He further noted that some of the differences between offspring and parents were not due solely to the environment but were themselves often inheritable. Evolutionary psychologists seek to understand the human mind by understanding the evolutionary process that designed it. To do this, they engage in a kind of reverse-engineering, trying to piece together how the minds we have today evolved little by little through the process of natural selection. They are not interested in the competition between species, but rather the competition between genes within the human species. Natural selection creates new traits and adaptations in a species by putting genes through a process of trial and error.
New genes arise in an individual organism by chance mutation.
If a new gene produces a trait that decreases the organism' s chances of reproduction, that gene, and the trait it produces, will not be passed on. This is the fate of the vast majority of genetic mutations. The mental mechanisms we inherit from our ancestors are therefore not necessarily adaptive to today's environment. Fear of insects is automatic, but parents have to work hard to teach their children to avoid speeding cars because that threat didn't exist in our evolutionary past. Those strains of humans that were not so optimized are no longer here.