RE: Parody of Science

Gatherer, D. (
Thu, 05 Aug 1999 09:15:31 +0200

Date: Thu, 05 Aug 1999 09:15:31 +0200
From: "Gatherer, D. (Derek)" <>
Subject: RE: Parody of Science
To: "''" <>


>Alan Rogers from the University of Utah has written a population simulation
>where he can vary the selective pressures. If he changes the parameters so
>that children require lots of parental investment, he _doesn't_ get
>dem.trans. effects.

Ahh, I see. Has the question been examined from the viewpoint of
hierarchical social niches?

I think so, but according to BM's review this later work is still

Roger's first model is referenced as:

Rogers AR (1990) The evolutionary economics of human reproduction.
Ethology and Sociobiology 11, 479-495.

in this model he was unable to simulate dem.trans.

BM also says however:

"Finally, Rogers, who was until recently unable to simulate an environment
in which optimal fertility decreases with wealth, now reports that in
environments in which inheritance greatly boosts an individual's ability to
earn an income - each dollar inherited generates on average two dollars of
earned income - wealthy parents can attain higher long-term fitness at
equilibrium than poorer parents by producing fewer children (AR Rogers

Although I don't have any data at hand, I would suspect that the
professional classes have a higher percentage of their offspring which
continue on to also become members of a professional class.

Yes, that would seem to be equivalent to Roger's 1 dollar gives 2 dollars
assumption above.

At the dem. trans. the barriers restricting movement between social classes
(both up and down) were to a large extent removed. So it would seem
reasonable to postulate that we would see an increased parental investment
required by the upper classes in order to insure that their children--and
children's children--achieved a similar status as the parent.

(Which is obviously a memetic rather than genetic pressure.)

This brings us to Boyd and Richerson, who hypothesised back in the mid-80s
that high status/role model individual are "imntated indiscriminately" (BM's
phrase) and that "if a suite of traits are imitated indiscriminately, low
fertility might spread", and they call this process "indirect bias" (rather
like Cavalli-Sforza's "cultural selection").

This has fertility as a purely memetic effect, sparked off presumably by
high-status-low-breeders stimulating behavioural imitation, which then, by
economic happy coincidence, raises the status of those who imitate them
(because they then have more spending money), and they themselves serve as
role models etc....

This of course, is a behavioural contagion, just like the suicide
behavioural contagions we were discussing (or rather not discussing,
somehow) a week or so back. Of course the implication is that dem.trans.
must exhaust itself:

A suicide contagion cannot run until everybody is dead (well, maybe it can,
but eventually even the worst outbreak will peter out by mechanisms we know
nought about). Likewise, a reproductive evolutionary suicide contagion like
dem. trans. will eventually result (in the absence of any mechanism from
Roger's unpublished model) in

a) a zero fertility population, or
b) slightly less extremely the disappearance of the low fertility classes,
as the high fertility classes just out compete them genetically (shades of
Herrnstein and Murray, ay caramba!)
c) the contagion will peter out before any of these drastic scenarios occur
and we shall revert to pre-dem.trans. reproductive patters - perhaps first
manifested as a sustained 'baby boom', but then turning into permanency.

I wonder what the "bird clutch" models would show if you could somehow
factor social standing into it? My guess is that the increased mating
opportunities afforded those of higher standing still would not be worth the
increase parental investment--that is, from a quantitative standpoint at
least. It could perhaps be argued that by having a larger pool of potential
mates to choose from such high status individuals could gain a qualitative
genetic advantage for their children.


Very interesting. I hadn't thought about that. However, perhaps the fact
that the high reproducing classes still have good survival rates shows that
any genetic qualitative disadvantage they may have as a consequence of low
mate pool choice, is not a large enough selective pressure to have any
evolutionary consequences, ie., they'll still win the evolutionary game in
the long run.

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