The Grey Alien trope almost always features a disproportionately large head, which often comes in unusual shapes to boot. There's nothing wrong with the trope, large brains are cool but what baffles me is how their necks don't snap and how they don't get back pain (at least none that we've seen them complain about). Logically they would have to be properly adapted to having larger heads. Human babies for example can carry a head one third the size of their body. But some aliens have much larger heads that can be about twice or thrice the size of a human head.

What is a realistic spinal structure for a large headed alien?

The average human head weighs about 10 to 11 pounds so a grey's head would approximately 20 to 30 pounds in total. With this in mind I strongly doubt that they would look anything like your typical sci-fi alien. For extra precision about the requirements: 1. they must be bipedal 2. no cybernetic enhancements.

  • 3
    $\begingroup$ The spine itself doesn't need much redesign. Look at the giraffe's neck: same bone structure and even same number of vertebrae! It just needs to be a bit thicker overall. $\endgroup$
    – KeizerHarm
    Jan 20, 2020 at 15:54
  • $\begingroup$ @KeizerHarm Indeed, but the spine itself doesn't hold the head upright. Muscles and ligaments also play a role here. Knowing this is necessary to depict the aliens accurately. $\endgroup$
    – user71341
    Jan 20, 2020 at 15:59

1 Answer 1


Awesome traps.



It is not only the science and the probing for the Grays. In their off hours they are total gym rats and if you mess with one it will snap you like a twig. Under their flowy robes those little guys are buff as stink. Most of all they develop their trapezius muscles - illustrated. These muscles attach to the back of the skull and lash it securely to the shoulder blades and spine. The Grays get pretty competitive about who has the sweetest traps. They are big on lats too.

Image from Gray's Anatomy, interestingly enough.

  • $\begingroup$ Neck muscles are one thing but wouldn't the weight of the head be a problem for the rest of the back as well? And if they need to hit the gym just to keep their head straight how would the young ones stand at all? $\endgroup$
    – user71341
    Jan 21, 2020 at 14:20
  • $\begingroup$ @LiveInAmbeR - the young Grays start really dumb, with tiny little heads. Only after they have proven themselves buff enough to deal with great brains do they start to grow them. Nonbuff Grays keep their small heads and remain woefully underemployed. $\endgroup$
    – Willk
    Jan 21, 2020 at 18:48

You must log in to answer this question.