Popular science-y webcomic xkcd has an associated feature called “What if?”, in which the author (a former NASA engineer) answers hypothetical questions from readers using back-of-the-envelope physics calculations. For instance, if you’ve ever wondered how many model rocket engines it would take to launch a real rocket into space, or if it’s possible to stop a runaway train by shooting it with enough BB guns, “What if?” has you covered.
Which got me thinking about ecological “What if?” questions. In the broadest sense, of course, much of science is about asking, and answering, “What if?” questions. What if assumptions X, Y, and Z were true? What if the top predators were removed from this ecosystem? What if we raised the annual catch quota for this fish? Etc. But I’m thinking here of amusingly hypothetical “What if?” questions, in the spirit of those addressed at xkcd.
The first one that comes to mind is “What if the Loch Ness Monster existed?” This is a question ecologists actually have asked several times, a literature reviewed in a fun little essay by Lawton (1996). Various independent lines of argument suggest that, if a piscivorous poikilotherm large enough to be called a monster existed in Loch Ness, the population size would have to be very small, on the order of ten to maybe a few hundred individuals. And of course, it’s questionable whether a population that small would have persisted since the end of the last glaciation 12,000 years ago. All of which of course suggests that the Loch Ness monster doesn’t in fact exist.
Can anyone think of other good fun ecological “What if?” questions? The Lab and Field recently did a post on how many gulls it would take to lift the giant peach in James and the Giant Peach. And of course, recent discussions of the physiological ecology of horse-sized ducks fall squarely into this category. Anyone have any other suggestions?
Silly “What if?” questions, such as about the existence of the Loch Ness monster, could be good exam questions for undergraduates. The students would enjoy them–but they’d also have to think. Plus, silly hypotheticals like “What if the Loch Ness Monster existed?” often have serious, non-hypothetical analogues, like “What if Ivory-Billed Woodpeckers still existed?” So asking this sort of “What if?” question on an exam doesn’t necessarily mean sacrificing relevance.
p.s. While this is all in good fun, facility with back of the envelope calculations or “guesstimation” is a really useful skill. You have to be able to get to the heart of the problem and strip away irrelevancies. The classic book on back of the envelope calculations is Polya’s How To Solve It.