IJEE Soapbox: A World free of pArAsites And vectors: Would it be heAven, or Would it be hell?

This is of course impossible, but Gould’s thought experiment is a useful conceptual exercise which brings out key issues of determinism versus randomness in history. More broadly, it can be illuminating to ponder all kinds of implausible and radical scenarios, in effect bracketing the real world with visions of possible worlds. What would our world now be like if, at some time in the past, a mad chemist had come up with a concoction which, after being liberally sprinkled across the globe, eliminated all parasites and their vectors, once and forever? And were such a massive perturbation of the global ecosystem possible, should we carry out this mass elimination? Thinking through such implausible scenarios is an example in ecology and evolutionary biology of a genre of historical analysis called “counterfactual history” (Bunzl, 2004). Winston Churchill, for instance, once mused about how history would have unfolded if Robert E. Lee had won at the Battle of Gettysburg (Churchill, 1931). As another, somewhat extreme example, what would have happened in world history if Pontius Pilate had taken pity on his captive, and released him into exile, rather than sending him on to a brutal execution? Think about it ... no Crusades, no Reformation, no Sistine Chapel, no Lourdes ... and on, and on, and on, one can spin out the ramifying causal implications of alteration in a single human decision. In such counterfactual exercises, one tweaks the past in some small but key way, and tries to gauge how that change might have reverberated through history. What I ISRAEL JOURNAL OF ECOLOGY & EVOLUTION, Vol. 56, 2010, pp. 239–250 DOI: 10.1560/IJEE.56.3-4.239