The artic ground squirrel is an amazing creature. Recently it was the first species of animal that was successfully induced into hibernation, and then back out of hibernation, and then back into hibernation. Now that’s pretty cool – and hibernation is pretty cool – but what’s really cool (actually I should say cold) is the fact that this squirrel hibernates at a temperature well below zero (as low as 23 degrees below celcius). Somehow though its blood doesn’t freeze because the blood has some sort of built in biological anti-freeze in it.
But even with this mysterious biological anti-freeze running through their veins these squirrels still have to fight to maintain even their frigid minimal body temperature. These guys are bunkering down for the winter in frozen ground two feet down that is damn cold (well below freezing). And that’s where the “manliness” part of this story comes in.
Most hibernators put on tons of fat before they enter the big sleep of winter. The fat is slowly burned and provides fuel for the flesh and brain of the creature to survive the ordeal. Normally this is fine. However fat can only supply so much glucose fuel and these frigid little vermin (purportedly) need a better fuel. That fuel is muscle. And what these researchers found is they get these muscles by jacking up their androgen (i.e. testosterone) production to massive levels during the summer season in an effort to do so.
This is true for both male and female arctic ground squirrels. Non mating season levels of androgens in males are reported to be between 10 and 200 times higher for similar squirrel species from lower latitudes, and for females the levels are reported to be between 40 and 100 times higher. These androgens however appear to be derived primarily from the adrenal gland though rather than the gonads (which is different than what is seen during their mating season when levels really are sky high)
My personal take on this research is that I trust the researcher’s raw data, I don’t question that. However I am skeptical of their interpretation of what they found. First of all, I have seen pictures of these squirrels and frankly they don’t look that buff to me. The researchers never bothered to compare lean body mass of one species of squirrel against another either, which you would think should be a key link in establishing the line of thinking supporting their hypothesis. But regardless, I thought it was an interesting and curious muscle related story nonetheless so I thought I would share