fallacycop responds to Bluejay:
quote:
quote:
But, since we can make people that are "less fit" survive and reproduce, we are not allowing natural selection to remove unfitness from our populations.
What are you talking about? People die premature deaths all the time for many different reasons, and the ones that survive to reproductive age do not all reproduce at the same rate, if at all.
Indeed. The fact that there are some fairly direct ways of killing a person off before puberty, however, doesn't change the fact that our modern technologies of sanitation and medicine have made it possible for people who would have died before puberty to survive and thus have the opportunity to reproduce.
Smallpox literally does not exist anymore. It used to be the leading cause of death. We've eradicated polio for all intents and purposes in most of the world. There's a reason they're called "childhood diseases" and they used to be quite fatal. If you made it to your first year, you were quite lucky.
But we've figured out how to vaccinate and thus prevent people from catching the diseases that would have killed them off. We no longer have that environmental factor affecting our evolution. The reason sickle-cell trait exists at all is because of malaria. Being heterozygous for sickle-cell provides a fair amount of protection against malaria. Since we no longer have many diseases affecting us, where is the selective pressure to develop traits that fight the disease?
We are seeing such a thing with HIV: There are some people who carry a gene such that their white blood cells do not have a protein that HIV requires in order to infect it. Thus, they seem to be immune to it (or, at least, certain strains). In a population that has HIV as a selective pressure, this trait would start to become more prevalent.
But suppose HIV didn't exist: What would be the selective pressure to make this trait common?
The fifth leading cause of death for all people is accident and for young people, it is the leading cause of death. Our ability to keep these people alive and thus survive to reproduce means the selective pressures that would affect behaviour and body morphology with regard to survival are not nearly as strong as they once were.
It isn't that there are no environmental pressures on us, but we have severely limited the effects of many. Do you really think that a population that developed sunscreen and used it religiously would have the same diversification of skin tone that a population that didn't have such protection would?
Rrhain
Thank you for your submission to
Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
™ Version 4.2
