Monday, 23 April 2012

Caste Exogamy ( Intercaste marriages) may be beneficial, Genetically !! Why not break-Caste barriers & have efficient offsprings??

Every family member contributes to the Gene pool..
Lets have a larger "gene pool" with variety of traits..
Probability of finding good Personal traits in Progeny will be Higher!!

Genetics explains that family lineage always contributes to one's personality. Everything is inherited by the progeny from previous generations through Genes. A wider & varied Gene pool will help in having Healthier Progeny..
There is a myth that "pure blood" or we can say, children of people from same caste or genetically identical groups are better in terms of Health & intelligence.
In societies, like the one, that is prevalent in our country. People follow caste system  and argue that Marriages done in the own closed group are beneficial for the preserverance or endurance of the Family Lineage or  VANSH..Children born to parents from so-called Superior caste/blood would be Superior in terms of Health & Intelligent..
But scientific studies indicate all together different scenario.. 
Nowadays, Racial mixing is the inevitable result of globalization.
Scientists are fascinated by theories that say mixing of genes/blood leads to a genetic advantage!!

Lets analyze- 
When people from different human populations marry – does it really brings the benefits; by reducing the number of recessive gene-pairs ambiguities??.
Humans have 23 pairs of chromosomes containing about 30,000 genes. Only the sex chromosomes break the ‘pairs’ rule. An individual who has two identical copies of a gene is called a "Homozygote", while someone who has two copies that differ is called a "Heterozygote".
When, different races or say people from different CASTE are responsible for procreation. Then obviously birth of HYBRID or a HETROZYGOTE offspring will take place. 
A differing gene pair in heterozygote gives advantage n extra flexibility & adaptability to environmental circumstances. So, resultant off-springs will be genetically efficient & healthier.
Its a well known & scientifically proven fact that HYBRIDS are better-genetically and Hetrozygote or the offsprings of people with different genes n traits are better in terms of :-
  • Survival & Life expectancy,
  • Adaptability to physical or Social environment,
  • Cognitive development ,
  • Motor development,
  • Intelligence & Intelligence Quotient(I.Q.)
  • Immunity(especially cell mediated immunity) etc.
  • Also, the recessive birth defects are less likely in people with different genes, ie. hetrozygotes.
Sociological Approach:-
Do we ever think why there were social norms related to "Gotra Exogamy"??
Earlier, social structure wasn’t that broad. Endogamy(marrying in close relations) would have been an easier choice.
But then too- HINDU marriage norms & our Shaastras insisted on Incest Taboo & Gotra-Exogamy .
"Incest taboo" is norm that prohibits practices of sexual relations between relatives. Sometimes relations between clan-members are excluded, even when no traceable genealogical relations exist.
 Exogamy is the custom of marrying outside a specified group of people to which a person belongs. In addition to blood relatives, marriage to members of a clan,kin or specific group are forbidden.
In Hindus Gotra exogamy is prevalent through out eras.
Hinduism speaks of incest in abhorrent terms. Hindus are fearful of the bad effects of incest and thus practice strict rules. Marriages within the gotra ie. "Swagotra marriages" are banned under the rule of exogamy in the traditional matrimonial system. People within the gotra are regarded as kin. i.e. Marriage between two people whose parents are related paternally up to 7 generations was prohibited. 
{Gotra is transferred down the male lineage while the Gotra of a female changes upon marriage. i.e upon marriage a woman belongs to her husband's Gotra and no longer belongs to her father's Gotra.
In that case, if only single Gotra is considered. There may be marriage between maternal Cousins; which is incest.}
Hence, atleast marriage with a person having same Gotra as of the original Gotras of all 4 grandparents is prohibited.
Human societies insisted on exogamy (outbreeding) because procreating with individuals who are more closely related means progeny may be more likely to suffer from genetic defects caused by inbreeding.
Inbreeding is the reproduction from the mating of two genetically related parents. It results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is called "Inbreeding depression"
Inbreeding or endogamy may result in a far higher phenotypic expression of deleterious recessive genes within a population than would normally be expected. As result-generations are more likely to show physical and health defects, including:
  • Lowered intelligence & IQ
  • Increased genetic disorders
  • Fluctuating facial asymmetry
  • Lower birth rate
  • Higher infant mortality
  • Reduced fertility both in litter size and sperm viability
  • Slower growth rate
  • Slower cognitive development.
  • Less adaptability
  • Reduced immunity.
  • Lowered emotional development.
The reduced genetic diversity that results from inbreeding means a species reduced environmental adaptability. A narrow range of certain immune systems genes in a population increases vulnerability to infectious diseases.Species may become Endangered.
eg. Parsis in India have reduced in numbers; due to smaller initial population size & inbreeding in closely related people.
Anthropological & Psychological approach :-  Stress on benefits of Exogamy...
Levi-Strauss’s alliance theory-The hypothesis of a "marriage-alliance" points out towards the necessary interdependence of various families & lineages. 
Weddings are seen as a form of communication.Alliance theory tries to understand the basic questions about inter-individual relations, or what constitutes society.
Alliance theory is based on the incest taboo: according to it, only this universal prohibition of incest pushes human groups towards exogamy.
Other anthropologists like Margaret Mead argue that nuclear family incest avoidance can be explained in terms of the ecological, demographic, and economic benefits of exogamy.
Westermarck effect, or reverse sexual imprinting, is a hypothetical psychological effect through which people who live in close domestic proximity during the first few years of their lives become desensitized to later sexual attraction.
Anthropologists insist that Incest taboo & Exogamy helps in mingling of cultures & acts as a unifying force amongst groups, castes or societies. Thus SOCIAL INTERACTION through marriage & progeny strengthens the SOCIAL BONDS.

Genetical & pathological Approach:-

Genetic disorders-Autosomal recessive disorders occur in individuals who have two copies of the gene for a particular recessive genetic mutation. Both parents will be carriers of the disease gene.As relatives share a higher proportion of their genes than do unrelated people, it is more likely that related parents will both be carriers of the same recessive gene, and therefore their children are at a higher risk of a genetic disorder.
Some preliminary evidence support effects on many such disorders including:-Cardiovascular diseases and Cancers.
Many previously not identified genetic disorders have first been recognized in highly endogamous communities and the mutation causing the disease may be unique to such communities.
One of the most famous example of a genetic disorder aggravated by "Royal family intermarriage" was House of Habsburg,. Royal family intermarriages were often practiced to protect property, wealth and position. 
The Family faced the aftermaths of Endogamy & of being Homozygotic.Famous in this case is the "Mandibular prognathism"or Habsburger (Unter) Lippe (Habsburg jaw/Habsburg lip/Austrian lip)-
a typical disorder for many Habsburg relatives over a period of six centuries. 
The condition progressed through the generations to the point that the last of the Spanish Habsburgs, Charles II of Spain, could not properly chew his food. Besides the jaw deformity, Charles II also had a huge number of other genetic physical, intellectual, sexual, and emotional problems.
Two different genetic disorders: Combined pituitary hormone deficiency and Distal renal tubular acidosis can explain most of the complex clinical profile of this king, including his impotence/infertility which in the last instance led to the extinction of the dynasty.
  • Another famous genetic disease that circulated among European royalty(including Queen Victoria's Parents) was Hemophilia.
Heterozygous advantage
It describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. The specific case of heterozygote advantage is due to a single locus known as overdominance.
When two populations of any sexual organism are separated and kept isolated from each other, the frequencies of deleterious mutations in the two populations will differ over time, by genetic drift.
It is highly unlikely, that the same deleterious mutations will be prevalent in both populations after a long period of separation. Since loss-of-function mutations tend to be recessive ; given that dominant mutations of this type generally prevent the organism from reproducing and thereby passing the gene on to the next generation.
The result of any "CROSS" between the two populations will be fitter than the parent.
Heterozygote advantage is a major underlying mechanism for heterosis, or "hybrid vigor", which is the improved or increased function of any biological quality in a hybrid offspring.
Genetically transmitted disease which can be prevented by HETEROZYGOSITY
  1. Sickle-cell anemia-A genetic disorder that is caused by the presence of 2 incompletely recessive alleles. When sufferer's RBC’s are exposed to low-oxygen conditions, the cells lose their healthy round shape and become sickle-shaped. This deformation results in loss of capacity of RBC’s to carry Oxygen, depriving parts of body,of oxygen. When untreated, a person suffers from anemia or painful bouts, often causing damage to internal organs & strokes. The disease results in premature death.
  2. Cystic fibrosis- CF, is an autosomal recessive hereditary disease of the lungs, sweat glands and digestive system. The disorder is caused by the malfunction of the CFTR protein, which controls inter-membrane transport of chloride ions, which is vital to maintaining equilibrium of water in the body. The malfunctioning protein causes viscous mucus to form in the lungs and intestinal tract.Earlier,Child born with CF had a life expectancy of only a few years, but modern medicine has made it possible for these people to live into adulthood. However, even in these individuals- CF typically causes sterility. It is the most common genetic disease among people of Europeans.The presence of a single CF mutation may influence survivorship of people affected by diseases involving loss of body fluid, typically due to diarrhea. The most common of these maladies is cholera.
  3. Triosephosphate isomerase-TPI is a central enzyme of Glycolysis.In humans, certain mutations within this enzyme affect the dimerisation of this protein are causal for a rare disease, triosephosphate isomerase deficiency. A mutations, which inactivate the enzyme.Null alleles formed are lethal when inherited homozygously .
  4.  Resistance to hepatitis C virus infection-increased consanguinity in a population increases its susceptibility to infectious pathogens such as tuberculosis and hepatitis whereas Genetic heterozygosity in humans provides increased resistance to certain viral infections. 
  5. MHC(Major histocompatibility complex) heterozygosity -Heterozygosity at MHC loci results in more alleles to fight against a wider variety of diseases, possibly increasing survival rates against a wider range of infectious diseases. Thus results in High immunity.
  6. Even Diabetes, Night-blindness, some Cancers, Hemophilia, Lactose intolerance , Gluten allergy etc. are said to be genetically dependent diseases.

We may conclude:-

Hybrids are more efficient as they perpetuate two cultures & two genetically  different lineages.
As, Marriage is socially accepted & sanctioned way of establishing a "Family of procreation"!!
It's psyhcological desire of everyone,to have efficient progeny..All want a Healthy Vansh & vanshaz..
Then ,

Why don't we take a step forward-to have healthy Off-springs??
Why don't we search, mates, across the closed group boundaries or the closed caste system??
Why we have a taboo on intermixing of castes?? 
Why don't we prefer INTERCASTE MARRIAGES??
I guess, there shouldn’t be a fear of loosing cultural identity...
As dominant genes never loose their identity by genetic drift.. Similarly Good cultural TRAITS will never disappear by social unification! 
Days of Varna system are gone.. There is no need of that strict social stratification & division of Karmas..
Accept EXOGAMY..!! 
Not only Gotra exogamy but accept CASTE EXOGAMY (intercaste marriages)!!
Racial mixing is going to be beneficial for upcoming generations!!
Break the caste barriers!!
Imagine a future Society with Progeny which will be -