Why are humans more closely related to Neanderthals than to chimpanzees?

Humans are more closely related to Neanderthals than to chimpanzees because they share a more recent common ancestor with Neanderthals. In phylogenetics, evolutionary relatedness is determined by the branching patterns of the "tree of life," where the proximity of a common ancestor indicates the degree of relationship.1

The common ancestor of modern humans and Neanderthals lived approximately 500,000 to 700,000 years ago. In contrast, the evolutionary lineage leading to modern humans diverged from the lineage leading to chimpanzees and bonobos about 7 million years ago.123

Genetic evidence further supports this closer relationship. Modern humans and Neanderthals share approximately 99.5 to 99.9 percent of their genome sequence identity, whereas the identity between humans and chimpanzees is roughly 96 to 99 percent. Additionally, genomic studies have confirmed that limited interbreeding occurred between Neanderthals and ancestral modern human populations after they migrated out of Africa, resulting in Neanderthal DNA being present in the gene pools of modern Eurasian populations.24