Survival of the fit or fittest?

[LawrenceOfArabia]

Im wondering, which do you believe the world lives on? survival of the fit or survival of the fittest? there is a diffrence btw.

I know its survival of the fit because for example, africans in central africa have sicle cell anemia, which is a dangerous disease, yet, without it they wouldnt survive the malaria found in the area. They are fit but not the fittest.

 

[Master.America]

Still, it is survival of the fittest.

Although they're immune to malaria, they still live shorter-than-normal lives and are thus less fit than those without sickle cell anemia.

 

[c9h13no3]

You are un-fittest.

 

[Goth.Kid]

They are immune because theyre ansestors died from it. They are here because they are the fittest.

 

[Gedrin]

Nope sorry but you are wrong. Those with ONE copy of the sickle cell anemia gene are resistant to malaria. They don't have sickle cell anemia at normal elevation. Sickle cell anemia is recessive.

It basically goes like this, blood cells infected with the parasite will often be destroyed because these cells are vulnerable to a reduction of oxygen. Thus these cells will deform and be destroyed while uninfected cells will be fine. High altitudes are of course a problem.

Two normal copeis are bad because you will likely die from malaria in that environment, and two sickle cell genes will also kill you.

Therefore in this case having one of each makes you the most fit.

 

[c9h13no3]

Heterozygote advantage what?

 

[Gedrin]

I had to simplify it somewhat lest it fly above the heads of too many ppl. After all in most HSs they teach the simplest of mendelean genetics, and sometimes not even that.

I would consider this more of environment dependant gene expression. After all being heterozygous in a country in which Malaria is not a problem you will not express a phenotype of this sort. That is if you consider malaria resistance to be a phenotype of being heterozygous for sickle cell anemia.