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Saturday, June 30, 2012

Hardy-Weinberg Law of Equilibrium

G.H Hardy an English Mathematician and W.Weinberg a German Physician developed  the law of equilibrium which became the foundation of modern population genetics.

The law of equilbrium is based on the principle that given certain assumptions the proportions of genotypes will remain constant from generation to generation.The following are the six conditions that must be assumed so that the Hardy-Weinberg equilibrium can be maintained.

1. Mating is at random any individual has an equal chance of mating with any other individual in the population.

2.All matings have the same fertility.

3.Natural selection is not acting on the alleles under study.

4.There is no overlap between generations.

5.The population is infinitely large.

No  human population meets all these six conditions but in order to carry out scientific analysis these conditions are assumed.

Friday, June 29, 2012

Ethnoecology

Ethno ecology has its roots in efforts to develop rigorous methods that upgrade the quality of cultural description.Deriving inspiration from concepts of structural linguistics it emphasizes the analysis of verbal behavior  and assumes that culture consists of an inventory of precepts and concepts of ideational  forms- and a set of principles ordering them.

Ethnoecology focuses on the task of adequately describing some domain of the culture bearer's tacit theory of the world.

Its emphasis upon perceptual environment and its general lack of serious consideration of interactions between cognitive domains or with the effective environment result in the narrowest  and least interactional  of modern approaches.

It aims at adequate emic description of cultural domains including the perceptual environment principally by means of formal semantic analysis.

Its analysis is restricted to intra cultural ecological relationships.

It deals with the effective environment it seeks to evaluate and predict the effects of various behavioural possibilites on the participants microenvironment that enviroment frequently being restricted to other people.

It makes assumption of a high degree of homogenity and stability in cultural categorization.

Thursday, June 28, 2012

Population Genetics

Population Genetics is concerned with the determination of the genetic structure of human population and the analysis of the factors that maintain or alter their genetic structure.The web of genetic relationships among consanguinity,mating patterns,gene flow and natural selection are all significant in the study of human populations.

The various concepts and principles that are used in Population Genetics are 

Mendelian Population- The genetic approach to human population generally uses the concept of Mendelian population defined by Theodosius Dobzhansky as follows
  
A reproductive community of sexual and cross fertilizing individuals which share in a common gene pool.

Each Mendelian population may contain several other smaller Mendelian population within it.The largest Mendelian population is a species because species do not share the same gene pool.They are distinct and are closed genetic system.

One of the important characteristics of a Mendelian population is that it is breeding isolate.A breeding isolate is a small or larger population in which its members find  their mates within the group itself.This may be due to several factors such as geographical,social,cultural,linguistics,religious and even psychological.As a consequence of prolonged breeding isolation differences in the genetic make up between different groups of human populations develop.In other words there are differences in gene frequencies  between one population and the other.

The determination of gene frequencies depends on sampling,counting and statistical manipulation of numbers.The estimation of gene frequencies is based on Mendel's two principles and on the Equilibrium Law that describes population gene frequencies under certain conditions.