People have "bloodlines," or adopt one another as family through mixing blood in "blood pacts." I can see why blood is symbolic of life and life force, but why is blood so often treated as though ancient peoples had some knowledge of genetics? Do umbilical cords bleed excessively?
Sorry for not putting a specific time and location for this, but it's pretty universal, going back to tribal cultures. For some reason, people that share genetic makeup are seen as "sharing blood." I suppose that our blood cells are one of many types of cells carrying our genetic information, and perhaps we more associate blood with genetics because of our cultural associations (I'm definitely not a geneticist so I can't claim if this is a 'chicken or egg' scenario), but I was just wondering if anyone knew why this was so prevalent. What is it about blood that we find so symbolic of (for lack of a better term) 'blood' relations.