STRANGE: What really makes you ill – Humans have an ancient Vitamin C genetic defect!

I was reading an article about a study on what makes you ill. I did not buy into all the thinking.

However, this caught my eye:
Humans, because of an ancient genetic defect, cannot produce vitamin C in their livers. Dogs, cats, cows, chickens and other animals do produce vitamin C in ample quantities internally. Two time Nobel Prize winner Linus Pauling made the case that heart disease in humans was a vitamin C deficiency and that we must supplement with vitamin C every day to avoid this number one killer of the population.

The above astounded me. I never knew of this. I would suppose that at some time our fantastic race will be able to surely fix this genetic defect? It seems we are rare among mammals in not being able to produce our own Vitamin C! How strange. This is something worth looking at more closely. I find this bizarre.