Strong reproductive isolation between humans and Neanderthals inferred from observed patterns of introgression. Author Affiliations Edited by Svante Pääbo, Max Planck Institute of Evolutionary Anthropology, Leipzig, Germany, and approved August 3, 2011 (received for review May 10, 2011) Abstract Recent studies have revealed that 2–3% of the genome of non-Africans might come from Neanderthals, suggesting a more complex scenario of modern human evolution than previously anticipated.
In this paper, we use a model of admixture during a spatial expansion to study the hybridization of Neanderthals with modern humans during their spread out of Africa. We find that observed low levels of Neanderthal ancestry in Eurasians are compatible with a very low rate of interbreeding (<2%), potentially attributable to a very strong avoidance of interspecific matings, a low fitness of hybrids, or both.
Footnotes Author contributions: M.C. and L.E. designed research; M.C. performed research; M.C. and L.E. analyzed data; and M.C. and L.E. wrote the paper. The Animal Connection and Human Evolution (Pat Shipman) Current Anthropology Volume 51, Number 4, August 2010Tuesday Jun 29 2010 11:58 AM/CA300269/2010/51/4/hensleys/ritterd/ritterd/QC1 complete/use-graphics/narrow/default/ (Chaney 2008).
In both the United States and Australia, 63%of households include pets, compared with 43% of Britishand 20% of Japanese households. In the United States, theproportion of households with pets is larger than those withchildren. The number of dogs in Japan exceeds that of chil-dren under the age of 12.Companion animals signiﬁcantly affect and improve hu-man health cross-culturally (Anderson, Reid, and Jennings1992; Beck and Meyers 1996; Headey and Grabka 2007;Headey and Krause 1999; Headey et al. 2003; Serpell 1991).Pet-owning and pet-assisted therapies beneﬁt handicapped,elderly, autistic, mentally ill, and criminal individuals (e.g. $186 million in China( People’s Daily The Scotsman The Hypothesis The Early Stage: Inventing Stone Toolsand Becoming a Predator 2.6 mya up to 200,000 years ago. Homo Australopithecus b a q4.
Our Neandertal Brethren: Why They Were Not a Separate Species. According to the late Harvard University biologist Ernst W.
Mayr, the greatest evolutionary theorist since Charles Darwin, “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.” Reproductive isolation is the key to understanding how new species form, and many types of barriers can divide a population and split it into two different groups: geographic (such as a mountain range, desert, ocean or river), morphological (a change in coloration, body type or reproductive organs), behavioral (a change in breeding season, mating calls or courtship actions), and others. After isolation, if members of the split populations encounter one another and cannot produce viable offspring that can themselves later successfully interbreed and produce viable offspring (hybrids such as mules are infertile), then these two populations constitute two different species. The Neandertal Genome. Ancient DNA From Siberia Fingers a Possible New Human Lineage.