Question

in 2010, dr. svante pääbo published research indicating that all modern ethnic groups, other than africans, carry traces of neanderthal dna in their nuclear genomes. his earlier work indicated no overlap between neanderthal mitochondrial dna and that of homo sapiens. which of the following is not a likely possible hypothesis that could be supported by this information? the shared nuclear dna is definitely the result of interbreeding between female neanderthals and male humans. the shared nuclear dna could be the result of interbreeding between male neanderthals and female homo sapiens. the shared nuclear dna could be a remnant of dna from a common ancestor shared by neanderthals and homo sapiens. the shared nuclear dna could be a remnant of dna from homo erectus, one of the most recent species since australopithecus.

Explanation:

• Mitochondrial DNA is maternally inherited. Since earlier work indicated no overlap between Neanderthal mitochondrial DNA and that of Homo sapiens, if the shared nuclear DNA was definitely the result of interbreeding between female Neanderthals and male humans, we would expect some overlap in mitochondrial DNA (as female Neanderthals would pass on their mitochondrial DNA). But there is no such overlap shown in the earlier work.
• Interbreeding between male Neanderthals and female Homo sapiens (option 2) would not necessarily lead to Neanderthal mitochondrial DNA in Homo sapiens (as mitochondrial DNA comes from the mother - Homo sapiens female in this case).
• Shared nuclear DNA could be from a common ancestor (option 3) as nuclear DNA can be inherited from a common ancestor without involving mitochondrial DNA inheritance patterns.
• Shared nuclear DNA could also be from Homo erectus (option 4) as a remnant, and this has no direct relation to the mitochondrial DNA non - overlap with Neanderthals.

Answer:

The shared nuclear DNA is definitely the result of interbreeding between female Neanderthals and male humans.