Outline Of Darwin's Theory Of Natural Selection

After the Beagle returned to England in October 1836, Darwin began reflecting on his observations and experiences, and over the next two years developed the basic outline of his groundbreaking theory of evolution through natural selection. But beyond sharing his ideas with a close circle of scientist friends, Darwin told no one of his views on the origin and development of life. Indeed, he did not publish his now-famous volume, On the Origin of Species by Means of Natural Selection, until 1859, more than 20 years after he had first formulated his theory. On the Origin of Species may never have been written, let alone published, if it had not been for Alfred Russel Wallace, another British naturalist who independently proposed a strikingly similar

Which do you think has the greatest effect on human variation? (20 marks. Length: 300-400 words).

The three primary causes of human variation are:

(1) Evolutionary processes, which affect genetic diversity within and between populations;

(2) Environment The variation among individuals that springs from their unique life experiences in specific environments; and

(3) Culture- the variation stemming from disparate cultural beliefs and practices inculcated during an individual’s formative years and reinforced throughout life.

Evolutionary processes, which affect genetic diversity within and between populations has the greatest effect on human variations A population’s total compliment of genes of referred to as a gene pool. In Homo sapiens, as well as in many animal populations, genes may have two or more alternate forms – a phenomenon called polymorphism. These differences are expressed in various physical characteristics, ranging from hair and eye colour to less visible difference in blood chemistry. Many of these traits vary in their expression in different world areas. For examples, we associate certain hair texture and skin colour with populations that can distinguished regionally on the basis of discrete physical traits are called

Mutations may result in evolutionary change only of they occur in the sex cells of individuals. Mutations are important in explaining human variation because they are ultimately the source of all genetic variation.

The evolutionary process that determines which new mutations will enter a population is natural selection. Through this evolutionary process, traits that diminish reproductive success will be eliminated, whereas traits enhancing the ability to reproduce will become more widespread. Throughout human populations gene flow is seen as a result for some physical characteristics. The genetic drift is particularly useful in explaining differences among genetically isolated populations, and also the processes of selection that alter allele