Question

From an evolutionary point of view, which is closest to humans?

• A. Dolphin
• B. Flying fish
• C. Shark
• D. Tortoise

Hint:

Look past body shape and ask which animal shares the same class, Mammalia, with humans.

Answer 1

The Correct Option is A

Step 1: Understanding the Question.
The question wants the animal among the four that shares the closest evolutionary relationship, meaning the most recent common ancestor, with humans.

Step 2: Key Concept.
Humans belong to class Mammalia, the group of warm blooded animals with hair, mammary glands, and, in most species, live birth. The more features an animal shares with humans, the more recent its shared ancestor tends to be, so the closest relative here should also be a mammal.

Step 3: Detailed Explanation.
Flying fish belong to class Actinopterygii, the ray finned bony fishes. They are cold blooded, breathe with gills, and lay eggs in water. This lineage split from the line leading to land vertebrates a very long time ago.
Shark belongs to class Chondrichthyes, the cartilaginous fishes. Sharks have a skeleton of cartilage, not bone, and this group is one of the oldest and most distant vertebrate lineages compared with mammals.
Tortoise belongs to class Reptilia. Reptiles are cold blooded, lay shelled eggs on land, and their line split from the ancestors of mammals well before mammals became a separate group.
Dolphin belongs to class Mammalia, the same class as humans. Dolphins are warm blooded, breathe air with lungs, feed their young on milk, and give birth to live young. Even though a dolphin's body looks fish like from the outside, that is only a case of adapting to life in water, not a sign of a fish ancestry. Sharing the same class as humans makes the dolphin the evolutionarily closest of the four.

Step 4: Final Answer.
The animal evolutionarily closest to humans among the options is the dolphin.