Explain, with examples, how the processes of natural selection and sexual selection are thought to have contributed to modern-day human behaviour. The processes of natural and sexual selection can help to explain why modern-day human behaviour has evolved. There are many physical and psychological characteristics that all human beings, across cultures, display today that have evolved from our ancestors, over thousands of years. As a result of the selection process, we have adapted in particular ways that best suit our environment thus enabling survival and increasing our chances of producing offspring that will inherit our genes.
This essay aims to explain what is meant by natural and sexual selection, what an adaptation is, and how the processes of selection are thought to have contributed to modern-day human behaviour. Natural selection takes place within a species when particular physical and behavioural characteristics that are beneficial to the survival of that species, within its current environment, are passed via genes to the next generation. The longer an individual can survive, the more likely they will be to produce more offspring and so pass on the particular gene.
The ‘fittest’ characteristics are those, most suited to an environment, which survive frequently through genetics. Less efficient characteristics will not be passed down through selection. The three premises for natural selection according to Barrett et al (as cited in Clegg, 2007) are: there needs to be variations in character traits between individuals in a species, these variations need to be inherited through genetics and there needs to be competition for resources (such as food) so that the individuals with the fittest genes will survive longer than those without, thus being able to produce more offspring. (Clegg, 2007)
The process of natural selection leads to adaptations in a species, some of which are suited to our environment today and some of which are not. Art is said to be an adaptation in human beings, by some, as it can improve social status and thus help us in finding a mate. For something to be an adaptation, the majority of individuals within a species must display the trait, so it must be ‘universal’. There will be special circumstances whereby some individuals will lack a trait and so will be less well equipped to survive in their environment. An adaptation must also be shown to increase survival and reproductive success and be “… fficient or economical in terms of energetic (calorific) costs to the individual. ” (Clegg, 2007, pg 122) A good example of an adaptation in modern day society is our desire for sweet foods. Eating sugar would have improved the survival chances of our ancestors through periods of low food resource and hence improved their chances of producing more offspring. Although a large percentage of the population today do not need to worry about food resources, we are genetically adapted to desire sweet foods. This is a good example of where the environment has changed but the adaptation is not considered ‘fit’ anymore. Clegg, 2007) Researchers gather a wide variety of evidence, including on non-human primates; hunter-gatherers and modern human populations; archaeological and cross –cultural (universality), to decipher whether a characteristic is an adaptation. Our possession and utilisation of ‘theory of mind’ is an example of modern-day human behaviour that has evolved through the process of natural selection and is an adaptation. Possessing it allows us to spot deception and manipulate people to our benefit by having an understanding of their thinking and their actions, by putting ourselves ‘in their shoes’. Clegg, 2007) Archaeological evidence, along with studies carried out on non-human primates, seems to suggest that theory of mind evolved fully at the same time Homo sapiens did. There is some evidence that points to chimpanzees, the closest primates to us in evolutionary terms, showing basic theory of mind, in that they appear to use deception when trying to gain food resources. (Whiten, 1997 as cited in Clegg, 2007) Today, through natural selection, theory of mind has become an adaptation because it helps us in social situations, to gain resources, find a suitable mate and form alliances, “… ll of which are important to our survival and reproductive success. ” (Clegg, 2007, pg 139) For example, if a man thinks that a prospective mate likes kind, considerate males, he may manipulate his chances of securing his mate by showing acts of consideration and generosity towards her. When research was carried out on younger and older children, the older children, who were beginning to possess full theory of mind, demonstrated how it was of benefit to them in understanding social relations and so highlighting its adaptive function. (Dunn & Brown (1993) as cited in Clegg, 2007)
Sexual selection is linked to natural selection but refers to traits, either physical or psychological, that have been selected for because they are beneficial in attracting a better quality and greater number of mates and improving the chances of reproductive success. Parental investment in our offspring plays a large part in sexual selection because it improves the offspring’s chances of reproduction. In terms of modern day human behaviour, babies crying is said to be an adaptive strategy in order for them to attract greater parental investment and improve their chance of survival and reproductive success. Travers (1972), as cited in Clegg, 2007) There is also evidence to suggest that woman have a string of short term partners with the aim of finding the mate who will provide the best long term parental investment and this is a further example of an adaptive strategy. (Greiling and Buzz, 2000; Schmitt et al, 2003; Wiederman, 1997, as cited in Clegg, 2007) Although the evidence is not conclusive, the characteristic of altruism in modern-day human behaviour is believed to be an adaptation because there is evidence to suggest it is inherited genetically, it is universal and it can improve survival and reproductive success.
For example, with relevance to sexual selection and mate choice (intersexual selection), evidence shows that men and women will look more positively on a potential mate and find them more attractive if they are seen as being altruistic and have “… cooperated generously”. (Farrelly et al (2006) as cited in Clegg, 2007, pg 150) In conclusion, evidence, derived from many sources, shows that the processes of natural and sexual selection have contributed to modern-day human behaviour in many ways.
We have adapted characteristics that have evolved over many years and this process will continue. In thousands of years new adaptations will have evolved that equip human beings better to their environment. Indeed, some of these adaptations may be better suited to today’s environment in a similar way the desire for sugary foods was best suited to our ancestor’s. Word count: 1091 References Clegg, H. (2007). Evolutionary psychology. In D. Miell, A. Phoenix, & K. Thomas (Eds), Mapping Psychology (2nd ed. , pp. 105 – 160). Milton Keynes: The Open University.