# [Spirits of Rock and Sky] how much does a skull weigh, anyway?



## reason (Oct 30, 2002)

http://www.twilightminds.com/sorasfull.html

The cultures of Spirits of Rock and Sky measure weight in units of (adult, average, subjective) fingerbones, skulls and bodies. Which leads me to an interesting problem; seems my concept of skull weight has been off base for quite the while. I'm tuning the economic assumptions for the setting, and getting the skull weight right is pretty important. Factor of two just isn't good enough 

My search for skull weights on Google turned up a lot of *really* strange pages, and stranger vendors. (Try it sometime). Lots of answers, none of them providing a useful convergence.

So here's one for the masses: what does the average adult human skull weigh? I'm at somewhere between 5 and 10lbs right now, based on sources, experimentation, and some math based on head weight, brain weight and head mass as fraction of body mass figures. As I mentioned, that factor of two isn't good.

So come on, weigh in here and help me out. Medical students with access to skulls and scales would be ideal 

Reason


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## Griswold (Oct 30, 2002)

By an odd twist of circumstances I found myself in a cadaver lab at my local community collage this morning helping someone with thier skull practicum. Aside from the names and locations of the various parts of the skull, I learned a few intresting tidbits of trivia.

The Average skull weighs 2.5 pounds empty, 11-14 pounds fully loaded.


hope that helps.

-G.


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## reason (Oct 30, 2002)

Griswold said:
			
		

> *
> The Average skull weighs 2.5 pounds empty, 11-14 pounds fully loaded.
> *




2.5lbs? That sounds low. The 11-14 sounds right; I've seen various figures in the 11-15 range for the weight of the head, all parts included. (7.5% of body mass was a mentioned figure).

The adult human brain is 3lbs according to my reference here...which means that everything else in the head is 7-11lbs. Seems like most of that would be skull.

So is that 2.5lbs with or without jawbone? How much does a jawbone weigh? 

Reason


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## Conaill (Oct 30, 2002)

Keep in mind that "fresh" bone probably weighs quite a bit more than dessicated old bone. In the body, bone is a living tissue and is bound to contain a substantial amount of moisture. Fossilized bone or simply old, dug-up bone would probably be quite a bit lighter. 2.5 lb for an old skull sounds about right.


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## Thorntangle (Oct 31, 2002)

Yep, having handled plenty of skulls dry and wet as a grad student, the 2-2.5 lb. figure is correct. The fresher, the heavier. 

You'd be surpised how much fat/liquid is in human bone. It can bleed grease for years.


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## reason (Oct 31, 2002)

Thorntangle said:
			
		

> *Yep, having handled plenty of skulls dry and wet as a grad student, the 2-2.5 lb. figure is correct. The fresher, the heavier.
> 
> You'd be surpised how much fat/liquid is in human bone. It can bleed grease for years. *




Really? That is interesting. File that one away...

This is the problem with writing up a world that involves building structures out of human bodies when one hasn't been a med student/mass murderer/graverobber. Lots of stuff surprises you.

Still, at least I have my figure now, many thanks guys  The economics of Spirits of Rock and Sky can be safely recalibrated.

Reason


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