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In the Land of Metal, there exists a tribe that has upheld the gospel of Manowar with such zeal that it modified their bodies.

Metalheads descend from humans, and may look human at a glance. A more careful examination, however, will reveal the traits their kind has acquired through the ages. These traits allow them to have a lifestyle that would be extremely harmful for humans; the man who tries to live like a metalhead usually does not live long.

Central to the life of the metalhead is headbanging. They bang their heads in the air for a number of reasons:

• To show others their emotional state, such as being happy, content, angry, anxious, frustrated, or simply out of their mind;


• As a greeting or compliment, or to thank someone for something;


• As a reflex to music being played that suits their tastes;


• As a mating display. They seem to be aroused by the flowing long hair of a potential mate oscillating in the air to the sound of metal.

Metalheads are able to bang their heads in the air for hours at a time without the need for rest, and without damaging their necks and brains. They are also able to continuously bang their heads to power metal, even at 180 bpm, with some record beating at 250 bpm. They also maintain this ability as long as they are fertile and sometimes into old age even.

Starting from an average human body for a template, what changes to anatomy would be required to allow for such an amazing headbanging capacity?

I was inspired by Brütal Legend's headbangers for this question:

They have traits such as stronger neck musculature and thick skulls, but I think those are more fit for headbutting than headbanging.

what changes to anatomy would be required to allow for such an amazing headbanging capacity?

As any student in Engineering is taught, when you have oscillating masses and one wants to improve frequency and reduce stresses, it is always a good idea to reduce the masses.

So, lighter skulls seems to be a must for your homo caput oscillantis.

Moreover our neck has a somehow faulty design: due to the way the neck muscles are connected to the skull they make a first type lever with the force arm shorter than the resisting arm, as a consequence they need to exert a much higher force to move the head than the weight of the head.

To improve headbanging the skull shall be modified: the neck has to move more to the center and the face has to become shorter, while the back of the head has to somehow extend.

Considering that on falling one cannot beat gravity, and this somehow limits the oscillating frequency of the headbanging, it would be also an improvement to develop stronger antagonist muscles on the throat region, so that they can actively pull down the face when it has to execute that part of the banging.

In our world, we do have an animal that habitually violently smashes its head against things at high frequency: the woodpecker.

Their heads have multiple adaptations to the repeated stresses caused by pecking, such as:

• A specific kind of spongy bone structure is lining the skull. It is compressible and most of it is located around the front of the back, where the forces are strongest. So your metalheads could have such spongy bone in their heads, probably differently aligned as the headbanging movement is not back-to-front like in woodpeckers.




• The hyoid bone (tongue bone) is much larger and interconnected, acting as a spring to further reduce the acceleration forces.




• The tongue itself is similarly longer and wraps around the braincase, acting like a kind of a harness.




• The brain itself is much flatter and smoother than usual, it is aligned have a maximum cross-section in the direction of the pecking, so it has the most possible surface to spread the impacts.




• During the actual striking, the woodpecker closes its third eyelid which keeps the eye in place, and strains its neck muscles, tightening everything around its brain, so it is not hitting against anything inside the head.

Their skulls and necks would eventually resemble those of our primitive ancestors.

First the most obvious: the neck. Since individuals with frail necks who cannot bang their heads for hours are sexually unattractive, broader vertebrae would drive evolution to produce stronger necks. These also provider broader spaces for stronger tendons to attach to the bones. These are absolutely nessecary to prevent disk herniation into old age.

Now to the skull: The constant oscillating of the skull puts preasure on the soft and squishy brain. Their skulls would eventually resemble those of woodpeckers: The bone structure is much thicker and sponge-like to cushion the brain.

Notably, the woodpecker's brain is surrounded by thick, platelike spongy bone. At a microscopic level, woodpeckers have a large number of trabeculae, tiny beamlike projections of bone that form the mineral "mesh" that makes up this spongy bone plate. These trabeculae are also closer together than they are in the skylark skull, suggesting this microstructure acts as armor protecting the brain.

Since headbangig pushes the brain alternatingly against the front and back of the skull, These are the parts that are most reinforced. The skull would get a slightly more oval form.

Such an rather oval skull could provide an opportunity for an alternative headbanging mechanism: by tendon tension. There is enough room on the posterior skull to attach thick, strong tendons, just like in the legs. And just like with running, they store the kinetic energy of the skull falling forward and pull it back like a rubber band without needing to excert all the energy with muscles alone. The conservation of energy would probably be an evolutionary advantage, so the metalheads would actually loose their broad necks.

The eyes (or more precisely the eye sockets) would also become slightly more prominent. If headbanging constitutes most of your social interactions, you cannot let your eyes blindly stare into nothing until you're done. The eyes have to follow the back-and-forth movement constantly and the corresponding muscles are trained from early age, eventually taking up more space in the skull.

The most realistic evolution pattern would be simply to develop stronger neck muscles and tendons. Imagine a normal person with a wrestler's neck.

Headbanging for hours means your headbangers will get a lot of blood flow to the brain, and a lot of blood flowing overall to transport all the oxygen needed.

That is all good cardiovascular activity, which means an overweight headbanger will be incredibly rare, also they would live longer due to the continuous activity. Physical activity also drastically reduces chances of diabetes and most times it can reverse it even with a poor diet.

Longer life mean more potential for reproduction, your metalheads will be fertile even in old age.

If they headbang to show emotions and they headbang most of the times it means their society will be really open and emotional as a whole.