It occurs to me that an objective measure of the amount of Fail in a given misidentification could be useful.

I propose the following:

A = the actual taxon of the pictured organism
B = the taxon as misidentified
T = the number of million years since A and B shared a common ancestor*
H = the number of million years since humans and our closest relatives,
the chimps, shared a common ancestor.

Taxonomy Fail Index (TFI) = T/H

In other words, the Taxonomy Fail Index scales the amount of error in absolute time against the error of misidentifying a human with a chimp.

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 in the last post has a TFI of 25.2, or slightly stupider than mistaking an opossum for a cat.

Snope’s insistence that scale insects are “beetles” (via Bug Girl) is even stupider, TFI = 58. In fact, now that we can quantify the Fail, we see that Snopes fails more than twice as hard as the possum cat.

See? Science can be fun.

* A quick and easy way to get ancestry dates is the timetree of life