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Ancient DNA

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1. What are two of the major challenges associated with studying ancient DNA?

2. Provide two key insights into the evolutionary history of Neandertals that have been derived from the analysis of mitochondrial DNA (mtDNA). In what ways might the use of mtDNA be misleading or limiting?

3. Who were the Denisovans? From an anthropological prospective, what is remarkable about their discovery?

4. Based on the recent publication of the Neandertal and Denisova genomes, describe the current model for putative hybridization and gene flow between these lineages and modern humans. Include in your answer the historical time, approximate geographic location of inferred hybridization events and the genomic extent of introgression.

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1. The two major challenges associated with studying ancient DNA are:

First, ancient DNA are too small to be identified, sometime scientist cannot extract ancient DNA from a mixture of samples (1). Ancient DNA are also subject to "chemical modification" that can change its genetic makeup, which make it difficult to analyze at time (1). In addition, ancient DNA can degrade in time, which make the quality of information extracted from it very poor.

Another problem in studying ancient DNA is that it is not always pure (1). Ancient DNA can be contaminated with DNA from other organisms when trying to collect it. For example, if you want to study an ancient DNA from a caveman, the ancient DNA that you have collected from the fossils of the caveman may contain other DNA from bacteria and fungi as well (1). Furthermore, the DNA from these microbes that contaminate your target DNA may be very abundant (1). So you may not be studying your target DNA of interest, but the DNA of other organisms. Studying ancient DNA poses a risk that the DNA being studied may be contaminated with DNA from other organisms, usually a mixture of bacteria, insect , and humans (1).

2. One insight into the evolutionary history of Neandertaks that have been derived from the analysis of mitochondrial DNA (mtDNA) is that the Neanderthal mtDNA sequences were ...

Solution Summary

Ancient DNA are a major issues when the researchers want to use it for analysis. The major challenges of studying ancient DNA are quality and reliability. Ancient DNA are too small and they often degrade when trying to analyzed them. They are subject to chemical modification and are not reliable for informational studied. Secondly, ancient DNA are not pure and can be contaminated with others material making the analysis extremely difficult and troublesome. One of the intriguing molecule for evolutionary study of ancient Neanderthal man is the mitochondrial DNA (mtDNA), which is highly conserved and is used to study ancient lineages of Neanderthals and Denisovans.

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