Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

The most important method of determining phylogenesis is based on gradual connecting of species that share new evolutionary features, called apomorphic traits (the opposite of an apomorphic trait is a plesiomorphic trait – the original evolutionary form of the trait). Traits that are so complicated that it can be assumed that they were formed in evolution only once and that species that share them did not form the trait independently, but inherited them from a joint predecessor, can be considered to be useful apomorphic traits for phylogenetics. If two species A and B share ten apomorphic traits, but share only seven apomorphic traits with a third species C, it can be assumed that species A and B branched off from a joint predecessor in evolution later than that predecessor from the species that was also a predecessor of species C.