# relative-rate of evolution

I am supposed to calculate the relative rate of evolution of two sequences (human and sheep) with a chicken serving as the outgroup. The sequences are pretty long, so I will just create a short example since I just want to learn the process (we are expected to use online resources to figure out our homework problems since it is an online class, but I can't find any examples).

Human: GGATGCGCCT
Sheep: GGACGCGCCT
Chicken: GGACACGCCT

Can someone show me how to do this? Here is my guess from the limited info I found, but I have little to no confidence that it is correct:

p-distance of human/chicken = 2
p-distance of sheep/chicken = 1
relative rate of evolution = 2/1 = 2

Is this correct? If not, can someone show me how to do it correctly?

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This kind of thing is normally calculated using the $K_{a}/K_{s}$ ratio, the ratio of synonymous to non-synonymous substitutions. It is not enough to count mutations for coding sequences, you should also take into account whether or not that mutation will actually change the resulting product.