I started thinking about this a little while ago. I remembered that when I was with my ex, how he used to get so incredibly insulted that I would even fathom the possibility that we evolved from primates. His angered, albeit entertaining defense was, "I am not a monkey!". I don't know that that defense really had anything to do with his religious beliefs, I think that in his mind, if the evidence turned out to be irrefutable (in his opinion, not mine), that it somehow makes him less than human, less than a man. What is everyone else's take on this? Have you ever met someone who was so insulted by this?
I see this as an example of a more widespread problem with how we construct self-esteem in this culture. When people internalize hierarchy as the only possible social structure, they measure their self worth by rank - who am I better than? So men can feel superior to women, children, and animals because they have more power (i.e. force, ability to do violence to get their own way). The alternative is Partnership culture, an egalitarian "I'm OK, You're OK" where we measure self-worth on personal accomplishments, values, and desirable traits.
Even highly educated academics can be hobbled by hierarchical mindset. For example, I'm much enthralled by the explanatory power of Paul MacLean's Triune Brain Theory. Never heard of it? Of course not. Because the neuroanatomy scholarly community refused to take seriously work which showed human beings have brains wired like three parallel processors. Oh NO!!!! Two of them, the Lymbic system and reptile brain, are animal-like (without language or symbolic thought). MacLean described the reception to his work as similar to denial. So your ex has lots of company, even among professionals who ought to know better.
We have this mechanism of just turning away from facts that make us uncomfortable. I find people who are egalitarian are less frightened by facts.