bookstore talk (October 2002)
The death of
Stephen Jay Gould last May was a shock to a lot of us; reading his
essays and his first big book, Ontogeny and Phylogeny (1977)
was what got me to reading more broadly about evolution.
one of Gould's important contributions as a paleontologist was to
convince us that there are long periods in evolution where species
don't change very much, that Darwinian gradualism doesn't guarantee
a steady course of improvements. And that there are periods -- not
at all inconsistent with Darwinian gradualism -- when things
progress considerably faster. I tuned right into what Steve was
saying since both of my main interests in evolution, the evolution
of the big brain in only several million years, and the use of the
Darwinian process in the brain to improve the quality of the next
sentence you speak in a matter of seconds, involve the search for
speedy ways of evolving things.
years ago, my wife and I had a long dinner with Steve. As it
happened we had had lunch that same day with Susan Sontag. And my
wife and I discussed afterwards that here we had an example of
two long-term cancer survivors, each of whom had already gotten
15-20 years of extra life after a grim prognosis. Not only back
from the dead, but just look at all the extra books that each were
able to write, because of catching the cancer in time. This form of
“buying time” is particularly important in some fields of
intellectual endeavor such as history, where people get better as
they get older -- and the near-doubling of the average human
lifespan in some countries has meant a lot in terms of being about
to turn knowledge into wisdom. Ernst Mayr's book What Evolution
Is is an example; he's 97, and he keeps getting better with each
want to know how you got hooked on writing - on the theory that it's
like other addictions, certainly gambling - so I thought that I'd
begin with a little biographical background. Then I'll read some
from the new book and refer you to the web page with all the pretty
pictures that I'd show if this weren't a slide-free talk. WC.com.
science writers who are mostly journalists who find science
increasingly fascinating, my books are more of an insiders view. I
seldom venture very far away from my scientific research interests -
brains, higher intellectual function more generally, evolutionary
mechanisms, human evolution, abrupt aspects of climate change,
sociobiology and the great apes, and some parts of linguistics.
people do the individual parts better than I do. My only advantage
is, in doing them all inside the same head. That's in the hopes of
carryover from one to another, in hopes of being able to spot the
interdisciplinary patterns - like the meterologist Alfred Wegener
who proposed continental drift at a time when no geologist or
geographer would believe it. Fifty years later, everyone believed
it. A lot of things fall between the cracks of our established
scientific disciplines. And we multi- disciplinary types try to
feed on them.
you very little.
11 books in 22 years, but it isn't really two years per book. In
1996 I had two books come out in the same week but that's because
one publisher was very slow.·
Were my parents
or grandparents writers?
No, and indeed I'm the first ever to go to college. But there might
nonetheless be some genes for writing books operating in my case.
One of my two cousins on my mother's side, Beatrice Bruteau, also is
the only person on her side of the family to ever attend college.
She too got a Ph.D. She too has written 11 books (I just caught up
with her, once again).·
She and I both
seem to have been afflicted with the salted peanuts syndrome: once
you start, you can never get enough. And you never finish the can
-- because writing, like all forms of research I suppose, always
raises more questions than it answers.
that science is often about posing the question in such a way that
you can force nature to give you a yes-or-no answer. Much of the
skill of being a good writer consists of seeking out the
illuminating questions. And there's no end to that. I'm so
addicted that I wouldn't trade my job for anyone else's, not even
trade Paul Allen (and certainly not with Bill Gates, who has to
endure a lot of insufferable people).
from Kansas (I learned my evolution later). I learned to write for
general readers between the ages of 14 and 17, in high school near
Kansas City - not because I had an ambition to write but just from
the usual accidents of opportunity. I did a lot of sports
photography and reporting, thanks to a great journalism teacher --
and then I had a great senior english teacher. College improved my
knowledge of what to write about, and how to think about it, not my
writing per se.
THE ASCENT OF
(1990) is the first time that I wrote about abrupt climate change.
Very influential in my career because Freeman Dyson read it. And
liked it, and kept telling editors about it when asked for his
advise; it led to my invitations in 1993 from Scientific
American and again in 1997 from the Atlantic Monthly.
But in 1991, I
had a good scientific idea about the darwinian aspects of brain
circuits. I figured out the circuits that could turn the Darwinian
crank that improves the quality from generation to generation, and
how to do it in known brain circuitry. [If I'm ever remembered for
anything from my scientific work, it might be that.] THE CEREBRAL
CODE (1996) has since come out in paperback and in German
translation. In the meantime, GAO and I redid our first book as
Conversations with Neil's Brain 1994), and I wrote a popular
book, How Brains Think, that's gotten a dozen translations.
Finally I had
time to work with the linguist Derek Bickerton on a book we'd been
planning for four years on Chomsky's problem of Universal Grammar
and how the brain could do it - and how evolution could have gotten
it started. That's Lingua ex Machina, now out in paperback
and a Spanish translation. All the earlier books are now back in
print in English; there was a while when you could only buy them new
in Dutch or German. For some reason, my books are more popular in
languages I cannot myself speak. At least it saves me from reading
aggravating book reviews.
·My 2002 book,
A Brain for All Seasons: Human Evolution and Abrupt Climate
Change, takes the 1998 Atlantic Monthly article and puts
human evolution in the context of hundreds of such abrupt coolings
in the last 2.5 mya. Here is part of the preface:
EVOLUTION from an apelike ancestor started about 5-6 million years
ago. This ancestor probably looked a lot like the modern bonobo
and chimpanzee, with which we share this common ancestor. It
probably had a pint-sized brain and only occasional upright
posture. We are, in a real sense, the third chimpanzee species,
the one that made a series of important innovations.
first departure from this chimplike ancestor was probably some
behavioral change - but behavior doesn't fossilize very well, and
so the first change we can observe in retrospect was that of the
knees and hips. They shifted toward our present form, well
adapted to a lot of two-legged locomotion. Then, much later, when
the ice ages began, toolmaking became common and the brain began
to enlarge and reorganize. So the period of hominid evolution
breaks neatly into two halves, each several million years long:
the period of adaptation to upright posture (plus heavens knows
what else), and the period of toolmaking and brain enlargement
(plus language and planning).
of the many scientists who try to figure out what's behind an
interesting correlation: What did the ice ages have to do with
ratcheting up our ancestor's brain size? Our australopithecine
ancestors, though they were walking upright, had an ape-sized
brain about 2.5 million years ago. Ape brains probably hadn't
changed much in size for the prior 10 million years.
when the ice ages began 2.5 million years ago, brain size started
increasing - not particularly in the other mammalian species, but
at least in our ancestors. About 120,000 years ago, in the warm
period that preceded our most recent ice age, modern type Homo
sapiens was probably walking around Africa with dark skin -
and sporting a brain that was three times larger than before the
first ice age chatters 2.5 million years ago.
it's not obvious what ice, per se, has to do with brain size
requirements. Our ancestors would simply have lived closer to the
tropics, were it too cold elsewhere. And it's not that much
colder in the tropics during an ice age (most of us would likely
rate it more comfortable). Something about the ice ages probably
stimulated the brain enlargement, but neither average temperature
nor average ice coverage seem likely to be the stimulus.
change is, of course, a standard theme of archaeology, all those
abandoned towns and dried-up civilizations. Droughts and the
glacial pace of the ice ages surely played some role in prehuman
evolution, too, though it hasn't been obvious why it affected our
ancestors so differently than the other great apes. The reason
for our brain enlargement, I suspect, is that each ice age was
accompanied, even in the tropics, by a series of whiplash climate
changes. Each had an abrupt bust-and-boom episode - and that, not
the ice, was probably what rewarded some of the brain variants of
those apes that had become adapted to living in savannas.
"climate change" is referred to in the press, it normally means
greenhouse warming, which, it is predicted, will cause flooding,
severe windstorms, and killer heat waves. But warming could also
lead, paradoxically, to abrupt and drastic cooling ("Global
warming's evil twin") - a catastrophe that could threaten the end
of civilization. We could go back to ice-age temperatures within
a decade - and judging from recent discoveries, an abrupt cooling
could be triggered by our current global-warming trend.
climate could become more like
Because such a cooling and drying would occur too quickly for us
to make readjustments in agricultural productivity and associated
supply lines, it would be a potentially civilization-shattering
affair, likely to cause a population crash far worse than those
seen in the wars and plagues of history. What paleoclimate and
oceanography researchers know of the mechanisms underlying such a
climate "flip" suggests that global warming could start one in
several different ways.
quarter century global-warming theorists have predicted that
climate creep was going to occur and that we needed to prevent
greenhouse gases from warming things up, thereby raising the sea
level, destroying habitats, intensifying storms, and forcing
agricultural rearrangements. Now we know that the most
catastrophic result of global warming could be an abrupt cooling
But I want to
give some flavor of the main body of the book, because it is written
in the style of correspondence: E-mail to a university seminar
group from a traveling professor, complete with pictures from the
asked by email, did Darwin really discover? It probably isn't
what you always thought.
wasn't evolution per se. There had been an active public
discussion of evolution since before
was born (his grandfather Erasmus even wrote poems on the
wasn't adaptations to fit the environment, as the religious
philosophers had already seized on that idea as suggesting design
from on high.
Nor was it "survival of the fittest." That idea had been floated
by Empedocles 2,500 years ago in ancient Greece, long before
Herbert Spencer, in the wake of
invented the phrase we now use.
certainly wasn't the basic biological and geological facts that
Darwin discovered, although during his voyage around the world,
and after discovering natural selection, Darwin did add quite a
bit in the factual line.
What Darwin contributed was an idea, a way of making various
disconnected pieces of the overall puzzle fit together, something
like trying to solve a jigsaw puzzle without a picture for a
model. He imagined the picture.
wasn't, however, the idea of descent from a common ancestor.
Diderot, Lamarck, and Erasmus Darwin had all speculated on that
subject two generations earlier. And there were trees of descent
around to serve as examples, given how by 1816 the linguists were
claiming that most European languages had descended from the same
Indo-European root language.
1837 Darwin had concluded that nature was always in the process
of becoming something else, though again there had been other
attempts like Lamarck's along this line. Darwin just looked at
the biological facts in a different way than his predecessors and
contemporaries, not forcing them to fit the usual stories about
how things had come about. Fitting facts to an idea is a primary
way in which progress is made in science, but a fit in one aspect
has often blinded scientists to more overarching explanations.
But even that wasn't his main contribution. Charles Darwin had an
idea that supplied a mechanism, something to turn the crank that
transformed one thing into another. Basically, Charles Darwin (in
1838 and, independently, Alfred Russel Wallace in 1858) had a good
idea about the process of evolution, how one thing could
turn into another without an intelligent designer supervising.
Out of all the variation thrown up with each generation (even
children of the same two parents can be quite unlike one another),
some variants fit the present environment better. And so, in
conditions where only a few offspring manage to reach adulthood
(both Wallace and Darwin got that insight from Malthus and his
emphasis on biological overproduction), there is a tendency for
the environment to affect which variants get their genes into the
Many are called, few are chosen by the hidden hand of what
labeled "natural selection." The name comes from the contrast to
animal breeding, so-called "artificial selection." It is, as
Ernst Mayr noted, an unfortunate term, as it suggests an agent
doing the natural selecting. …
years [after his big book], Darwin realized that he needed to add
an "inheritance principle," to emphasize that the variations of
the next generation were preferentially done from the more
successful of the current generation (the individuals better
suited to surviving the environment or finding mates). This
means, of course, that the new variations were not just at random,
but were centered around the currently-successful model. In other
words, they were little jumps from a mobile starting place,
variations on a theme, not big jumps where the starting place
becomes irrelevant because the jump carries so far. (Warning:
Except for the pros, half of the people who write about evolution,
whether pro or con, may be confused about this important
short-distance randomness aspect.)
Many variations, of course, are not as good as the parents -
nature appears not to worry about this waste, to our distress -
but a few variants are even better than their parents. And so,
with passing generations, there is a chance for drift to occur
towards the better solutions to environmental and mate-finding
challenges. Perfection you don't get, but occasionally you do get
something that, locally, could be called "progress" - that
ill-defined something that makes us so impressed by the Darwinian
process. Nature can be seen to pull itself up by its own
bootstraps, amidst a huge waste in variations that go nowhere.
Then, from the
rift valley in Kenya:
Here at Lake
Naivasha, there are also hippos in the night (mama, papa, and
junior, I was told at breakfast by the cousin [BTW, this is a
different cousin, she's a visiting professor in Kenya....
Only 26 km west of here, up the Mau Escarpment, is Enkapune Ya
Muto rock shelter ("Twilight Cave"), currently a hot topic because
it contains the earliest evidence of beads - such decorative art
is the first evidence of the modern mind. About 50,000 years old,
it is earlier than in Europe (where cave art is the more
spectacular evidence). All of those millions of years of bigger
brains, and finally evidence of thinking somewhat like us.
short boat ride away is Crescent Island, where one can walk, in
the company of a guide with whom the herds are familiar, among the
giraffes and waterbuck and gazelles. Obsidian flakes are
everywhere, some of which are just the sort that hominid
toolmakers would have prized. Some microliths can be found here,
even hafted ones from a few thousand years ago. The reason that
volcanic glass is so prevalent is that, just offshore, there's an
old volcano lurking in the depths.
My cousin kept exclaiming over the obsidian, passing me one flake
after another. I kept saying, after a brief inspection, that the
proffered flake was probably not archaeological, but merely
happenstance. Still, if you were in the [found object] stage of
tool use, this island would have been heaven, what with such
single-edged razorblades everywhere. Such a place could have been
where hominids discovered the virtues of sharp edges and, when
they exhausted the local supply, made the transition from
found-object tool use to Glynn Isaac's shatter-and-search
The giraffes and the archaeologically suggestive obsidian flakes
are surely the reason why most people visit Crescent Island, but
I actually came because of reading about the climate cores
recently drilled offshore. Crescent Island Crater is underwater,
just offshore. Old volcanic craters are not uncommon hereabouts,
but the significance of this one is that it provided a protected
underwater basin from which comes a lake-bottom core, one with a
nice 1,100-year-long record of local climate, showing all its ups
and downs via the inferred salinity of the old lake bottom layers.
story told by the Crescent Island crater sediments is that the
Medieval Warm Period (from about 500 to 1315) was a bad time for
Africa. It is known from other sources that these were years of
drought-induced famine, political unrest, and large-scale
migration of tribes. What the cores say is that the lake shrank
dramatically, and for many decades at a time.
Paradoxically, the Little Ice Age (roughly 1315-1865, when most of
the world was generally about 1°C cooler, thanks to one of those
minor 1,500-year-long climate rhythms) was a good time in East
Africa, thanks to how it affected East African rainfall. The
good times were relatively uneventful periods of political
stability, consolidation of kingdoms, and agricultural success.
And thus growth of populations.
interrupted even the five-century-long good times in East Africa
were serious episodes of bad times. Such were concentrated in
three periods... when Lake Naivasha (and many a big lake in East
Africa) was shrunken and salty.
even in the absence of human modification of climate via fossil
fuels and cutting down forests, it looks as if Africa is subject
to episodes of prolonged (30, 65, and 80 years) drought even in
otherwise good times. ....
Droughts are often regional, such as the Dust Bowl of American
Midwest and Great Plains from 1931-1939. Numerous farms had to be
abandoned, and overall agricultural productivity dropped sharply;
my mother tells me that when it rained in Kansas City, it rained
Sometimes there are seesaws operating, where one region improves
at the expense of another. But there are also some droughts that
are worldwide, everywhere getting hit at about the same time.
Everyone loses (except maybe for the waterhole predators), almost
everywhere (except maybe Antarctica and the South Atlantic Ocean,
where few people can live). They are the aforementioned "abrupt
cooling episodes" but they could equally well be called "severe
drought episodes" or "dust storm centuries." Temperature is often
the easiest thing to measure, thanks to the oxygen isotope ratio
correlating with air temperature, but it is not necessarily the
tend to concentrate on the downside of droughts because of all the
human misery they cause. But an evolutionary biologist also looks
at the recovery, because the transition is often a boom time.
Things become possible in boom times that are difficult in the
more static periods before and after the transition period.
recovery period is the main point of my theorizing about human
origins. I think all terrestrial mammals suffered from the
downsizings, but that our ancestors got some opportunities that the
other great apes did not – and that’s how abrupt climate change
helped to make up human. Perhaps I will end with the two quotations
that start the book:
The first is
from the anthropologist, essayist, and poet LOREN EISELEY, from
The Night Country, 1971:
is the time when man was changing into man. But, like a river
that twists, evades, hesitates through slow miles, and then leaps
violently down over a succession of cataracts, man can be called a
crisis animal. Crisis is the most powerful element in his
quote is from the contemporary atmospheric scientist RICHARD B.
ALLEY, The Two-Mile Time Machine, 2000
think of the climate as a drunk: When left alone, it sits; when
forced to move, it staggers."
And that’s our
biggest problem for the future, not gradual climate change. It’s
the next time that the climate staggers, and everywhere gets into
trouble at the same time within ten years.