Why not say instincts are behaviors that are adaptive (that is, encourage survival)?
Of course, one can often think of good reasons why many of these would be biologically adaptive. For example, it seems like people must eat to stay alive and must engage in sex so as to produce the next generation. But the obviousness of its adaptive function is not a very useful criterion because in many cases it is difficult to be sure what the biological advantage is. Is it adaptive to mourn lost loved ones or to tell stories? Possibly, but its hard to be sure just why. The reasons can be very complex and nonobvious. Another example is same-sex preference which is fairly widespread in humans. It seems obviously nonadaptive to some people. But a community of genetically related individuals might benefit in many ways even if some members fail to reproduce. For example, some young and aggressive males in each generation lose their lives engaging in `macho’ behavior (sometimes in important battles and sometimes in frivolous fights and dares) before bearing children. Similarly some indiv
