why don’t we have fat and muscle surrounding our brains as an added protective layer over our skulls?
In: Biology
Heat retention. The brain uses a large portion of our energy and the temperature range from normal to heat stroke is all of 3 degrees C. Also because of all of the blood vessels in the brain, a lot of the body’s heat is pumped through your head.
Just being hot makes you think slower and make more mistakes.
Muscle tissue has the sole purposes of enabling movement of the body and organs, fat tissue is mostly only for energy storage. So neither of those two tissues really qualify as a protective tissue and if we start thinking evolution it makes little sense for an individual to have increased reproduction rates because of two ridiculously energy cost intensive tissues around the skull which already protects the brain.
Tissues that are fit for acting as protective Barriers are bone, skin, and mucous membranes and those are already pretty solidly implemented into our heads at this point. Anything beyond that would probably just drive the cost-effect balance into negative and would decrease our fitness as individuals, thus leaving us more susceptible to natural selection which would lead to a relatively fast extinction of such a muscle-fat-head human.
We do, only the very top of the skull doesn’t have skeletal muscle attached. There’s a specialized type of skin called scalp that covers the skull, it’s extra thick and tough for added protection. All skin has a layer of subcutaneous fat as well. Inside the skull there’s several more layers of protection called the meninges, made up of three layers; the dura mater which it tough and thick, the arachnoid mater which is spongy and the pia mater which is thin and delicate. The brain itself also floats in a tub of liquid called cerebrospinal fluid that flows between the meninges and through the brain itself via a system of ventricles and canals, supporting it and further cushioning it.
Brains are so fragile they literally float in a pool of fluid. When you get a concussion it means you hit your head hard enough for your brain to float through the fluid and bash into the inside of your skull.
Adding protections to the outside of your skull doesn’t prevent that from happening. And your skull itself really is quite durable.
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