From: Scott Chase (email@example.com)
Date: Sun 03 Aug 2003 - 00:32:21 GMT
>From: Keith Henson <firstname.lastname@example.org>
>Subject: Re: Memes and population size was: Memetic trapping and wars.
>Date: Mon, 07 Jul 2003 20:06:29 -0400
>At 06:00 PM 07/07/03 -0400, Scott wrote:
>>>From: Keith Henson <email@example.com>
>>>It is an interesting point that a particular set of technology memes may
>>>(very likely does) require a population larger than some critical number.
>>And in smaller populations genetic drift becomes important.
>"According [to] Flood, "No other surviving human society has ever been
>isolated so long or so completely as were Tasmanian Aborigines over the
>last 8000 years." (p. 173) During this period of isolation, the Tasmanians
>developed several physical traits which were unique. They had the widest
>nasal index of any people ever recorded. Their heads were shorter and
>broader than those of their ancestors, the Australians."
>>Due to sampling errors allelic frequencies may fluctuate wildly and either
>>go to fixation or loss from a population, regardless of selection value.
>Re fixation, they are the only known exception for people living at such a
>high latitude. They never lightened their skin, staying as dark as the
>Australian Aborigines. Perhaps it takes a higher level of clothing
>technology before you get selection for lighter skin from rickets, or
>lighter skin mutations just didn't happen, or they were getting enough
>vitamin D from their diet.
>>There could be instances, like with Tasmanians, of a cultural drift, where
>>important technologies that aid survival of individuals of a population
>>are lost from cultural memory (ie- forgotten). It would have been
>>advantageous for individuals to have some memory of these practices, but
>>if nobody that can pass the technologies to future population members
>>survives, then these traditions vanish.
>In fact, there is a *dynamic* process here. Cultural elements are lost at
>a certain rate and created at a certain rate. It makes sense that the rate
>of creation would be so many per million people per unit of time. If the
>people communicate these memes, useful (or at least fashionable) cultural
>elements accumulate if the group is large. Memes are lost from generation
>to generation if the group is smaller than the size where new meme creation
>does not keep up with the rate at which cultural elements are being lost.
In reading Richard Klein and Blake Edgar's book _The Dawn of Human Culture_
(2002. John Wiley & Sons, Inc. New York) I learned of something called the
"Movius line" which is a putative boundary in Asia that demarks the apparent absence of Acheulean technology (ie hand axes) east of the line toward Southeast Asia. This technology is indexed west of the line, in Africa and Europe. Klein and Edgar have a map on page 111 that has an arrow pointing to this "Movius line". From the context it looks like this boundary (named after Hallam Movius) applies to *Homo erectus* and its migration into Asia.
There are two possible explanations offered for this apparent absence of
1. the people migrating into Asia lacked the hand axes because they had
migrated "before hand axes were invented" (Klein and Edgar, page 130)
2. There was a "technological bottleneck" where these people migrated after
the invention of hand axes, but lost lost this innovation from their
cultural memory due to some cicumstance such as not having proper material
resources to craft hand axes. The "technological bottleneck" hypothesis is
attributed by Klein and Edgar to Nicholas Toth and Kathy Schick.
The technological bottleneck explanation for the "Movius line" reminded me
of this exchange between Keith and I and I'm glad I still have Keith's post
saved. Maybe technological bottleneck events have impacted human cultural
evolution from time to time. Keith's example of the Tasmanians losing memory
of certain technologies sounds like a technological bottleneck associated
with cultural drift. The Explanation for the Movius line could likewise be
an example, but that would depend not only on cultural drift being a viable
hypoteses for the loss of Acheulean traditions of hand axe manufacture
(especially if it can compete with the hyppothess that the migration into Asia occurred *after* the emergence of this technology), but also would depend on the "Movius line being real nd not apparent.
The info in these URL's could take some wind out of the sails of Movius and
a technological bottleneck:
Aside from this interesting tangent, the meat of Klein and Edgar's book
rests on a contentious hypothesis for the dawn of human culture, that it's
based on a neural event facilitated by some mutation 5000 years ago. They
cite Gould and Eldredge earlier in the book yet this putative mutational
event sounds more saltational than punctuational to me. They assume this
shift allowed for language and mental modeling of the environment. They use
a loss of function mutation seen in cases adversely impacting human speech
as evidence for an assumed gain of function quasi-saltational event. I
wouldn't look at a condition that impairs language processing due to a
single gene mutation as providing evidence for a single mutational event
that gave humans language *de novo*. Language processing probably involves
many genes (perhaps a gene complex) and the evolution of language could have
involved the cumulative co-option of several genetic factors that were
involved in other processes. Sounds marginally better than some magical
mutation mumbo jumbo and I'm neither an anthropologist, a linguist, nor a
geneticist. Klein and Edgar's book has many good points and the hand waving
about a mutational revolution underlying the dawn of human culture should
not detract too much.
[Klein and Edgar, page 270] (bq)"In our view, the simplest and most economic
explanation for the "dawn" is that it stemmed from a fortuitous mutation
that promoted the fully modern human brain."(eq)
In their enthusiasm, they may have take things a litle too far.
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