Which of the following features is closely realted with the evolution of humans?

Options

A. Loss of tail
B. Shortening of jaws
C. Binocular vision
D. Flat nails

Explanation

To determine which feature is closely related to the evolution of humans, we can analyze the options provided in the question.

### Step-by-Step Solution:

1. **Understanding Human Evolution**:
- Humans evolved approximately 25 million years ago. Understanding the timeline and key evolutionary changes is essential.

2. **Evaluating the Features**:
- **Loss of Tail**:
- Early primates like Ramapithecus and Dryopithecus did not have a tail. However, the loss of a tail is not a defining feature of human evolution, as it is also present in other primates.
- **Shortening of Jaws**:
- In early human ancestors, the jaw was large and protruding (prognathous). Over time, the jaw structure changed to become less protruding (orthognathous), which is a significant evolutionary change associated with human development.
- **Binocular Vision**:
- Binocular vision was present even when the jaw was prognathous, so it is not a feature that specifically relates to human evolution.
- **Flat Nails**:
- The presence of flat nails is not directly linked to the evolutionary changes that define humans.

3. **Identifying the Correct Feature**:
- Among the features analyzed, the **shortening of jaws** is the most closely related to human evolution. This change reflects adaptations in diet and the development of speech.

4. **Conclusion**:
- Therefore, the feature that is closely related to the evolution of humans is the **shortening of jaws**.

### Final Answer:
The feature closely related to the evolution of humans is the **shortening of jaws**.

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