In recent evolution news, a research article published this month in the Proceedings of the National Academy of Sciences has demonstrated that the brains of elephants and humans have followed similar adaptive paths.
The collaborative study, undertaken by scientists from several U.S. universities, analyzed the phylogenomic patterns displayed by genes linked to brain metabolism in fifteen different vertebrate groups; including eleven placental mammals, a marsupial, a monotreme, a bird and an amphibian. Of specific interest to the researchers was the evolutionary history of the elephant brain, which has many physical and functional similarities to that possessed by humans.
Although about four times larger, the brains of elephants are like human brains in that they boast extensive regions of neocortex. The neocortex is the neurological structure responsible for an animal’s sensory perception, motor commands and higher thought processes. Elephants were of particular interest in the study because they - like humans - are known for displaying intelligence, complex social behavior and empathy.
In conducting the research, the scientists examined the occurrence of both synonymous and non-synonymous nucleotide substitutions within each brain-linked gene. Synonymous substitutions can be thought of as ‘silent’ because these changes don’t illicit a change in the resulting amino acid. By contrast, non-synonymous substitutions do result in the incorporation of a different amino acid, and therefore advent a potential for novel risks or benefits on which natural selection can act.
In the case of the brain genes evaluated in this study, the scientists found that when compared to the other vertebrate groups the genomes of elephants and humans show increased frequencies of non-synonymous substitutions in areas responsible for the brain’s aerobic metabolism. So, not only are brains of both elephants and humans relatively large, but they’ve also followed a similar adaptive path in obtaining their current state.
Goodman, M., Sterner, K., Islam, M., Uddin, M., Sherwood, C., Hof, P., Hou, Z., Lipovich, L., Jia, H., Grossman, L., & Wildman, D. (2009). Phylogenomic analyses reveal convergent patterns of adaptive evolution in elephant and human ancestries Proceedings of the National Academy of Sciences, 106 (49), 20824-20829 DOI: 10.1073/pnas.0911239106
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