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This 'tree' is really a pyramidal neuron of cerebral cortex.  The axon exiting at bottom goes long distances, eventually splitting up into 10,000 small branchlets to make synapses with other brain cells.
William H. Calvin

University of Washington
Seattle WA 98195-1800 USA


No-slides 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. 

In particular, 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.

      A few 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 book.

 

Organization of evening talk:

·Readers often 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.

      Unlike 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.

        Lots of 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.

 

Statistics tell you very little.

·I've written 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.

 

   It's said 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).

 

Writers background

I'm actually 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 MIND (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:

 

HUMAN 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.

     The 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).

      I'm one 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.

        But 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.

      Now, 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.

      Climate 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.

      When "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.   Europe's climate could become more like  Siberia's.  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.

       For a 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 and drying.

 

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 field.

 

What, someone asked by email, did Darwin really discover?  It probably isn't what you always thought.

           It wasn't evolution per se.  There had been an active public discussion of evolution since before Darwin was born (his grandfather Erasmus even wrote poems on the subject).

           It 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 Darwin, invented the phrase we now use.

           It 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. 

          It 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.

           By 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 next generation.

          Many are called, few are chosen by the hidden hand of what Darwin 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. …

       

        A few 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.

           A 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 toolmaking.

           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.

        The 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. 

 

But what 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.

          So, 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 mud....

         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 most relevant.

           We 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.

  

And that 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:

 

"My specialty 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 definition."

 

 

The second quote is from the contemporary atmospheric scientist RICHARD B. ALLEY,  The Two-Mile Time Machine, 2000

 

"You might 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. 

 

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