There is a strange story unfolding in the Sonoran desert, the hero of which is the Southern Grasshopper Mouse. Weighing in at under an ounce, it looks cute enough but is in fact, pound for pound, tougher than Wolverine…
and needs to be..
because the favorite breakfast of Onychomys Torridus, the Desert Claw, is the most poisonous scorpion in North America.
The Arizona Bark Scorpion hospitalizes thousands of people every year. It was responsible for 800 deaths in Mexico during a peak period in the eighties. You froth at the mouth, convulse and die.
The scorpion’s Latin name gives more clues, Centruroides Sculpturatus, pointed tail with toxins that may as well be coming at you like a two inch stone chisel driven by a four pound lump hammer.
It ought to make short work of any mouse whose body weight is several thousand times less than even a small human. Just a scratch should kill it instantly. The mouse piles in for the feast regardless. It may not even defend itself from the scorpion’s tail. When it inevitably gets stung something amazing happens. A protein built into the mouse’s nerve cells not only blocks the toxin, it converts it into analgesic. The mouse endures a moment of pain but not enough to put it off its meal let alone kill it.
The scorpion loses every time.
What do you think it might be like to neutralize and turn into medicine toxic situations that you otherwise can only avoid or be poisoned by? There’s a deep poetic metaphor in there somewhere but for the moment I feel more enamored with the trixy question of how the mouse managed to develop such bio-chemical ninja skills in the first place.
Evolution, as we are taught it, requires random changes in genetic markers plus a process of selection to evaluate these chance occurrences one way or another. In other words, Nature is reactive.
The main sticking point with the negative stimulus argument is that you have to survive the encounter in order to adapt to it…. a fact that limits the evolutionary dance of Torridus to two equally unlikely alternatives.
Either the mice are genetically disposed to immunity, ie, by the strangest quirk of fate they just happened to randomly develop ahead of time the precise amino acid required to ‘build’ into their acetylcholine receptors giving them a thousand fold immunity to toxins they had as yet never met, but are now curiously just across the way.
Or, the grasshopper mouse population decided that the meager pickings of the desert was just their cup of tea and exposure to lethal toxins was an environmental hazard they would simply have to negotiate along the way. ie venom which will put a seriously crimp in the chances of you passing on your last will and testament let alone your genes.
A third alternative, that an arms race in bio-chemical warfare has been ongoing since time immemorial with each party slowly developing its arsenal has a certain poetic ring to it, undermined by the single salient fact that the scorpion was a desert killing machine before the mouse even existed. Scorpions as we know them were doing their thing 430 million years ago in the Silurian period. A mouse that was not also a rat is only 33 million years old. The Scorpion poison was perfected before the mice ever emerged.
So, at one time Point-Tail-of-Stone-Chisel and Desert Claw did not share territory. Then they did. For Torridus to survive the encounter he would either have to chance his paw and get himself killed again and again before defenses could ever be created let alone passed on to healthy babies, sacrificing generations of mice to attain the final vintage of biochemical Reserve needed to survive dinner..
or Nature simply handed it out, as and when it was needed, just as any good Mother would, ahead of the meal.
Either way it’s a miracle.
