from fossils suggest that the Neanderthals were already slowly dying out around the time they breeded, so if they had continued without interbreeding, we would most likely be without Neanderthal DNA and they still wouldn't exist.
DeleteWe can't know for sure what characteristics we would lack, but we most likely wouldn't be lacking in many traits. The Neanderthals, although sometimes portrayed as very different from modern humans, actually closely resembled modern humans. One article from National Geographic states that some of their genes are helping strengthen our immune system, so we do gain some helpful traits from the Neanderthals. Read more here--> https://genographic.nationalgeographic.com/neanderthal/