Evolution
Evolution is the change in heritable traits of populations over generations. Its core claims — that all species share common ancestors, and that natural selection shapes them — make up one of the best-supported ideas in all of science.[1] What makes it so solid isn't one experiment but the way independent lines of evidence all point the same way: the fossil record preserves the sequence of change across deep time; homologous structures expose shared ancestry in anatomy; DNA nests every species in one branching family tree; and evolution has been watched happening in the lab and the wild.[2] Each was gathered separately, yet they converge on the same tree of life.[3]
Here is that tree — every branch a shared ancestor. Start at the centre and zoom in, branch by branch, all the way down to individual species (including us):
The last universal common ancestor and everything descended from it — one connected family, ~3.5–3.8 billion years old.
The centre is your current focus; life radiates outward to its descendants, with individual species in green. Click a branch to zoom into it (rings with a halo have more inside — e.g. Eukaryotes → Animals → Vertebrates → … → Great apes → Homo sapiens); click the centre or a crumb above to zoom back out.