In chapter 15 Lende uses examples of his own research, which deals with adolescent drug use and abuse in Colombia to address how someone should go about doing research using the evolutionary theory for behavioral problems. He addresses that there are two main components that go into substance abuse: “intensification and reinstatement”, since for drug users usually the substance is a higher priority for them than other aspects of their life and even after they stop using drugs, they may relapse on to their old habits. Lende also points out the factors that lead to addiction, such as sociocultural stress, an environment in which the substance is easy to find, as well as multiple brain systems.
Lende then goes into the five steps that he used to do his research. Step one is the human organism point of view, in which he looked at the interaction between human biology and culture. One must keep in mind the negative and positive outcomes that can occur while looking at how people behave.
The second step is adaptive analysis which focuses on the proximate level and how the adaptions that we have gone through in the past along with the present environment is what shapes how the neuropsychological system’s functioning has adapted.
The third step is phylogenetic comparison, where Lende explains that it is crucial to use animal models to understand brain evolution and behavioral disorders.
The fourth step is malfunction and discordance, which focuses on how there is a mismatch between today’s environment and in the environment in the past, and how that can lead to maladaptive behaviors.
The final step goes into the methods one should take while doing their research, putting an emphasis on combining ethnography and epidemiology.