Genetic Mutations

• Researchers at the University of Chicago believe that the sophistication of the human brain was brought about by an "enormous number of mutations in a short period of time" through an intense selection process that favored complex cognitive abilities. Our brains are disproportionately big in comparison to other mammals, suggesting that the human species is unique in evolutionary terms. The research, the results of which were published in the journal "Cell" in December 2004, was led by Bruce Lahn, an assistant professor of human genetics at the University of Chicago and an investigator at the Howard Hughes Medical Institute. The team of scientists proposed this super-fast evolutionary theory after examining the DNA of 214 genes involved in brain development in humans, rats, mice and macaques. They compared mutations and their effects on genes to determine the pressure of natural selection, finding that the human genes had evolved much more quickly than those of the other animals.
  
  

Timeline

• Critical thinking enables us to evaluate, analyze and process information, and to apply it in a way that will benefit ourselves and others. This evolutionary process began a few tens of millions of years ago, a short time in evolutionary terms, according to Professor Lahn. Homo erectus, the precursor to modern humans, is believed to have evolved in Africa about 1.7 million years ago. Early modern humans, with their more rounded skulls, first emerged in Africa at least 130,000 years ago and began leaving Africa 50,000 years ago.
  
  

Social Factors

• Professor Lahn suggests that the development of human society may be linked to increased cognitive ability. This implies that, as human society became more sophisticated, intelligence became more of an advantage. "As humans become more social, differences in intelligence will translate into much greater differences in fitness, because you can manipulate your social structure to your advantage," Professor Lahn explained.
  
  

Scientific Debate

• Critical thinking skills are a good example of modern human behavior. Scientists are still debating whether these skills developed from a sudden biological and genetic revolution or a more gradual revolution that cultivated in the exodus from Africa 50,000 years, according to Hillary Mayell, writing in "National Geographic News." Common elements of modern behavior include the ability to plan ahead, technological innovations, and adapting to changing conditions and environments.