Liberal Creationism, or: Yippee, It’s Bell-Curve Time Again!

vimothy

yurp
I'd say 'category' is putting it too strongly, as categories tend to be discrete, well-defined and mutually exclusive. Racial variation in humans doesn't usually have sharp cut-offs* - millennia of interbreeding and migration have put paid to that. For example, many people in North Africa and parts of the Arabian peninsula are of mixed Arab and African descent, and even within the 'indigenous' white Northern-European population of Britain, there is a mixture of Germanic, Celtic and pre-Celtic gene markers. This is of course without taking account individual mixed-race people whose parents come from different ethnic groups.

Ok, fair enough. I'm certainly no scientist. I do think that your point about interbreeding and migration is pretty obvious, though.

EDIT for the EDIT:

On the subject of genetic variation, it has been shown pretty conclusively that humans have far less variation than do other species of primates: you could analyse the DNA of any two people in the world selected at random and they will show much greater similarity than would two chimps taken from breeding populations just a few hundred miles apart.

It's interesting, but is it relevant?

Apologies for the terrible mixed metaphor.

:eek:
 
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mixed_biscuits

_________________________
On the subject of genetic variation, it has been shown pretty conclusively that humans have far less variation than do other species of primates: you could analyse the DNA of any two people in the world selected at random and they will show much greater similarity than would two chimps taken from breeding populations just a few hundred miles apart.

How do scientists measure the degree of variation?
 

Mr. Tea

Let's Talk About Ceps
How do scientists measure the degree of variation?

It's quite easy: see what proportion of Individual A's genes are identical to Individual B's. The higher the proportion, the less the variation. You can map 'genetic trees' of population, species, genera etc.: the more variation between two populations, the greater the length of time since those populations diverged from a common ancestor. If you do this with primates, all the other great apes show up as big long branches, sometimes with widely-separated 'twigs' even within a single species, while humans look like a polarded tree - many tiny, stubby branches very close together.
 
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Mr. Tea

Let's Talk About Ceps
Here we are:
ng0201_155_F1.gif

Compare the degree of branching among humans to that of the other great apes.
 

Guybrush

Dittohead
Many great arguments everyone!

Mr Tea: Apropos of humans’ relatively limited degree of genetical variation, are there any examples of even very small genetic variations playing a major part in affecting a human’s bodily features?
 

Mr. Tea

Let's Talk About Ceps
Many great arguments everyone!

Mr Tea: Apropos of humans’ relatively limited degree of genetical variation, are there any examples of even very small genetic variations playing a major part in affecting a human’s bodily features?

As far as I'm aware, just a single faulty gene (out of the 3 billion in the human genome) can put you at increased risk of certain cancers, heart disease, metabolic dysfunctions, etc. etc. (which could certainly affect one's bodily features if it led to a congenital deformity such as dwarfism).

If you're talking about the variation of normal (i.e. non-pathalogical) genes in human populations, well, look around you! There are big differences in how people look, aren't there? Both between people of different 'race' (the '' are there because, as I said above, there are no hard-and-fast racial categories) and between people of basically the same ethnic origin. On the other hand, some ethnic groups are much more homogenous than others: for example, Somalis have quite distinctive facial features (moreso than, say, white Britons, who come historically from a very mixed stock).

That said, as far as I'm aware only a pretty small proportion of our genes encode for visible characteristics, so how similar or dissimilar two people look isn't necessarily a good indicator of how genetically similar they are. That said, I think it's a very big leap from acknowledging this to claiming there's "no such thing as race".
 
N

nomadologist

Guest
This last post by Mr. Tea struggles to get halfway to where your average biologist already has been conceptually.

If "racial" difference is predicated upon how people look, then it ignores most of the much more important gene markers and is biologically meaningless.

I have never met a biologist who believes in race as a biological fact, btw.
 

Mr. Tea

Let's Talk About Ceps
Well what do we actually mean by 'race' here? If we're talking about the old classification of all of humanity into Caucasoid, Negroid or Mongoloid, each of which has a characteristic eye-width: pinky-length ratio or whatever, then of course I don't believe in it, and neither has any serious geneticist for a long time, of course. But there are nonetheless hereditary characteristics that are correlated to ethnicity, which is what I mean by 'race'. Isn't a bit thing in pharmaceuticals right now tailoring drugs to specific racial groups, since drugs that are very effective for some groups might not work for others, or because some groups are more prone to certain illnesses?
 
N

nomadologist

Guest
Well what do we actually mean by 'race' here? If we're talking about the old classification of all of humanity into Caucasoid, Negroid or Mongoloid, each of which has a characteristic eye-width: pinky-length ratio or whatever, then of course I don't believe in it, and neither has any serious geneticist for a long time, of course. But there are nonetheless hereditary characteristics that are correlated to ethnicity, which is what I mean by 'race'. Isn't a bit thing in pharmaceuticals right now tailoring drugs to specific racial groups, since drugs that are very effective for some groups might not work for others, or because some groups are more prone to certain illnesses?

It's a big thing in pharmaceuticals to find something like elevated rates of heart disease in African-Americans (DUUH their more often than not inner-city lives are probably 10x more stressful than your average white middle class person's), so that, of course, this will mean black people will all run out and ask their doctor for a Plavix script.

At my last job we published a cardiology journal and all the findings about heart disease in African-Americans are highly controversial and have been widely challenged.
 
N

nomadologist

Guest
Ethnicity and race are very different concepts, and ethnicity is usually tied to national origin so it has political origins that can mean it rivals racism as a useless category.
 

Mr. Tea

Let's Talk About Ceps
At my last job we published a cardiology journal and all the findings about heart disease in African-Americans are highly controversial and have been widely challenged.

OK, so there are going to be cases where genetic differences are masked or 'faked' by environmental/social factors, but there are still things like sickle-cell disease which occur far more often in people of certain 'racial' origins than others.
 

Mr. Tea

Let's Talk About Ceps
Or that occur in people with common ancestors.

Which is more likely among people identifiably of the same 'race' than people selected at random from a mixed population, isn't it? I'm more likely to have an ancestor in common with another white British person - or even another white person from elsewhere in the world - than with an indigenous Kenyan or a Han Chinese, aren't I?
Of course without tracing out someone's entire family tree as far back as you want to go, you can only talk about likelihoods for an individual, but these likelihoods become trends when you look at large populations.
 

Guybrush

Dittohead
Wait a minute here. The first problem with this report is that recent findings seem to completely debunk the idea that we "all originated in africa", and that, in fact, there seems to be evidence of homo sapiens evolving in parallels at the same time around the earliest signs of human life we can find in Africa.

From what I can tell, the ‘Out-of-Africa’ theory enjoys the strongest support by far. But that’s not really important as the ‘multiregional hypothesis’, if anything, seems to lend even more credence to the hereditarians’ view.

How many times were these studies conducted, and by whom under whose auspices? Have these studies been replicated by anyone?

I highly doubt it.

Actually, they have been replicated. Three times. (Sort of.) From the report:

Three studies of East Asian children adopted by White families support the hereditarian hypothesis. In the first, 25 four-year-olds from Vietnam, Korea, Cambodia, and Thailand, all adopted into White American homes prior to 3 years of age, excelled in academic ability with a mean IQ score of 120, compared with the U.S. norm of 100 (Clark & Hanisee, 1982). Prior to placement, half of the babies had required hospitalization for malnutrition.

In the second study, Winick, Meyer, and Harris (1975) found 141 Korean children adopted as infants by American families exceeded the national average in both IQ and achievement scores when they reached 10 years of age. The principal interest of the investigators was on the possible effects of severe malnutrition on later intelligence, and many of these Korean children had been malnourished in infancy. When tested, those who had been severely malnourished as infants obtained a mean IQ of 102; a moderately well-nourished group obtained a mean IQ of 106; and an adequately nourished group obtained a mean IQ of 112.

A study by Frydman and Lynn (1989) examined 19 Korean infants adopted by families in Belgium. At about 10 years of age, their mean IQ was 119, the verbal IQ was 111, and the performance IQ was 124. Even correcting the Belgian norms upward to 109 to account for the increase in IQ scores over time (about 3 IQ points a decade; see Section 13), the Korean children still had a statistically significant 10-point advantage in mean IQ over indigenous Belgian children. Neither the social class of the adopting parents nor the number of years the child spent in the adopted family had any effect on the child’s IQ. (p. 259 f.)​
 
N

nomadologist

Guest
Ok, then talk about population trends. "Races" are another story.
 
N

nomadologist

Guest
From what I can tell, the ‘Out-of-Africa’ theory enjoys the strongest support by far. But that’s not really important as the ‘multiregional hypothesis’, if anything, seems to lend even more credence to the hereditarians’ view.



Actually, they have been replicated. Three times. (Sort of.) From the report:

Three studies of East Asian children adopted by White families support the hereditarian hypothesis. In the first, 25 four-year-olds from Vietnam, Korea, Cambodia, and Thailand, all adopted into White American homes prior to 3 years of age, excelled in academic ability with a mean IQ score of 120, compared with the U.S. norm of 100 (Clark & Hanisee, 1982). Prior to placement, half of the babies had required hospitalization for malnutrition.

In the second study, Winick, Meyer, and Harris (1975) found 141 Korean children adopted as infants by American families exceeded the national average in both IQ and achievement scores when they reached 10 years of age. The principal interest of the investigators was on the possible effects of severe malnutrition on later intelligence, and many of these Korean children had been malnourished in infancy. When tested, those who had been severely malnourished as infants obtained a mean IQ of 102; a moderately well-nourished group obtained a mean IQ of 106; and an adequately nourished group obtained a mean IQ of 112.

A study by Frydman and Lynn (1989) examined 19 Korean infants adopted by families in Belgium. At about 10 years of age, their mean IQ was 119, the verbal IQ was 111, and the performance IQ was 124. Even correcting the Belgian norms upward to 109 to account for the increase in IQ scores over time (about 3 IQ points a decade; see Section 13), the Korean children still had a statistically significant 10-point advantage in mean IQ over indigenous Belgian children. Neither the social class of the adopting parents nor the number of years the child spent in the adopted family had any effect on the child’s IQ. (p. 259 f.)​


Need I remind you that the only people who can adopt Asian children in the U.S. are generally successful and wealthy?

And who cares about IQ test results? They are not results that can be mapped onto "real world success" in any significant or mathematical manner.
 
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