Читать книгу Abnormal Psychology - William J. Ray - Страница 105

Psychopathology from an evolutionary perspective goes beyond the traditional psychological and physiological considerations. Considering the evolutionary perspective, we ask additional types of questions. One question might be, how long in terms of our human history has a particular psychopathological disorder existed? As noted in Chapter 1, a WHO study examined the presence of schizophrenia in a number of countries with very different racial and cultural backgrounds (Sartorius et al., 1986). What these authors found was that despite the different cultural and racial backgrounds surveyed, the experience of schizophrenia was remarkably similar across countries. Likewise, the risk of developing schizophrenia was similar in terms of total population presence (about 1%). Further, the disorder had a similar time course in its occurrence, with its characteristics first being seen in young adults.

If you put these facts together, it suggests that schizophrenia is a disorder that has always been part of the human experience. Because it is found throughout the world in strikingly similar ways, this suggests that it existed before humans migrated out of Africa. The genes related to schizophrenia were carried by early humans who migrated from Africa, and thus, its presence is equally likely throughout the world. Given these estimates as to the history of the disorder, one might ask why schizophrenia continues to exist. We know, for example, that individuals with schizophrenia tend to have fewer children than individuals without the disorder. Fewer children with these genes would over time lead to even fewer children with the genes. Thus, we might assume that schizophrenia would have disappeared over evolutionary time in that it reduces reproductive success and has a genetic component. However, this is not the case.

This creates a mystery for evolutionary psychologists to solve. In order to answer this question, we can draw on many considerations. Perhaps, in the same way that sickle-cell anemia is associated with a protection against malaria, schizophrenia protects the person from another disorder. Or, perhaps like the reaction of rats to stress, which results in depression-like symptoms, the symptoms seen in schizophrenia are the result of a long chain of stressful events in which the organism breaks down in its ability to function. Psychopathology could even go in a more positive direction and be associated with creative and nontraditional views of the world. For example, there are a number of accounts that have noted greater creativity in families of individuals with schizophrenia.

The evolutionary perspective helps us ask such questions as what function a disorder might serve as well as how it came about. In the same way that pain can be seen as a warning system to the body to protect it from tissue damage, anxiety may have evolved to protect the person from other types of potential threats. For example, many of the outward expressions of social anxiety parallel what is seen in dominance interactions in primates. Submissive monkeys avoid contact with most dominant ones in much the way that human individuals experiencing social anxiety avoid dominant members of their group. This suggests the possibility that anxiety may have its evolutionary origins in dominance structures. If this were the case, then we might expect to see some relationship to sexual instinctual processes—as is the case with dominance. The evolutionary perspective also helps us think about what might be solutions to how psychopathology should be treated. As touched on in Chapter 1, these are some of the questions I will discuss in this book.

One perspective of the evolutionary approach has been to redirect psychology back to the basic processes of human existence such as survival, sexual processes, and social behavior. We can then ask what types of disorders are found within each broad category. We can also consider the developmental and social processes and ask how these processes may be involved in psychopathology. Thinking in these terms, we may come to discover that disorders that have very similar end states may have developed from distinct beginning conditions. Depression, for example, can result from extreme stress that brings forth self-preservation instincts. Depression can also result from the loss of significant people in one’s life. Further, loss of social status is also associated with depression. Thus, what appear to be similar symptoms may have been produced by separate and distinct trajectories.

Another psychopathology that has been approached from an evolutionary perspective is the category of personality disorders. Personality disorders reflect a rigid approach to dealing with social relationships. Two commonly discussed personality disorders are psychopathic personality and histrionic personality disorder. Psychopaths are described as manipulative, callous, dishonest, and self-centered. They are antisocial in the sense that they display no need to follow the traditional rules of a society and little remorse or guilt for their actions. For example, they would contract and collect money for a job they had no intention of doing. They would clearly qualify as those whom evolutionary psychologists refer to as cheaters. On the other hand, individuals with a histrionic personality disorder overly seek the attention of others and are very emotional in their reactions. They can be manipulative in their interpersonal relationships.

Harpending and Sobus (1987) suggested that the psychopathic and the histrionic personality styles represent different adaptive strategies in relation to sexuality. Both of these personality types were viewed by Harpending and Sobus as cheaters. Given that it is more common to see male psychopaths and female hysterics, these researchers suggest that this results from different reproductive strategies. A male cheater in a sexual relationship should be able to persuade a female to copulate with him while deceiving her about his commitment to her and his willingness to offer resources for the offspring. A female cheater, on the other hand, would exaggerate her need for the male and make herself appear helpless and in need so that he would give her additional attention and resources. She would also be willing to put her own needs ahead of those of her offspring even to the extent of abandoning them. The work of Harpending and Sobus shows how evolutionary thinking can help to explain possible motivational factors of a particular disorder as well as the demonstrated gender differences.

Submissive monkeys avoid contact with dominant ones, just as humans experiencing social anxiety avoid dominant members of their group.

© iStockphoto.com/DavidCallan

Overnight sleep study: sleep disturbance is often associated with psychopathology.

Muammer Mujdat Uzel/E+/Getty Images

Let’s look at another well-studied process—sleep—as a model for thinking about psychopathology. Since sleep disturbance is often associated with a variety of psychopathological disorders, this will let us consider how normal processes may be influenced to appear pathological. Most people would like to go to sleep when they want to and not be awakened during the night. However, evolution is not always about what makes us feel good. The critical question from an evolutionary perspective is what function sleep plays. In considering this question, we can look at sleep as a model for how we might approach other basic psychological processes.

One initial question to ask is this: Has sleep been shaped by natural selection? Some researchers answer yes to this question (Nesse & Williams, 1994). They offer at least five reasons for why this is so. First, sleep is found in a variety of organisms and is perhaps universal among vertebrates. However, not all animals sleep in the same way. Elephants and cows spend most of their sleep time standing up. Dolphins sleep with one half of their brain, while the other half remains awake. Second, all vertebrates share similar mechanisms that control sleep and dreaming. These mechanisms are found in the more primitive areas of the brain. Third, the pattern of sleep seen in mammals with periods of rapid eye movement and faster EEG activity within the sleep period is also seen in birds. Since the evolution of birds went down a different pathway before the time of dinosaurs, this suggests that sleep is a very primitive and basic mechanism. Fourth, in examining the sleep patterns across species, there appears to be support for the idea that these patterns adapted to match the ecological niche of that particular animal. Fifth and finally, all animals show deficits in response to a lack of sleep. Currently, a variety of researchers are seeking to determine the function of sleep. The best evidence suggests that it allows for restoration of certain physiological processes. There is also evidence that sleep consolidates information learned during waking hours. One conceptual idea is that, given the light–dark cycle produced by the earth’s rotation around the sun, sleep developed as a protective mechanism since it is more dangerous to be out alone at night.

In summary, we can ask critical questions concerning psychopathology that relate to other evolutionary processes:

1 We can ask if the experience of mental illness is universal. If it were not universal, then it would be difficult to argue that we should study psychopathology from an evolutionary perspective. If it is a universal process such as emotionality or language, then we can begin to ask about the nature of mental illness and how its existence fits into our history as humans.

2 We can ask if there is an adaptive value to the behaviors and experiences displayed in psychopathology. It is easy to see that there is a value in not trusting what someone tells you some of the time, but is there any adaptive value in not trusting what anyone tells you all of the time or to think that everyone is always out to get you?

3 We can look for evidence of psychopathology across human history. This includes the question of whether we see signs of psychopathology in nonhuman species.

4 We can seek to understand the nature of psychopathology. That is to say, should we consider psychopathology to be qualitatively different from normal functioning, or is it the situation in which normal processes have been taken to the extreme? We know, for example, that allergic reactions are situations in which our immune system is overreactive. We also know that fever is the process by which body temperature is raised to fight infection. However, the fever uses energy and can damage the body.

5 We can ask if it is protective in some manner. Like carrying the trait for sickle-cell anemia, does having schizophrenia or depression, for example, make you less likely to experience another disorder?

6 We can ask if psychopathology is a recent process. That is, should we consider psychopathology as the result of a mental system that evolved in the Stone Age and is interacting with a high-paced modern environment? For example, aggression in teenage gangs may reflect behaviors that were adaptive in previous times but are no longer adaptive for society today.

These questions are not mutually exclusive. As you will see, they also represent some of the ways scientists and others have sought to understand psychopathology. From an evolutionary perspective, the study of psychopathology begins with the three instincts of survival, sexuality, and socialness. From this perspective, psychopathology becomes a disturbance of these instinctual processes. Throughout this text, I will return to considerations of how certain evolutionary processes might contribute to psychological disorders.

Concept Check

 One of the main themes of evolution is the manner in which organisms are in close connection with their environment. Animals live in nature, but for humans there is another layer of complexity. Describe three uniquely human characteristics that impact our connectedness to our environment. What role do they play in psychopathology?

 What are the six critical questions an evolutionary perspective asks concerning psychopathology?