An anthropologist utilizes various hereditary and environmental factors for racial classification. There is different views on relative influence of heredity or inherited traits and those external agents ie the environment or surroundings on racial traits.
In multiracial societies racial groups differ greatly in regard to social and cultural factors such as socioeconomic status, healthcare, diet, and education. All these traits can be considered as environmental factors in relation to racial traits. Dermatoglyphic process which involves studying ridges and patterns of finger, palms, toes and soles from different angles by applying various processes. Human chromosomes also serves as an hereditary trait to classify various groups into races.
Impact of heredity on Racial traits-
- Heredity leads to transmission of acquired traits from one generation to next.
- Mutation give rise to new characters.
- Mutations favored by natural selection might become hereditary.
- Inbreeding over the time leads to these characters becoming race specific.
Impact of Environment on Racial traits-
- Bergman’s Rule- People living in warm areas have greater body bulk than those living in cold areas
- Allen’s Rule- People living in cold areas have small appendages
- Glogger’s Rule- People living in hot & damp places tend to have very dark skins.
• Socio economic factors influence genetic characters that may become race specific in the long run like Endogamy, Preferential Marriages, Clan Affiliations, Caste etc.
• These factors influence development and hereditary retention of certain genetic characteristics.
• Differences in nutrition habits and status produce physical differences in the long run
• Migration leads to introduction of new foods
• Nutrition in turn is influenced by Climate and Culture
• Too much of dependence on one staple crop leads to certain vitamin deficiencies
• These deficiencies in turn may act as selective forces within a population
All these deficiency diseases eliminate large number of populations, esp. the children and the average body size becomes small.
• In non lethal cases, there is a delayed growth and permanent stunting
• In cold areas, there is little or no agriculture and the chronic deficiencies leads to stunted growth
Environment is capable of producing genetic effects that become hereditary
• Ex. Mutations caused by UV Radiation
Certain peculiar mutations that are favored by natural selection might become hereditary and thus race specific.
Racial traits arise and sustained due to impact of heredity and environment. Both heredity and environment complement each other in formation of races.
Professor Virchow has given following hypothesis on variation-
1. No secondary (inherited) variation can take place unless preceded by a primary (acquired) variation.
2. No primary variation can take place without an external cause.
3. Secondary variations do not arise from or depend upon external causes, although they may be influenced by them.