<P> The expansion of modern human population is thought to have begun 45,000 years ago, and may have taken 15,000 - 20,000 years for Europe to be colonized . </P> <P> During this time the Neanderthals were slowly being displaced . Because it took so long for Europe to be occupied, it appears that humans and Neanderthals may have been constantly competing for territory . The Neanderthals had larger brains, and were larger overall, with a more robust or heavily built frame, which suggests that they were physically stronger than modern Homo sapiens . Having lived in Europe for 200,000 years, they would have been better adapted to the cold weather . The anatomically modern humans known as the Cro - Magnons, with widespread trade networks, superior technology and bodies likely better suited to running, would eventually completely displace the Neanderthals, whose last refuge was in the Iberian peninsula . After about 25,000 years ago the fossil record of the Neanderthals ends, indicating that they had become extinct . The last known population lived around a cave system on the remote south - facing coast of Gibraltar from 30,000 to 24,000 years ago . </P> <P> From the extent of linkage disequilibrium, it was estimated that the last Neanderthal gene flow into early ancestors of Europeans occurred 47,000--65,000 years BP . In conjunction with archaeological and fossil evidence, the gene flow is thought likely to have occurred somewhere in Western Eurasia, possibly the Middle East . Studies show a higher Neanderthal admixture in East Asians than in Europeans . North African groups share a similar excess of derived alleles with Neanderthals as do non-African populations, whereas Sub-Saharan African groups are the only modern human populations that generally did not experience Neanderthal admixture . The Neanderthal - linked haplotype B006 of the dystrophin gene has also been found among nomad pastoralist groups in the Sahel and Horn of Africa, who are associated with northern populations . Consequently, the presence of this B006 haplotype on the northern and northeastern perimeter of Sub-Saharan Africa is attributed to gene flow from a non-African point of origin . </P> <P> Evidence published in 2014 from genome analysis of ancient human remains suggests that the modern native populations of Europe largely descend from three distinct lines: Hunter - gatherers who lived 45,000 years ago and most probably originated in the second human migration out of Africa into Europe, early agriculturists who moved into Europe about 9,000 years ago and mixed in, and finally a population of pontic - caspian steppe nomads who contributed DNA (and Indo - European languages) to a wide range of modern humans including native Americans . </P>

Where did humans first appear a. south america b. africa c. asia d. europe