Question

Based on these data alone, state a hypothesis for which two species are more closely related to humans. What is your reasoning?

Short answer

Gibbons are closer to humans as compared to monkeys due to more similarity in their genome.

Step-by-step solution

Homo sapiens as species 

Homo sapiens is the scientific term for modern humans. Humans belong to a large group called homo or genus homo. In this genus, some other members are also present, like Homo neanderthal, Homo habilis, but Homo sapiens are the only surviving members.

The homo group comes under the Hominidae family, while the close members like chimps and orangutans are members of the Pongidae family. So, the difference between humans and great apes is present at the family level, but they all are members of order primates.

Monkeys and humans homology  

It can be observed from the data given on the beta-globin chain; monkeys share less homology or similarity with humans as their amino acid chain differs at eight different places in one 46-amino acid chain.

It gives a percentage similarity of around 95%; the more the percentage of similarity at the molecular level, the more will be the resemblance at the structural and functional status.

Gibbon and human homology

The differences can be observed in the analysis of the amino acid chain of gibbons and humans for beta globulin protein. Differences are observed at only two places, and the percentage of similarity, in this case, is around 99.

The percentage of similarity of gibbons is four percent more than the monkeys, indicating more closer relationship with humans.