human evolution

Hey Mary357, I believe this question is from Nelson 12?

Although I don't have the answer, I found this resource you could read.

Evolutionary tree for apes and humans based on cleavage maps of mitochondrial DNA.

The high rate of evolution of mitochondrial DNA makes this molecule suitable for genealogical research on such closely related species as humans and apes. Because previous approaches failed to establish the branching order of the lineages leading to humans, gorillas, and chimpanzees, we compared human mitochondrial DNA to mitochondrial DNA from five species of ape (common chimpanzee, pygmy chimpanzee, gorilla, orangutan, and gibbon). About 50 restriction endonuclease cleavage sites were mapped in each mitochondrial DNA, and the six maps were aligned with respect to 11 invariant positions. Differences among the maps were evident at 121 positions. Both conserved and variable sites are widely dispersed in the mitochondrial genome. Besides site differences, ascribed to point mutations, there is evidence for one rearrangement: the gorilla map is shorter than the other owing to the deletion of 95 base pairs near the origin of replication. The parsimony method of deriving all six maps from a common ancestor produced a genealogical tree in which the common and pygmy chimpanzee maps are the most closely related pair; the closest relative of this pair is the gorilla map; most closely related to this trio is the human map. This tree is only slightly more parsimonious than some alternative trees. Although this study has given a magnified view of the genetic differences among humans and apes, the possibility of a three-way split among the lineages leading to humans, gorillas, and chimpanzees still deserves serious consideration.

Hey Mary357,

according to the textbook, it asks:

a. How does the mitochondrial DNA of humans compare with chimpanzees?
b. How many base-pair differences are typically found between the mtDNA of any two distantly related people?
c. How many base pairs could be sequenced in the Neanderthal mtDNA?
d. How many differences were detected between the Neanderthal sequence and that of a modern human?
e. Does this DNA evidence suggest that Neanderthal are archaic members of the modern human species or members of a different species? Explain.

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Answers

(a) There are 56 differences between the mitochondrial DNA of humans and chimpanzees.
(b) The average number of differences is seven.
(c) The Neanderthal sequence was a 379-base-pair region.
(d) There were 28-base-pair differences detected.
(e) This suggests a common ancestor some 600 000 years ago. Since a similar mitochondrial DNA analysis suggests that all modern humans appear to share a common ancestor from about 150 000 years ago, we would conclude that it is very unlikely that Neanderthals are descendents of this same ancestor and that humans and Neanderthals are separate species.