In comparing the genomes of humans and those of other higher primates, it is seen that humans have a large metacentric pair we call chromosome 2 among our 46 chromosomes, whereas the other primates of this group have 48 chromosomes and any pair like the human chromosome 2 pair is not present; instead, the primate groups each have two pairs of midsize acrocentric chromosomes. What is the most likely explanation?
A) The ancestral organism had 48 chromosomes and at some point a centric fusion event occurred and provided some selective advantage.
B) The ancestral organism had 46 chromosomes, but primates evolved when one of the pairs broke in half.
C) At some point in evolution, human ancestors and primate ancestors were able to mate and produce fertile offspring, making a new species.
D) Chromosome breakage results in additional centromeres being made in order for meiosis to proceed successfully.
E) Transposable elements transferred significantly large segments of the chromosomes to new locations.

Question

Quizplus · Accepted Answer

The presence of a large metacentric pair in humans suggests that a fusion event occurred in our lineage. The other primates' karyotypes suggest that they have ancestral acrocentric chromosomes that have not undergone this fusion event.

In Comparing the Genomes of Humans and Those of Other