From dwelling in caves to landing on the moon, humans owe their achievements to the amazing organ called the brain. However, as it turns out, human brain evolution with its increased metabolic capacity and brain size has a costly by-product - schizophrenia.
A new study led by Philipp Khaitovich, from the Max-Planck-Institute for Evolutionary Anthropology, supports this long held idea that certain neurological diseases are by-products of increases in metabolic capacity and brain size that occurred during human evolution.
In the study, the researchers sought to look for differences in gene expression and metabolite concentrations by investigating brains from healthy and schizophrenic humans and comparing them with chimpanzee and rhesus macaque brains.
"We identified molecular mechanisms involved in the evolution of human cognitive abilities by combining biological data from two research directions: evolutionary and medical," explained Khaitovich.
To prove the theory, the authors used new technical approaches to really put the theory to the test.
They identified the molecular changes that took place over the course of human evolution and considered those molecular changes observed in schizophrenia, a psychiatric disorder believed to affect cognitive functions such as the capacities for language and complex social relationships.
It was found that expression levels of many genes and metabolites that are altered in schizophrenia, especially those related to energy metabolism, also changed rapidly during evolution.
"Our new research suggests that schizophrenia is a by-product of the increased metabolic demands brought about during human brain evolution," said Khaitovich.
The authors concluded that this work paves the way for a much more detailed investigation.
"Our brains are unique among all species in their enormous metabolic demand. If we can explain how our brains sustain such a tremendous metabolic flow, we will have a much better chance to understand how the brain works and why it sometimes breaks", said Khaitovich.
The study is published in BioMed Central''s open access journal Genome Biology.