In both fields, it is understood that genes not only code for particular traits, but also contribute to certain patterns of cognition and behavior. Evolutionary psychology focuses on how universal patterns of behavior and cognitive processes have evolved over time.
Therefore, variations in cognition and behavior would make individuals more or less successful in reproducing and passing those genes to their offspring. Evolutionary psychologists study a variety of psychological phenomena that may have evolved as adaptations, including fear response, food preferences, mate selection, and cooperative behaviors Confer et al. Whereas evolutionary psychologists focus on universal patterns that evolved over millions of years, behavioral geneticists study how individual differences arise, in the present, through the interaction of genes and the environment.
When studying human behavior, behavioral geneticists often employ twin and adoption studies to research questions of interest. Twin studies compare the rates that a given behavioral trait is shared among identical and fraternal twins; adoption studies compare those rates among biologically related relatives and adopted relatives. Both approaches provide some insight into the relative importance of genes and environment for the expression of a given trait.
In humans, genetic variation begins with an egg, about million sperm, and fertilization. Fertile women ovulate roughly once per month, releasing an egg from follicles in the ovary.
Essay on Nature vs Nurture: Twin Studies and Adoption
The egg travels, via the fallopian tube, from the ovary to the uterus, where it may be fertilized by a sperm. The egg and the sperm each contain 23 chromosomes. Chromosomes are long strings of genetic material known as deoxyribonucleic acid DNA.
DNA is a helix-shaped molecule made up of nucleotide base pairs. In each chromosome, sequences of DNA make up genes that control or partially control a number of visible characteristics, known as traits, such as eye color, hair color, and so on.
A single gene may have multiple possible variations, or alleles. An allele is a specific version of a gene. So, a given gene may code for the trait of hair color, and the different alleles of that gene affect which hair color an individual has. When a sperm and egg fuse, their 23 chromosomes pair up and create a zygote with 23 pairs of chromosomes. Therefore, each parent contributes half the genetic information carried by the offspring; the resulting physical characteristics of the offspring called the phenotype are determined by the interaction of genetic material supplied by the parents called the genotype.
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Figure 7. Most traits are controlled by multiple genes, but some traits are controlled by one gene. A characteristic like cleft chin , for example, is influenced by a single gene from each parent. When someone has two copies of the same allele, they are said to be homozygous for that allele. When someone has a combination of alleles for a given gene, they are said to be heterozygous. For example, smooth chin is a recessive trait, which means that an individual will only display the smooth chin phenotype if they are homozygous for that recessive allele bb.
What type of chin will their child have? The answer to that depends on which alleles each parent carries. If the woman is homozygous for cleft chin BB , her offspring will always have cleft chin. It gets a little more complicated, however, if the mother is heterozygous for this gene Bb. Figure 8. The capital B represents the dominant allele, and the lowercase b represents the recessive allele. In the example of the cleft chin, where B is cleft chin dominant allele , wherever a pair contains the dominant allele, B, you can expect a cleft chin phenotype.
You can expect a smooth chin phenotype only when there are two copies of the recessive allele, bb. Sickle-cell anemia is just one of many genetic disorders caused by the pairing of two recessive genes. For example, phenylketonuria PKU is a condition in which individuals lack an enzyme that normally converts harmful amino acids into harmless byproducts. If someone with this condition goes untreated, he or she will experience significant deficits in cognitive function, seizures, and increased risk of various psychiatric disorders. Because PKU is a recessive trait, each parent must have at least one copy of the recessive allele in order to produce a child with the condition Figure 9.
Figure 9. In this Punnett square, N represents the normal allele, and p represents the recessive allele that is associated with PKU. So far, we have discussed traits that involve just one gene, but few human characteristics are controlled by a single gene. Most traits are polygenic : controlled by more than one gene.
Height is one example of a polygenic trait, as are skin color and weight. Where do harmful genes that contribute to diseases like PKU come from? Gene mutations provide one source of harmful genes.
Nature vs Nurture essay outline
A mutation is a sudden, permanent change in a gene. While many mutations can be harmful or lethal, once in a while, a mutation benefits an individual by giving that person an advantage over those who do not have the mutation. Recall that the theory of evolution asserts that individuals best adapted to their particular environments are more likely to reproduce and pass on their genes to future generations. In order for this process to occur, there must be competition—more technically, there must be variability in genes and resultant traits that allow for variation in adaptability to the environment.
If a population consisted of identical individuals, then any dramatic changes in the environment would affect everyone in the same way, and there would be no variation in selection. In contrast, diversity in genes and associated traits allows some individuals to perform slightly better than others when faced with environmental change.
This creates a distinct advantage for individuals best suited for their environments in terms of successful reproduction and genetic transmission.
Skip to main content. Module 3: Biopsychology. Search for:. Learning Objectives Investigate the historic nature vs. Examples of an extreme nature positions in psychology include Chomsky , who proposed language is gained through the use of an innate language acquisition device. Another example of nature is Freud's theory of aggression as being an innate drive called Thanatos. Characteristics and differences that are not observable at birth, but which emerge later in life, are regarded as the product of maturation.
The classic example of the way this affects our physical development are the bodily changes that occur in early adolescence at puberty. However, nativists also argue that maturation governs the emergence of attachment in infancy , language acquisition and even cognitive development as a whole. From this point of view, psychological characteristics and behavioral differences that emerge through infancy and childhood are the results of learning. It is how you are brought up nurture that governs the psychologically significant aspects of child development and the concept of maturation applies only to the biological.
For example, Bandura's social learning theory states that aggression is learned from the environment through observation and imitation. This is seen in his famous Bobo doll experiment Bandura, Also, Skinner believed that language is learnt from other people via behavior shaping techniques. Freud stated that events in our childhood have a great influence on our adult lives, shaping our personality. He thought that parenting is of primary importance to a child's development , and the family as the most importance feature of nurture was a common theme throughout twentieth century psychology which was dominated by environmentalists theories.
In practice, hardly anyone today accepts either of the extreme positions. This question was first framed by Francis Galton in the late 19th century. This view has cropped up time and again in the history of psychology and has stimulated much of the research into intelligence testing. A modern proponent is the American psychologist Arthur Jenson.
Finding that the average I. It was more to do with the social and political implications that are often drawn from research that claims to demonstrate natural inequalities between social groups. Today in Britain many believe that the immigration policies are designed to discriminate against Black and Asian ethnic groups. For many environmentalists there is a barely disguised right-wing agenda behind the work of the behavioral geneticists. In their view, part of the difference in the I. More fundamentally, they believe that differences in intellectual ability are a product of social inequalities in access to material resources and opportunities.
To put it simply children brought up in the ghetto tend to score lower on tests because they are denied the same life chances as more privileged members of society.
Essay: Nature vs. Nurture or Both | SchoolWorkHelper
Now we can see why the nature-nurture debate has become such a hotly contested issue. What begins as an attempt to understand the causes of behavioral differences often develops into a politically motivated dispute about distributive justice and power in society. It is equally relevant to the psychology of sex and gender, where the question of how much of the alleged differences in male and female behavior is due to biology and how much to culture is just as controversial.
Researchers in the field of behavioral genetics study variation in behavior as it is affected by genes, which are the units of heredity passed down from parents to offspring. Behavioral genetics has enabled psychology to quantify the relative contribution of nature and nurture with regard to specific psychological traits.
One way to do this is to study relatives who share the same genes nature but a different environment nurture. Adoption acts as a natural experiment which allows researchers to do this. Rather than the presence or absence of single genes being the determining factor that accounts for psychological traits, behavioral genetics has demonstrated that multiple genes — often thousands, collectively contribute to specific behaviours.
Thus, psychological traits follow a polygenic mode of inheritance as opposed to being determined by a single gene. Depression is a good example of a polygenic trait, which is thought to be influenced by around genes Plomin, This means a person with a lower number of these genes under would have a lower risk of experiencing depression than someone with a higher number. Twins monozygotes are of extraordinary importance when studying heredity because they share identical copies of genes.
When I was growing up she always kept the house perfectly ordered. She insisted on every little thing returned to its proper place,… I learned from her. What else could I do?
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