Can we learn from creationists – people who deny evolution? I think so. It is not enough to say, as Richard Dawkins notoriously did: "If you meet somebody who claims not to believe in evolution, that person is ignorant, stupid or insane…" That's a dead end.

Conversation is a two-way street, and if I want creationists to learn from me, I must at least in principle be ready to learn from them.

My recent Conversation article, How to slam dunk creationists when it comes to the theory of evolution, led to brisk correspondence with a number of thoughtful creationists, so it would be useful to examine their arguments on their merits, if only to sharpen our own.

Creationists always ask about the origin of complex systems, that is, systems that require many interacting parts. How could one part have evolved unless the others were already in place?

Think of the eye with its need for retina, lens, and pupil; flowers and pollinators; male and female; and so on. Here I think we need to answer at three different levels.

Inside the mind of a creationist

At the most general level, creationists are saying that when we don't understand how something could have happened by natural means, we should attribute it to supernatural intervention. This I consider a toxic argument, which prevents further investigation.

Going down a level, these arguments assume that a complex system would not work unless all its parts were already in place and fully functioning.

Well, perhaps it would not work as effectively, or in the same way, but even an incomplete system would serve as the starting point for evolution, with the other parts added later.

Consider for example the blood clotting system, which involves the operation of a large number of successive steps in order to stop bleeding, and the bacterial flagellum, a kind of "motor" used by some bacteria to propel themselves, through the combined action of many different protein molecules.

Creationists parade these as examples of intelligent design, ignoring how much we already know about how they evolved from simpler systems.

Finally, getting down to specifics, what creationists' questions are actually doing is setting out a series of excellent research programmes, many of them (such as the studies of blood clotting and the flagellum) already well under way.

My own reading has certainly benefited from creationist questions about the eye, the appearance of new species, the evolution of parasites and whether all evolution is progress (the answer, surprisingly, is "no", since most mutations are random and whether a mutation occurs or not is unrelated to how much use it might actually be. So some are beneficial, some are neutral and some can survive by chance even if harmful to the organism).

Asking the big questions

Another common question: if we evolved from monkeys, why are there still monkeys? Answer: we have not evolved from present-day monkeys, any more than the English language has evolved from present-day German.

Our last common ancestor with a monkey was more than 25 million years ago, and we've all moved on a bit since then.

And what about the missing links between us and apes, and other gaps in the fossil record? Did Darwin himself not describe the poverty of the fossil record in his time as the gravest objection to his theory?

Yet things were already changing in his lifetime, with the discovery of an Archaeopteryx fossil, a genus of bird-like dinosaur, in time for the 4th edition of Origin of Species.

There still are missing links, and there always will be. But we now have hundreds of thousands of fossils, all at the right place in their geological sequence, and if like the creationists we reject evolution, every one of these must be interpreted as a separate act of creation.

The record is, inevitably, incomplete, but separate creation should not have left any record at all.

Consider, for example, our knowledge of human evolution. A century ago, the only relevant fossil species were Java Man (now known as Homo erectus) and, of course, our Neanderthal cousins.

Then, in 1924, came the discovery of the Taung Child skull, now classified as Australopithecus africanus, and since then a steady stream, showing not one, but three or four lineages, of which we are the only one surviving. The Smithsonian Museum explains it well here.

Creationists raise numerous other important questions and issues, both scientific and philosophical.

For instance, not seeing evolution actually occurring around us – except we do, actually, all the time; the only reason we need a new flu shot every year is that the flu virus is rapidly evolving.

Even bigger questions

What did our last common ancestor with chimps look like, they ask. And how could our considerable difference from chimps be achieved with so little difference in our DNA? Good questions, and we are still in the process of discovering the answers.

The origin of life? We don't know, but there's lots of interesting work going on. Notice, though, that this isn't really a question about biological evolution itself, but about what had to happen before that evolution got started.

And what of historical science (the study of the past) versus the operational science that we can repeat in the laboratory – philosophers have quite a lot to say about this, and why it is misguided to claim, as creationists do, that historical science is inferior.

If the record tells us that something happened, then we must accept that it happened, even if we can't explain how. A key example is the antiquity of the solar system, established from the rock record at a time when it seemed physically impossible for the Sun to have generated so much energy for so long.

And lastly, creationists complain, evolution doesn't explain consciousness, define morality, or give meaning and purpose to our lives. But should we expect it to? There is much to think about here; much to learn from.

The ConversationWith evolution, as with everything else, we are blind to our own confirmation bias. We see what we want to believe, and avoid questions that might make us uncomfortable.

But such questions are by far the most instructive, and we must thank those who raise them, whether they want our thanks or not.

Paul Braterman, Hon. Research Fellow; Professor Emeritus, University of Glasgow.

This article was originally published on The Conversation. Read the original article.