[skydaypat]

(I apologize for going off-topic a bit..)

Our 10 fingers and toes are precisely why we all use a base 10 number system, so I doubt humans originally had 12. A number system could just as easily be based around any different number, like hexadecimal (base 16), octal (base 8 ), and binary (base 2) in computers. But humans chose decimal (base 10), most likely because of our fingers.

I think 12 gets used frequently in "standard" measurement because it is evenly divisible by four different numbers (not counting 1 of course), whereas 10 is only evenly divisible by one number. You can take 1/2 foot, 1/3 foot, 1/4 foot, and 1/6 foot and be using whole numbers of inches (6, 4, 3, and 2 inches, respectively). But if you want 1/3 of a meter... that's 33.33333 (endless repetition) centimeters, or 333.33333 millimeters. 1/6 of a meter? That would be 16.66666cm, or 166.66666mm.

60 and 360, being multiples of 12, are thus conveniently also multiples of 2, 3, 4, and 6 just like 12. So it is very easy to talk about 1/2 an hour (30 minutes), 1/3 of an hour (20 minutes), 1/4 of an hour (15 min.), 1/5 of an hour (12 min.), 1/6 of an hour (10 min), and 1/12 of an hour (5 min.). With an "hour" based on 10 or 100 minutes, fractions of an hour outside of 1/2 (and 1/4 for 100) would quickly result in having to use decimal points, which tends to be more confusing and difficult for people trying to do mental calculations.

I'm not arguing against the metric system, only pointing out that for civilizations without calculators and computers, measurements based on numbers like 12 were much easier to deal with than measurements based on 10.