Remine & Haldane on sci.bio.evolution

In article <e7rkoj$2qgt$1@xxxxxxxxxxxxxxxxxxx> on June 27th in
sci.bio.evolution "Perplexed in Peoria" <jimmenegay@xxxxxxxxxxxx> wrote:

"Walter ReMine" <science@xxxxxxxx> wrote in message news:e7p1k5$1kf8$1@xxxxxxxxxxxxxxxxxxxxxx
Perplexed in Peoria wrote:
Though I suspect Walter is wrong both
about the limit (Walter makes it too low) ...

That misrepresents me. The "limit" is not mine, and I did not "make"
the limit (much less make it "too low"). The limit comes from Haldane,
and evolutionists never revealed its meaning to the general public. I
did. You cannot blame the "limit" onto me.

Felsenstein recently mentioned a 1968 paper by Sved. Quoting from
the introduction of that paper:

Haldane (1957) was apparently the first to approach concisely
the problem of estimating evolutionary rates and to put forward
the view that the intensity of selection observed for most species
implied that there must be an upper limit to the possible rate
of their evolution. In discussing this point, he introduced the
notion of "the cost of natural selection". Assuming selection
to occur through the death in each generation of a constant
proportion of individuals carrying a particular gene, he calculated
that the total number of "selective deaths" occurring in the
replacement of that gene is of the order of 30 times the population
size, independent of the strength of selection involved. From
this he concluded that there could not be much more than one
substitution per genome per 300 generations on the average, based
on the view that most species could not tolerate a depression in
fitness of more than 10% per generation due to this cause. A
similar figure was accepted by Kimura ...

Ok, Walter, I agree. It is not your limit. ...

That depends very much on which particular "limit" you're talking
about, as well as the extent to which it is represented as being
applicable to the general course of evolution. It is certainly true
that in _The Cost of Natural Selection_ (1957) Haldane gave an estimate
of one every 300 generations as a _typical_ (but _not_ _absolute_) upper
bound on the rate at which he believed beneficial substitutions could
have occurred during the course evolution.

If you consult Haldane's summary on page 524 of _The Cost of Natural
Selection_ you will find the following words:

"It is suggested that, _in horotelic evolution_ [emphasis mine--djw],
the mean time taken for the mean time taken for each substitution is
about 300 generations."

While it is clear from the his preceding discussion (on pages 530-523)
that Haldane believed the horotelic (slow) mode of evolution to have
been far more common, he also acknowledged (on page 523) that episodes
of tachytelic (fast) evolution have "doubtless been important", though
"probably exceptional". He wrote:

"Evolution by natural selection can be very rapid if a species,
like the first land vertebrates, or the first colonists of an
island, finds itself in an environment to which it is very ill-
adapted, but in which it has no competition, and perhaps no
predators and very few parasites. If so selection might be so
intense as to reduce the capacity for increase to one tenth of
that of its adapted descendants, and it could yet hold its own.
Such episodes have doubtless been important, and account for
tachytelic (Simpson, 1953) evolution. But they are probably
exceptional."

Nowhere in _The Cost of Natural Selection_, or anywhere else, as far
as I am aware, did Haldane ever give an explicit figure for the rates
of beneficial substitution that he thought might have occurred during
the course of human evolution. Indeed, many, or even most, of the
conditions he mentioned in the first sentence of the paragraph quoted
immediately above seem likely to have held for significant periods
during the course of human evolution. It therefore seems very doubtful
to me that Haldane would have agreed that his "representative" limit of
one beneficial substitution every 300 generations would have been
rigidly applicable to it.

Thus, the figure of 1667 which Mr Remine touts as the alleged maximum
number of nucleotides which evolutionary theory would allow to be
selectively replaced in a human-like population in the course of 10
million years of evolution can _not_ be reasonably attributed to Haldane.
That figure is Mr Remine's alone, and he is telling fibs whenever he
misattributes it to Haldane.

It is nevertheless also true that Mr Remine was not the first to try and
apply Haldane's bound on the rate of beneficial substitution to human
evolution. In a letter to _The American Naturalist_ (Vol XCVI, No. 887,
March-April, 1962), the biologist E.O. Dodson presented a calculation
very similar to Mr Remine's. Dodson's calculations yielded "a maximum
of something over 200 gene substitutions over the past million years" of
human evolution. It seems reasonable to me to assume that Dodson would
have been willing to extrapolate his estimate to "a maximum of something
over" 2000 gene substitutions over the past ten million years, a figure
which more or less agrees with Mr Remine's.

It is noteworthy, however, that Dodson rounds his final estimate to only
a _single_ significant digit, instead of the ridiculously over-precise 4
significant digits to which Remine gives his.

--------------------------------------------------------------------------
David Wilson

SPAMMERS_fingers@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
(Remove underlines and upper case letters to obtain my email address.)

.

Relevant Pages

  • Re: Remine & Haldane on sci.bio.evolution
    ... Haldane was apparently the first to approach concisely ... notion of "the cost of natural selection". ... proportion of individuals carrying a particular gene, ... you can get two units worth of evolution for the cost of one. ...
    (talk.origins)
  • Re: Remine & Haldane on sci.bio.evolution
    ... The limit comes from Haldane, ... notion of "the cost of natural selection". ... applicable to the general course of evolution. ... of beneficial substitution that he thought might have occurred during ...
    (talk.origins)
  • Re: Remine & Haldane on sci.bio.evolution
    ... The limit comes from Haldane, ... notion of "the cost of natural selection". ... applicable to the general course of evolution. ... of beneficial substitution that he thought might have occurred during ...
    (talk.origins)
  • Re: Remine & Haldane on sci.bio.evolution
    ... The limit comes from Haldane, ... notion of "the cost of natural selection". ... applicable to the general course of evolution. ... of beneficial substitution that he thought might have occurred during ...
    (talk.origins)
  • Re: Remine & Haldane on sci.bio.evolution
    ... notion of "the cost of natural selection". ... Am I correct in believing that the reference to "sexual recombination" ... evolution for the cost of one. ... It also seems to suggest that Haldane ...
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