In good speaking, should not the mind of the speaker know the truth
of the matter about which he is to speak?
I do not know where to find in any literature, whether ancient or
modern, any adequate account of that nature with which I am
acquainted. Mythology comes nearest to it of any.
HENRY DAVID THOREAU
Mankind is poised midway between the gods and the beasts.
The main conclusion arrived at in this work, namely, that man is
descended from some lowly - organized form, will, I regret to
think, be highly distasteful to many persons. But there can
hardly be a doubt that we are descended from barbarians. The
astonishment which I felt on first seeing a party of Fuegians on
a wild and broken shore will never be forgotten by me, for the
reflection at once rushed into my mind - such were our
ancestors. These men were absolutely naked and bedaubed
with paint, their long hair was tangled, their mouths frothed in
excitement, and their expression was wild, startled, and
distrustful. They possessed hardly any arts, and, like wild
animals, lived on what they could catch; they had no
government, and were merciless to everyone not of their own
He who has seen a savage in his native land will not
feel much shame, if forced to acknowledge that the blood of
some more humble creature flows in his veins. For my own
part, I would as soon be descended from that heroic little
monkey, who braved his dreaded enemy in order to save the
life of his keeper; or from that old baboon who, descending from the
mountains, carried away in triumph his young comrade from a crowd of
astonished dogs - as from a savage who delights to torture his
enemies, offers up bloody sacrifices, practices infanticide without
remorse, treats his wives like slaves, knows no decency, and is
haunted by the grossest superstitions.
Man may be excused for feeling some pride at having risen, though
not through his own exertions, to the very summit of the organic
scale; and the fact of his having thus risen, instead of having been
aboriginally placed there, may give him hopes for a still higher
destiny in the distant future. But we are not here concerned with
hopes or fears, only with the truth as far as our reason allows us
to discover it. I have given the evidence to the best of my ability;
and we must acknowledge, as it seems to me, that man with all his
noble qualities, with sympathy which feels for the most debased,
with benevolence which extends not only to other men but to the
humblest 1 living creature, with his godlike intellect which has
penetrated into the movements and constitution of the solar
system - with all these exalted powers - Man still bears in his bodily
frame the indelible stamp of his lowly origin.
The Descent of Man
I am a brother to dragons, and a companion to owls.
JACOB BRONOWSKI was one of a small group of men and women in any age
who find all of human knowledge - the arts and sciences,
philosophy and psychology - interesting and accessible. He was not confined to a
single discipline, but ranged over the entire panorama of human
learning. His book and television series, The Ascent of Man, are a
superb teaching tool and a remarkable memorial; they are, in a way,
an account of how human beings and human brains grew up together.
His last chapter/episode, called “The Long Childhood,” describes the
extended period of time - longer relative to our lifespan than for any
other species - in which young humans are dependent on adults and
exhibit immense plasticity - that is, the ability to learn from their
environment and their culture. Most organisms on Earth depend on
their genetic information, which is “prewired” into their nervous
systems, to a much greater extent than they do on their extragenetic
information, which is acquired during their lifetimes.
beings, and indeed for all mammals, it is the other way around.
While our behavior is still significantly controlled by our genetic
inheritance, we have, through our brains, a much richer opportunity
to blaze new behavioral and cultural pathways on short time scales.
We have made a kind of bargain with nature: our children will be
difficult to raise, but their capacity for new learning will greatly
enhance the chances of survival of the human species. In addition,
human beings have, in the most recent few tenths of a percent of our
existence, invented not only extragenetic but also extrasomatic
knowledge: information stored outside our bodies, of which writing
is the most notable example.
The time scale for evolutionary or genetic change is very long. A
characteristic period for the emergence of one advanced species from
another is perhaps a hundred thousand years; and very often the
difference in behavior between closely related species - say,
lions and tigers - do not seem very great. An example of recent evolution of
organ systems in humans is our toes. The big toe plays an important
function in balance while walking; the other toes have much less
They are clearly evolved from fingerlike appendages
for grasping and swinging, like those of arboreal apes and monkeys.
This evolution constitutes a respecialization - the adaptation of an
organ system originally evolved for one function to another and
quite different function - which required about ten million years to
emerge. (The feet of the mountain gorilla have undergone a similar
although quite independent evolution.)
But today we do not have ten million years to wait for the next
advance. We live in a time when our world is changing at an
unprecedented rate. While the changes are largely of our own
making, they cannot be ignored. We must adjust and adapt and
control, or we perish.
Only an extragenetic learning system can possibly cope with the
swiftly changing circumstances that our species faces. Thus the
recent rapid evolution of human intelligence is not only the cause
of but also the only conceivable solution to the many serious
problems that beset us. A better understanding of the nature and
evolution of human intelligence just possibly might help us to deal
intelligently with our unknown and perilous future.
I am interested in the evolution of intelligence for another reason
We now have at our command, for the first time in human
history, a powerful tool - the large radio telescope - which is capable
of communication over immense interstellar distances. We are just
beginning to employ it in a halting and tentative manner, but with a
perceptibly increasing pace, to determine whether other
civilizations on unimaginably distant and exotic worlds may be
sending radio messages to us. Both the existence of those other
civilizations and the nature of the messages they may be sending
depend on the universality of the process of evolution of
intelligence that has occurred on Earth. Conceivably, some hints or
insights helpful in the quest for extraterrestrial intelligence
might be derived from an investigation of the evolution of
I was pleased and honored to deliver the first Jacob Bronowski
Memorial Lecture in Natural Philosophy in November 1975, at the
University of Toronto. In writing this book, I have expanded
substantially the scope of that lecture, and have been in return
provided with an exhilarating opportunity to learn something about
subjects in which I am not expert. I found irresistible the
temptation to synthesize some of what I learned into a coherent
picture, and to tender some hypotheses on the nature and evolution
of human intelligence that may be novel, or that at least have not
been widely discussed.
The subject is a difficult one. While I have formal training in
biology, and have worked for many years on the origin and
early evolution of life, I have little formal education in, for
example, the anatomy and physiology of the brain. Accordingly, I
proffer the following ideas with a substantial degree of
trepidation; I know very well that many of them are speculative and
can be proved or disproved only on the anvil of experiment. At the
very least, this inquiry has provided me with an opportunity to look
into an entrancing subject; perhaps my remarks will stimulate others
to look more deeply.
The great principle of biology - the one that, as far as we know,
distinguishes the biological from the physical sciences - is evolution
by natural selection, the brilliant discovery of Charles Darwin and
Alfred Russel Wallace in the middle of the nineteenth century.* It
is through natural selection, the preferential survival and
replication of organisms that are by accident better adapted to
their environments, that the elegance and beauty of contemporary
life forms have emerged.
* Since the time of the famous Victorian debate between Bishop
Wilberforce and T. H. Huxley, there has been a steady and notably
unproductive barrage fired against the Darwin/Wallace ideas, often
by those with doctrinal axes to grind.
The development of an organ system as
complex as the brain must be inextricably tied to the earlier
history of life, its fits and starts and dead ends, the tortuous
adaptation of organisms to conditions that change once again,
leaving the life form that once was supremely adapted again in
danger of extinction. Evolution is adventitious and not foresighted.
Only through the deaths of an immense number of slightly maladapted
organisms are we, brains and all, here today.
Biology is more like history than it is like physics; the accidents
and errors and lucky happenstances of the past powerfully prefigure
the present. In approaching as difficult a biological problem as the
nature and evolution of human intelligence, it seems to me at least
prudent to give substantial weight to arguments derived from the
evolution of the brain.
Evolution is a fact amply demonstrated by the fossil record and
by contemporary molecular biology. Natural selection is a
successful theory devised to explain the fact of evolution. For a
very polite response to recent criticisms of natural selection,
including the quaint view that it is a tautology (“Those who survive
survive”), - see the article by
Gould (1976) listed in the references
at the back of this book. Darwin was, of course, a man of his times
and occasionally given - as in his remarks on the inhabitants of
Tierra del Fuego quoted above - to self - congratulatory comparisons of
Europeans with other peoples.
In fact, human society in pretechnological times was much more like that of the compassionate,
communal and cultured Bushman hunter - gatherers of the Kalahari
Desert than the Fuegians Darwin, with some justification, derided.
But the Darwinian insights - on the existence of evolution, on natural
selection as its prime cause, and on the relevance of these concepts
to the nature of human beings - are landmarks in the history of human
inquiry, the more so because of the dogged resistance which such
ideas evoked in Victorian England, as, to a lesser extent, they
still do today.
My fundamental premise about the brain is that its
workings - what we sometimes call “mind” - are a consequence of
its anatomy and physiology, and nothing more. “Mind” may be a
consequence of the action of the components of the brain
severally or collectively. Some processes may be a function of
the brain as a whole. A few students of the subject seem to
have concluded that, because they have been unable to isolate
and localize all higher brain functions, no future generation of
neuroanatomists will be able to achieve this objective. But
absence of evidence is not evidence of absence.
recent history of biology shows that we are, to a remarkable
degree, the results of the interactions of an extremely complex
array of molecules; and the aspect of biology that was once
considered its holy of holies, the nature of the genetic material,
has now been fundamentally understood in terms of the
chemistry of its constituent nucleic acids, DNA and RNA, and
their operational agents, the proteins. There are many
instances in science, and particularly in biology, where those
closest to the intricacies of the subject have a more highly
developed (and ultimately erroneous) sense of its intractability
than those at some remove.
On the other hand, those at too
great a distance may, I am well aware, mistake ignorance for
perspective. At any rate, both because of the clear trend in the
recent history of biology and because there is not a shred of
evidence to support it, I will not in these pages entertain any
hypotheses on what used to be called the mind - body dualism, the idea
that inhabiting the matter of the body is something made of quite
different stuff, called mind.
Part of the enjoyment and indeed delight of this subject is its
contact with all areas of human endeavor, particularly with the
possible interaction between insights obtained from brain physiology
and insights obtained from human introspection. There is,
fortunately, a long history of the latter, and in former times the
richest, most intricate and most profound of these were called
“Myths,” declared Salustius in the fourth century, “are
things which never happened but always are.”
In the Platonic
dialogues and The Republic, every time Socrates cranks up a myth
parable of the cave, to take the most celebrated example - we know
that we have arrived at something central.
I am not here employing the word “myth” in its present popular
meaning of something widely believed and contrary to fact, but
rather in its earlier sense, as a metaphor of some subtlety on a
subject difficult to describe in any other way. Accordingly, I have
interspersed in the discussion on the following pages occasional
excursions into myths, ancient and modern. The title of the book
itself comes from the unexpected aptness of several different myths,
traditional and contemporary.
While I hope that some of my conclusions may be of interest to those
whose profession is the study of human intelligence, I have written
this book for the interested layman. Chapter 2 presents arguments of
somewhat greater difficulty than the rest of this inquiry, but
still, I hope, accessible with only a little effort. Thereafter, the
book should be smooth sailing.
Occasional technical terms are usually defined when first
introduced, and are collected in the glossary. The figures and
the glossary are additional tools to aid those with no formal
background in science, although understanding my arguments
and agreeing with them are not, I suspect, the same thing. In
1754, Jean Jacques Rousseau, in the opening paragraph of his
Dissertation on the Origin and Foundation of the Inequity of
Important as it may be, in order to judge rightly of the natural
state of man, to consider him from his origin ... I shall not follow
his organization through its successive developments. . . . On this
subject I could form none but vague and almost imaginary
conjectures. Comparative anatomy has as yet made too little
progress, and the observations of naturalists are too uncertain to
afford an adequate basis for any solid reasoning.
Rousseau’s cautions of more than two centuries ago are valid still.
But there has been remarkable progress in investigating both
comparative brain anatomy and animal and human behavior, which he
correctly recognized as critical to the problem. It may not be
premature today to attempt a preliminary synthesis.
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