Schizophrenia: the illness that made us human

Any hypotheses concerning the origins of humans must explain many things. Among these are: 1, the growth in brain size around two million years ago; 2, the presence of subcutaneous fat; 3, the near absence of change or cultural progress for around 2 million years after the brain grew in size; 4, the cultural explosion which began somewhere between fifty thousand and one hundred thousand years ago with the emergence of art, music, religion and warfare; 5, the further cultural explosion around ten thousand to fifteen thousand years ago which developed with the emergence of agriculture and which has continued since. Since the brain, like subcutaneous fat, is particularly rich in lipids, and since the microconnections of the brain are substantially lipid in nature, it is suggested that changes in lipid metabolism are what differentiated humans from the great apes. The growth in brain size and in the quality of subcutaneous adipose tissue may have occurred because of changes in the proteins which regulate the rate of delivery of fatty acids to tissues, notably lipoprotein lipases and fatty acid binding proteins. The creativity which occurred one hundred thousand years ago may have resulted from changes in phospholipid-synthesizing, -remodelling and -degrading enzymes which largely determine the microconnectivity of neurons. Family studies and adoption studies indicate that schizophrenia in a family member is associated with an increased risk of the illness in other family members. It is also associated with an increased risk of schizotypy, manic-depression, dyslexia, sociopathy and psychopathy. On the other hand it is also an indication of an increased likelihood of high creativity, leadership qualities, achievements in many fields, high musical skills and an intense interest in religion. I propose that the characteristics which entered the human race about one hundred thousand years ago and which ended around two million years of cultural near-stagnation are precisely those shown by the families of people with schizophrenia. I propose that these features are caused by variations in phospholipid biochemistry which are responsible both for schizophrenia and for our humanity. This would help to explain why schizophrenia is present to approximately the same degree in all races. It is the illness which made us human prior to the separation of the races.