Human Evolution Paragraph 5

Another example of modern convergent evolution is human adaptation to tropical rainforests. Tropical rainforests are harsh environments for humans. They are marked with high pathogen activity, high temperatures and abundant rainfall, as well as ferocious animals. This type of unforgiving environment likely resulted in human adaptations in response to selective pressures. Researchers studied 660,918 SNP’s looking for outliers in populations living in a tropical rainforest and genetically related populations living outside of the tropical rainforest in Africa, North America and South America. “The most significant positive selection signals were found in genes related to lipid metabolism, the immune system, body development, and RNA Polymerase III transcription initiation. The results are discussed in the light of putative tropical forest selective pressures, namely food scarcity, high prevalence of pathogens, difficulty to move, and inefficient thermoregulation (Carlos Amorim et al., 2015).” Researchers identified seven clusters in five separate chromosomes that show positive selection for potential rain forest adaptations. Two of the clusters only showed evidence of positive selection in North America and South America. Two other clusters only showed evidence of positive selection in Africa. The other three clusters were found in both continents. This is clear evidence of convergent evolution in modern human history.