Fat utilization hypothesis

The fat utilization hypothesis attempts to explain differences between humans and great apes as well as Neanderthalians as differences in lipid metabolism. It was developped by David F. Horrobin, Stephen Cunnane, Michael Crawford and others. As Horrobin remarks in The Madness of Adam and Eve: How Schizophrenia Shaped Humanity, one thing that often attracts the attention of children at the zoo watching chimpanzees and gorillas is the fact that our close relatives, especially females, are much less round than their human counterparts. Horrobin summarized the differences in catchy terms: whats makes us human are Breasts, Buttocks and Brains. These three body parts are characterized by their high fat content.

Horrobin describes how several lines of evidence suggest that the disordered and exuberant neural connections seen in schizophrenia, which requires large amounts of highly unsaturated fatty acids as building blocks (60% of the brain is made up of phospholipids), is an extreme variant of something that propelled the evolution of the human brain, with is caracterized inter alia by an enhanced microconnectivity. He emphacizes that schizophrenia's distribution in all human populations is about the same (although the disease can deteriorate differently depending on environmental factors), a fact that gives credence to the hypothesis that schizophrenia appeared at the same time as humanity.

In Survival of the fattest: fat babies were the key to evolution of the large human brain Cunnane and Crawford describe marine lipid utilization as an obligate step in human evolution.

This evolutionary biology hypothesis has broad implications in medicine.