(Anthropology Paper I)

Syllabus Section: 9.1 Human Genetics

 

Introduction

Human Genetics, as the name indicates, describes the study of inherited variation as it occurs in human beings. The inheritance of many traits, including human traits is at present fairly well known. The biochemical studies on the constituents of the chromosomes have given essentially the correct picture how heredity really works at the molecular level. Genes can be the common factor of the most inherited traits. Genes have become prominent in the nature versus nurture debate. Study of human genetics can be useful as it can answer questions about human nature, behaviour as well as understand the diseases and disease treatment, and genetics of human life.

Human Genetics Background & Evolution

• The science of genetics emerged from the famous work of Father Gregor Mendel (1822-1884) while working at the Augustinian monastery of St Thomas at Bruno in Moravia with the common garden pea. He published the results of his studies in 1866 and thereby laid the foundation of modern genetics.
• In his paper, Mendel proposed some basic genetic principles — the law of segregation, and the law of independent assortment.
• The first one states that each parent contains two copies of a unit of inheritance (later called gene), however, any one of two genes (called allele) can be transmitted to the offspring through the gamete. Which allele in a parent’s pair of alleles is inherited is a matter of chance.
• The second principle states that the segregation of such gene pair (allele) occurs independently in respect of other gene pair, i.e. the paired genes (allelic pairs) separate from one another and are distributed to different sex cells. The result is that new combinations of genes present in neither parent are possible.
• However, during his (Mendel) lifetime very few people realised the importance of his path breaking research. In 1901, Hugo de Vries, Carl Correns and Erich von Tschermak realised that Mendel’s observations, conclusions and hypothesis have great importance in the field of genetics.
• During early 1900s, researchers noted that chromosomes behave like Mendel’s traits and also inherited in random combinations.
• In 1909 Wilhelm Johansen renamed Mendel’s characters as ‘gene’ and William Bateson coined the term ‘genetics’ to study genes.
• Thereafter researchers repeated and confirmed Mendel’s hypothesis and his (Mendel) ideas on the inheritance of traits became more widely accepted and is now termed as Mendel’s laws of inheritance.
• Another milestone in the field of genetics is the discovery of the model for the structure of DNA as a genetic material by J.D. Watson and F.H.C. Crick in 1953.
• This was probably the keystone that unlocked an explosion in the field of human genetics as a form of molecular revolution.

Objectives of Human Genetics:

• • Deals with principles of hereditary and variation of gene.
  • Used in pedigree analysis, twin study etc. in understanding the nature of inheritance.
  • Used in understanding the processes like mutation, migration, isolation, selection etc. which helps in understanding changing gene frequencies in human population

Following are some of the fields where human genetics may contribute its knowledge for the betterment of the human society.

• To understand basic principles of inherited variation in man and to understand application of genetics in human life, and
• To answer questions about human nature, understand the diseases and development of effective disease treatment and health care.

Human Genetics and its Branches

Human Genetics is the scientific study of variation and hereditary in Human Beings.

1. 1. Classical Genetics/Mendelian Genetics/Formal Genetics: It is the oldest branch of Human Genetics; it studies the transmission of traits and their influence on the different expressions.
   2. Development Genetics: Deals with the development of Human embryo.
   3. Cyto Genetics: It deals with the study of Human chromosomes and chromosomal abnormalities and their consequences.
   4. Molecular Genetics: It reveals the constitution of gene. It examines structure, organization, transmission and function of genes and regulation of their activity.
   5. Population Genetics: It focuses on stability and change in gene frequencies.
   6. Immunological Genetics: It studies the Genetics of production of different types of anti-bodies, histocompatibility and transplantations.
   7. Biochemical Genetics: Examines Genetic error of metabolism.
   8. Bio-Metrical Genetics: Studies hereditary of quantitative traits as weight, Height and intelligence etc.
   9. Radiation Genetics: Effects of radiation on the Genetic make-up of Human Beings.
   10. Pharmaco Genetics: Studies drug induced disorders.
   11. Ecological Genetics: It studies the adjustment and adaptations of Human population.
   12. Anthropo Genetics: Deals with Micro-Evolution i.e., evolution at Gene level.
   13. Evolutionary Genetics: It studies the Genetic basis of change overtime that results in the formation of Human species.
   14. Medical Genetics: It studies inheritance of disease in families and treatment used for Genetic counseling.
   15. Behavioral Genetics / Psychological Genetics: It studies the Genetic basis of mental behavior and abnormal behavior.
   16. Methodological Genetics: It deals with the Genetics of disputed child, illegal immigrant and penetration of crime.
   17. Experimental Genetics: On the basis of conducting experiments.
   18. Eugenics: It is the science of improving the in born qualities of Human race and obtaining the better heritage by judicious breeding.
   19. Euthenics: It examines the science of improving the already existing human race.
   20. Euphenics: It examines the symptomatic treatment of Genetic diseases. It is concerned with the control of several inherited Human diseases