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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