The difference between humans and other primates does not lie in the number of genes, but in the expressive models of these genes. This idea was known for a long time, but it was not demonstrated. Now, a group of researchers from Germany and China have found differences between these models analyzing brain samples of humans, chimpanzees and macaques. Scientists have followed the expression of 12,000 genes and have found that the activity of 702 genes expressed in the prefrontal cortex is much more limited in chimpanzees and macaques than in humans. The number of models of human expression was 12 times greater than that of others. And researchers say that the genes studied participate in the creation of synapses of neurons, so they have to do with brain development.