Sometimes it's easy to make a mistake when picking a photo of an animal — presenting an image of a rat instead of a mouse, for example. Or mistaking a crane fly for a mosquito. But whoever made this missing cat poster has taken the crown for animal mis-classification.
In any case, there is now a way to express just how much the possum featured in the missing poster is not a cat, because biologist and blogger Alex Wild has come up with a brilliant method of quantifying the extent of taxonomic misidentification. He calls it the Taxonomic Fail Index (TFI) and it's actually a pretty straightforward little equation:
Taxonomy Fail Index (TFI) = T/H
Where T = the number of million years since the two species (the correct species and the species an organism is misidentified as) shared a common ancestor; and H = the number of million years since humans and our closest relatives, the chimps, shared a common ancestor (about 6.4).
"In other words," writes Wild, "the Taxonomy Fail Index scales the amount of error in absolute time against the error of misidentifying a human with a chimp." He continues:
If I were to run a story about Sarah Palin, but accidentally illustrate it with a photo of a bonobo, that would be a taxonomy fail of magnitude 1.
The classic Taxonomy Fail of possum/cat has a TFI of 24.6.
The yellow jacket/honey bee fail...has a TFI of 25.2, or slightly stupider than mistaking an opossum for a cat.
Let's try putting the equation to work, shall we? This image is from a post I wrote back in August about how rats were not actually responsible for the Black Death.