The Telomere Fusion Event in Human Evolution (Chromosome 2)

One of the most striking differences between human and great ape genomes is the number of chromosomes. All great apes (chimpanzees, bonobos, gorillas, orangutans) have 24 pairs of chromosomes (2n = 48), whereas modern humans (Homo sapiens) have 23 pairs (2n = 46)y raised a evolutionary puzzle: if humans and other apes share a common ancestor, how did humans “lose” a pair of chromosomes? The prevailing explanation is that two ancestral ape chromosomes fused end-to-end in an early human ancestor, producing a single composite chromosome (human chromosome 2). This telomere fusion event is supported by multiple lines of scientific evidence and is now considered a hallmark example of human evolutionary history. Below, we examine the evidence for this chromosomal fusion, compare human and ape karyotypes, review the historical studies that confirmed the event, discuss its evolutionary significance, and address alternative interpretations (including intelligent design and ancient intervention hypotheses).

Photo by National Cancer Institute