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dna, cookbooks, maps and chimpanzees

Let's take it as a given that 98% of human dna is similar to that of a chimpanzee.

For those who believe that it is a spiritual dimension that makes humans different, the closer this % is to 100, the better supported is the claim that genetics does not suffice to account for the differences between humans and their closest neighbors on the tree of life.

It is worth pointing out that a 2% difference in (non-junk) dna doesn't necessarily imply a similarly low level of phenotypic difference. To think that it does is to take dna as a kind of model or image of the human body. But it isn't: it's a set of instructions on how to grow, or as Richard Dawkins says in The Greatest Show, it is more like a cookbook than a blueprint. An even more creative simile by RD: a set of instructions for "auto-origami." In such a case, a slight difference in the instructions can yield a great difference in the final product. Think of a cake without baking soda. That might be less than 2% of the volume of the cake, but oh what a difference!

Moral of that story: it is a mistake to posit a linear relationship between the percentage of difference in phenotype and the percentage of difference in genotype.
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Leo White said…
Also, the lessor the difference in DNA between human and chimp, the stronger the argument that something other than a difference in DNA differentiates us phenotypically
from chimps
11:16 AM
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