Human evolution is, of course, the same as that for other organisms. Natural selection operates on the physical & behavioral variation among groups and populations, with individuals who are able to raise more offspring to reproductive age having greater genetic representation in at least the following generation. This does not imply that such variation is in itself qualitatively "better", it simply represents a mix that is well-suited to a particular environment, situational climate or resources conditions, avoiding predation or ravages of disease, and results in more offspring surviving compared with other individuals in that or other groups. If conditions change, then those characteristics or adaptations may not be appropriate for new conditions and there is no expectation that they make those individuals better suited to future conditions. It is difficult to identify which specific changes were acted on by selection, which traits may be associated with others that are under selection (but not themselves under direct selection), or that represent stochastic variation that is not being modified by selection. Anthropologists make reasoned arguments about what we think may have been characteristics that were under selection in the past (i.e., bipedal locomotion, loss of body hair, feeding on high-quality foods, cooperation among group members, technological skills, etc.). However, these inferences are almost always open to scientific skepticism and potential re-evaluation.

Evolution is complicated and nuanced, but at its core it is simply descent with modification. Mutations and changes in our DNA overtime lead to some individuals being more fit (having more offspring). Mutations and changes that confer a fitness advantage to those carrying them will tend to become more frequent in a population over many generations. It is important to remember that natural selection acts on variation that is already present within a population; natural selection itself does not create variation. Overtime, populations are able to adapt to their environment by natural selection increasing the frequency of beneficial mutations or genetic variation. It is also important to note that much of the DNA variation has resulted from genetic drift, and not from natural selection. Ultimately, evolution in humans is the same in humans as it is in all other life on earth.

The modern synthesis recognizes that both mutation and natural selection are responsible for the evolution of new or modified traits.