4Frogs Can Swim, Croak and Fight, Brain or No Brain
As those of you with ticklish feet are only too aware, if something unexpectedly brushes against your foot, your foot will automatically move away from whatever's touching it. Whether or not you then punch whatever was touching it in the face depends on just how ticklish you are.
The exact same withdrawal reaction can be seen in frogs, except the frog doesn't even need to have a head in order for the reaction to happen. Don't believe us? Check it out:
There you have a video proving that a decapitated frog is able to dance a jig upon the demand of not-at-all-evil scientists. It's like a crossover event between Michigan J. Frog and whatever your biggest fear is. That's fairly damn impressive on its own, but let's face it, there's only so much any creature without a head can do. So what happens if you leave the frog's head intact but take out its brain, you ask?
Well, thanks to the "let's chop out its brain and see what the hell happens" approach to science taken by 19th century neurologist David Ferrier, we can tell you. A headed but brainless frog actually behaves very similarly to a frog with its gray matter perfectly intact: If you turn it upside down, it will right itself; if you pinch its feet, it will hop away; if you put it in water, it will swim to the side and climb out. And perhaps most disturbing of all, it will even croak contentedly if you stroke its back.
Frogs 1, Highlanders 0.
So, What Makes This Abomination Possible?
The first factor that results in frogs' zombielike tendencies is the power of the reflex reaction, which fires the necessary electrical impulses that cause a muscle to expand or contract. These reactions bypass the brain -- going back to the human foot moving away from an unexpected tickle, you don't think, "Argh! Something's tickling my foot and I really must move it," you think, "Argh! My foot just jerked, what the hell was tickling it and does it have a face I can punch it in?!"
But it's important to note that this automatic withdrawal action will not continue if a human doesn't have a brain -- we simply cannot survive without our gray matter, because our behavior relies so heavily on input from the cerebral master of our central nervous system. Even breathing, which we don't need to consciously control and could be considered a reflex action, is regulated by (and therefore reliant on) our brainstem.
Otherwise known as the designated driver to our permanently drunken consciousness.
So this is where the second factor comes into play: the relative simplicity of a frog's anatomy. The lack of brain results only in a lack of spontaneity, and Ferrier noted that if energy can be artificially supplied, the frog will continue to respond to external stimuli for an indefinite period. So all the brainless frog needs is energy and the occasional scientific prod in order to act like a regular animal -- indefinitely, or at least until science gets bored with poking a zombie amphibian. (Which will never, ever happen. Science lives for that shit.)
What's even more interesting, though, is that studies have shown that a frog sans brain will react more consistently than one with a brain, which suggests that the brain, while it doesn't control these impulses, may actually suppress them. Frogs could coldly and effectively run shit if their pesky brains weren't getting in the way.
Oh, and by the way, frogs aren't the only creatures for whom heads are an optional accessory ...
3Headless Fruit Flies Are Actually More Responsible Than Headfull Fruit Flies
We couldn't put it much better than Herman T. Spieth from the Department of Zoology, University of California:
Female [fruit flies] ... will live for several days after they have been decapitated. Such beheaded females assume an upright stance comparable to that of a normal fly and can and do engage in complex actions such as preening, flying and, under duress, walking.
We're not sure what qualifies as "duress" for a headless fly, but moving on.
Although species-specific variations occur, males ... will court their decapitated females. All decapitated females of all species studied to date treat the courting overtures of the males as if they were noxious foreign stimuli.
That's right: Chop off a female fruit fly's head, and ... not much changes, really. If anything, it serves to make the flies' behavior more humanlike -- the males still just want to have sex with her, while she in turn treats their sexual advances as "noxious foreign stimuli."
"Man, Brenda used to be so cool before she got her head chopped off. What a bitch."
So, What Makes This Abomination Possible?
First of all, surviving without a head is not as impossible as one might imagine, provided one has something almost like a spare brain in their chest that manages walking, flying and other day-to-day things like circulation and respiration.
Wait a minute -- how can they react to light when, the last time we checked, their eyes are on their heads? You know, the heads they no longer freaking have? Easy -- they have a sort of backup set of eyes: light-sensitive cells in, of all places, their tiny little fly kidneys.
But why do the female flies turn into prudes as soon as science goes all Game of Thrones on them? The explanation is rather simple, really: Since they hear via their antennae -- antennae that they no longer have (what, no sound-sensitive cells crammed somewhere in the vicinity of their asses?) -- the females can't listen to the males chirping whatever the fruit fly equivalent of a Barry White song is. And no sexy, sexy music equals no fruit fly lovin'.
A tragic loss for the world.