Many creationists have claimed that evolution is unfalsifiable. Numerous examples of potential ways to falsify common descent have been proposed. Richard Dawkins said that "If there were a single hippo or rabbit in the Precambrian, that would completely blow evolution out of the water. None have ever been found."[9][10][11] Similarly, J.B.S. Haldane, when asked what hypothetical evidence could disprove evolution, replied "fossil rabbits in the Precambrian era".[12]
Similarly, the evolution of the great apes and humans from a common ancestor predicts a (geologically) recent common ancestor of apes and humans. This assertion could have been disproven with the invention of DNA analysis. Molecular biology identifies DNA as the mechanism for inherited traits. Therefore if common descent is true, human DNA should be more similar to great apes than other mammals. If this is not the case, then common descent is falsified. DNA analysis has shown that humans and the great apes share a large percentage of their DNA, and hence human evolution has passed a falsifiable test.
Popper himself drew a distinction between common descent and the process of natural selection. While he agreed common descent was falsifiable (he used the even more drastic example of the remains of a car in cambrian sediments),[13] Popper said that natural selection "is not a testable scientific theory but a metaphysical research programme".[14] However, Popper later said "I have changed my mind about the testability and logical status of the theory of natural selection, and I am glad to have the opportunity to make a recantation."[15] He went on to formulate natural selection in a falsifiable way and offered a more nuanced view of its status. He still felt that "Darwin's own most important contribution to the theory of evolution, his theory of natural selection, is difficult to test." However, "[t]here are some tests, even some experimental tests; and in some cases, such as the famous phenomenon known as 'industrial melanism', we can observe natural selection happening under our very eyes, as it were. Nevertheless, really severe tests of the theory of natural selection are hard to come by, much more so than tests of otherwise comparable theories in physics or chemistry."[15]