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Being hit in the head with a blunt object, or accelerating too fast (in a rocket) can cause serious brain injuries for people.

There are animals who seem to fare better, like woodpeckers. Apparently, they have some soft tissue and neck muscles adapted to cushion the impacts. Also rams seem to have a bone structure adapted to minimize the brain damage from impact.

But, these animals also have smaller brains than people. I think their adaptation won't be good enough to guarantee brain safety against most impacts and sudden accelerations if their brains were our size.

What would be a good set of adaptations for people to be more resistant to concussions and sudden accelerations, that wouldn't make them look too different from us?

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  • $\begingroup$ some ideas here: newscientist.com/article/… $\endgroup$
    – IronEagle
    Apr 23, 2022 at 18:32
  • $\begingroup$ More on woodpeckers and why they are a) amazing and b) sadly not useful in this case, their woodpecking force reaches 1500g, and they cushion their skull by, among other things, wrapping their tongue around it from the inside. Mostly, however, they redirect the energy to the rest of their body to protect their brain, which only works because the force is applied very reliably through the beak; hit them on the head with a rock (*) and they are not much more protected than another bird. (* don't do this) $\endgroup$
    – Ottie
    Apr 23, 2022 at 21:32
  • $\begingroup$ helmet+fat suit $\endgroup$
    – LWS SWL
    May 2, 2022 at 0:19

3 Answers 3

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Non-newtonian cerebrospinal fluid

Protection from impact forces (blunt object etc) vs sudden acceleration/deceleration may not use the same mechanisms; in fact, if we had a more elastic skull, we'd probably suffer less from some deceleration injuries, but more from impact [1].

One of the reasons is that the brain is able to slosh around the skull a bit more than desirable - or more specifically, it has no good way to dissipate its acceleration through heat, except quite violently against the inner wall of the skull. This is because the cerebrospinal fluid is, well, a fluid, and does little to protect against non-compressive forces. Let's change this.

When experiencing "normal" forces, as those generated by movement, the CS fluid remains a fluid; this allows it to carry out its normal functions of waste clearance, homeostasis, lubrication, protection from normal wear, etc. When struck with sudden force, however, the CS fluid behaves in a non-Newtonian manner and becomes suddenly very viscous, effectively turning into a thick "glue" that a) limits the sloshing (so that the brain moves less relative to the skull, albeit experiencing more shear stress internally) and b) is able to dissipate much more energy in the form of heat, because of its higher viscosity.

[1] We probably rarely needed deceleration protection before the widespread adoption of cars, and our evolution may have optimised for protection against rocks to the head instead.

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Pneumatization of calvarium.

https://www.semanticscholar.org/paper/Hyperpneumatization-of-the-temporal%2C-occipital-and-Rebol-Munda/5ce992b733d447b0d7b9eedb63332a17ddf43044

Hyperpneumatization of the temporal, occipital and parietal bones J. Rebol, A. Munda, M. Tos Published 1 September 2004 Medicine European Archives of Oto-Rhino-Laryngology and Head & Neck

Hyperpneumatization of the temporal bone with extension into the occipital bone and even the parietal bones is a rare condition. According to a review of the literature, it mostly appears unilaterally in men and on the right side. Often it is discovered when complications like pneumatocele or pneumocephalus appear. The authors review and analyze all reported cases of hyperpneumatization, its symptoms, complications and treatment. We present a patient with extensive pneumatization found in the mastoid process, temporal bone, occipital bone and both parietal bones, who was discovered accidentally....

pneumatizaton of skull bones

Pneumatization of skull bones can happen as an anatomic variant. Bones contain air instead of marrow. Your concussion resistant persons have pneumatization of the bones of the skull. They serve as crumple zones like the shock absorbing bumpers of a car. The exterior table of bone crumples into the interior gas space, absorbing the force rather than transmitting it to the brain through what is normally a series of liquid containing interior spaces (and causing a concussion), or accelerating the head (and causing deceleration injury to the brain).

This would not protect the brain from rapid acceleration of the entirety of the body in a rocket, without impact to the skull. For that you need slower accelerating rockets.

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The brain is fairly well insulated against shocks. The arachnoid space* helps put a distance between the skull and the brains, reducing the damage a shock ripple could do.

The problem is when the brain inside that space needs to accelerate/decellerate too fast. It will impact the skull across the arachnoid space and bruise the brain tissue. So your best bet is to increase the distance where the brain tissue can slow down, which means a larger head or a smaller brain.

Thats about it I guess. The evolved creatures specifically have systems in place to cushion the head against shock and/or have smaller brains with larger space to move in to begin with. Maybe a cushioning reflex could be added to accelerate/decellerate the head along the same direction the impact will send the brain in order to reduce the speed difference and/or increase the distance over which you can accelerate/decellerate the brain.

  • not sure about the translation. This space is filled with spinal fluid to cushion the brain further.
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