[From Bruce Abbott (2000.12.16.2110 EST)]
Mary Powers 2000 12.16 --
Surely there is some reasonably nice way for people to say they disagree
with Chris Cherpas.Not saying anything at all would do for starters.
To whom do you refer? And to which of Chris's posts? I'm afraid I haven't
noticed anything on CSGnet that might have elicited your condemnation.
Bruce A.
[From Bill Powers (2000.12.17.0453 MST)]
Bruce Abbott (2000.12.16.2110 EST)--
To whom do you refer? And to which of Chris's posts? I'm afraid I haven't
noticed anything on CSGnet that might have elicited your condemnation.
Funny thing. Nobody sees anything wrong with his own remarks. Could that
possibly be explained using PCT?
Best,
Bill P.
[From Bruce Abbott (2000.12.17.0740 EST)]
Bill Powers (2000.12.17.0453 MST) --
Bruce Abbott (2000.12.16.2110 EST)
To whom do you refer? And to which of Chris's posts? I'm afraid I haven't
noticed anything on CSGnet that might have elicited your condemnation.Funny thing. Nobody sees anything wrong with his own remarks. Could that
possibly be explained using PCT?
My _own_ remarks? Bill, I made a one word reply ("no") to Chris's evolution
post a couple of days ago. I haven't referred to it since. Hardly grounds
for complaining that Chris is getting unfair treatment.
Mary said:
Surely there is some reasonably nice way for people to say they disagree
with Chris Cherpas.
Not saying anything at all would do for starters.
This implies that folks have been using some rather nasty ways of saying
they disagree with Chris. In fact, so far as I am aware, nobody has been
saying anything at all, expecially not in the couple of days preceding
Mary's remark, which just comes out of nowhere, with no context to support it.
Which is why I'd like Mary to explain her remark. Let's stop beating around
the bush.
Bruce A.
[From Chris Cherpas (2000.12.20.0330 PT)]
I appreciate any/all of the recent posts about evolution
that were intended to illuminate. There are two, related,
points that I think are relevant to PCT:
1) The size of the brain in the lineage leading to humans appears
to have tripled between 2 million and 100,000 years ago.
Would we expect that successive layers were added
corresponding to those theorized in HPCT, e.g., programs
followed by principles, followed by system concepts?
2) The radical difference between the brains of humans and other
primates is generally easier to account for on the basis of selective
mating, rather than via physical or interspecies pressures -- if
you disagree, I'd be interested in knowing how/why.
Assuming a (roughly) serial evolution of successive HPCT layers
(i.e., the answer to question #1 above would be "yes"),
what mating preferences, and corresponding references in the
opposite sex for displaying what is preferred, would be missing
from the current human repertoire as one strips away layers
(i.e., system concepts, principles, programs...)?
A specific example I mentioned in a previous post was whether
imitating successful courting would be possible without the
system concept layer.
Best regards,
cc
[From Bruce Gregory (2000.1220.0735)]
Chris Cherpas (2000.12.20.0330 PT)
I appreciate any/all of the recent posts about evolution
that were intended to illuminate. There are two, related,
points that I think are relevant to PCT:1) The size of the brain in the lineage leading to humans appears
to have tripled between 2 million and 100,000 years ago.Would we expect that successive layers were added
corresponding to those theorized in HPCT, e.g., programs
followed by principles, followed by system concepts?
You are assuming that the levels in PCT are reflected by "layers" in the
brain. I know of no evidence to support this conjecture.
2) The radical difference between the brains of humans and other
primates is generally easier to account for on the basis of selective
mating, rather than via physical or interspecies pressures -- if
you disagree, I'd be interested in knowing how/why.
You are ignoring the possibility that genetic variation might lead to a
rapid increase in the size of the brain in the absence of selection
pressures. In other words, a fairly simple change in the genome might lead
to a large change in the phenotype. This can't be ruled out as far as I am
aware.
BG
[From Chris Cherpas (2000.12.20.0740 PT)]
Bruce Gregory (2000.1220.0735)--
You are ignoring the possibility that genetic variation might lead to a
rapid increase in the size of the brain in the absence of selection
pressures. In other words, a fairly simple change in the genome might lead
to a large change in the phenotype. This can't be ruled out as far as I am
aware.
I think selection is almost certainly involved. I don't know
of genetic mutations that accumulate in a particular direction
(e.g., bigger brain) without differential reproduction.
Does "no selection pressure" mean that there's never been a
reproductive advantage in humans having a bigger brain?
OK, if no selection were involved, then a bigger brain would
have not improved the chances of reproducing more; but I would
think that the individuals who kept the smaller brain would
have a reproductive advantage because of less overhead...
Our big brain is a resource hog, using disproportionate
amounts of oxygen, blood, and glucose (i.e., considering
the amount of total body weight it takes). Also, the big
brain has been one reason why babies and mothers have died
during labor. This seems like a lot of trouble for something
that's reproductively neutral.
Best regards,
cc
[From Chris Cherpas (2000.12.20.0800 PT)]
Bruce Gregory (2000.1220.0735)--
You are assuming that the levels in PCT are reflected by "layers" in the
brain. I know of no evidence to support this conjecture.
I am assuming you need more brain to have more HPCT levels,
but, of course, the same sized brain could just be organized
differently (e.g., Neaderthals had bigger brains than
Homo Sapiens). Still, my view of HPCT is that it represents
a vertical organization of the nervous system -- more directly
obvious at lower (nerve-ending, spinal) levels.
The upper/outer-most layers of the brain do appear to
be the most recent.
Best regards,
cc
{from Bruce Gregory (2000.1220.1116)]
[From Chris Cherpas (2000.12.20.0740 PT)
I think selection is almost certainly involved. I don't know
of genetic mutations that accumulate in a particular direction
(e.g., bigger brain) without differential reproduction.
It's called genetic drift.
Does "no selection pressure" mean that there's never been a
reproductive advantage in humans having a bigger brain?
OK, if no selection were involved, then a bigger brain would
have not improved the chances of reproducing more; but I would
think that the individuals who kept the smaller brain would
have a reproductive advantage because of less overhead...Our big brain is a resource hog, using disproportionate
amounts of oxygen, blood, and glucose (i.e., considering
the amount of total body weight it takes). Also, the big
brain has been one reason why babies and mothers have died
during labor. This seems like a lot of trouble for something
that's reproductively neutral.
From a adaptationist perspective that's no doubt true. See _The Spandrels
of San Marcos_ for an alternative perspective. I know of no evidence to
refute the idea that if a phenotypic change is not disastrous, it may well
prevail even if it does not confer reproductive advantage. The problem with
the adaptationist approach is that it is immune to refutation. Sexual
selection is the ultimate gotcha. It doesn't contribute to survival? Then
it must be the result of sexual selection.
BG
Best regards,
cc
i.kurtzer (2000.1220.1015)
[From Bruce Gregory (2000.1220.0735)]
> Chris Cherpas (2000.12.20.0330 PT)
>
> I appreciate any/all of the recent posts about evolution
> that were intended to illuminate. There are two, related,
> points that I think are relevant to PCT:
>
> 1) The size of the brain in the lineage leading to humans appears
> to have tripled between 2 million and 100,000 years ago.
>
> Would we expect that successive layers were added
> corresponding to those theorized in HPCT, e.g., programs
> followed by principles, followed by system concepts?You are assuming that the levels in PCT are reflected by "layers" in the
brain. I know of no evidence to support this conjecture.
The derth of evidence is possibly a result of not clearly defining a
hierarchical structure for _functions_ and an overemphasis on localizability
of function. Further, a continuing argument has been betweeen hiercharchy
vs loops, which is less a contrast than the meat and potatoes of HPCT.
Although the anatomy still being worked out t is very clear that many
regions are interconnected in nested feedback loops; for example, there are
nested loops moving from brainstem nuclei forward through thalamus to
primary sensory cortex then motor cortex back through to both (inner)
thalamus and brainstem (outer). And thats the first 5-6 synapses. The
cortical-basal ganglia and cortico-cerebellar connnections are all both
reciprocal and significant; and these systems are again connected to the
brainstem nuclei and to spinal nuclei. However, the enormous number of
detail and a basic idea of what these nested loops do still needs to be
worked out. This is actually open to many of you out there. If you have
access to a good university then you can read up on the anatomy of a
particular bit of jelly and develop hypotheses. Hint-hint. Warning, the
simple diagrams will rapidly give way to a staggering complexity but there
are some good intro's. I suggest Gordon Shepard's "Synaptic Organization of
the Brain".
Lastly, on evolution, there is some evidence of layered evolution via
duplication and rearrangement of function. Schematically, A synapses to B;
later B splits into B1 and B2 and A synapes to both; later still A synapses
primarily to B1 while B2 is driven primarily by B1; similarly, B2 then
feedbacks to B1 and A, and B1 to A). This can be seen in the SII, or
somatosensensory cortex II, where it receives inputs in parallel with SI in
cats and from SI in monkeys.
i.
[From Chris Cherpas (2000.12.20.0820 PT)]
Bruce Nevin (2000.12.20 10:56 EST)--
...When a female of another type of simian
comes into estrus (heat), there is a general free-for-all of competition
among the males, with a dominance hierarchy, sneaky hanky panky with
outlier adolescents, and so on, all well demonstrated. Then when estrus
ends and the sexy juices stop flowing it all stops. She is no longer
sexually attractive. With humans, there are two crucial differences. One,
women are attractive to men largely irrespective of their hormonal cycle;
This would seem to relate to the fact that ovulation in humans
is invisible to would-be mates.
and two, women are *selectively* attractive to *particular* men. To a
surprising degree (getting past rhetoric and hyped norms), what is a
turn-on for one is a pass for another. How did we get there, and why?
Ergo, sexual preferences for corresponding traits in potential mates.
A monkey can only groom one other monkey at a time, but an individual who
can comment on other individuals in some way can maintain relationships
with 4 or 5 other individuals witnessing the commentary. Here comes your
topic of mimickry for starters, Chris. The earliest form of gossip probably
was nonverbal parody, I should think, such as has been observed among these
animals. (You'll have to look into the literature for yourself, it is quite
extensive I believe.) With more alliances, you can support a larger group
size; and with a larger groups surviving better than smaller groups,
individuals who can support more alliances through gossip survive better
than those who cannot.
I think that the gossip may provide even more basis for sexual
selection, independent of survival advantages, too. Relatives
of potential mothers, for example, might be influential in the
choice of mates.
Hope this helps.
How this relates to the evolution of HPCT functionality is what
I'm ultimately shooting for, however speculatively, in this forum,
so what you've said provides some of the pieces to my puzzle.
Best regards,
cc
[From Bill Powers (2000.12.20.0945 MST)]
Chris Cherpas (2000.12.20.0330 PT)--
Assuming a (roughly) serial evolution of successive HPCT layers
(i.e., the answer to question #1 above would be "yes"),
what mating preferences, and corresponding references in the
opposite sex for displaying what is preferred, would be missing
from the current human repertoire as one strips away layers
(i.e., system concepts, principles, programs...)?
Good approach. I'd prefer seeing it handled by comparative studies, because
guessing about things that happened before recorded history can't really
settle anything. In the animal kingdom there are doubtless organisms that
have no system concepts, and other that lack principles _and_ system
concepts, and so forth down to bacteria which may control nothing higher
than sensations. Of course when such a study is actually undertaken, one of
the first casualties might be my particular definitions of levels, but that
wouldn't sadden me too much. A multidisciplinary cross-species
investigation of hierarchical control would be a hell of an impressive
undertaking.
It's hard for me to see how selective mating could produce a brain size
larger than any that exist in a given population. Seems to me that mutation
is also essential.
Best,
Bill P.
[From Bill Powers (2000.12.20.0955 MST)]
Bruce Gregory (2000.1220.0735)--
You are assuming that the levels in PCT are reflected by "layers" in the
brain. I know of no evidence to support this conjecture.
You'll see some attempts at finding evidence in B:CP. I got a lot of my
ideas about what levels might exist from studying some neuroanatomy and
other readings, but my acquaintance with the literature of localization
never was great. The most direct evidence is experiential and behavioral.
Best,
Bill P.
[From Bill Powers (2000.12.20.1006 MST)]
i.kurtzer (2000.1220.1015)--
Lastly, on evolution, there is some evidence of layered evolution via
duplication and rearrangement of function. Schematically, A synapses to B;
later B splits into B1 and B2 and A synapes to both; later still A synapses
primarily to B1 while B2 is driven primarily by B1; similarly, B2 then
feedbacks to B1 and A, and B1 to A). This can be seen in the SII, or
somatosensensory cortex II, where it receives inputs in parallel with SI in
cats and from SI in monkeys.
Isaac, I am SO glad you are out there doing what you do.
Best,
bill P.
[From Bruce Gregory (2000.1220.1318)]
i.kurtzer (2000.1220.1015)
Lastly, on evolution, there is some evidence of layered evolution via
duplication and rearrangement of function. Schematically, A synapses to B;
later B splits into B1 and B2 and A synapes to both; later still A synapses
primarily to B1 while B2 is driven primarily by B1; similarly, B2 then
feedbacks to B1 and A, and B1 to A). This can be seen in the SII, or
somatosensensory cortex II, where it receives inputs in parallel with SI in
cats and from SI in monkeys.
I agree with your post up to this point. I don't understand the meaning of
"layered evolution" in this (or any other!) context. What does duplication
and rearrangement, for which we have evidence, have to do with "layered
evolution"?
BG
i.kurtzer
[From Bruce Gregory (2000.1220.1318)]
>i.kurtzer (2000.1220.1015)
>
>Lastly, on evolution, there is some evidence of layered evolution via
>duplication and rearrangement of function. Schematically, A synapses to
B;
>later B splits into B1 and B2 and A synapes to both; later still A
synapses
>primarily to B1 while B2 is driven primarily by B1; similarly, B2 then
>feedbacks to B1 and A, and B1 to A). This can be seen in the SII, or
>somatosensensory cortex II, where it receives inputs in parallel with SI
in
>cats and from SI in monkeys.
I agree with your post up to this point. I don't understand the meaning of
"layered evolution" in this (or any other!) context. What does duplication
and rearrangement, for which we have evidence, have to do with "layered
evolution"?
The term "layered evolution" was a shorthand for the sucessive addition of a
new level of control throughout the evolutionary record. Others have used
even more high-falootin' phrases such as "metasystem transition" but the
point is the same. I was describing a known instance in physiology where a
higher level system is created by duplication and shuffling.
i.
[From Bruce Gregory (2000.1220.1349)]
i.kurtzer
The term "layered evolution" was a shorthand for the sucessive addition of a
new level of control throughout the evolutionary record. Others have used
even more high-falootin' phrases such as "metasystem transition" but the
point is the same. I was describing a known instance in physiology where a
higher level system is created by duplication and shuffling.
If I ever say "metasystem transition" I hope you'll wash out my mouth with
soap...
BG
[From Bruce Nevin (2000.12.20 10:56 EST)]
Chris Cherpas (2000.12.20.0330 PT)--
2) The radical difference between the brains of humans and other
primates is generally easier to account for on the basis of selective
mating, rather than via physical or interspecies pressures -- if
you disagree, I'd be interested in knowing how/why.Assuming a (roughly) serial evolution of successive HPCT layers
(i.e., the answer to question #1 above would be "yes"),
what mating preferences, and corresponding references in the
opposite sex for displaying what is preferred, would be missing
from the current human repertoire as one strips away layers
(i.e., system concepts, principles, programs...)?A specific example I mentioned in a previous post was whether
imitating successful courting would be possible without the
system concept layer.
Dunbar and Lovelace (in the Johansen/Edey book about the hominid Lucy) both give very interesting accounts of the social factors favoring (and favored by) increased cognitive ability.
Animals may be compared as to their reproductive strategy. Oysters are very prolific of potential offspring but provide zero nurturance and protection. Apes, our ancestors, went to the other extreme. An ape mother must nurture her single baby 5 years or before she can have another baby. Whereas infants of other simians grasp the mother with hands, feet, and often tail, leaving the mother's hands free for climbing and foraging, apes must use one or both hands to hold the baby. Foraging was made more difficult because monkeys evolved a capacity to eat unripe fruit, whereas we apes like most critters cannot tolerate the tannins that make unripe fruit bitter and spoil our digestion. The branch that became the great apes and chimps moved deeper into the forest. The branch that became hominids (and the now extinct africanus and robustus lines) moved out into the open.
Lovelace makes a convincing argument that erect posture preceded this move. He does not connect it to competition with monkeys for food, as Dunbar does, but to the problem of procreation. Locomotion is a way out of the reproductive blind alley where the apes were (and are) trapped. The mother can stay close to a home base, where all the resources and sanctuaries are familiar and near. The male has hands free to bring her gifts. But more fundamental under this is sex. When a female of another type of simian comes into estrus (heat), there is a general free-for-all of competition among the males, with a dominance hierarchy, sneaky hanky panky with outlier adolescents, and so on, all well demonstrated. Then when estrus ends and the sexy juices stop flowing it all stops. She is no longer sexually attractive. With humans, there are two crucial differences. One, women are attractive to men largely irrespective of their hormonal cycle; and two, women are *selectively* attractive to *particular* men. To a surprising degree (getting past rhetoric and hyped norms), what is a turn-on for one is a pass for another. How did we get there, and why?
Skipping the marginal corollaries in related species, which Lovelace discusses, what this does is enhance the safety of the female staying near home base and helping mothers (or being helped by other females) with the care of infants. And what it does is support particular males developing references to provide food and other gifts to particular females and their offspring.
Back to Dunbar. In the open country, group size had to increase. Individuals physically on the margins of a group are most vulnerable to predators, and in a small group a higher percentage are on the margins. But group size is limited by the number of alliances that each individual can maintain. Dunbar has some numbers about monkey bands, human village size, and so on, and the numbers support his thesis quite well.
Simians (among others) maintain social groupings by grooming. Grooming is time intensive. An individual can maintain grooming relations with only a few others, and the rest of the time must be for foraging, sleep, escape, group movement, etc. These grooming relations establish and maintain alliances that have obvious benefit for survival and health of mothers and their offspring.
A monkey can only groom one other monkey at a time, but an individual who can comment on other individuals in some way can maintain relationships with 4 or 5 other individuals witnessing the commentary. Here comes your topic of mimickry for starters, Chris. The earliest form of gossip probably was nonverbal parody, I should think, such as has been observed among these animals. (You'll have to look into the literature for yourself, it is quite extensive I believe.) With more alliances, you can support a larger group size; and with a larger groups surviving better than smaller groups, individuals who can support more alliances through gossip survive better than those who cannot.
With the linear growth of allies, you have an exponential growth of relationships to keep track of -- not only me to her, but her to my other allies and her to "our" adversaries. This demands (and is supported by) greater cognitive capacity. With this greater cognitive capacity comes the possibility of more sophisticated gossip, the refinement of animal cries (already denotative) to words, the institutionalizing of word-groupings that circumstantially go together into particular preferred sequences, the institutionalizing of particular ways of sequencing words analogically extended to other words in novel sequences giving rise to syntax and the origins of language, all of which requires (and is supported by) increase in brain size. Which is possible only by extending the infant's time in utero and with an extended period of dependency (childhood), and is possible only in context of a protected home base for mothers and infants, social cooperation, etc.
That's a quick Cook's Tour. Those two books should give you plenty to chew on. I am sure that Lieberman's book is very worthwhile, but haven't read it, and the other titles I mentioned, and beyond that the literature of primate studies is quite large, not to mention other social critters, like that remarkable work on Grey Parrots.
Hope this helps.
Be well,
Bruce Nevin
At 03:34 AM 12/20/2000 -0800, Chris Cherpas wrote:
[From Bruce Nevin (2000.12.20 14:15 ET)]
Chris Cherpas (2000.12.20.0740 PT)
At 07:56 AM 12/20/2000 -0800, Chris Cherpas wrote:
Our big brain is a resource hog, using disproportionate
amounts of oxygen, blood, and glucose (i.e., considering
the amount of total body weight it takes). Also, the big
brain has been one reason why babies and mothers have died
during labor. This seems like a lot of trouble for something
that's reproductively neutral.
Big brain and upright posture -- most obviously the latter, certainly because of childbirth/childhood consequences the former -- make no evolutionary sense without reproductive advantage. Read Lovelace and Dunbar.
Bruce Nevin
[From Chris Cherpas (2000.12.20.1600 PT)]
Bill Powers (2000.12.20.0945 MST)--
It's hard for me to see how selective mating could produce
a brain size larger than any that exist in a given population.
Seems to me that mutation is also essential.
I wasn't explicit about the sources of variation upon which
selective mating would operate. If the species were totally
monogomous and mated assortively (i.e., top guy mates with
top gal, 2nd bananas pair up, and so forth), then those at
the bottom of the barrel would presumably have offspring
that were much less viable, given that selective mating is
based to any extent on fitness indicators. That would move
the average for mate preferences and traits preferred, but
without a source of variation other than recombination,
there would be no reason to expect brain sizes much larger
than the largest in the starter population. With polygyny,
the process would move faster (the rich get richer and the
poor get poorer model), but without another source of
variation, there would be no obvious way to get a larger
largest brain.
So, yes, I'm assuming mutation (and I generally do when
considering evolution). The more genes needed to produce
a structure, the more chances there are for mutations to
screw it up. So, mating preferences based on complex (multi-gene)
phenotypes (like more powerful brains) would be even more indicative
of fitness than simpler reproductive advertisements, like
florescent genitals.
Best regards,
cc
[From Chris Cherpas (2000.12.1630 PT)]
Chris Cherpas (2000.12.20.0740 PT)--
I think selection is almost certainly involved. I don't know
of genetic mutations that accumulate in a particular direction
(e.g., bigger brain) without differential reproduction.
Bruce Gregory (2000.1220.1116)--
It's called genetic drift.
I agree that you can get accumulated changes via genetic
drift (without selection) but, then, I don't think of drift as
involving mutation, but rather as the outcome of recombination.
A genetic drift account of big-brained humans would be favored
if our proto-humans were a small population that essentially
lost its "smaller brain size" alleles and just fixed on the
"biggest brain size" allele, out of the starter sample set.
That situation would also result in little likelihood of
any further changes (e.g., via selection) since there'd be
no variation left from which to select.
Bruce Gregory (2000.1220.1116)--
See _The Spandrels of San Marcos_ for an alternative perspective.
Good reference. A finch in the hand is worth two in the imagination.
Bruce Gregory (2000.1220.1116)--
The problem with the adaptationist approach is that it is immune
to refutation. Sexual selection is the ultimate gotcha. It doesn't
contribute to survival? Then it must be the result of sexual selection.
I agree in principle, and didn't mean to [over]state my proposal so
as to assume a pure adaptionist approach -- i.e., one that would preclude
other possibilities. Nor have I seen an argument that makes selective
mating an impossibility.
Best regards,
cc