(My latest book God vs. Darwin: The War Between Evolution and Creationism in the Classroom has just been released and is now available through the usual outlets. You can order it from Amazon, Barnes and Noble, the publishers Rowman & Littlefield, and also through your local bookstores. For more on the book, see here. You can also listen to the podcast of the interview on WCPN 90.3 about the book.

Because of the holidays and travel overseas where internet access will be sporadic, I am taking some time off from writing new posts and instead reposting some of my favorites (often edited and updated) for the benefit of those who missed them the first time around or have forgotten them. New posts will start again on Monday, January 18, 2009.)

There is no doubt that Darwin’s ideas about evolution by natural selection carry a huge emotional impact. For many people the idea that “we are descended from apes” is too awful to contemplate and is sufficient reason alone to dismiss any claim that natural selection holds the key to understanding how we came about. (Of course, we are not descended from apes. The more accurate statement is that apes and humans share common ancestors, making them our cousins, but even this refinement does not take away the stigma that supposedly comes with being biologically related to animals such people consider inferior.)

This unease about being biologically linked to other species is widespread and transcends any particular religious tradition. In Sri Lankan rural areas, one would frequently see monkeys on trees by the side of the road. As children when we were passing them, almost invariably someone would point them out and say things like “Your relatives have come to see you.” Similarly, if one said that one was going to visit the zoo, this would also result in the question as to whether one was going to visit one’s relatives. This kind of humor among children was commonplace, and reflected a reflexive instinct that humans were superior to all other animal forms, and reinforced the belief that some sort of special creative process must have been at work to produce us.

But if the thought of being related to apes gives some people the creeps, imagine how much worse it will for them to realize that as we go farther back in evolutionary time, we are cousins to all sorts of life forms that might make people even more squeamish.

Reading Richard Dawkin’s book The Ancestor’s Tale (2004) I found that I myself was not immune from that kind of emotional reaction, even though I have no problems intellectually with accepting natural selection and all its consequences.

For example, I had little difficulty emotionally accepting that the apes and monkeys are my cousins, partly because, I suppose, that idea has been around for a long time and I have simply got used to it. Also a common ancestor to the humans and apes would not look very different from us now and is easier to envisage. But as the evolutionary clock went back in time, and I started imagining what my deep ancestors looked like, I had a variety of reactions.

The idea that I had common ancestors with dogs and cats and horses (those evolutionary branches separated from the human branch at about 85 million years ago (Mya)) did not cause me any problems. I kind of liked the idea that my dog Baxter and I can trace our separate lineages back to a time when we both had a common ancestor. It is clear that our common ancestor would not look much like present-day humans or dogs, but I cannot imagine what it might have looked like apart from having some of the common characteristics shared by dogs and humans, like being four-limbed, warm-blooded, invertebrates.

More annoying was the realization that the branch that led to the rodents like rats, squirrels and rabbits only separated from the human branch at 75 Mya, meaning that those animals that we consider vermin and would not think of having in our houses, actually have a closer relationship to humans (since our common ancestors lived more recently) than those whom we love and welcome into our homes as pets, like dogs and cats.

Somehow, the emotional reaction of finding oneself having common ancestors with dignified and majestic animals like whales (85 Mya) and elephants (105 Mya) is positive while being linked to things like snakes (at 305 Mya) felt kind of icky.

A hard bridge to cross (again I mean emotionally) was accepting that frogs and toads and salamanders shared a common ancestor with me at about 340 Mya, perhaps because I share the common perception that these animals are slimy.

Going back further, I had little negative emotional reaction to realizing that I had a common ancestor with sharks at 460 Mya but the thought that flatworms and I were related at 630 Mya was harder to take. I suppose that this is because sharks are usually perceived as admirable and graceful (if dangerous) animals while I have never liked worms, seeing them as somehow disgusting. Perhaps I will now have warmer feeling towards them, seeing that we are relatives.

Once I got over the emotional hurdle of being able to accept the fact that worms and I have common ancestors, the rest was pretty easy to accept, perhaps because the earlier life forms that our common ancestors took had to be so different that I could not really relate to them (let alone imagine them) in any way. Thus it was a breeze to accept that I am related (however distantly) with sponges, bread moulds, amoeba, and bacteria.

It was amusing to keep monitoring my emotional reactions as I read about the backward evolutionary journey. But like most difficult journeys, taking that first step is the hardest. And now I have a better understanding why many religious people simply cannot take that first step and acknowledge that chimpanzees are our cousins, in fact are the closest cousins we have in the animal kingdom, with our common ancestor living just 6 million years ago. Because once you accept that, then you have embarked on journey whose inevitable end is that you end up as one with a bacterium. It is hard to think of you being created in god’s image after that.

Thus I am somewhat sympathetic to those people who find Darwin’s ideas hard to stomach and desperately seek to find a more palatable alternative. However, I think their task will prove hopeless, since the basic tenets of evolution are here to stay and so we may as well get used to it.