If Not Darwin, Who?

What would physics look like if Einstein had never existed, or biology without Darwin? In one view, nothing much would change—the discoveries they made and theories they devised would have materialized anyway sooner or later. That’s the odd thing about heroes and heroines of science: They are revered, they get institutions and quantities and even chemical elements named after them, and yet they are also regarded as somewhat expendable and replaceable in the onward march of scientific understanding.

But are they? One way to find out is to ask who, in their absence, would have made the same discovery. This kind of “counterfactual history” is derided by some historians, but there’s more to it than a new parlor game for scientists (although it can be that, too). It allows us to scrutinize and maybe challenge some of the myths that we build around scientific heroes. And it helps us think about the way science works: how ideas arise out of the context of their time and the contingencies and quirks of individual scientists.

For one thing, the most obvious candidate to replace one genius seems to be another genius. No surprise, maybe, but it makes you wonder whether the much-derided “great man” view of history, which ascribes historical trajectories to the actions and decisions of individuals, might not have some validity in science. You might wonder whether there’s some selection effect here: We overlook lesser-known candidates precisely because they weren’t discoverers, even though they could have been. But it seems entirely possible that, on the contrary, greatness always emerges, if not in one direction then another.

I say “great man” intentionally, because for all but the most recent (1953) of the cases selected here I could see no plausible female candidate. That’s mostly a consequence of the almost total exclusion of women from science at least until the early 20th century; even if we looked for an alternative to Marie Curie, it would probably have to be a man. But the statistics of scientific Nobel Prizes suggests that we’re not doing much better at inclusion even now. This underuse of the intelligence and creativity of half of humankind is idiotic and shameful, and highlighting the shortfall in an exercise like this is another argument for