topics: |  biology | evolution | philosophy | science | history | sexual-selection

Traces the controversial history of two aspects of darwinisim: sexual
selection and altruism.

Alfred Russel Wallace, the co-inventor of natural selection, strongly
disagreed with Darwin on sexual selection.  The theory was ignored for over
a century.  It gained strength - John Maynard Smith suggests in his
foreword - with the feminist movement which struck a chord with the idea of
"female choice" central to sexual selection.

Cronin, a professor of Biology as well as Philosophy, is ideally suited for
the task.  As Smith says in his 2-page foreword,

	There is a recent fashion in the history of science to throw away the
	baby and keep the bathwater - to ignore the science, but to describe
	in sordid detail the political tactics of the scientists.  Helena
	Cronin, I am happy to say, does not belong to this school.

Cronin highlights the role of Darwinism by emphasizing the gulf between our
thought systems today and from the world before Darwin.  She writes
lyrically, covering nthe science in depth, along with the history,
throwing in some Popperian insights into the process by which these ideas
developed.

Excerpts

Ch.1: Walking archives

We are walking archives of ancestral wisdom.  Our bodies and minds are live
monuments to our forebears’ rare successes. This Darwin has taught us.  The
human eye, the brain, our instincts, are legacies of natural selection’s
victories, embodiments of the cumulative experience of the past. And this
biological inheritance has enabled us to build a new inheritance: a
cultural ascent, the collective endowment of generations. Science is part
of this legacy, and this book is about one of its foremost achievements:
Darwinian theory itself. [opening lines, p.3]

The story is a success story: a tale of two puzzles that had stubbornly
resisted explanation, and how Darwinism finally resolved them. One puzzle is
the problem of altruism, epitomised by the ant of this book's title; the
other is the problem of sexual selection, the peacock.  - p.3

Ants: sharing, caring, community-minded creatures - act for good of others
	even at extreme cost to themselves.

With our eponymous hero, the peacock, the difficulty lies in his splendid
tail.  It flies in the face of natural selection.  And 'peacocks' tails' -
ornaments, colours, songs, dances -- abound throughout the animal kingdom,
from insects to fish to mammals.

Why study obsolete theories in science?

[Science history - views of the world as science saw it - is revealing; ]
we must learn to value old ideas even when they have disappeared from
textbooks of today.  As John Maynard Smith says:

         He [it happens to be Ernst Mayr] remarks on the need to avoid
    writing a Whig history of science, but that is the kind of history he has
    written. To be fair, I cannot imagine how a man who has striven all his
    life to understand nature, and who has fought to persuade others of the
    correctness of his understanding, could write any other kind of
    history.
        Unfashionable as it may be to say so, we really do have a better
    grasp of biology today than any generation before us, and if further
    progress is to be made it will have to start from where we now
    stand. So the story of how we got here is surely worth telling. Of
    course, we may not all agree about exactly where we are...  More
    important, a Whig history will seldom give the reader the pleasure that
    comes from a sudden and unexpected glimpse into an unfamiliar mind from
    the past. Mayr's history affords a different pleasure: an understanding
    of a powerful and creative mind of the present, and of its intellectual
    roots.  - John Maynard Smith, _Did Darwin get it right?_, 1988

argues for a need to consider the history of ideas.

Ch 2: A world without Darwin

[This chapter deals at length with the context in which Darwin presented
his ideas.  It discusses the earlier ideas on biological adaptation and
diversity, and notes how Darwin used this to construct his model. Points
out how Darwin focused not only on the amazing adaptations and the unity in
diversity, but also on the infelicities in the "design" of living
creatures, the vestigial organs and other imperfections that exist owing to
the history.  Also, that he notes how in many situation, such redundant
organs have been adapted to other uses.

The chapter closes with a Popperian view of how arguments proceed.  While
Popper had taken the example of Newton on Galileo and Kepler, Cronin focuses on
Darwin. ]

Rivals to darwinism

alternative theories - [Bowler 1984], [Rehbock 1983], [Ruse 1979] - were
unimpressive to the extreme. p.8

Before 1859 much of natural history was closely wedded to natural
theology... With God at its side, natural history came up with the
inevitable answer to where all this apparently conscious design came from:
that it was actually designed - the work of the supreme designer. p.11

[the word "natural", in theology or religion, is used to distinguish it
from its revealed counterpart just like natural history (biology), or
natural philosophy (physics).

Hume’s Dialogues Concerning Natural Religion, is a spoof of the
utilitarian argument, sharply critical of natural religion, which is why he
withheld its publication during his lifetime.

[Hume's character Cleanthes says:]

    Look around the world, contemplate the whole and every part of it: you
    will find it to be nothing but one great machine, subdivided into an
    infinite number of lesser machines, which again admit of subdivisions to
    a degree beyond what human senses and faculties can trace and
    explain. All these various machines, even in their most minute parts, are
    adjusted to each other with an accuracy which ravishes into admiration
    all men who have ever contemplated them. The curious adapting of means to
    ends, throughout all nature, resembles exactly, though it much exceeds,
    the productions of human contrivance - of human design, thought, wisdom,
    and intelligence. Since therefore the effects resemble each other, we are
    led to infer, by all the rules of analogy, that the causes also resemble,
    and that the Author of nature is somewhat similar to the mind of man,
    though possessed of much larger faculties, proportioned to the grandeur
    of the work which he executed.

    By this argument a posteriori ... do we prove at once the existence of a
    Deity and his similarity to human mind and intelligence.

One can immediately see how natural history could reverse this theological
argument: not design in nature as proof for God, but the manifest existence
of God as an explanation for nature's adaptive design...

Two pre-darwinian themes

Two themes explaining adaptation (utilitarianism) vs diversity (unity of
design or idealism).  Both were aligned to the conscious design
theological argument.

  * Utilitarianism-Creatiionism: systematised and popularised in archdeacon
	  William Paley's Natural Theology (1802): Look at an instrument as
	  intricately wrought as a watch, and you can see immediately that it
	  must have a watchmaker.  Similarly, an object as complex and
	  well-adapted as an organism must have a designer.

  * Idealism: the idea of a grand design - "proof of providential design",
	  an "unity in design".  Originally mooted by Edinburgh Edward Forbes
	  and his anatomist teacher Robert Knox (who later became notorious
	  for buying cadavers for dissection from the murderers Burke and
	  Hare).  By the 1850s, had displaced utlitirianism ('subserviency of
	  means to an end')

Though the idealists looked down upon utlitarian-creationists and their
appeal to "final causes, they themselves appealed with exquisite vagueness
to powers exerted by ideal patterns (Aristotelian notion, more like formal
causes).  But the scientific position still was an argument for conscious
design.  p.14-15

Darwin, who was well-versed in both these literatures - he was intimately
familiar with Paley - realized that the diversity aspects could be easily
explained by evolution - but not so easily the adaptation:

	In considering the Origin of Species, it is quite conceivable that a
	naturalist, reflecting on the mutual affinities of organic beings, on
	their embryological relations, their geographical distribution,
	geological succession, and other such facts, might come to the
	conclusion that each species had not been independently created, but
	had descended, like varieties, from other species. Nevertheless, such
	a conclusion, even if well founded, would be unsatisfactory, until it
	could be shown how the innumerable species inhabiting this world have
	been modified so as to acquire that perfection of structure and
	co-adaptation which most justly excites our admiration.
			- Darwin, Origin of Species, introduction

 

 The distorted eyes of the sand sole (Pegusa lascaris) tell a tale of
 adaptive 'imperfection' - if I were you, I wouldn't start from here. p.24

 quotes Darwin:
    The Pleuronectidae, or Flat-fish, are remarkable for their asymmetrical
    bodies. They rest on one side... But the eyes offer the most remarkable
    peculiarity; for they are both placed on the upper side of the head.
    During early youth, however, they stand opposite to each other, and the
    whole body is then symmetrical... Soon the eye proper to the lower side
    begins to glide slowly round the head to the upper side; but does not
    pass right through the skull, as was formerly thought to be the case.  It
    is obvious that unless the lower eye did thus travel round, it could not
    be used by the fish while lying in its habitual position on one side. The
    lower eye would, also, have been liable to be abraded by the sandy
    bottom. - Darwin, Origin of Species, ch.VII,

Imperfections and Vestigial organs

Perhaps the most powerful argument in Darwin relates to the many examples
of imperfections - vestigial and rudimentary organs, which would be hard to
explain for any "design" based theory.   Darwin expands on these in
Chapters 14 and 15 of the O of S.

    Organs or parts in this strange condition, bearing the plain stamp of
    inutility, are extremely common, or even general, throughout
    nature. ...
    In the mammalia, for instance, the males possess rudimentary mammae; in
    snakes one lobe of the lungs is rudimentary; in birds the "bastard-wing"
    may safely be considered as a rudimentary digit, and in some species the
    whole wing is so far rudimentary that it cannot be used for flight.  What
    can be more curious than the presence of teeth in foetal whales, which
    when grown up have not a tooth in their heads; or the teeth, which never
    cut through the gums, in the upper jaws of unborn calves?

    In reflecting on them, every one must be struck with astonishment; for
    the same reasoning power which tells us that most parts and organs are
    exquisitely adapted for certain purposes, tells us with equal plainness
    that these rudimentary or atrophied organs are imperfect and useless.

    On the view of descent with modification, the origin of rudimentary
    organs is comparatively simple... [They] may be compared with the letters
    in a word, still retained in the spelling, but become useless in the
    pronunciation, but which serve as a clue for its derivation. On the view
    of descent with modification, we may conclude that the existence of
    organs in a rudimentary, imperfect, and useless condition, or quite
    aborted, far from presenting a strange difficulty, as they assuredly do
    on the old doctrine of creation, might even have been anticipated in
    accordance with the views here explained.
		- Ch.15, Origin of Species

[In the last, Darwin uses residual spelling in language to explain
evolution; today linguists increasingly turn to evolution to explain
changes in language...
darwin also mentions the adaptive function of legacy organs ]
    an organ may become rudimentary for its proper purpose, and be used for a
    distinct one: in certain fishes the swim-bladder seems to be rudimentary
    for its proper function of giving buoyancy, but has become converted into
    a nascent breathing organ or lung.
[this argument was resurrected, with greater force, as Stephen Jay Gould's
spandrel theory]

In chapter 14 of the Origin of Species, we have:

    We have seen that the members of the same class, independently of their
    habits of life, resemble each other in the general plan of their
    organisation. This resemblance is often expressed by the term “unity of
    type”; or by saying that the several parts and organs in the different
    species of the class are homologous. The whole subject is included under the
    general term of Morphology. This is one of the most interesting departments
    of natural history, and may almost be said to be its very soul.

    What can be more curious than that the hand of a man, formed for grasping,
    that of a mole for digging, the leg of the horse, the paddle of the porpoise,
    and the wing of the bat, should all be constructed on the same pattern, and
    should include similar bones, in the same relative positions?
    ...
    Nothing can be more hopeless than to attempt to explain this similarity of
    pattern in members of the same class, by utility or by the doctrine of final
    causes. The hopelessness of the attempt has been expressly admitted by Owen
    in his most interesting work on the ‘Nature of Limbs.’

[Cronin points out that]
Owen was not "forced to 'admit'" this point, on the contrary, he was drawing
attention to it as evidence against the utilitarian-creationist view and in
favour of his hown. p.28

Popperian analysis of Darwin

How darwin uses the earlier work is one of the main interests of Cronin
here.  It forms "a telling correction of empirical implications of previous
theories, a significant new look to old data."

[Darwin attempts to demonstrate his theories greater "unity and explanatory
power" by comparing these with earlier theories.  For the
utilitarian-creationist, rudimentary organs were an anomaly, causing them to]
briskly abandon the idea of exact adaptation and retreating instead to some
kind of total harmony, such as the principle of plenitude or symmetry.
Darwin was contemptuous of all such empty appeals:

    In works on natural history, rudimentary organs are generally said to
    have been created “for the sake of symmetry,” or in order “to complete
    the scheme of nature.”  But this seems to me no explanation, merely a
    restatement of the fact.

    Nor is it consistent with itself; thus the boa-constrictor has rudiments
    of hind-limbs and of a pelvis, and if it be said that these bones have
    been retained “to complete the scheme of nature,” why, as Professor
    Weismann asks, have they not been retained by other snakes, which do not
    possess even a vestige of these same bones?

And this from his work on Orchids:

    every single detail of structure which characterises the male
    pollen-masses is represented, with some parts exaggerated and some parts
    slightly modified, by the mere rudiments in the female plant.  ...
    At a period not far distant, naturalists will hear with surprise, perhaps
    with derision, that grave and learned men formerly maintained that such
    useless organs were not remnants retained by the principle of inheritance
    at corresponding periods of early growth, but were specially created and
    arranged in their proper places like dishes on a table (this is the
    comparison of a distinguished naturalist) by an Omnipotent hand "to
    complete the scheme of nature."

Post-Darwinian theories: Lamarckism

Lamarckian theory can be summerd up in the phrase use-inheritance.

Use : an organisms activity shapes the organism appropriately for that
	activity.  The more a giraffe stretches its neck, the longer its neck
	becomes; the more a blacksmith uses his biceps the larger they grow.
	And also disuse: the less an ostrich uses its wings, the less capable
	they become.
inheritance of these acquired characteristics.  Features acquired
	through use and disuse are passed on to progeny.

This summary may not be authentic Lamarck, but it is as the theory was
understood or taken up at least in Britain.

Most Darwinians, including Darwin himself (but not Wallace) accepted
use-inheritance as a subsidiary agent in evolution.

The novelist and polemicist Samuel Butler felt that Darwinism excluded
mind, will, intention from any serious role in nature.  On the other hand,
Lamarckism provided a central role for "purpose".

Another champion of Lamarckism was Arthur Koestler, who argues for a
political lure of Lamarckism.  In his The case of the midwife toad
(1971), he tells the story of Paul Kammerer, an experimental biologist who
worked in Vienna around the time of WW1.  Here is Kammerer expressing one
reason for his faith in Lamarckian inheritance:

	the individual's efforts are not wasted; they are not limited by his
	own lifespan, but enter into the life-sap of generations... By
	teaching our children and pupils how to prevail in the struggles of
	life and attain to even higher perfection, we give them more than
	short benefits for their own lifetime...
				- Case of the Midwife Toad, p. 17

[Lamarckism had its political negatives as well] - the legacy of
victimisation, colonisation, deprivation would propagate their patterns of
deprivation through inheritance. The biologist JBS Haldane pointed out how
this aspect was being welcomed in some quarters:

    Lamarckism is now being used to support reaction. A British biologist who
    holds this view thinks that it is no good offering self-government to
    peoples whose ancestors have long been oppressed, or education to the
    descendants of many generations of illiterates.
		- JBS Haldane, Science and Everyday Life 1939
		  (from the essay Evolution and Its Products: Is Darwinism Dead?)

Sexual selection in the male Proboscis monkey

 
The male proboscis monkey - while female and youngsters have sharply upturned
noses, the male develops a gigantic, pendulous cucumber that keeps growing
from age 7+, reaching upto 7", and drooping down over the mouth so he has to
push it aside while eating.  Partly, it serves as an amplifier, sounding like
a double bass.  But, ludicrous as he may look to us, perhaps he goes to these
lengths to satisfy female taste.  - p.176

review

from review by M.R. in Biology And Philosophy, v. 9(2), 1994: p.253-259
http://www.springerlink.com/content/t03010hh70362774/

Beautifully written, good strong examples, a nice sense of history, flashes
of humour, plain forthright conclusions.  [Originally written, but not
published] nearly ten years ago, it is now not only far more polished, but
(and I write now purely from memory) there has been something of a
development of style and content. When Cronin wrote first, her analysis was
more philosophical and historical. Now, as she tackles the key evolutionary
questions of altruism (the "ant" of the title) and of sexual selection (the
"peacock"), I think it fair to say that the emphasis has shifted more to the
question of science as science. Cronin's concern is first and foremost with
the problems for their own sake.

In her preface, Cronin offers "especially thanks and appreciation to Richard
Dawkins", and [while] she does show this influence, both in style and in
ardent Darwinian conclusions, we have more than just a rerun of The Blind
Watchmaker, for by restricting her scope she isable to offer much more detail
on specific issues. I much appreciated the discussion of the work of the
psychologists Leda Cosmides and John Tooby, who have been looking in some
detail at the possible evolutionary foundations for some of our most basic
reasoning patterns...

blurb:
This book is a success story. It explains two long-running puzzles of the
theory of natural selection. How can natural selection favour those, like the
ant, that renounce tooth and claw in favour of the public-spirited ways of
the commune? How can it explain the peacockās tail, flamboyant and a burden
to its bearer; surely selection would act against useless ornamentation?
Helena Cronin's enthralling account blends history, science and philosophy in
a gripping tale that is scholarly, entertaining and eminently
readable. ... selected by Nature and New York Times as one of the best
scientific books in 1992.
[professor : Philosophy at LSE + Zoology at Oxford]