We Share a Surprising Number of Genes With Other Animal Species

While we humans may look markedly different from one another, we are remarkably similar at the genetic level. Any two individuals share approximately 99.9% of their DNA sequence, meaning a miniscule 0.1% difference accounts for all the genetic variation among humans — our size, shape, facial features, and so on. Perhaps even more surprising are the genetic similarities between humans and other species. Humans and chimps, for example, share a surprising 98.8% of their DNA. Most of the genes in humans and chimps are nearly identical, but identical genes are used in different ways and in varying amounts across species, which explains our very notable differences. For example, a wide range of species have the PAX6 gene, which is responsible for the development of distinctly different eyes in everything from humans to fish, flatworms, parakeets, and water fleas.