Beer beetles

The Australian beetle Julodimorpha bakewelli attempts to mate with discarded beer bottles, sometimes to the point of its own death.

Bernard Dupont, CC BY-SA 2.0, via Wikimedia Commons

Back in the early 1980s a couple of entomologists were studying a large jewel beetle species known as Julodimorpha bakewelli. This beetle has a brownish carapace pocked with numerous indentations. In the right light, its surface resembles a stubby, a kind of Australian beer bottle:

Simon Laird, CC BY-SA 3.0, via Wikimedia Commons

The entomologists found that male beetles were so taken with the empty beer bottles that they, uh, mistook them for female beetles and decided to mate with them. And because these bottles were so impressively large compared to actual mates, they just kept going until exhaustion set in. The horny beer beetles collapsed and were consumed by ants. (Australian ants, as you may recall, can be rather dangerous.)

The resulting research won an Ig Nobel Prize in Biology in 2011, alongside a wasabi alarm clock and a dizziness study of discus-throwers. But it has an interesting scientific connection that transcends confused beetle sex: junk food.

Animals evolve to respond to particular stimuli – food, mates, danger, and so on. But sometimes a “supernormal stimulus” will exploit a similarity to that stimulus, driving the animal to excess in pursuit of its bounty. We can see this, for example, when birds favour the larger eggs of cuckoo-like interlopers over their own eggs. For us humans, junk food represents a kind of supernormal stimulus – it’s impossibly sweet, salty, and/or fatty compared to most unprocessed foods.

So, in the end, we’re all beer beetles.

[Thanks to an anonymous reader.]

Leave a Reply