Introduction to Psychology/Human Development
Biological Basis of Behavior
Like every other aspect of life, behavior is determined largely by an individual's DNA makeup. DNA can be considered as a "blueprint" for every aspect of life. Evolutionary psychologists study the role of natural selection in the passing on of behavioral and other psychological traits. Genetic makeup is generally believed to account for much of an individual's temperament.
Structure and Function of DNA
The nucleic acids are the largest of the organic molecules. DNA stands for deoxyribonucleic acid. It is made up of units called nucleotides, which themselves are composed of an a deoxyribose 5-carbon sugar molecule, a nitrogen base, and a phosphate group. These nucleotides are bonded in columns by phosphate covalent bonds (very strong), and are laterally bound to other nucleotides with weaker hydrogen bonds. Nucleotides are arranged such that they form genes, which are specific biochemical units that code for a characteristic. In DNA replication, DNA is split and transcribed to form proteins, which are the basic structural units of life. Individual-to-individual variance, introduced in reproduction and meiosis, is the basis for different personality traits and differences in temperament between individuals.
Natural Selection in Behavioral Traits
The theory of natural selection may be applied to psychological, as well as biological traits. This is known as evolutionary psychology or the evolutionary perspective.
The basic idea of evolutionary psychology is this; genetic mutations are capable of altering not only an organism's physical traits, but also its behavioral traits. Like physical traits, these mutations may help the organism reproduce and pass its mutation on to the next generation. This theory explains how behaviors like mating rituals and migration came to be multi-generation rituals in some species.
Presently, the evolutionary psychology perspective is extremely controversial as it is unable to be scientifically proven in a laboratory setting and is, by definition, very susceptible to hind-sight bias.
In Early Human Development
Consider the following- in a population's gene pool, the normal genotype is for an infant that is unattached to its mother- it will crawl away and does not have any "love" or other significant attachment to its mother. Over time, mutations accumulate and there develops another genotype that causes infants to become uncomfortable and cry when their mothers leave. Naturally, the crying infant that signals distress will have more protection from the elements and other predatory environmental forces. Thus, the "attached" infant will have a higher chance of survival. Over many generations, more "attached" infants will survive to mate and pass on the allele for secure attachment. Thus, a new behavior has developed by means of natural selection.
This illustrates the basic idea behind evolutionary psychology in human development; that the innate behaviors of very young children are pre-programmed in their genotypes and that we can understand these behaviors by studying the environmental forces that surrounded our ancestors.
Piaget's Theory of Cognitive Development
See link for more information on Piaget. http://www.learningandteaching.info/learning/piaget.htm
The Nature-Nurture Controversy
One of the central debates in psychology involves the origin of human behavior. Is it, as theorized by many, caused by biological factors present in the human body, or is it caused by interactions between the individual and its environment (including other individuals of its species) that finally lead to changes in both behavior and even physical structure? This debate has often been termed Nature versus Nurture, and is not an easy one to solve.
Nature Human behavior is the result of already-present biological factors
Strict adherents of the nature philosophy often use genetic code as support for their theory. It contains the instructions for millions of protein commands that eventual determine our basic structure as human beings. But is it definitive? And can it be changed?
Nurture Human behavior is the result of interaction with ones environment
As for Nature adherents, there is also strong evidence that supports followers of the Nurture philosophy. It is well documented that interaction with ones environment can provoke changes in brain structure and chemistry, and that situations of extreme stress can cause problems like depression.
- * http://en.wikipedia.org/wiki/Erikson%27s_stages_of_psychosocial_development