Re: What are race promoters promoting?
gkeyes6988@aol.com
27 Nov 1996 02:52:54 GMT
Subj: Re: What are race promoters promoting?
Date: 96-11-26 03:09:45 EST
From: susansf@netcom.com (Susan S. Chin)
To: gkeyes6988@aol.com
In article <19961125145700.JAA16642@ladder01.news.aol.com> you wrote:
: (Susan 1)
: Susan S. Chin wrote:
: : >My understanding is that races are geographical variants of a
species.
: : >The morphological differences between populations become greater the
: : >farther apart these populations are.
: (Greg 2)
: Phenotypic variation is based upon present environment, not past
: environment.
(Susan 3)
>What exactly do you mean by this?
As you say, lots of things in the genotype aren't expressed in phenotype.
If
someone is heterozygous for blue eyes, there are no blue eyes in the
phenotype. Environment has nothing to do with this at all; what
determines
this is the simple fact that blue is recessive. The child can be born in
Ghana, Malaysia, or the Moon -- no blue eyes.. What determines the
likelihood of any given child in a population having blue eyes (being
homozygous for blue) is the FREQUENCY of that gene in the population.
What determines it in a specific child is the genotypes (not the
phenotypes) of the parents.
Other aspects of phenotype are affected directly by the environment, and
these have mostly to do with development. The Genotype may set a person's
maximum height at six feet, but malnutrition keeps it from being expressed
in
this way -- developmental adaptation. Same goes for the larger lung
cavity
that even someone whose parents were from sea level will develop if raised
in
the Himalayas. So yes, Phenotype is in part a reaction to the
environment,
but biological adaptation occurs at the genotypical level:
"In terms of natural selection, Individuals cannot adapt; they just
produce
offspring as well as they can under the circumstances. Biological
adaptation
occurs only BETWEEN generations as the result of differential reproductive
success among all the individuals of the population. Biological
adaptations
then, MUST have a genetic basis. As environments change so do selection
pressures and so also does the reproductive success of various GENOTYPES
(Nelson and Jurmain 1982:160)" (last emphasis mine).
(Greg 2)
: What you mean is that past environments caused a change in gene
frequency
: (higher frequency of short stature in the Ituri) or, in other words, a
: change
: in genotype. If the Ituri and the Bantu had similar genotypes, they
would
: have similar phenotypes because they share a similar developmental
: environment.
(Susan 3)
>What I meant is that adaptations to past environments selected for
>certain traits which are advantageous in a given environment. These
>traits come about as a result of the interaction between the genotype and
>the environment, otherwise known as the phenotype.
A phenotype is an observed phenomenon, not a process. What you speak of
here
is natural selection. In most cases only phenotypically expressed
characteristics offer advantages to be selected for, though this is not
always the case -- sickle cell, a recessive trait, is only beneficial to
those
who are heterozygous for it and deadly to those who have it expressed in
their phenotype.
(Greg 2)
: Assuming that your argument that these three groups originated in
: different local environments that shaped the frequencies of genes in
their
: respective
: populations disparately is true, then in what sense are they all
"Negroid"
: ( you say, remember, that there are three basic types, and I assume that
: this is the one all three of these fall into)?
(Susan 3)
>On the basis of geographic origins. All 3 groups are African. I'm not
>making any statements about their genotypic similarities, since it's
>well known that there is a much higher degree of genetic variation in
>African populations than is found elsewhere in the world.
So as long as populations are geographically proximate, they comprise a
race,
regardless of their evolutionary relationship? Race is a circle drawn
around territory, and everyone in the circle is that race?
(Susan 3)
>For those who prefer to view race as a social category, why not add
>geography to it? No one can deny one's evolutionary history, family
>lineage, if discernible?
This seems to contradict the above. Do people have to be closely related
genetically to comprise a race (by your standards) or not? Geography and
family lineage are not the same!
(Greg 2)
: Once again, I agree that there is variation from one human population to
: the next -- it just isn't a bounded variation.
>I don't believe "bounded variation" was ever mentioned, or implied in any
>of my posts. Just because races exist (IMO), they have to be
discontinuous?
I'm going to take this one below, under the "no pure races" point.
: (Susan 1)
: : >The similarities between populations
: : >are due to similar adaptations to environmental demands.
: (Greg 1)
: : Since humans use culture to do the bulk of their adapting, actual
: : adaptational differences are few (like the sickle cell trait). Most
: other
: : so-called adaptations to climate are the result of phenotypic
plasticity
: : or non-adaptive factors like gene drift and the founder affect.
(Susan 3)
>If you're familiar with Bergman's Rule and Allen's Rule, I don't see how
>adaptations to the environment (which encompasses more than just climate)
>can be viewed as a chance factor.
I am familiar with them. What I'm saying here is that much adaptation to
climate is really acclimation or developmental, but not biological
adaptation. Neither acclimation not adaptation are chance factors. The
chance factors are things like drift and the founder's affect. Much human
variation has little to do with any sort of adaptation.
: (Susan 2)
: *If humans used culture to do the bulk of their adapting, at
: *what point did this begin? When we became anatomically modern Homo
: *sapiens, we stopped evolving biologically? Obviously the human lineage
: *has evolved biologically through time, why would you expect this to
stop
: *at Homo sapiens? Or at the level of "races"?
: (Greg 2)
: Note first that I did not say biological adaptation was absent -- on the
: contrary, I even gave an example of it (the sickle cell trait is an
: adaptation to malaria). What I said is that most adaptations are made
: culturally. Amazon basin groups did not adapt physically to eat the
: poisonous Manioc root, they developed a technology (cooking) to
: make the root edible to their already existing systems.
(Susan 3)
>Those same Amazon basin groups had already evolved in their skin color,
>body type, hair type to this environment long before the technology came
>along. (assuming this is their original long term habitat)
No, actually they brought it with them across the Bering land bridge from
Asia, through rain, sleet, and snow. Though it took generations, they did
not
lose their melanin and then regain it. This is the problem with your
whole
geographic argument: it assumes that most human beings have stayed put for
the past 200,000 years and only recently begun to mix, that things like
'body
type' bear a perfect fit to some past environment. It is nowhere so clear
that this is not true than in the Americas. In a few millennia, the
people
now in the Amazon passed through umpty-teen climate zones, had to learn to
identify, hunt, gather and process entirely new flora and faunas. Biology
does not work fast enough to do this. They did it with culture.
Name 4 (unique) physical adaptations to the New World environment in any
NA
population and explain the selective pressure that produced it.
(Greg 2)
: Melanesians and Australian aborigines also have dark skin
: and you are probably right, this is due to a history in the tropics --
but
: that doesn't make them evolutionarily very close to either Bantus or
: pygmies.
: The race concept implies similar characteristics are based on close
: genetic affiliation.
(Susan 3)
>A geographic concept doesn't necessarily imply evolutionary closeness.
So again, you can have race without close genetic similarity within the
race? And above you identified a "geographic approach" with "not denying
ones lineage.".
(Greg 2)
: Other 'adaptations' -- such as larger lung cavities in high altitude
: populations -- are developmental -- a result of phenotypic plasticity,
not
: of a change in gene frequency (evolutionary adaptation).
(Susan 3)
>This is how I would distinguish genotype vs phenotype. Take two
>individuals up to a high altitude, have them train at that altitude for 5
>years. At the end of this period, will they both perform at the same
>level due to environmental adaptations with larger lung capacity?
You may have to re-word this -- I'm not sure enough of what you meant to
say
to comment on it.
(Susan 3)
>Phenotype is plastic to a certain extent, but it is constrained also by
>the underlying genotype.
I agree.
: (Susan 1)
: : >This racial differentiation occurred once early hominids spread
beyond
: : >Africa and the Old World.
: (Greg 1)
: : This is certainly one view of human origins -- that Homo erectus
evolved
: : separately into H. sapiens in different places...
: (Susan 2)
: *I made a very general statement in saying "early hominids spread beyond
: *Africa and the Old World." Are you disputing the idea that the human
: *lineage began in Africa, and spread from there? Early hominids does not
: *imply Homo sapiens!
(Susan 3)
>I should have added Homo erectus, since some now feel Homo habilis
>could have been the first to leave Africa, and not erectus.
Yeah -- I think it's exciting, but I won't make habilis an emigrant until
this is firmed up.
: (Susan 1)
: : > Limited interbreeding between populations lead to these
: : >phenotypic differences which we can easily recognize as a "racial
: type,"
: *... The definition of phenotype used here is "the
: *observable expression of the genotype." Phenotypes are *based* on
: *genotypes, how else would these observable characteristics come about?
: (Greg 2)
: Yes, but phenotypic adaptations are not heritable. A Norwegian can tan
: all he or she wants, but their child will not be born tan.
(Susan 3)
>No, but an obvious phenotypic characteristic of a Norwegian is his/her
>very light skin color, a phenotypic adaptation to their (or ancestors')
>northerly environment. Phenotypic adaptation also implies underlying
>genotypic changes in my usage.
Many characteristics of the phenotype (of an individual) have nothing to
do
with changes in the genotype, but only with that genotype and the
developmental environment.
>In what circumstance would it be adaptive for a light skin colored person
>to tan? Biologically adaptive, that is. (We're not talking Bain de
>Soleil!!)
The phenotype is just the observable expression of the genotype. It is
not
biological adaptation.
>We're not using phenotype in the same way.
Not exacly, anyway. See way above.
(Greg 2)
: Only if there is a
: change in gene frequency (genotype) will that happen. In suggesting
that
: people evolve to meet the needs of particular environments -- and then
: carry
: these traits with them to new environments (i.e the pygmies being in
some
: environment that selected for shortness -- whatever environment that
would
: be
: -- and then carrying it with them to their present homeland where they
are
: surrounded by much taller groups) you suggest a change in genotype, not
: phenotype. And of course, genotypes do vary from group to group, but
not
: in
: a simplistic "racial" way -- unless you want to admit to hundreds or
even
: thousands of "races" which still grade into one another.
(Susan 3)
>There is an interaction going on between the phenotype, the environment,
>selection for certain traits thru time (no Lamarckians here), and of
>course a change in the gene frequency of the population which favors
>certain phenotypes. None of this happens overnight obviously.
>At no time did I involve the genotype in my races by geography idea. You
>seemed to think I meant genotype, when in fact, I've only talked about
>phenotypes, the observable characteristics of the organism.
When you invoke the phenotype to speak of biological adaptation, the
genotype is a given, because phenotypes don't "evolve".
But I observe that Ituri, Bantus, and !Kung have wildly different
phenotypes.
You say they are still the same race because they all live in Africa and
have dark skin. And populations that are neither geographically proximate
nor likely to be close
genetic relatives (Nigerians and Pintupi) may share similar phenotypic
traits
(very dark skin). In grouping people by "what you see" (phenotype) you
still
select what you count as salient. Skin color? Hair texture? Nose shape?
Blood type?
: (Greg 1)
: : Another view (from the one you propose above) is that there has been
: : considerable gene flow throughout human history, and that humanity
: : represents a continuum of physical variation which we arbitrarily
divide
: : into artificially discreet races.
<bunch of stuff snipped>
(Susan 3)
>It probably doesn't matter how you or I view races then. What's there is
>there. We can choose to view them as we see them. What you see as a
>continuum of human physical variation arbitrarily divided, I see as a
>continuum of human variation with discernible patterns due to the
>evolutionary history of the populations. The fact that we're not able to
>quantify or characterize races or reach a consensus doesn't make them any
>less real or any more artificial.
Yep. But I never said there couldn't be discernable patterns.
(Greg 2)
: Human variation exists. Racial typologies are messy because they are
: artificial. They conceal the real sources and extent of variation.
(Greg 3)
>When did racial typologies come into this? What are these real sources of
>variation?
Well, you brought up the "three basic types" classification in your
original
post. That certainly qualifies as a typology. Presumably, too, if you
think races are real, then they are also finite, describable, namable, and
capable of being ranked in some hierarchy of relatedness. Typological.
I mean that the real sources of variation are not several pristine
geographically adapted races "mixing". See below.
: (Greg 2)
: These came right off of my shelves, and thus may not be as "current" as
: you
: would like. If you want even more current ones, I can get them easily
: enough. I'm surprised, actually, that you even ask for this. If you
: want
: more sources, I'll get them, but please don't accuse me of using older
: sources because newer ones don't back me up: that would be a pain for me
: and
: ultimately embarrassing for you.
(Susan 3)
>By asking for a current citation, I've accused you of using older
>sources? That never occurred to me, actually.
>Thanks for the sources though.
(Greg 2)
: For the sake of clarity, I'll repeat: the consensus of physical
: anthropologists today -- whether you agree with them or not -- is that
: race typologies are neither demonstrable nor useful as research tools.
(Susan 3)
>Using geographic origins to characterize the patterns in human variation
>is not my definition of racial typologies.
This was a response to your request for me to produce sources
demonstrating
that the "3 race" typology you brought up in your initial post was no
longer
accepted by most physical anthropologists.
(Greg 2)
: (speaking of the history of 'racial' typology)
: "The fact is, generalized references to human types such as "Asiatic" or
: "Mongoloid" "European" or "Caucasoid," and "African" or "Negroid" were
at
: best mere statistical abstractions about populations in which certain
: physical features appeared in higher frequencies than in other
: populations; no example of "pure" racial types could be found.
(Susan 3)
>The concept of "pure" racial types never came up either. Characterizing
>races by geography doesn't imply that the racial groups are "pure" by any
>means.
Let me quote what you said in your original post: **This racial
differentiation occurred once early hominids spread beyond Africa and the
Old World. Limited interbreeding between populations lead to these
phenotypic differences which we can easily recognize as a "racial type,"
physical anthropologists recognize 3 major groups. Subsequent migrations
have obviously blurred the lines of what criteria should be used or can
be used to differentiate the "races." **
You certainly seem to imply that they WERE pure, if no longer due to
'blurring'. Putting the pure races in the past only begs the question.
And here:
**Races don't exist because not everyone fits into a discrete category, it
therefore is arbitrary?**
You seem to imply here that while some people may not be easily classified
into a race, others can be -- that the category exists even if there are
exceptions.
: "Human racial classification is of no social value and is positively
: destructive of social and human relations. Since such racial
: classification
: is now seen to be of virtually no genetic or taxonomic significance
: either,
: no justification can be offered for its continuance (R. Lewontin in
: EVOLUTIONARY BIOLOGY 1972, volume 6 pg 397)"
(Susan 3)
>This is unfortunate. I personally feel studying human "racial" variations
>could lead to understandings of human adaptations and the source of this
>variation. By denying that there is a pattern to it, implies that this
>variation is somewhat meaningless.
Physical anthropologists today certainly think variation is patterned.
This dilemma you offer race=pattern, any other approach=chaos, is a false
one.
Oops -- and I seem to have run out of room. Any ideas on how to condense
this ? I'll answer the rest of the post later.
--Greg
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