What do monarch butterflies, salmon, lobsters, bats, mole rats, and marine nudibranch mollusks have in common? As I’m sure you already knew, all of these species (among others) can sense and use magnetic fields.
Source: Magnetic protein may provide animals with navigation information
Garmin and TomTom declined to comment 😉
Do humans that have an uncanny ability to navigate have a higher concentration of that protein? And if you choose to refer to the protein as “midichlorians” – know that no jury will convict me.
How Would This Have Been Selected via Evolution?
A real answer would presumably require chasing the protein back to the genes that code for it; and then doing phylogenetic work on them; but off the cuff I’d imagine that a likely scenario would be the protein spending most of its developmental history being selected for because of its role in iron binding/transport/manipulation/storage (since, with the exception of horseshoe crabs with their freaky copper-based blood, and various anaerobic goo, iron-related chemistry is life critical for most multi-cellular organisms); with evolutionary optimization for suitability as a magnetic sensor coming fairly late in the game, after most of the original development remained adaptive enough to survive for other reasons.
My [layman’s] understanding is that it is fairly common for novel mutations to be based on re-purposed chunks of other systems (both because it’s highly unlikely to get enough mutations in the same time and place to just conjure up something novel); and because some of the mechanisms behind mutation allow for the accumulation of multiple copies, some more accurate than others, of genes to accumulate, which leaves room for a mutation that allows for a new function without killing the organism by denying it whatever the prior function was.
Given the importance of iron-based and iron-manipulating proteins for metabolic purposes, I’d assume that the ferromagnetism wasn’t even on the table until much later.