evolutionary psychology

Evolutionary psychology is an approach in the social and natural sciences that studies the psychological behaviours and adaptations of humans to the changing physical and social environment. It’s basically a combination of evolutionary biology and cognitive psychology. In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He believed that all plants and animals had evolved from a few common ancestors by means of natural selection. The theory is based on the assumption that living organisms face environmental challenges.

This means that those who adapt best to the environment will have a greater chance of surviving, having children, and passing on their genes to the next generations. Darwin’s theory of natural selection explains how species acquire adaptive characteristics to survive in an ever-changing environment. According to his theory, those members of a species who have characteristics which are better suited to the environment will be more likely to breed, thus to pass on these traits. Organisms with specific genetic traits that enhance survival are said to be naturally selected.

Once study demostrating an adaptive behaviouris that by Charles & Bargh (1999) who investigated the human tendency to mimic the behaviour in another in a social situation. They called this the “Chameleon effect”. The chameleon effect basically refers to the tendency to adopt the postures, gestures, and mannerisms of interaction partners (nonconscious mimicry). As human beings, we mimic eachother due to the desire to fit in and belong (Social glue), therefore having a more chance of survival and less chances of depression. Charles & Bargh (1999) aimed to investigate the occurrence of a chameleon effect in an interview situation.

The reserch hypotheisis was that the frequency of participants/ interviewees ‘foot-tapping’ and ‘face-rubbing’ mannerisms will be greater when with an interviewer who taps their foot and rubs their face than with an interviewer who does not demostrate these behaviours. In the investigation, there were two conditions; one, the interviewer displays foot-tapping and face-rubbing mannerisms and the two, the interviewer does not display foot-tapping and face-rubbing. Using the chameleon effect, they argued that unconscious habit of imitating behaviours such as foot-tapping enables rapport-building and social bonding between individuals.

Charles & Bargh (1999) discovered significant results, foot-tapping and face-rubbing mannerisms were positively correlated between the interviewer and interviewee. Foot-tapping was more positively correlated and increased by 50%, on the other hand, face-rubbing increased by 20%. This provides evidence to illustrate how mimicry occurs in human beings to a significant level, it therefore supported their hypothesis, stating that unintentional mimicry and imitation facilitates social bonding. Charles & Bargh (1999), had it’s strengths and weaknesses.

Strengths of this lab experiment was that ot was standerdized and controlled. Therefore, it was quite accurate and reliable. Also another advantage was that, the participants were not aware of the aim or hypothesis of the experiment, therefore reduced demand characteristics. However, the experiment was based on a western sample, therefore, there may be differences in behavioural pattersn and also it was unethical because tha participants weren’t informed of the study although later on, it was justified to them. Fear? Disgust? It’s all in our genes. Evolutionary psychology helps to explain how we became who we are today.

Also tells us much about ourselves, our fears, emotions and cravings. It’s all in our genes, and the lives our ancestors lived generations ago. Dan Fessler, an anthropologist, assists in the effort to understand how the world in which our ancestors evolved forced them to avoid things and others just to survive. His primary area of reserch is the ‘disgust emotion’. He states that, “The emotion allowed our ancestors to survive long enough to produce offspring, who in turn passed the same sensitivities on to us”. To prove his point he conducted experiments on pregnant women.

Which were designed to show how disgust can protect a woman during her most risky times, like the first trimester of pregnancy. Nausea and loss of appetite during pregnancy may have evolved as a way to protect the mother and the fetus against diseases which could threaten the fetus. ‘Disgust’, has evolved as a food-rejection response to prevent contamination and the spread of illness. Fessler et al (2005) was aimed to investigate if disgust sensitivity in the first semester of pregnancy was evelated as predicted. It procceded as a web-based survey which was completed by 691 women throgh pregnancy-related websites.

No reward was offered for participation. The womens mean age was 28. 1 years. The questionnaire asked participants to indicate current level of nausea on 16-point scale. They answered questions to test their disgust sensitive in eight different areas: food, contact with animals, body products, contact with dead animals, hygiene contact with toilets. As expected, women in the first trimester scored much higher in disgust sensitivity than those in the second and thrid trimesters, particularly when the scenario increased the possibility of contact with others or eating contaminated food.

However, the data was collected through questionnaires, this is not an effective way of measuring disgust. It would have been more reliable if the participants dealed with real disgust-eliciting objects. Although, the results indicated that nausea and vomiting are evolved behaviour because they limit the likelihood that pregnant women will eat dangerous foods. Mental disorders can also be explained from an evolutionary perspective. Mental disorders are emotional disorders people experience, such as; anxiety, depression or anger.

Such emotions are seen as being abnormal, because they are not useful for our genes. Depression is a condition of mental disturbance, typically with lack of energy and difficulty in maintaining concentration or interest in life. People with depression are so weak and damaged, that it is difficult to see how such emotions could be useful. However, natural selection has shaped emotion regulation mechanisms that often rise to normal but useless suffering. It is understandable, then, that clinical depression is thought to be a pathology- a major dysfunction of the brain.

In most cases, rates of oragn dysfunction increase with age, with low rates in adolescents and young adults, and the highest rates in elderly. These patterns are regular with evoloutionary theories of aging which state that selection against dysfunctional traits decreases with age, as there is a decreasing probability of surviving to late ages. Evolutionary psychology and its purpose in evolutionary medicine suggests how behaviour and mental conditions (such as, depression), may be past adaptions to recurring reproductive problems faced by our ancestors.

It has been hypothesized that depression is an evolutionary adaption because it helps prevent infection in both the affected individual and his/her kin. Firstly, depression allows one to conserve energy and allocate energy to the immune system more efficiently. It further prevents infection by discouraging social interactions and activities that may result in exchange of infections. Likewise, depressed mothers may interact less with their children, reducing the probability of the mother infecting her kin. Lastly, the lack of appetite with depression may also reduce exposure to food-borne parasites.

According to a recent study by scientists from the Univeristy of Las Palmas de Gran Canaria and the Univeristy of Granada, discovered a direct relationship between eating fast foods and the risk of developing depression. The study sample consisted of 8,964 participants who part of the SUN project. The subjects had never been diagnosed with depression or taking anti-depressants. For six months, they were assessed and by the end of it all, found that 493 participants were diagnosed with depression or started to consume anti-depressants.

The findings reveal that consumers of fast food are 51% more likely to develop depression than minimal or non-consumers. The results also showed that those participants who ate the most fast food were more likely to be single, less active and have poor dietary habits, and also common for individuals in this group to smoke and work over 45 hours per week. Furthermore, the connection between the two is so stron that, “the more fast food you consume, the greater the risk of depression”.

Evolutionary theory proposes that food preferences have developed as a result of natural selection, helping our ancestors to survive in the environmental conditions. It suggests that our digestive system has been evolved to break down necessary foodstuffs into nutrients so they are absorbed into the bloodstream and metabolized. Food preferences might be understood as an adaptive urge to seek out food which provided energy. Most evolutionary adaptations are thought to have occured in the Pleistocene Era (between 10,000 and 2 million years ago).

In this environment food was only periodically available therefore had a preference for energy rich, fatty food. This could be why people overeat and become fat today. Burham & Phelan (2000) suggests that a preference for fatty food meant our ancestors would eat foods that was high in calories so they would survice when food was scarce. This preference for high calorie food has stayed with us now as we have much more fatty foods available to us, hence why we prefer food that is bad for us. However, this argument is flawed as it does not explain why evolution is not occuring as rapidly today.

In Western cultures, there is no longer a hunter-gatherer culture so we should be seeing a move away from fatty food preferences which cause health problems. It also has social implications as it removes personal responsibility from overeating and could be used as an excuse for obesity. Evolutionary psychologists also suggest that we have evolved to avoid poisonous foods. This explains why many people have a sweet tooth; sweet-tasting foods are both indicative of high calorie contents and are rarely poisonous. In contrast bitter tastes are often poisonous.

We humans have 27 bitter taste receptors and only 2 sweet ones suggesting they are more sensitive to bitter-tastes. However, the sensitivity for bitter tastes decreases with age. Dr Gillian Harris, found out that newborn babies have a preference for sweet things and a dislike for bitter things. He also discovered that these preferences are the same all over the world, which suggests this preference is caused by evolutionary means. This can be explained by the early mammals who mainy ate fruits, therefore, sweet foods such as fruits now triggers the release of dopamine which bring about pleasure.

Vise versa, most poisons have a bitter taste, so this could be explain why we dislike bitter foods. Salt on the other hand, is essential to survival as it prevents dehydration and is often a popular taste. Carnivorous animals such as lions do not crave salt as it is in plentiful supply in raw meat, however, herbivores do as their grazing foods are low in salt. Although, this doesn’t explain why salt cravings have still remained high despite the fact of us eating meat and acquiring a high supply of salt.

Dudley et al (2008), discovered that ants who lived 60 miles inland areas preferred a 1% salt solution to a sugary one (regardless of it being 10 times more concentrated). However, carnivorous ants did not display this difference as they obtained sufficient salt from their prey. Researchers have also applied this to humans, suggesting salt preferences help to maintain competitiveness, on the other hand, today it’s often eaten in excess depite it leading to health risk such as high blood pressure. In general, the approach is sucessful as it’s backed up by scientific research.

Unfortunately, too many statements have been made and the approach very deterministic as it ignores individual differences (For instance, not all people favor sweet tastes and some people dislike meat). Evolutionary psychologists hold that behaviours or traits that occur universally in all cultures are good candidates for evolutionary adaptations. Altruism involves the unslefish concern for other people. It involves doing things simply out of a desire to help, not because you feel obligated to out of duty. It’s a traditional virtue in many cultures, and a core aspect of various religious traditions.

If there were species whose only concern was themselves, they wouldn’t survive for long, would just quickly die off and leave the more selfless behind. Therefore, altruism exists for a purpose, and that purpose being survival of the race. Altruism has always been an interesting issue for evolutionary theorists, the fact that an organism engages in a behaviour that comes at a great personal cost and seems to benefit only other individuals was difficult for natural selection to explain. Until, the concept of inclusive fitness was introduced by Hamilton in 1964, that evolutionists had a satisfactory theoretical framework for discussing altruism.

Inclusive fitness is often referred to as ‘kin selection’, because according to this concept, natural selection favours behaviours that benefit others who share our genes, especially closely related people. Therefore, a mother who sacrificies her life for the survive of her children may actually be engaging in a behaviour that is genetically adaptive. However, the concept of kin selection is rather limited in that it cannot explain the whole range of altruistic behaviours observed in humans and other animals. For instance, it cannot explain altruistic acts that are aimed at other individuals who arent known to be genetic kin.

The theory of reciprocal altruism was developed by Trivers in 1971, as an attempt to expalin cases of obvious altruism among unrelated organisms. For reciprocal altruism to work there is no need for the two individuals to be relatives, however, it is necessary that they should interact with each other more than once, and have the ability to recognize other individuals with whom they have interacted in the past. Social psychologists are interested in understanding why altruism occurs. They refer the aspect of altruism as pro-social behaviour.

Pro-social behaviour refers to any action that benefits other people, no matter what the motive or how the giver benefits from the action. However, altruism involves true selflessness. Kin selection theory predicts that animals are more liekly to behave altruistically towards their relatives than towards unrelated members of their species. There will be a survival advantage over a group containing lots of altruists over a group composed of selfish organisms. A process of between-group selection may thus allow the altruistic behavviour to evolve.

The idea that group selection might explain the evolution of altruism was first mentioned by Charles Darwin. Altruism makes good sense from the genes point of view, a gene wants to maximize the number of copies of itself that are found in the next generation; one way of doing that is to cause its organism to behave altruistically towards other bearers of the gene. Warneken & Tomasselo (2006) was aimed to investigate if humans and captive chimps help someone if given the oppurtunity. It proceeded with the experimenter making it clear to the chimp and humans that they need help with something.

The results proved that humans in fact help most of the time, and that chimps help when they understand the goal of the experimenter. It was concluded that helping behaviour may be inborn and determined by genes which makes evolutionary sense since strong social bonds mean that groups may be more likely to survive and that altruism may have evolved from a common ancestor that both humans and chimps share. However, they only used captive chimps, whom may have been helping the expermineter who actually was their caretaker, therefore, behaving altruistically because they know the caretaker provides them with food.

Where human behaviour is concerned, the difference between biological altruism, defined in terms of fitness consequences, and ‘real’ altruism, defined in terms of one’s conscious intentions to help others, does make sense. As argued by Elliot Sober in 1994, an action performed with the conscious intention of helping another human being may not affect their biological fitness at all, so would not count as altruistic in the biological sense. On the other hand, an action undertaken without the conscious intention of helping another, may boost their biological fitness greatly! Therefore, altruism and morals, do help us survive.

Not as individuals, but as a species. Sexual selection is a type of natural selection but refers to slecetive pressures to choose the right mate. This selection typically refers to the process of choice over members of the opposite sex. Evolutionary psychologists argued that men and women faced different adaptive poroblems in mate selection, which explains sex differences in reproductive strategies and mate selection. Mate selection is an important adaptive problem for both sexes in the selection of a suitable mate. It’s basically adaptive for all living creatures so as to ensure survival of genes.

There are certain characteristics that will either lead to lower reproductive sucess or high reproductive success. Therefore, both males and females are faced with difficulties in adaptation when selecting a mate. As seen with the peacocks, the males compete to be chosen by females, according to Darwin, because females choose whom they mate with, males have to compete for access to females, therefore they evolved with such beautiful brightly coloured tails which are large and unwidely enough to pose a significant survival disadvantage in the process of attracting the females.

Since females have to make a greater investment in off-spring they are more choosy about whom they mate with, this choosiness means that males have to compete with each other in order to be chosen. From an evolutionary perspective, men and women are seeking the same thing, that is the greatest possible likelihood of mating with someone with whom they will have healthy offspring and pass on their genes to the next generations. Males seek fertaile females, which basically means that they are drawn to signs indicating those with good reproductive capacity.

Preferably, seeking for younger mates. However, on the other hand, females seek economic security for their few possible offspring. They are drawn to cues indicating availability of resources, dominance and high status. Devendra Singh, a professor who’s highly known for his research regarding the evolutionary significance of waist-to-hip ratio (WHR). In 1993, he was the first to reveal the concept and significance of this ratio as an indicator of attractiveness. Singh (1993) proposed that WHR served as an honest marker of female age/ reproductive status and health.

He asked participants to examine 12 randomly arranged line drawings representing four levels of WHR at three levels of body weight and rank them in order of attractiveness. Singh discovered that in all weight categories, males and females rated the figue with the lowest WHR (0. 7) as being more youthful, healthy, reproductively capable and attractive. Participants rated the figure of normal weight with the WHR of 0. 7 as being the most attarctive and the underweight figure with a WHR of 0. 7 was rated as being the most youthful but not as attractive or reproductively capable.

Therefore, noting that lower levels of WHR correlated to lower risks of disease and greater fertility. Singh (1993) has shown that men prefer certain waist-to-hip ratio in woman. A 70% WHR shows health and fertility in women and that’s what men prefer. Basically seen as a very reliable experiment, as well as observable, conclusive finding were concluded. The weakness is that this kind of experiment was issued to ‘male-americans’, therefore we cannot generalize this example. Although subsequent research demostrated the cross-cultural appeal of a low waist-to-hip ratio.

However, it was criticised for the fact that findings from the WHR reaserch was based on sets of line drawings and thus lack ecological validity. Henss (2001) corrected this by using morphed photographs displaying the same female body with a different WHR and again found that a lower ratio was associated with higher ratings of attractivenss. In 1989, Buss aimed to investigate if evolutionary explanations for sex differences in human mate preferences are found in cultures with varying ecologies, places, ethinc/racial make up, religion and political inclinations.

Buss (1989) aimed to find out what males & females desire in a mate in terms of characteristcs and if these desires are culturally universal. David Buss (1989) collected an amount of cross-cultural questionnaire data to address the hypothesis about evolved human mating psychology. More than 10,000 respondants in 37 different cultures. In 36 of 37 cultures, females rated financial prospects as more important than did males. In all 37 cultures, males preffered younger mates and females preffered older mates. In 34 cultures, males rated good look an important characteristic and In 23 cultures, males rated chastity as more important.

Buss conluded that sex differences involving mate preferences for earning potential, relative youth and physical attractiveness were strongly confirmed across cultures. His finding supported the evolutionary explanations of human behaviour, specially that mating behaviour should differ according to gender, reflecting the differences in reproductive capacities of males and females. Basically, the sample size was large enough and it was a very reliable method, also because of the use of two questionnaires reduced the likelihood of demand characteristics.

However, ecological validity was low as what we say in a questionnaire may not reflect how we pick mates in real life situations. Sex differences in jealousy, jealousy is basically an emotion and typically refers to negative thoughts and feelings of insecurity, fear and anxity over an anticipated loss of something, particulary in preference to a human connection. According to Evolutionary Psychologists, men and women both tend to look for partners who are likely to be faithful to them, however, the risks of an unfaithful partner are different in each sex.

If a man is unfaithful, then the risk is that his resources will be diverted to the other woman and her children. If a woman is unfaithful, there’s a risk that she may become pregnant and the male will unknowingly be investing his resources in offspring who do not possess his genes. If evolutionary theory is correct it would be expected that jealousy would manifest itself in different ways in males and females: females should be more concerened with the male developing a relationship with another woman (emotional infidelity) and males should be more concerened with the female copulating with another male (sexual infidelity).

This evolutionary view has been supported by research carried out by David Buss (1992). He carried out a ‘self report’ study where males and female participants were asked to imagine a romantice relationship where their partner is either having sex with someone else, or falling in love with someone else. And state which of the two would cause them the greatest distress. The results showed that female participants stated that they would be more upset by the emotional infidelity more often than male participants, while sexual infidelity tended to be more upsetting for males than females.

David Buss (1992) also used physiological measures as a more objective way of testing the level of jealousy in each scenerio. As it was predicted, the male participants had higher heart rates and galvaic skin responses when considering sexual infidelity, while on the other hand, emotional infidelity produced the largest physiological response in females. Buss (1992) study can be criticised though as the participants were American college students.

The sample may not represent the larger population, because college students are young and have less experience of relationships than older people. Another problem of the study is that participants may have made inferences about what the infidelity means. Critics of evolutionary psychology however maintain that generated hypotheses are simply modern, just-so stories. The phrase ‘just-so’ was popularized by the publication of Rudyard Kipling’s Just-so stories, that contains fictional and on purpose fanticize tales for children, in which the stories pretend to explain animal characteristics.

The study of evolution and evolutionary psychology has been influenced by animal studies. Charles Darwin noted that humans have a number of behaviours in common with other animals. However, apart from the moral issues of using animals in research, Cardwell argues that studying animals can lead to ‘anthropomorphism’, which is the error of seeing animal characteristics in people and human characteristics in animals. Just because animal behaviour looks like human behaviour, that doesn’t mean it has the same causes.

There is an issue of defining psychological mechanisms. In order for something to be inherited it has to exist. Certain psychological mechanisms that have been identified by evolutionary psychologists such as ‘jealousy’ and ‘depression’ are abstract opinions. These conditions may not actually exist, and so therefore are impossible to inherit- so the whole debate on the inheritance of certain adaptations collapses. Biological researchers often adopt a ‘reductionist’ approach to the study of human behaviour.

This is a micro-level of research, which breaks down complex behaviour into smallest parts. This micro approach is criticised for being overly simplistic in explaining behaviour. However, it’s important to have detailed knowledge of the components of human behaviour in order to understand how several factors may interact to cause certain behaviours. “It’s not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most adaptable to change” ~Charles Darwin

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