Introduction
There are different forces which are associated with the evolution of human beings. These include natural selection, genetic drift, mutation and the mating structure of a population. Various evolutionary biologists have agreed on the first three forces. The fourth force is treated as new and it is not explained in a traditional setting.
However, there have been disputes regarding the impact of each force among biologists. For example, the population mating structure is a categorization that is used to organize different phenomena of the human evolution. Though many scientists agree on the phenomena, they organize them in different ways. This paper will therefore illustrate how the four forces of evolution impact variation within a population as well as between populations.
Natural selection
This is defined as the difference in the reproduction of organisms which results from the traits that organisms adapt from their environment. The components that are important in this context include differential reproduction, heritable traits, and the adaptation of the organisms to the environment.
Differential reproduction is linked with the way in which organisms adapt to the environment such that if the adaptive traits of these organisms are transmitted to the next generation, the behavioral and physical traits of species change. This makes it possible for the species to adapt to their environment better.
Genetic drift
This refers to the changes in the regularities of allele over time due chance. Chance changes the frequencies in allele thereby altering the probability of transferring the allele to the subsequent generations. This process is compared to tossing a coin in each generation. The degree of bias is therefore influenced by the frequency of allele in that generation. When the size of a population is small, the overall effect of genetic drift is to repair the alleles. This means that if genetic drift is a continuous process, the alleles become fixed by chance.
Mutation
Mutation is described as the error to copy DNA by organisms. The different classifications of mutation depend on the type of a cell that is affected by mutation and the amount of DNA that has been mutated. The mutations that affect the human cells comprise of somatic mutations and germinal mutations. Somatic mutations influence other cells of the body other than those that produce the gametes directly.
Germinal mutations on the other hand affect those cells which turn into gametes directly. Since there are many somatic cells in humans compared to germinal cells, most of the mutations in human beings are therefore somatic. These mutations do not have any effect on an organism when they occur in a section of the DNA that is unused.
They just influence the physiology of the cells. However, germinal mutations are described as the life force behind evolution. Their role is to introduce new genetic material to species. Without germinal mutations therefore, there would be no forces of evolution such as natural selection, genetic variation, and genetic drift. The concept of evolution would also be nonexistent.
Population structure
This refers to the temporal, physical, behavioral, and physiological factors which influence the nonrandom mating among different species. The population structure of human beings influences the genetic diversity that exists between them.
For example, those people who are born and raised in the tropical rain forests are more likely to mate with people who are born and raised in the same geographical area. This scenario is also observed within national boundaries where the local populations also mate with the people from those boundaries.