Anthropology: From a Genetic Perspective, Essay Example

From a genetic perspective, the larger and more complex human brains must arise from human-specific functional properties of the genes that underlie brain biology. Recent studies have shown that genes exert a strong influence on the overall volume of the brain in humans and on the size and morphology of specific functional domains in the brain such as the frontal lobes, the sensorimotor cortex, and Broca’s and Wernicke’s speech areas (Thompson, 2001). Cognitive abilities and personality traits in humans have a strong genetic component and cognitive abilities and brain size are moderately related.

Unlike teeth, skulls, and bones, hair is a poor candidate for preservation and even though fossilized skulls do confirm the increase in human brain sizes, the architecture of spine and hips show when our ancestors first stood erect, there is no fossil record of when humans lost body hair and first used clothing thus, anthropologist Mark Stoneking turned to body lice to find the answer. Similarly, by comparing the impressions brain left on the inside of skills, Paleoneurologists are documenting when structures that power the human mind rose and how our ancestors lived and thought.

In the summer of 2006, scientists discovered a gene called HAR1 (human accelerated region) that is present in animals from chickens to chimps to people and it had changed in only 2 of its 118 chemical “letters” from 310 million years ago (when chickens and chimps split) to 5 million years ago. But 18 letters changed when human lineage split from chimps which show that the high rate of change is a sign that evolution keeps conferring advantages on those who carry it, starting with Australopithecus (Begley and Carmichael, 19 March 2007). According to the researcher Catherine Pollard of the University of California, Davis who reported the HAR1 discovery, “HAR1 is present in neurons that play a role in the geometry and layout of the cortex,” so it likely helped the cortexes of our ancestors develop the elaborate folds characteristic of a complex brain.

In 2005, Matthew Rockman of Duke University and colleagues discovered that a gene called PDYN, which regulates production of a molecule called prodynorphin (responsible for neurochemicals that underlie perception, behavior or memory), began accumulating changes 7 million years ago, soon after our oldest direct ancestor appeared. Some anthropologists such as Robert Sussman of Washington University contend that cohesive groups and cooperation between members rather than hunting prowess is what helped out ancestors survive. This position is supported by the genetic evidence because scientists believe that a hormone called oxytocin that operates in the brain of both male and female and which promotes trust during interactions with other people existed in the ancestor of both humans and chimps (Begley and Carmichael, 19 March 2007).

Thus, Paleoneurology holds a great promise to answer evolutionary questions that fossilized skulls record is unable to answer and help us bridge the missing links in the evolutionary chain.

References

Begley, Sharon and Mary Carmichael. “Beyond Stones and Bones.” Newsweek 3 March 2007: 52-58.

Thompson, P. M. “Genetic influences on brain structure.” Nature Neurosci 2001: 1253–1258.