Adam and Eve Didn't Exist -- The Molecules Tell Us Why
If humans are descended from a non-human ancestor, which biology shows definitively, then the story of Adam and Eve is wrong in its particulars without question. It is not even a valuable metaphor for people who don't accept it as true, because it suggests that humans have some special status beyond that of other creatures. Additionally, it suggests that we have "dominion" over the earth, which is a terrible idea that has created a very dangerous mindset in many human beings.
What is the evidence then, for common descent?
In a word, it's overwhelming. We'll look at it in greater detail now.
The most important evidence for common descent can be appreciated by anyone who does a broad survey of the existing kinds of life on earth. What we see are gradations of forms with variations on various types. This is what we would expect if the process of speciation were of a branching nature, with new forms coming from established ones.
However, there are molecular evidences that are real "smoking guns". This happens when an animal has a functioning gene that becomes inactivated. The animal will sometimes die, but occasionally environmental factors allow it to survive with the gene no longer active. When this happens, all the descendants of that animal will carry a "pseudogene" on their genetic code that looks very much like an active ancestral form but no longer functions. We'll focus on the most important one that establishes without question that humans are descended from other primates.
Simians and anthropoids (including chimps, orangs, baboons, gorillas and humans) are unable to make their own vitamin C (ascorbic acid). The reason for this is that the normal mammalian enzyme that makes vitamin C (called gulonolactone oxidase) is impaired from functioning properly in these animals. There was a deletion mutation and multiple point mutations that keep it from being functional.
Interestingly, the other wet-nosed primate groups, lemurs, monkeys etc., do indeed make their own vitamin C and they are capable of surviving without this as a portion of their diet.
Here's where the story becomes interesting. The mutations that create the inactive enzyme in humans are nearly identical with those of the simian apes. We can see minor variations but the main sequence remains amazingly similar. However there are other mammals that also don't make vitamin C. These include bats and also guinea pigs.
This seems like a monkey wrench in the system. Are we suggesting that these other mammals also descended from prosimians? A closer look reveals the answer. When we examine the actual sequences of the genes of mammals for gulonolactone oxidase we see a clear pattern. Humans, chimps and orangs have nearly identical sequences. Guinea pigs have very different sequences however. Don't take my word for it, scroll down on this page and look at them yourself.
This is exactly the pattern we would expect if it happened by adaptive radiation from a common ancestor. If we assume that the common ancestor of all prosimians ate a diet high in fruits and other foods high in ascorbic acid, the mutation would not have been limiting to life in that ecology. However, we must also assume that for most animals living on a diet that did NOT include ascorbic acid, the mutation would be lethal.
Thus, all the mammals that exist with a mutation in gulonolactone oxidase eat foods high in ascorbic acid, or they die. However, they do not have the same mutations unless they are otherwise closely related. Thus, the mutations in guinea pigs are the same as other guinea pigs. The mutations in apes and anthropoids are the same as other prosimian descendants. Although I am not aware of bats having gulonolcatone oxidase sequencing done at this time, we can assume pending the results that the same pattern will appear.
Scurvy is a horrible disease and has been a great plague to man whenever he takes long trips through hostile territory. Many humans have died for lack of ascorbic acid.
Therefore, the idea of a loving God, who made Adam and Eve with his hands is defied by the simple fact that monkeys could seafare easily on a diet of fish and clams, but we cannot. We must have vitamin C. Yet it would have been trivial for God to give us back the enzyme that makes vitamin C for us.
You can believe many different things, but to believe God exists, and he created Adam and Eve and all their descendants lovingly, you also have to believe he created them in a way that would make them horribly sick if they went without ascorbic acid for a period of time. To me this makes him seem a monster. A much simpler and more rational explanation is that there was no Adam and Eve and that our ancestors were a population of fruit-eating mammals who lost an important enzyme.