Eli5 How come humans have less chromosomes than chimps?


I just learned that dogs have 78 chromosomes, compared to our 46. And then I saw that chimps also have a couple more chromosomes than us as well. Do they have more genetic information than us? Can dogs or chimps’s bodies do things (metabolically) that we can’t do? And how does this increase or decrease of chromosomes occur? The few medical conditions where humans have extra chromosomes tend to not be beneficial, why is that?

In: Biology

Two chromosomes fused together, specifically chromosome 2 in humans. Chromosomes have end markers called telomeres, specific sequences of DNA nucleotides. In humans there was a mutation that caused the telomeres to no longer encode properly, fusing the chromosomes together. There is still a set of ‘almost telomere’ markers in the middle.

Note: People with trisomy (e.g. Down Syndrome) don’t have “more chromosomes” the same way chimpanzees have more chromosomes. Humans usually have 23 pairs of chromosomes (22 normal ones and one pair of sex chromosomes), while chimps have 24 pairs. People with trisomy don’t have an additional pair, instead one of the “pairs” is actually a triple.