Genesis and Evolution - Tom Larkin

What we are saying is that if there was no real biblical Adam and Eve there would still be a mitochondrial Even and a Y-chromosome Adam. Any sexually reproducing population will have these two MRCA's. There is a set of these Adams and Eves for chimps, bears, bats, and so on. They are simply a product of pedigree collapse, where maternal and paternal lines tend to end which leaves just one line remaining.

So where does the science part come in, with respect to Evolution?

It is not that hard of a concept to understand. Take my brother-in-law as an example. He has 4 brothers and no sisters. This means that his mother's mitDNA line ended with her. Any father who has no children or only daughters will have his Y-chromosome lineage stop.