Why do scientists believe evolution occurred?

Answer 1

Charles Darwin developed the Theory of Evolution by Natural Selection before most of the fossil evidence for the theory existed. He looked at the micro-evolution practised by pigeon breeders, the evidence on the Galapagos Islands and elsewhere, and realised that evolution was the only explanation that made sense. He saw that related species were to be found in close proximity, evidence of evolution from a single parent species, whereas a single act of Special Creation ought to have placed the species anywhere on the globe where the environment was suitable.

The fossil record shows clear evidence of evolution over a period of more than a billion years. Certainly, at first, there were no transitional species among the many species that had been found, although scientists saw much that did confirm the Theory of Evolution. That has changed, because many transitional species have been found. A recently discovered 220-million year old fossil, Odontochelys semitestacea, is a new species of turtle that had a fully formed shell on its underside, but only a small partial shell on its back, extending from its backbone. As well as a partial shell, Odontochelys semitestaceaalso had ribs that had begun to widen, thus demonstrating that the fully developed shell of later turtles evolved from the ribs of earlier species. Tiktaalik roseae is the name of a newly discovered lobe-finned fossil fish from the late Devonian period, that is a transitional form to amphibians, with basic wrist bones and simple fingers, as well as the robust ribcage necessitated by existence out of water. Odontochelys semitestacea and Tiktaalik roseae are two more pieces in the jigsaw that shows conclusively how life on Earth evolved from earlier species.

Scientists can now use DNA evidence from modern species to support the fossil record, as further evidence of evolution.