Living forever?
Reply #63 - September 25, 2014, 03:12 PM
Even just having one allele makes you resistant to malaria. So if there's malaria around, you're going to lose a lot of the normal guys, and, as always, you're going to lose people with sickle cell at different rates anyway, but the carriers of sickle cell will be incredibly successful. Some of their kids might be a different story.
I'm a little confused by this whole discussion. Could affect, or does? Certainly if there was like a doomsday pandemic sweeping around, you might get a good look at people clearly needing to sink or swim, but otherwise, what are we really talking about here? The extent to which we see human evolution today is most noticeable in the extremes, and, like it always is in genetics, sickle cell is a perfect example. In an area where malaria thrives and sickle cell exists, sickle cell is probably going to increase as malaria does.
This is evolution, this is evolutionary pressure, as slow and as subtle as it pretty much always has been. The much more interesting question now, and I guess this is what some people on here were going for, is how our advances in medicine will change--not stop--evolution. We can easily hypothesize what will happen if we went into this population and increased the treatment and preventative measures against malaria, and gave genetic counseling.
Sometimes, evolution is a lot about what isn't there, who isn't there, diseases/disorders that are common in certain populations but absent in another. Even when we buffer the extremes where you do see pressure on certain populations, which we have been, evolution will still be working slowly, and, again, most visible by imagining who isn't among us, some people we never even knew tried to come into existence and just got those unlucky combinations that were obligate lethals. And that does change what is generally out there to be inherited in the world and in which proportions they were available.
Genetics is way too complex for me to believe that one could look at a very brief window in human history, and right now, it is brief, and think we've grown beyond our need to really evolve in that classical way. It's not like before, but it's not gone away, either. If nothing else, we will likely always have to contend with new mutations, new environmental factors very likely to increase said mutations, and, very likely, the general increase of instances of genetic disorders that were once too debilitating for the sufferer to pass on very often, and all the repercussions of all the combinations we try cramming together to make a person. Certain combinations get a shot. If you can withstand your particular environment, you can thrive. Others get scrapped well before reproductive age, sometimes right off the bat.
Topic: Living forever?