Anthropology.net

I am now two-thirds done with my psychiatry rotation. It has been a fascinating experience so far. I’ve seen the gamut of psychiatric cases, depressed people who cut their necks through and through, to florid schizophrenics worried that the Hiroshima bomb will go off any moment. The treatment of psychiatric conditions like depression or schizophrenia often revolves around regulating monoamine neurotransmitters like serotonin, norepinephrine and dopamine.

Dopamine is an important neurotransmitter that functions in a lot of behaviors and reactions, such as movement, lactation, aggression, fear, etc. In diseases like Parkinson, dopamine levels lower and movement becomes uncontrolled. In other diseases like schizophrenia, either dopamine levels are high or response to dopamine is higher, and paranoia & hallucinations manifest. Treating schizophrenia involves blocking dopamine receptors. As you can imagine, a common side effect of antipsychotics is movement disorders — or Parkinsonism.

So why am I on this neuropsychiatric kick on an anthropology blog? Our cultural and behavioral predisopostions ultimately boil down to chemicals in our brain interacting and stimulating other areas. One of the most important functions of dopamine is in the reward system of the brain, an area called the nucleus accumbens that primes pleasurable behavior to repeat, such as sex, eating, and drugs.

In this video, Robert Sapolsky of Stanford Neurology makes the distinction between how dopamine levels rise in the anticipation of pleasure and not as a response to pleasure. I especially like that comment he made regarding reward and religion, “There’s no monkey out there willing to lever press because St. Peter is down the line.”

In the open access paper, “Metabolic changes in schizophrenia and human brain evolution,” Phillipp Khaitovich and team have compared the gene expression and metabolite concentrations in the healthy human brain to a schizophrenic brain. Their results indicate that the biggest differences between a normally functioning brain and an unhealthy one was in 9 genes and metabolites involved in energy metabolism and energy-intensive cognitive functions.

If you remember, this paper from earlier this year, you’d wouldn’t be entirely shocked and awed by Khaitovich et al.’s finds. That’s because in this previous gene expression analysis, mice who were feed a human cooked diet (Supersize Me) versus a ‘chimp’ diet exhibited expression and regulation differences in genes involved in metabolism and detoxification. The authors of this PLoS One paper wrote that they think that the ‘introduction of cooking, have caused a relaxation of selective constraints on diet-related genes.’

In line with this hypothesis, Khaitovich and his team write that advent of cooking reduced the energy needs of our digestive system, freeing up calories for our brains. Our relatively small digestive systems funnel up 20% of total energy to the brain, whereas in non-human primates only 13% energy is allocated.

Khaitovich, P., Lockstone, H.E., Wayland, M.T., Tsang, T.M., Jayatilaka, S.D., Guo, A.J., Zhou, J., Somel, M., Harris, L.W., Holmes, E., Pääbo, S., Bahn, S. (2008). Metabolic changes in schizophrenia and human brain evolution. Genome Biology, 9(8), R124. DOI: 10.1186/gb-2008-9-8-r124