Instructions: On the below are three student generated arguments for the pro-side of the hypothesis that ancient AM humans interbred with Neanderthals in Europe and Asia. Your assignment is to take a side: pro or con. There really is no middle ground either we have evidence of breeding or we do not. It can’t be that you think ancestral humans maybe bred with Neanderthals but there is not enough evidence for it. YOU MUST TAKE A SIDE!

CON-SIDE: Refute the arguments below with evidence. The paper you turn in will be each of the following paragraphs followed by a paragraph describeing the evidence that refutes this argument.

OR

PRO-SIDE: Each of your three paragraphs (the evidence you have for the con-side) followed by a paragraph that refutes the evidence you presented.

6 paragraphs no more! It do not want an introduction or conclusion section. It just want you to present the evidence that you believe discredits the evidence presented in the earlier paper (below or was yours). You may quote the three paragraphs directly. The original writing is in each paragraph that follows the original paragraph. If you do not understand please ask for clarification. We do not have time to reprepare these.

PRO-Side arguments:

Similarities in morphology of the mandible between Neanderthals and AMH suggest that the features are a result of interbreeding. In 1957, the mandible of RiparoMezzena, a Middle Paleolithic rockshelter in the MontiLessini (NE Italy, Verona), was discovered (Condemi 2013). Mitochondrial DNA (mtDNA) analysis and direct dating confirm that the mandible belongs to a late Neanderthal, the only genetically typed Neanderthal of the Italian peninsula (Condemi 2013). Condemi et al. utilized comparative morphology and shape analysis to demonstrate the morphology of the lower jaw appears to be in between the receding lower jaw (no chin) of classic Neanderthals and the projecting lower jaw (strongly developed chin) of AMHs. The incipient mental trigone of the late Neanderthal displays a much more modern morphology (Condemi 2013). In addition, the results of linear Discriminant Function Analysis (DFA) depicts the position of the Mezzena mandible to be within the modern human shape space, while possessing strong shape similarities with some Neanderthal specimens (Condemi 2013). Change in morphology of the mandibular chin among the fossils of Mezzena and other late Neanderthals could have been the result of a small degree of interbreeding with AMHs.

Comparison of DNA sequences between Neanderthals and Anatomically Modern Humans (AMH) show that Neanderthals share more genetic variants with non-Africans than with Africans due to interbreeding. Recent analyses of 100 mg of bone powder removed from the bone of the Mezzena mandible for DNA extraction and PCR analysis revealed that Neanderthal genomes have closer genetic af?nities with modern non-Africans than with West Africans (Condemi 2013). In addition, Green et al. identified single-nucleotide polymorphism (SNP) alleles by comparing one randomly chosen sequence from an AMH against that of a Neanderthal, demonstrating Neanderthals are equally close to present day Europeans and East Asians. However, Neanderthals are significantly closer to non-Africans than to Africans (Green 2010).

The success rates of interbreeding are observed to be low and imply that there are effective barriers to gene flow between Neanderthals and AMH. Using spatially explicit simulations, Currat and Excoffier computed the expected amount of admixture among Neanderthals and AMH to be less than 2%. The observed low rates can be describeed by assortative mating and/or low fitness of hybrids, and are compatible with the previously observed lack of mtDNA introgression (Currat 2011). If both species interacted for 10,000 years during the range expansion of modern humans, to produce introgression levels of 1–3%, Neanderthals and AMH only have to mingle, on average, once every 23–50years, which shows that they were extremely rare events (Currat 2011).

References:
Condemi et al. “Possible Interbreeding in Late Italian Neanderthals?New Data from the Mezzena Jaw (MontiLessini, Verona, Italy).”PLoS ONE (2013) 8:e59781.

Currat M, Excoffier L. “Strong reproductive isolation between humans and Neanderthals inferred from observed patterns of introgression.” Proceedings of the National Academy of Sciences.(2011) 108:15129–15134.

Green et al. "A Draft Sequence of the Neandertal Genome." Science. (2010) 328:710-722