Genetic Diversity.

In honor of my Immunology midterm tomorrow... a lesson on MHCs:

We all know that inbreeding is bad, but why is it really bad? When selecting a mate, you ideally want to choose one that is the least genetically similar to you (but of course you would never be able to know this unless you've had your genome sequenced... so when in doubt, just don't mate with relatives!). The more different your major histamine complexes (MHC) are to those of your partner, the more different MHCs you will be able to jointly contribute to your offspring. And why is a variety of MHCs important? MHCs are responsible for recognizing pathogens in the body. The more diverse your MHCs, the more pathogens your body will be able to recognize and elicit an immune response against. With a greater ability to recognize and then fight these pathogens, the more chance of survival you have. Why did some people survive the Spanish Flu epidemic, whereas others died? Well, the survivors had better immune systems. Believe it or not, there is a group of women in Nigeria (I think they are from this country (??)) who are even immune to HIV/AIDS. These women have been exposed multiple times and have never been effected. If a world-wide HIV/AIDS epidemic breaks out, then we know who will survive and carry on their super immune system genes! A case in point: the quality of your immune system is so important for your survival.