Monkeys get no respect. For a species that humans have studied, owned, laughed at, poked and prodded, they have gotten from us anything but. How do I know this? Take your average creationist (IDC'er - whatever) and they'll tell you themselves: "My daddy warn't no monkey, no sir!" Some flavor of that is the primal cry when the subject of Commom Descent comes up, for example.
But why the monkey? Evidence shows that we share a more common DNA profile than say, a polychete worm or slug (though some humans no doubt come closer than others). Beyond the DNA, we share mothering behaviors, stress reactions and community living, among others. We also share a propensity take from others things that don't belong to us, sneak copulations, and power tripping conflicts among the alpha males.
For various reasons, many can't get behind the science because if we share a
high sequence percentage, then it follows that we share a
low percentage with every other organism with a helix. We're still made of the same stuff and bang-zoom, Common Descent. I just don't get the diss on our monkey cousins when it would be far more dramatic to come back with something like "my daddy warn't no nasty, bottom feeding sightless nematode." So foreign a creature would surely evoke a more universal revulsion. I know
my daddy warn't none of that
myself.
Maybe that's it. Maybe in our closeness we can idenify with the Monkey more than we would care to admit. So, it comes down to denial of the physical evidence (wonder what Clarence Darrow would have done with that?) when we witness those things in monkeys that we really hate about ourselves. And, if we are so alike, we are capable of things we might not be able to stop or control.
So, we humans go on dealing death to pry things from others that don't belong to us, or over some percieved slight, in denial that a different truth might exist; an even bigger truth that frightens and confuses the closed-minded primitive hindbrain. If we deny our simian lineage, we are able to believe we are above such things - not subject to the same propensities we see in them and pre-destined for that corner office in the food chain.
Besides, we wouldn't want to get any bright ideas. After all, Monkey see, Monkey do.