1-5 When taking place at the genomic level, epigenetic modifications do not consist of mutations, but of chemical modifications of the DNA or of DNA-associated proteins, with important consequences on chromatin structure and gene expression. In both cases epigenetic changes can be implemented for very long periods of time – in many cases throughout the whole lifetime. This does not mean that, in species where adaptation relies primarily on epigenetic changes (eg, in Homo sapiens),

genetics is out of the game. It means that, in the course of evolution, developmental strategies have been genetically Inhibitors,research,lifescience,medical selected to allow an extreme use of adaptation processes taking place in individuals through the process of epigenetic individualization. Not all Inhibitors,research,lifescience,medical animal species are equal when it comes to individualization. Since the nervous system (the brain in particular) is the most important – although not the only – interactive organ, its evolution is a key factor in the complexity and wealth of our interactions with the surrounding world. In short, if humans are individuals to

an extreme, it is because they are social-extreme individuals. Small causes with dramatic Inhibitors,research,lifescience,medical consequences In the context of the general process of evolution, this short review is intended to summarize our present understanding of the enormous leap that we could call “humanization,” permitted by the dramatic differences between Homo sapiens and his closest cousins, Pan paniscus and Pan troglodytes, from which he separated approximately 7 million years ago. These

Inhibitors,research,lifescience,medical differences are obvious from a morphological, cognitive, and cultural point of view. In terms of morphology, the first variable to consider is size. Among primates, the size of the brain is grossly proportional to that of the body. This rule is easily understandable if one realizes that the brain is primarily, and at its origin, an organ with sensory-motor functions; this is why plants do not need a nervous system. Applied to Homo sapiens, this rule Inhibitors,research,lifescience,medical Linifanib (ABT-869) would mean a brain weighing approximately 500 g for a body weighing 75 kg, meaning that we have an excess of 900 g of brain matter. In addition to this size difference, say between NSC683864 chimpanzees and humans, there are also structural differences, since this increase is not proportional between all structures. A good example is the relative decrease in the size of areas devoted to vision or smell in humans and, conversely, the increase in the size of areas devoted to language (barely present in the chimpanzee) and, above all, to associative and cognitive tasks. This forces us to consider mechanisms that not only have allowed a size increase, but also have modified the positioning of boundaries between territories, ie, cortical areas.