12.2 - Variation in Humans

Relation of Variation to Human Inheritance

As you have already learnt in Chapter 11, different characteristics in humans are controlled by dominant and recessive alleles. Dominant or recessive trait expressed is different from one individual to another individual, depending on the genetic content of the individual. This is what causes variation in humans.

Characteristics and Human Traits

• Dominant

  • Height: Tall
  • Types of hair: Curly hair
  • Tendency to use hands: Right-handed
  • Presence of dimples: Yes
  • Ability to roll tongue: Can roll tongue
  • Types of earlobe: Free earlobe

• Recessive

  • Height: Short
  • Types of hair: Straight hair
  • Tendency to use hands: Left-handed
  • Presence of dimples: No
  • Ability to roll tongue: Cannot roll tongue
  • Types of earlobe: Attached earlobe