Different physiological variations are found in different populations such as HB level, blood pressure, fat level etc. Among this, sensory variations are important
physiological variations studied in Indian and foreign populations.
• Among various sensory mechanisms most thoroughly surveyed are (1) Ability to taste phenylthiocarbamide (2) Red and Green colorblindness.
• 1 PTC(Phenylthiocarbamide) Tasting Ability
- An autosomal polymorphic trait : Tasters-genotype TT and Tt ; Non Taster-tt
- Sex differences-female more sensitive to taste
• 2 Red Green colorblindness
- Used as a genetic marker in human variations.
- X-Linked Trait
- Individuals fail to distinguish red and green from each other.
• Studies done for Red Green Colorblindness :
- (a) India:-In South India by Veera Raju , Rao & Reddy , Naidu ,Shanti Devi etc.
- (b) Outside India
Turkey-Bokesoy and Togan
Balkans-Ibrahimov and Khimov
Nigeria-Scott
Myanmar-Sint and Maya.
• Population variations in PCT tasting
- Females more sensitive to PCT tasting-statistically significant differences.
- In Balkans, Burmese and Nigerian populations, female are more sensitive than male but difference is not statistically significant. Muslims in India also do not show sex differences in population for PCT tasting.
• Population variations in Red-Green colorblindness : Being an X-linked disorder, it is more common among male than female populations.
• Prevalence of R-G colorblindness
| Male | Female | |
| Overall | 7-10% | 0.5-1% |
| Caucasoid | 8% | 0.64% |
| Asian | 5% | 0.25% |
| Africans | 4% | 0.16% |