section_path: Development/Evolution
section_name: Evolution
paragraph_text: Evolution
  
  The mind has a long evolutionary history starting with the development of the nervous system and the brain. While it is generally accepted today that mind is not exclusive to humans and various non-human animals have some form of mind, there is no consensus at which point exactly the mind emerged. The evolution of mind is usually explained in terms of natural selection: genetic variations responsible for new or improved mental capacities, like better perception or social dispositions, have an increased chance of being passed on to future generations if they are beneficial to survival and reproduction.
  
  Minimal forms of information processing are already found in the earliest forms of life 4 to 3.5 billion years ago, like the abilities of bacteria and eukaryotic unicellular organisms to sense the environment, store this information, and react to it. Nerve cells emerged with the development of multicellular organisms more than 600 million years ago as a way to process and transmit information. About 600 to 550 million years ago, an evolutionary bifurcation happened into radially symmetric organisms with ring-shaped nervous systems or a nerve net, like jellyfish, and organisms with bilaterally symmetric bodies, whose nervous systems tend to be more centralized. About 540 million years ago, the bilaterally organized organisms separated into invertebrates and vertebrates. All vertebrates, like birds and mammals, have a central nervous system including a complex brain with specialized functions while invertebrates, like clams and insects, either have no brains or tend to have simple brains. With the evolution of vertebrates, their brains tended to grow and the specialization of the different brain areas tended to increase. These developments are closely related to changes in limb structures, sense organs, and living conditions with a close correspondence between the size of a brain area and the importance of its function to the organism. An important step in the evolution of mammals about 200 million years ago was the development of the neocortex, which is responsible for many higher-order brain functions.
  
  The size of the brain relative to the body further increased with the development of primates, like monkeys, about 65 million years ago and later with the emergence of the first hominins about 7–5 million years ago. Anatomically modern humans appeared about 300,000 to 200,000 years ago. Various theories of the evolutionary processes responsible for human intelligence have been proposed. The social intelligence hypothesis says that the evolution of the human mind was triggered by the increased importance of social life and its emphasis on mental abilities associated with empathy, knowledge transfer, and meta-cognition. According to the ecological intelligence hypothesis, the main value of the increased mental capacities comes from their advantages in dealing with a complex physical environment through processes like behavioral flexibility, learning, and tool use. Other suggested mechanisms include the effects of a changed diet with energy-rich food and general benefits from an increased speed and efficiency of information processing.