A HUNDRED years ago, scientists were sure of many truths. The greatest experts were certain that the universe had always existed and was always the size it is now. Most biologists were sure that proteins, not DNA, were responsible for heredity. Biochemists believed that, outside the nucleus, the interior of a human cell contained little more than busy enzymes – a “biochemical bog” that carried out all the reactions that are essential to life. These sureties were all wrong. Yet scientists reacted to challenges to their accepted truths with dismissal and scepticism.
I began to see how common this knee-jerk reaction was as I researched on how scientists reconstructed the journey of our body’s atoms from the big bang to now. So many theories that we now consider great breakthroughs were at first waved off, like annoying gnats. Why? We all know that some researchers are territorial, or fear a new theory will undercut their work. But why did entire communities of scientists reject groundbreaking ideas – even those backed by sound evidence?
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Puzzled, I tried to categorise the reasons why and found six cognitive biases that arose so often I gave them nicknames. For instance, the “Too Weird to be True” bias led Albert Einstein to initially reject Georges LemaĂ®tre’s theory of the big bang. The “As An Expert, I’ve Lost Sight Of How Much Is Still Unknown” bias convinced scientists that organic molecules couldn’t exist in space – until Charles Townes proved them wrong. The “You Look For and See the Evidence That Matches Your Existing Theory” bias (commonly known as confirmation bias) impeded our understanding of diseases like scurvy and beriberi, which were killing millions. żěè¶ĚĘÓƵs tried to explain these illnesses with the ancient Greek theory of humors, then germ theory, before arriving at the concept of vitamin deficiency.
How could so many brilliant scientists have been so ignorant? If you look a little deeper, you will find that none of us is immune. A Microsoft executive once said: Just the other day, I was sure that my missing keys couldn’t be in my desk drawer because I would never put them there. When covid-19 struck, we all thought we would be back at work in just a few weeks.
But cognitive biases aren’t simply weaknesses that trip us up. They are also strengths. As psychologists Daniel Kahneman and Amos Tversky have shown, our brains are crammed with biases. Many are there for a reason: we couldn’t survive without them. We have to make assumptions in order to live. We would be paralysed if we constantly questioned whether the sun will rise tomorrow. Often, ideas that seem too weird to be true are, in fact, too weird to be true. Unconscious assumptions offer us shortcuts that allow us to avoid constantly rethinking everything.
We will never be entirely rid of biases. That is why even scientists, who pride themselves on carefully interpreting evidence, are prone to them. Biases are part of the human condition, and scientists need to be aware their brains are full of them. As those I profiled discovered, our cells are crammed, not just with enzymes, but with a mind-boggling assortment of molecular machines. DNA, not protein, is the molecule responsible for heredity. And the universe was once contained in a tiny point of space and time.
All kinds of things are possible that we would never expect. That is the beauty of life. The history of scientific innovation encourages us to remain humble, examine evidence with an open mind and try to see the world not as we would like it to be, but – to the extent that we can – as it truly is. Understanding this helps us to appreciate the amazing world we live in.
Dan Levitt is the author of What’s Gotten Into You: The story of your body’s atoms, from the big bang through last night’s dinner
