The plot above shows the phylogeny of the different members of the human cdk family. In one hand, the cdks 7,9,10 seem to have a same ancestor. On the other hand, cdks 4 and 6 are clearly related, while cdk 8 would also share the same root but with a prior independent evolution from the common ancestor of cdk 4 / 6.

Cdk 1, 2, 3 and 5 appear to have a commmon ancestor which would have lead to the cdk 5 first, then to the Cdk 1 and finally to both Cdk2 and Cdk 3.

We could have thought that every related cdks should have a similar function. However, this does not seem to be the current case. We consider that posible recombination between no homologous chromosomes would have led to duplications in some of the chromosomes. This theory would be consistent with the distribution of the genes among the chromosomes (see data below).

Once there were two copies of the same gene, one of them would have been able to evolve without functional constriccions (due to the presence of the other copy). Thus, the velocity of evolution in these genes would be much rapid and could have led to the current functions that we perceive nowadays.