Hi Professor Venema,
In plain English, what you’re saying is that science can’t rule out an original couple, if they lived more than 1 million years ago. Dr. Gauger will probably welcome that admission.
For my part, I can’t see why a 2-million-year-old Adam and Eve is any more at odds with what Genesis is saying than, say, a 100,000-year-old Adam and Eve.
However, if I were to identify the chief flaw of the ancient Adam and Eve scenario, it would be this: modern human behavior doesn’t appear until 100,000 years ago. Homo erectus may have had foresight (transporting tools over distances of more than 10 kilometers), the ability to control fire (although this is hotly disputed) and even a sense of aesthetics (judging from the elegance of some Acheulean tools), but it almost certainly lacked the capacity for art, religion and science. This means that in some ways it was less human than we are - which means that if we are to believe in Adam and Eve, we have to give up belief in human equality.
It is instructive to compare Homo erectus with modern-day tribes whose lifestyle has been described by some as “primitive.” Members of these tribes have relatively little trouble in adapting to the cognitive demands of civilization, some making the transition in as little as a generation. I doubt very much whether Homo erectus could have done that. And I also doubt whether anyone could have preached the Gospel to Homo erectus.