- Evolution does not attempt to address the question of the origin of life: for that, see abiogenesis. The two are commonly conflated.
- Evolution is not a random process but one guided by the process of natural selection. A common misconception is that the absence of conscious intervention means that the process becomes random.
- Evolution does not need to be directed (although some believe it is). It is not accidental or random, but it is a process, like bouncing a ball, or generating a fractal, that appears to create an intelligent pattern, but which on inspection is very simple.
- Humans never evolved from chimpanzees; instead they share a common ancestor (possibly Sahelanthropus tchadensis) that existed around 7 Ma in the late Miocene epoch. Some scientists think the split may have occurred several million years earlier.
- Evolution says nothing about cosmology, the big bang, or where the universe, galaxy, solar system, or earth came from. Evolution is only about life.
- Evolution does not need to be slow. Millions of years are not required to see evolution, or even speciation in action.
- Evolution does not happen within a single creature: a chimp cannot be born a chimp and turn into a gorilla. You need at least one generation to observe evolution. To be provable evolution, you need quite a few generations, in order to establish that the changes remain in subsequent generations, though.
- Evolution does not require an increase in complexity. A population can evolve to become simpler, and have a shorter genome – often called “devolve”, but that is a misnomer.
- Evolution does posit “transitional forms”… but not “endpoint forms”. That is, every animal, plant, fossil that exists, is an example of a transitional form. Evolution is a constant process.
- It is often claimed that there are no “transitional forms”. When people say “transitional forms” they generally mean “a common ancestor for two populations”: of which there are many.
- Evolution has been observed, countless times, in and out of the laboratory.
- Some believe that as Evolution is a “theory”, it is merely a hypothesis, rather than a proven fact of life. Evolution is a “theory” in the same way as the theories of gravity, thermodynamics, etc. The word “theory” has a different meaning in a scientific context than in a casual, which may have lead to this misunderstanding.
- Evolution does not claim that phenotypic changes (changes caused by the environment, such as larger size due to better diet, amputations, etc) can be passed from generation to generation.
- The claim that “all (or almost all) mutations are harmful” is false. One study gives the average number of mutations that arise in a human conception to be around 128, and an average number of harmful mutations per conception of 1.3.
- Evolution does not happen within just one creature: you need the entirety of a population to observe evolution. You need some of them to breed, and some not to.
- Evolution is not progress from “lower” to “higher”. In that sense, “Evolution” is a misnomer.
EDITED 2011.09.18 to add obligatory XKCD link.