Upvote:5
Given that Adam and Eve were created in a perfect state (albeit one that didn't preclude their ability to choose to sin), and given that God told them to "Be fruitful and multiply, and fill the earth, and subdue it; and rule over the fish of the sea and over the birds of the sky and over every living thing that [am]moves on the earth" {Genesis 1:28}, why would we presume that those two were not a "minimum viable population"?
The population post-Flood was only 8 (and two of them are not recorded as having more children), and yet today we have a global population of ~7 billion.
Upvote:6
You can interpret the story of Adam and Eve literally. What you're attempting to do is what all scientists do, assume that the situation today has always been the same and estimate incorrectly.
What you fail to realize is that DNA has probably been copied a few trillion times from cell to cell to cell to human to cell to human. All things copied tend to break down, become unstable and begin to produce error.
If the DNA was perfect (containing not a single error), as we can expect it to be, in Adam and Eve's time, or even in Noah's time, then this would not be a problem. Modern science has already learned that every human being on the planet contains genes from one dominant male and one dominant female.
New DNA studies suggest that all humans descended from a single African ancestor who lived some 60,000 years ago. To uncover the paths that lead from him to every living human, the National Geographic Society launched the Genographic Project, headed by Spencer Wells. (link)
The particulars could very easily be up for debate, but the premise that a single male and single female were the start of it all, is truly the only evidence that we have.