Passage–6

A bat’s wings may look like sheets of skin. But underneath, a bat has the same five fingers as an orangutan or a human, as well as a wrist connected to the same cluster of wrist bones connected to the same long bones of the arm. What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern?

Question: Which one of the following is the most logical, scientific and rational inference that can be made from the above passage?

The correct option is: Man and the aforementioned animals have a shared evolutionary history.

Step-by-Step Explanation:

1. Analyze the Passage:
The passage highlights a remarkable similarity in the underlying skeletal structure of limbs across very different species: humans, orangutans, bats, moles, horses, and porpoises. Despite these limbs being adapted for completely different functions (such as grasping, flying, digging, running, and swimming), they all share the same basic structural plan of bones (e.g., five fingers, wrist bones, and long arm bones).

2. Understand Homologous Structures:
In biology, organs or skeletal elements of animals that, by virtue of their similarity, suggest their connection to a common ancestor are called homologous structures. The passage describes classic examples of homology.

3. Scientific and Rational Inference:
- Why do such diverse animals share the same bone blueprint? The most logical and scientific explanation is that they did not develop this identical underlying pattern independently by chance (which rules out "coincidence").
- Instead, they inherited this basic structural design from a common ancestor. Over time, as different species adapted to different environments and lifestyles, these limbs evolved to perform different functions, but the fundamental bone architecture remained.
- Therefore, the presence of these similar structures (homologies) is direct evidence that humans, bats, moles, horses, and porpoises share a common evolutionary origin or history.

4. Evaluate the Options:
- Option 1 & 2: While biodiversity refers to the variety of life, the anatomical similarity described is a specific indicator of evolutionary lineage, not just a general example of biodiversity.
- Option 3: Attributing this structural similarity to a mere "coincidence" is scientifically incorrect and ignores the fundamental principles of evolutionary biology.
- Option 4: Correctly and scientifically infers that the shared structural pattern points directly to a shared evolutionary history.