Which of the following is not atavistic in humans ?

Options

A. Tail in some babies
B. Enlarged canines
C. Six fingers
D. Dense body hair

Answer

To determine which of the following is not atavistic in humans, we need to understand the concept of atavism. Atavism refers to the reappearance of traits or characteristics in an individual that were present in their remote ancestors but have been absent in intervening generations.

### Step-by-Step Solution:

1. **Understand Atavism**: Atavism is the reappearance of ancestral traits in an individual. This means that certain characteristics that were once common in distant ancestors may occasionally appear in modern individuals.

2. **Analyze the Options**:
- **Tail in Some Babies**: This is considered atavistic because some human infants are born with a small tail-like structure, which is a trait seen in some of our distant ancestors.
- **Enlarged Canines**: Enlarged canines can also be seen as atavistic traits since our ancestors had larger teeth suited for a different diet.
- **Dense Body Hair**: This is another atavistic trait, as our ancestors had more body hair for protection against the elements.
- **Six Fingers**: The presence of six fingers (polydactyly) is a genetic variation rather than a reappearance of an ancestral trait. It is not considered atavistic because it does not reflect a characteristic that was present in our ancestors but has since been lost.

3. **Conclusion**: Among the options provided, the characteristic that is not atavistic in humans is **six fingers**.

### Final Answer:
The correct answer is **six fingers**.