Actually it is a pretty good analogy puroresu. Race is basically one of those socio-cultural pseudo-biological what-nots. Science officially recognizes race as nothing more than a word.
Bad analogy again. The existence of variation within a race doesn't negate the differences between races. Suppose the tallest adult member of RACE A is 7 feet, and the shortest is 5 FEET. The tallest adult member of RACE B is 6 feet, and the shortest is 4 feet. There would be considerable variation within each race, and considerable overlap as well. But the fact would remain that ONLY RACE A grows to heights of 7 feet. And in our real world, ONLY certain races have black skin, or white skin, etc.
Deficient correlative judgment. And easily refuted. Based on geographical history size can be quite the divergent factor. For example Forest Elephants and Bush Elephants are totally alike ....except for their sizes (the forest tuskers are much smaller). Why? It is hard to survive well it a forest if you are big. Same thing with Nile crocodiles ....where the environment is optimal (eg numerous large prey) those crocs regularly attain sizes of 18 feet (some even 20 plus), while in other areas they rarely get to over 10 feet. Environmental factors.
.....Sickle-cell anemia....
Simplest explanation of all actually. The genesis of SCA stems from the fact that in Africa malaria is the biggest killer. Most of the continent has the anopheles mosquito, which transmits malaria (the female needs human blood to breed, and its saliva transmits the disease). A study was done that showed that Africans with SCA (and many have it ....especially around the lakes and river regions) have a surprisingly high resistance to malaria. The only drawback is that red blood cells for a person with SCA do not have a high efficacy level when it comes to oxyhemoglobin, hence the people easily get tired an what-not. However when you consider that malaria kills thousands a week in Africa then having SCA is an easy trade-off. Once again this is an environmental factor. Sadly when Africans came to the US those with the gene for SCA had all the bad side-effects and no positive (since the anopheles mosquito is not prevalent here).
Actually i remember this joint genetic analysis that was done between people of various tribes in Kenya, and it was noticed that there was more genetic variation between, say, a kikuyu and a maasai, than between either and a briton!
It is basically a pseudo-science .....on the same level as the whole 'once race is more intelligent than another B.S. In both cases the prevalent factor is NURTURING and ENVIRONMENT , with intelligence being due to the first and 'race' being due to eons of the second.
Classifying Humans As a first step to identifying links between social definitions of race and genetic heritage, scientists need a way to divide groups reliably according to their ancestry. Over the past 100,000 years or so, anatomically modern humans have migrated from Africa to other parts of the world, and members of our species have increased dramatically in number. This spread has left a distinct signature in our DNA.
To determine the degree of relatedness among groups, geneticists rely on tiny variations, or polymorphisms, in the DNA--specifically in the sequence of base pairs, the building blocks of DNA. Most of these polymorphisms do not occur within genes, the stretches of DNA that encode the information for making proteins (the molecules that constitute much of our bodies and carry out the chemical reactions of life). Accordingly, these common variations are neutral, in that they do not directly affect a particular trait. Some polymorphisms do occur in genes, however; these can contribute to individual variation in traits and to genetic diseases.
As scientists have sequenced the human genome (the full set of nuclear DNA), they have also identified millions of polymorphisms. The distribution of these polymorphisms across populations reflects the history of those populations and the effects of natural selection. To distinguish among groups, the ideal genetic polymorphism would be one that is present in all the members of one group and absent in the members of all other groups. But the major human groups have separated from one another too recently and have mixed too much for such differences to exist.
Polymorphisms that occur at different frequencies around the world can, however, be used to sort people roughly into groups. One useful class of polymorphisms consists of the Alus, short pieces of DNA that are similar in sequence to one another. Alus replicate occasionally, and the resulting copy splices itself at random into a new position on the original chromosome or on another chromosome, usually in a location that has no effect on the functioning of nearby genes. Each insertion is a unique event. Once an Alu sequence inserts itself, it can remain in place for eons, getting passed from one person to his or her descendants. Therefore, if two people have the same Alu sequence at the same spot in their genome, they must be descended from a common ancestor who gave them that specific segment of DNA.
Why the clean separation between the two? Can you explain to me why the brain is static under environmental pressure?
No, if you're heterozygous for SCA you produce normal hemoglobin, and in fact can function as an aviator, etc. It's the people who have two copies of the sickle cell gene that have the anemia.
There are similar conditions, the thalassemias, that affect people in the Mediterranian area.