Passage for Questions 6-10

II. There were humans long before there was history. The archaic humans loved, played, formed close friendships and competed for status and power, but so did chimpanzees, baboons and elephants. There was nothing special about them. Nobody, least of all humans themselves, had any inkling that their descendants would one day walk on the moon, split the atom, fathom the genetic code and write history books. The most important thing to know about prehistoric humans is that they were incognisant animals with no more impact on their environment than gorillas, fireflies or jellyfish. Biologists classify organisms into species. Animals are said to belong to the same species if they tend to mate with each other, giving birth to fertile offspring. Horses and donkeys have a recent common ancestor and share many physical traits. They will mate if induced to do so but their offspring, called mules, are sterile. Mutations in donkey DNA can therefore never cross over to horses, or vice versa. The two types of animals are consequently considered two distinct species, moving along separate evolutionary paths. By contrast, a bulldog and a spaniel may look very different, but they are members of the same species, sharing the same DNA pool. [203 words] (Extracted from Sapiens: A Brief History of Humankind by Yuval Noah Harari)

The passage explains the concept of species classification by

The correct option is: Focusing on the DNA pool they share

Step-by-step Explanation:

1. Analyze the Question: The question asks how the author explains the concept of species classification based on the provided passage.

2. Examine the Passage: In the second half of the passage, the author defines a species by explaining that animals belonging to the same species mate with each other to produce fertile offspring, thereby sharing the same DNA pool. The author uses two key comparisons:

- Horses and Donkeys: Although they can mate, their offspring (mules) are sterile, meaning mutations in donkey DNA cannot cross over to horses. Because they move along separate evolutionary paths and do not share a DNA pool, they are classified as two distinct species.

- Bulldog and Spaniel: Although they look physically different, they belong to the same species because they can interbreed and share the same DNA pool.

3. Evaluate the Options:

- Option 1: Incorrect. The passage uses horses, donkeys, bulldogs, and spaniels to explain reproductive compatibility and genetic flow, not behavioral differences.

- Option 2 ("Focusing on the DNA pool they share"): Correct. The presence or absence of a shared DNA pool (via fertile offspring) is the central criteria explained in the text for defining whether animals belong to the same species.

- Option 3: Incorrect. The text contrasts horses with donkeys (different species) and bulldogs with spaniels (same species), not horses and bulldogs with donkeys and spaniels.

- Option 4: Incorrect. Environmental impact is mentioned earlier regarding prehistoric humans, gorillas, fireflies, and jellyfish, not in the context of species classification using horses/donkeys/dogs.