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, while the other primates of this group have 48 chromosomes and any pair like the human #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 chromosome in humans, along with the absence of such a chromosome in other higher primates, suggests that a centric fusion event occurred in the human lineage after it diverged from the other primates. This fusion likely provided some selective advantage, potentially through increasing the stability of meiosis or providing the potential for new gene interactions.

In Comparing the Genomes of Humans and Those of Other