[Dimensio]

I'll return the questions: Why would such a "defect" survive in preference to a functioning gene if natural selection were operative?

It wouldn't be a detriment if it occured in a population that was already making use of plentiful food sources that provided vitamin C.

[UnbelievingScumOnTheOtherSide]

It wouldn't be a detriment if it occured in a population that was already making use of plentiful food sources that provided vitamin C.

And since you don't know whether that was the case or not, you have another wild-assed guess. Yes, if you assume evolution and a continuous availability of environmental vitamin C you can hypothesis that there would be no detriment to natural selection. But you cannot then use that as evidence of evolution because that was one of your assumptions!

[UnbelievingScumOnTheOtherSide]

It wouldn't be a detriment if it occured in a population that was already making use of plentiful food sources that provided vitamin C.

And since you don't know whether that was the case or not, you have another wild-assed guess. Yes, if you assume evolution and a continuous availability of environmental vitamin C you can hypothesize that there would be no detriment to natural selection. But you cannot then use that as evidence of evolution because that was one of your assumptions!

By the way, it doesn't do any good to shuffle them around because no matter which two you assume you have two unknowns for assumptions. You cannot solve two unknowns in one equation. And since natural selection has not been proven to cause macro-evolution, you cannot use it as an independent assumption.