Re: Genetic Evolution (was: HGHG)
Lane Singer (lsd@ix.netcom.com)
30 Jan 1995 07:54:26 GMT
In <tlathropD36L2I.3sA@netcom.com> tlathrop@netcom.com (Tom Lathrop) writes:
[continued from previous post]
>>[Lathrop]
>>>>I happen to believe that black Africans and their descendants, as a
>>>>group, are less intelligent than whites or Asians. I may be right or
>>>>wrong in this, but it is certainly possible, just as it is possible
>>>>that they have, as a group, darker skin and curlier hair.
Yes, we know you do Tom. Why?
>>>[Singer]
>>>HGHG, p156.
[quote (with ellipsis) deleted]
>>[Lathrop]
>>>Note the ellipsis everyone; something important was omited.
>
>>Oh really? Then why didn't you include it here, so that you could
>>back up your implication of dishonesty on my part with fact? Or
>>is it really not pertinent to anything I have said? here it is:
>>
>>"Because genetic divergence was subject more to random than
>>selective forces,--> much of the gradient of the human gene pool
>>goes from west to east. The first principal component therefore
>>extends in this direction and explains 35% of the total human
>>variation,<-- showing only moderate, if any, influence of climatic
>>factors at the level of the nuclear genes investigated, but a
>>greater influence on genetic factors involved in the adaptation
>>of bodily surface characteristics which notoriously respond to
>>climate. A dichotemy is thus observed between genetic data, and
>>observations based on the physical constitution..."
>>
>>As they say "moderate, if any, influence of climatic factors" on
>>anything other than "bodily surface characteristics which notoriously
>>respond to climate." So what does this say about your whole
>>"winterlander" hypothesis, other than that they had a Vitamin D
>>deficiency in their diet?
>
>Interestingly, even after making a big show of including the entire
>quote,
Look who's talking about "a big show" :)
> you still leave out the part which indicates that Cavalli-Sforza
>was talking about *Asia*, not the entire world.
I am not a mind reader, Tom, that I know the issue of Asia is of
heightened relevance for you. Would you have me transcribe all
500 pages, just so I don't accidently leave out anything you might
find pertinent for some mysterious reason?
>And why, after all
>that indignation over my pointing out the ellipse in your quote, did
>you go and delete the three paragraphs where I tried to show why the
>part you left out was important?
<sigh>
>Let me reinsert them...
>
>>>You have been using this quote a lot in other posts, so I'd better
>>>address this. What Cavalli-Sfortza is saying is that "body build and
>>>bodily surface characteristics" are not necessarily good indicators of
>>>genetic relatedness. And he is absolutely right. I was well aware,
>>>even in high school, that the dark skin of Africans, southern Indians,
>>>and Australians did not imply that these people formed a group. This
>>>is the "dichotomy" Cavalli-Sforza is talking about.
So? He is also saying that they are surface characterisics which are
very responsive to genetic selection due to climatic pressure. That
is really all that is at issue here for me. You may continue to interpret
it to your heart's content, but you have not touched upon any reason
why my interpretation should be viewed as inaccurate.
>>>So what *does* Cavalli-Sforza consider a good indicator of
>>>relatedness? Well, in the example you quoted from, in the part you
>>>omited, he points out that in Asia "much of the gradient of the human
>>>gene pool goes from west to east", that the "first principal component"
>>>extends in this direction, and that the north-south climatic variation
>>>in Asia has little effect on this. In measuring relatedness, it's
>>>these "principle components" that matter, not appearence.
>>>
>>>But Lane, an east-west genetic gradient is exactly what I expect to see
>>>in Asia, as part of the long continuous transition from Caucasoids in
>>>Europe to Mongoloids in east Asia. Once again, I have no problem
>>>whatsoever with Cavalli-Sforza's conclusions. You are the one
>>>obsessing on physical appearance, not me.
Ignoring your rather hilarious last sentence, please clarify
your statement of a "long continuous transition from Caucasoids
in Europe to Mongoloids in east Asia." Are you implying that
Asians are derived from Europeans?
If you will just step over to the map, you will see that Africa is
also to the west of Asia. Africans migrated to Asia some 70,000
years ago. Some Asians traveled back west and and some Africans
traveled north to populate the European continent about 35,000
years ago.
>Lane, I expect you'll go on misusing this quote no matter what I do,
>but maybe I can explain it for everyone else.
I'm glad you're not smug, Tom.
>One -- *any* set of genes can evolve quickly if there is sufficient
>selective presure.
>
>Two -- most of the human genome does not evolve quickly, and has been
>stable for millions of years (note that we share 98 percent of our
>genes with Chimpanzees).
This is not the first time you have used this analogy. We are not,
genetically, 98% comparable to Chimps. Our closeness to the
Chimps was derived by comparing amino acids in hemoglobin.
It was not a genetic comparison of the sort covered in HGHG for
human populations. Nor is it anything that would compare to the
ongoing Human Genome Project, which hasn't even released
results yet. There would have to be a Chimpanzee Genome Project,
in any event, to collect the pertinent information.
> This is because most of the genome codes for
>proteins and enzymes and such that are well optimized, and are not
>normally under much selective pressure.
Tell me, Tom. How would you describe genes that code for neuro-
transmitters?
>If you look at the genome as a
>whole, most of the change comes from random genetic drift. When two
>populations separate, their genomes begin to drift apart in a fairly
>regular way. Because this drift, in genes that are not under great
>selective pressure (most of the genome), is somewhat predictable (in a
>statistical way), we can use it to learn something about how a given
>population is related to other populations, and how long ago they might
>have separated. This is what Cavalli-Sforza is trying to do in his
>book.
>
>Three -- some sets of genes, such as those that code for skin color, or
>body build, or intelligence (maybe!),
I think it somewhat dishonest of you to make such an assertion in
this thread without backing it up in any way. You have never
addressed what genes you think might be involved in intelligence.
>*are* put under a lot of
>selective presure when people move from one environment to another.
>Traits like this are in a sense superficial (which is not necessarily
>the same as "unimportant"), not because they can change quickly (any
>set of genes can do that under the proper circumstances), but because
>they *have* changed quickly, under the influence of non-random external
>forces, and that makes them useless for the sort of statistical
>analysis that Cavalli-Sforza is engaged in. What this means in
>practice is that you cannot claim that Africans, south Indians, and
>Australians form a proper group simply because they are all dark
>skinned. *This* is what Cavalli-Sforza is pointing out in this quote.
>He is noting that in Asia even though the climatic gradient goes from
>north to south the genetic gradient (i.e., the gradient of those genes
>which drift in a predictable way, and are thus useful for determining
>how groups are related) goes from west to east.
I have no problem with this at all, nor have I ever stated one.
In fact, I seem to recall posting on this long before we started
this thread. I don't recall that you ever followed up on that,
though it wasn't part of our conversation.
>Now Lane has seized upon this quote and used it to insist that since
>certain "bodily surface characteristics... notoriously respond to
>climate", it therefore follows that race, which as far as he is
>concerned is entirely a matter of "surface characteristics", has
>nothing to do with how human populations are related to each other.
I don't believe I said that. You are putting a lot of words into
my mouth here, a liberty I haven't taken with you.
>Note that he entirely ignores the possibility that human intelligence
>might be one of the traits that responds to environmental stress.
It doesn't bear a lot of comment. What, exactly, do you define as
environmental stress, and how was one population subject to more
of it than another?
>This
>is because he is intent on using this quote to argue that it isn't
>*possible* for people from different parts of the world to differ
>significantly in intelligence,
This is false. More of your misinterpretations.
>the way they manifestly differ in other
>(supposedly more superficial) traits. To a less biased observer the
>weakness of this argument is clear; we simply don't know enough about
>either the human genome or the genetics of intelligence to draw such a
>conclusion, however much some people (for example the clueless reviewer
>of HGHG in Time Magazine) would like to.
:)
This =is= rather amusing. I haven't made any statement to the effect
that intelligence doesn't vary by population. I don't believe that it does,
but I have said, in response to your strong assertions that it does vary,
that we do not have sufficient understanding, data, or knowledge at this
time to answer this question one way or the other. Now you, in this
statement, suddenly claim to be agnostic on the issue, while attempting
to paint me as some sort of biased, true believer. Why don't you take
a look at your opening paragraph in this post, Tom?
Continued next post.
Singer
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"men remain in ignorance as long as they hate, and they hate unjustly
as long as they remain in ignorance." Tertullian
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