…smoosh their hands together in a blood pact? I’d imagine you could get all sorts of nasty diseases and wouldn’t your body freak out at someone with a different blood group?
Chief risks of this behavior would be acquiring either HIV, Hep B, or Hep C. There are other blood-borne pathogens that could be passed this way, but they’re far more uncommon than those three.
The minimal amount of blood exchanged would make blood group incompatability problems a non-issue.
Ah, thanks, mental note - Don’t do that!
If you make a deep cut in your palm, you might cut a nerve, tendon or artery.
If your blood brother does not have HIV or hepatitides, you’re almost in the clear (he might have dengue fever or other contagious illness). If your blood brother has unknown status but is “low risk”, your chance of contacting HIV might be 1 in 100,000. If your blood brother likes injecting crack or is otherwise high risk, your chance of getting HIV might be 1 in 10,000. If your blood brother has HIV, your chance might be as high as 1 in 1000.
In the emergency room, we often see needlestick injuries. I estimate HIV risk using Vertesi’s method to try to decide whether to initiate prophylactic medicines. This method is easy to use and understand, but it is just an estimate.
http://www.caep.ca/template.asp?id=0867239757B441F78C265B04547245D1
Why some people can’t be satisfied with a contract written in blood is beyond me.
(minor hijack)
So, does anyone actually do this in the real world? Obviously, it’s big among the Klingons, and I recall seeing similar sorts of rituals in other fictional sources. Is it a real tradition in some particular group of people? Google just reveals that “blood” shows up in a lot of totally awesome band/MMORPG clan/etc names.
I’m told that the ritual is done with spit in the American South. You become spit brothers after spitting in your own palm and shaking hands with your brother-to-be.
I grew up in the south, and I can tell you I never ever once heard of the phrase “spit brothers”. The spitting and shaking hands is generally understood as an expression of sincerity when making a mutual agreement to do something… i.e. “let’s spit on it” as opposed to “let’s shake on it.”
I’ve read that in feudal Japan, crossing the urine stream was a way of sealing an agreement, no idea if that’s actually true. Seems more sanitary than spitting.
I would think you would be in greater danger from the bugs on the knife than anything you would get from the partner.