Question

Chimpanzees and gorillas share the trait of knuckle-walking, which humans do not generally have. Why do most scientists NOT classify chimpanzees and gorillas as each other's closest relatives?

1) The majority of genetic evidence places chimpanzees closest to humans, not to gorillas.

2) Fossil evidence suggests that knuckle-walking was present in ape ancestors and is not a uniquely derived trait for chimpanzees and gorillas.

3) Chimpanzees and humans share more unique features in common than either share with gorillas.

4) Fossil apes that are thought to be closest to humans show adaptations for knuckle-walking, implying that humans have secondarily lost the trait.

5) All of the above.

Answer 1

Chimpanzees and gorillas are not each other's closest relatives. Genetic and fossil evidence, as well as shared unique features with humans, support this.

Step-by-step explanation:

The majority of genetic evidence places chimpanzees closest to humans, not to gorillas. Fossil evidence suggests that knuckle-walking was present in ape ancestors and is not a uniquely derived trait for chimpanzees and gorillas. Chimpanzees and humans share more unique features in common than either share with gorillas. Fossil apes that are thought to be closest to humans show adaptations for knuckle-walking, implying that humans have secondarily lost the trait. Therefore, all of the above are reasons why most scientists do not classify chimpanzees and gorillas as each other's closest relatives.