The Evolutionary Significance of Psychoative Drugs

Drugs are a prominent aspect of our society whether it is obvious or not.  Not only are they seen in the hands of criminals, but they can be found in everyday products.  Most common are drugs of the psychoactive variety.  They are the substances that have mental effects once they have entered the body.  Caffiene, for instance, is a common psychoactive drug that can be found in many beverages, especially coffee. 

The addicting nature of these drugs is a well known fact.  Why then, do so many people of this earth feel the need to seek out these mind altering substances?  More importantly, why do they have the effect that they have on humans? 

Some experts, such as Sullivan and Hagen, have come to the conclusion that humans have evolved to utilize the chemicals that are present in these substances.  Ronald K. Siegel believes that the relationship between humans and psychoactive substances is so strong that the drive to find and consume these substances can be considered a "fourth drive," a biological drive that accompanies urges as strong as hunger, thirst, and sex.  


The hypotheses for why humans pursue these substances are many. Whatever the reason, it is well documented that humans have been using psychoactive drugs for millennia, and with such a long record of use it is not out of the question that the conclusion that these experts have presented has some sense of truth.  Perhaps we, as humans, are designed for drugs, and drugs are designed for us.