A German scientist did a study in which he showed a group of 6-month-old babies pictures of the same size and color  Some pictures showed flowers or fish, and others showed spiders or snakes  They found that the babies did not respond significantly to pictures of flowers or fish, but all had significantly larger pupils when shown pictures of spiders or snakes
Most adults have a fear of spiders or snakes
 As a result, the scientist believes fear of dangerous animals is something we are born with, not learned