An evolutionary psychologist studies how humans have changed (or evolved) through the years in order to be better adapted to their life. This may include changes in memory, perception, consciousness, learning, cognition, and personality. Evolutionary psychologists conduct research in order to find out which psychological traits have been created through the process of adapting to the environment. For example, evolutionary psychologists have studied natural selection. They discovered that certain traits become "phased out" because they are no longer beneficial to humans. An evolutionary psychologist might, for example, study how short-term memory has changed as the human environment has changed.