Question: Do different animals have a different numbers of chromosomes?

Anthony Redmond answered on 7 Jan 2019:

Yes! And there is a whole field of study focused on chromosome evolution. This is because changes in chromosome numbers often occurs along with changes in the order of genes along chromosomes, as well as portions of the genome that regulate genes, which can cause changes in how the proteins produced by genes interact and work in the body. This means chromosome changes can be involved in causing disease or promoting unique adaptations.

As an example of different chromosome numbers between animal species, humans actually have a reduced number of chromosomes than our closest relatives, chimpanzees, and other apes. This is because two ape chromosomes are fused into one (what we call Chromosome 2) in humans. There are even some links between this and vitamin B12 production, which is important for brain development. But research is still needed for us to tell if this chromosome fusion event was important in shaping our human brain!