Question

Which of the following is not related to evolutionary changes in skull, eye and brain among the primates?

• A. Stereoscopic vision
• B. Binocular vision
• C. Reduced Olfaction
• D. Increased sensory modalities

Hint:

Remember the primate evolutionary trend: a move towards a visually-dominant world. This means forward-facing eyes for depth perception and a smaller snout because smell became less critical. Anything that contradicts this visual-primacy model is likely the incorrect option.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Primate evolution is characterized by a suite of adaptations, particularly related to an arboreal (tree-dwelling) lifestyle. A major trend is the shift in sensory reliance from smell to vision. This led to significant changes in the skull, eyes, and brain.
Step 2: Detailed Explanation:
Let's analyze the options in the context of primate evolution:
- Stereoscopic vision: This is the ability to perceive depth and 3-D structure, resulting from the brain processing visual information from two forward-facing eyes. It is a hallmark of primate evolution, crucial for judging distances when leaping between branches. This is a related change.
- Binocular vision: This refers to the overlapping fields of view from having two eyes located at the front of the skull rather than on the sides. It is the anatomical basis for stereoscopic vision and is a key primate trait. This is a related change.
- Reduced Olfaction: As primates became more reliant on vision, their sense of smell (olfaction) became less important. This is reflected in the reduction of the snout (rostrum) and the olfactory regions of the brain. This is a related change.
- Increased sensory modalities: This implies that primates developed entirely new types of senses (like echolocation or electroreception), which they did not. Instead, they re-prioritized and enhanced existing senses, primarily vision, at the expense of another (olfaction). The overall number of sensory modalities did not increase. Therefore, this statement is not an accurate description of primate evolutionary changes.
Step 3: Final Answer:
Stereoscopic vision, binocular vision, and reduced olfaction are all fundamental evolutionary changes in primates. The concept of "increased sensory modalities" is incorrect; primates re-specialized their sensory toolkit, they did not add new senses to it.