Charles Darwin was a fan of diversity. But in his day, it didn’t mean what it does today. Rather, in 1859’s ‘Origin of Species’ Darwin predicted that a plot of land growing an assortment of different varieties of grasses would be more productive than a single-species plot. His hunch was that complementary species would not compete and would make different use of the various resources they needed, such as minerals in the soil. It’s an idea that has been proven empirically by lots of scientists since then. A particularly interesting experiment, by a University of Toronto team, found that productivity was directly proportional to the evolutionary distance of related species. In other words, a field of distant cousins would be more productive than a field of closely related grasses. This of course is completely in line with Darwin’s thinking. He imagined that a field where some grasses had deep roots and others were shallow, and where different varieties preferred different nutrients, would make better use of the soil than a monoculture field of clones. 

When I told the mixed-grasses story to my impassioned questioner, she was delighted. She took it as proof that I agreed with her that team diversity was key. Timorously, I smiled and had to disappoint her. You see, the team-dynamic analogue of a mixed field is that different people make different use of the information they are given. That is, two different people will hear the same piece of information and draw different value from it. I might see the sales figures as representing the success of our strategy. To you, they might scream that our strategy was flawed because the product is being used in a different way than we expected. Equally, I might see market growth as a predictor of future success and you might see it as an indicator of new competitive entrants in the medium term. And our different ways of seeing things, once we’ve discussed and reconciled them, help our team make sense of the world and move forward. The point is that Darwin teaches us that it’s not diversity per se that is valuable but its consequence. We need people who think differently from each other.

By this point, my interlocutor was beginning to give me the look that means ‘aren’t we saying the same thing then?’ It was time to break the bad news to her. You see, the moral of Darwin’s story is that what works is a cognitively diverse team – people who, because of personality, background or both think differently from each other. Now there may be some association between gender and ethnicity and thinking patterns but if so it is not very strong. By populating your team with a variety of men and women with different skin tones, you don’t necessarily get cognitively diverse team. The only way you can ensure cognitive diversity is by deliberately testing and recruiting for it, regardless of anything else. Of course, there may be many other very good reasons to have a gender-and ethnically-diverse team – social equity, for example – but it is a poor way of getting to cognitive diversity. 

In my experience, cognitively diverse teams are more productive but not without the deliberate leadership effort required to build and manage them. Firstly, leaders have
to actively select people on the basis of their cognitive traits and build mixed teams. This isn’t easy. Not many firms test for thinking style and finding people with the sort
of brain-wiring you need isn’t always easy. In any case, selecting on the basis of cognitive processes often runs counter to traditional approaches. If your primary selection criteria are education and experience, don’t be surprised if you get a lot people who think, for example, like pharma industry science graduates. Secondly, diversity is an unstable mixture. It can just as easily lead to personality conflict as to cognitive synergy. The leader has to create a culture of respect and value for different ways of seeing the world.

As Darwin would have told you, diversity is a good thing. But cognitive diversity is what is needed to make teams productive. Different thinkers exploit information more fully than a team of group-thinkers. To confuse cognitive diversity with other, laudable kinds of diversity is a kind of category error, however well-intentioned my questioner was.

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