section_path: Causes/Nature
section_name: Nature
paragraph_text: Nature
  
  Although many fears are learned, the capacity to fear is part of human nature. Many studies have found that certain fears (e.g. animals, heights) are much more common than others (e.g. flowers, clouds). These fears are also easier to induce in the laboratory. This phenomenon is known as preparedness. Because early humans that were quick to fear dangerous situations were more likely to survive and reproduce; preparedness is theorized to be a genetic effect that is the result of natural selection.
  
  From an evolutionary psychology perspective, different fears may be different adaptations that have been useful in our evolutionary past. They may have developed during different time periods. Some fears, such as fear of heights, may be common to all mammals and developed during the mesozoic period. Other fears, such as fear of snakes, may be common to all simians and developed during the cenozoic time period (the still-ongoing geological era encompassing the last 66 million of history). Still others, such as fear of mice and insects, may be unique to humans and developed during the paleolithic and neolithic time periods (when mice and insects become important carriers of infectious diseases and harmful for crops and stored foods).