William H. Calvin, "The Mind’s Big Bang." An after-dinner speech in San Diego (5 August 2000). See also http://WilliamCalvin.com/2000/SanDiegoSpeech.htm.
Webbed Lecture Collection
William H. Calvin
University of Washington
The Mind’s Big Bang
William H. Calvin
upper Paleolithic art and tools speak,
it says here, “of a mental world we readily recognize as our own,” to quote
Richard Leakey - who, for the last year, in one of the
strangest power-sharing arrangements ever seen, has been the number two man in
the government of Kenya, with powers perhaps greater than those of Al Gore.
He was elected to that position, as best as I can tell, by the World
Bank, as a condition for resuming financial aid to the corrupt Kenyan
government, which they did this last week after a three-year hiatus.
I remember how impressed I was in 1976 when Don Kennedy gave up the fun
of doing neurobiology in order to become the Commissioner of the FDA, and then
president of Stanford, and now editor of Science.
For Richard Leakey to give up doing paleoanthropology to try to rescue
his country from a corrupt tribal coalition seems even more magnanimous, if
anything. But let me now turn to a
simpler time, the one Richard Leakey was speaking of, the far-simpler times
before it, and why things took a big step up in complexity about 40,000
toolmaking bursts on the scene rather suddenly between 50,000 and 35,000 years
ago, compared to the infrequent progress in toolmaking since the common ancestor
with the chimpanzees about 5 million years ago.
And it occurs about when cave art makes us aware that something symbolic
might also be happening (see the pictures in the July 2000 National
Geographic). As Ian Tattersall says, “This… stands in dramatic contrast to the
relative monotony of human evolution throughout the five million years that
preceded it. For prior to the
Cro-Magnons, innovation was… sporadic at best.”
has been a big puzzle in human evolution, obvious a half-century ago, and it has
only become more puzzling as they’ve gotten more sites and more dates.
Most of you already know about it because of the tendency of
paleoanthropologists to speak of anatomically-modern Homo sapiens
starting perhaps 150,000 years ago and, separately, starting about 40,000 years
ago, of behaviorally-modern Homo sapiens.
did a new species appear then? Not
by the usual criterion, based on fossil evidence.
By 150,000 years ago, there were people that looked like us.
They likely had modern brain size but, judging from their art and
technology, they didn’t think like us. The
British anthropologist Kenneth Oakley suggested in 1951 that the art-and-tools
efflorescence of the Upper Paleolithic might have been when fully modern
language appeared on the scene.
then, did anatomically-modern humans just talk silently to themselves, like the
animals in Gary Larson cartoons? Most
people assume they did. They
believe that our pet cats and dogs think, and certainly apes.
So let me tell you what I always say to such statements about the great
apes: If they could talk to
themselves with the complexity we seem to assume, they could think
complex thoughts. And if they could
think complex thoughts, they’d be able to plan ahead and do
other things clearly advantageous to themselves.
We’d see the evidence for complex thought in their behavior,
even if they didn’t talk about it. Indeed
talking like a 2-year-old wouldn’t imply complex thought, so the issue really
isn’t speech per se.
And after you’ve learned enough animal behavior to also know what they don’t do, you begin to wonder. If chimps had complex thought, for example, they’d be the terror of Africa. Instead of their ganglike hit-and-run raids on their neighbors, chimps would make war on their neighbors using stockpiling of supplies and staged, coordinated attacks. We do not see that. No one sees much evidence of logical planning in the chimps, not the kind of planning where two or three novel stages need to be worked out in advance of acting. No such evidence in chimps, and certainly not in Gary Larson’s talking fruit flies.
it is easy to miss evidence. As the
archaeologists say, absence of evidence is not evidence of absence.
But since the great apes don’t much plan for tomorrow, I’m willing
for the moment to consider that complexity of thought may not be present in
them. And maybe this same viewpoint
ought to be applied to our ancestors, too, at least considering the possibility
that complex thought is not much older than the evidence that Tattersall and
Leakey are talking about, at 40,000 years ago.
efflorescence of technique is what is sometimes called “The mind’s big
bang.” I will first review what
is meant by complex thought, especially structuring of thought and extended
consciousness. Then, I will ask two
questions: 1) What was thought like
back in “antebellum” days? 2)
What brain mechanisms might kick in, to produce the efflorescence?
This will lead me to a brief final discussion of speciation’s possible
role in the spread of the higher intellectual functions.
Structuring as a Candidate for the Big Difference
We tend to think that there
was a gradual development of novel vocalizations and words for over a million
years or more. And there were
likely even short sentences like our two-year-olds produce (for which you
don’t need structure to understand their meaning).
Eventually the long sentences of structured language (and thought)
developed - perhaps gradually, perhaps
more suddenly. A great deal of
what’s important for language doesn’t involve syntax, but structuring really
makes long sentences fly, and likely complicated thoughts as well.
There are certainly major predecessors to structured language.
Body postures communicate mood and intention (dogs communicate dozens).
Arm or face posture sequences provide even more bandwidth for
broadcasting your feelings and intentions, when trying to persuade others to do
things your way.
Species-specific vocalizations get a big addition from culturally-defined
“words” (whether gestural or spoken), whose learned meaning depends much
more on context for their interpretation.
Next come word combinations, such as short sentences, of the 2-yr-old
variety. So far we’re mostly
talking about what in 1990 Derek Bickerton called “protolanguage” and this
unstructured language (you can guess the meaning without any help from word
order or inflections) is what you see in toddlers and speakers of pidgins.
sentences, however, are too ambiguous without some mutually understood
conventions about internal structuring into phrases and clauses.
A clause with its verb may be embedded in a phrase, and vice versa, ad
infinitum. Such conventions constitute syntax and each dialect has a
different way of doing things. “Universal
grammar” highlights the tendency of all human groups to use a restricted set
of structuring possibilities; not every scheme is possible, and that restriction
likely has something to do with the way in which the average human brain is
you have a syntax (kids most obviously pick them up in the second year, and
start producing longer sentences between 18 and 36 months), you can convey
complicated thoughts. And hopefully
think them first, so as to avoid that blues lament of Mose Allison, about when
“Your mind is on vacation but your mouth is working overtime.”
It is this last step up to syntax that is the usual candidate for the
mind’s big bang, not the language-lower-case stuff that, though essential,
falls short of capital-L Language per se.
But the mental machinery for syntax is likely shared, at least in part,
with other things that require some structuring.
planning for uncertain futures (not just the seasons) and their associated
agendas (contingencies are structuring)
2. logical trains of inference that allow us to connect remote causes through
intermediate stages to present effects (and a propensity to guess at chains of
causation, useful both for doing science and for fooling yourself).
with made-up rules (hopscotch, not just play) and dance,
4. our fascination with discovering hidden patterns, seen in music
(not just rhythm but four-part harmony), crossword puzzles, and doing science.
And perhaps the mental machinery is shared in part with some nonintellectual functions as well, such as
accurate throwing (not just flinging, which many chimps do, but practicing to hit smaller
and smaller targets),
2. extensive tool making (especially tools with which to make other tools - multiple stages again, like prepared cores),
Note that music beyond rhythm, planning beyond the predictable seasons, and the logical chaining of ideas - are all things that involve the novel, not just learned repetitions like singing the national anthem for the Nth time. Novel structured stuff is what we usually call “higher intellectual function.”
economist said that “There are no free lunches” obviously didn’t read
Darwin and his successors. Pay via natural selection for one functionality like planning
or language, and you may get the others like music mostly “for free.”
Not only is there is a great deal of multiple use in evolution but you
can see a low-tech reminder on many a street corner.
Those curb cuts were paid for by the wheelchair considerations but such
“wheelchair ramps” are largely used - and for free -
by suitcases and skateboards, bicycles and tricycles.
free uses may, of course, pay for subsequent improvements.
I can remember the traffic jams that used to occur at the wheelchair
ramps at airports, as the wheeled suitcases all queued up, awaiting their
chance at the slot - this resulted in making curb cuts as wide as
the crosswalk. So we see how one
secondary use did eventually pay for additional improvements.
When robotic developments enable both wheelchairs and suitcases to climb
seven-inch-high stairs, they'll find curbs easy. The curb cuts may become obsolete for their original functions,
though still frequented by bicycles and skateboards.
the point remains: secondary use
initially gets a free ride, and any improvements don’t necessarily displace
the primary use. The structure
remains multifunctional. The name
changes to reflect the most obvious high-order use - and since the brain is very good about
multiple use, maybe our high-order uses ought to be seen in this curb-cut
context. All this is, of course, meant to
be a parable: I want you to see the story of complex thought as a parallel
to curb-cut uses. Bickerton and I address
some of the possible preadaptations for syntax in our Lingua ex Machina
book. As Liz Bates is fond of
saying about so-called language cortex, these areas seem to have “kept their
day jobs.” They haven’t turned
pro, true specialists like the neurosurgeons who have forgotten how to deliver
babies. And I would add that some
of the secondary uses of the shared mental circuitry, like logical chains of
reasoning, are so amateur that maybe they too are not ready for prime time, that
we’re winging it, in relying so much on them.
At the short-sentence stage of protolanguage, the speed of articulation
or the duration of the speech buffer may not be important - though I think that Phil Libermann’s
argument does apply later on. Instead,
I like to imagine a version of structured thought that is too slow for repartee.
It might be handy when you have time to think about things overnight, and
so it can influence agendas and contingent planning -
but even if you could speak a complex novel sentence aloud, no one might be able
to interpret it, without thinking about it overnight.
So conversational language may not have been the first “killer
application” of structured thought. It
could have been something closer to the contingency or precision aspects of
plan-ahead (“planning first, repartee last,” I call this scenario) - and, of course, if you want to speculate
about the “wheelchair” that initially paid for it, remember that accurate
throwing requires an exquisite amount of planning, that it has big immediate
payoffs in terms of high-calorie meals -
and that if you miss the first time, dinner runs away.
What was thought like before structuring?
love to speculate about what life was like “before modern consciousness.”
It isn’t just novelists. The
archaeologist Steven Mithen speculates about how Neanderthals thought, recalling
Dan Dennett’s description of “rolling consciousness” without memory
storage, the sort of thing that allows you to drive a car and carry on a
conversation at the same time, but not be able to recall the stop signs along
the route. One of the reasons that
paleoanthropologists like Ian Tattersall like to talk about consciousness
kicking in at 40,000 years ago is that modern humans then seem so much more
capable of high-end functions.
Personally, I hate to use the C word and other such big, loaded words to describe things that I think of in more textured, fine-grain terms. Many of you will recall that quip by Francis Crick, about the border between the living and the inorganic, which used to be a big dichotomous debate. Well, said Crick, the boundary disappeared into so much molecular biology - and the same thing was going to happen to consciousness as a concept, that it would disappear into so much neurobiology. But I do think the archaeologists and paleontologists are all on to something, whatever they call it in their groping around for mechanism and metaphor, and that it perhaps points to the structuring of thought.
have trouble thinking about unstructured thought because we can do it so
effortlessly. I may be forced into
unstructured language when traveling abroad, but I can still structure the
English version before I try to translate it into my halting, agrammatical
German-with-gestures. My purpose
here is simply to provide a few examples that might illuminate what mental life
might have been like for everyone, all the time, back in antebellum days.
before structuring might have something to do with what some followers of Freud
like to call “primary process” in our mental lives.
The notion is that primary perceptual stuff got an addition called
“secondary process.” Secondary
stuff involves symbolic representations of an experience, not merely the
primary-process experience itself. Secondary
stuff is capable of being logical, even occasionally achieves it.
Then there are the Piagetian stages. Their
distinctions are hard to summarize briefly so let me stick to the
neurologists’ descriptions instead.
Oliver Sacks’ description of an eleven-year-old deaf boy, reared
without sign language for his first ten years, nicely shows what mental life is
like, when lacking syntax:
distinguished, categorized, used; he had no problems with perceptual
categorization or generalization, but he could not, it seemed, go much beyond
this, hold abstract ideas in mind, reflect, play, plan.
He seemed completely literal -- unable to juggle images or hypotheses or
possibilities, unable to enter an imaginative or figurative realm.... He seemed,
like an animal, or an infant, to be stuck in the present, to be confined to
literal and immediate perception….
Similar cases also illustrate that any intrinsic aptitude for language
must be developed by exposure during early childhood. Joseph didn't have the opportunity to observe syntax in
operation during his critical years of early childhood:
he couldn't hear spoken language, nor he was ever exposed to the syntax
of sign language.
Tony Damasio’s extended consciousness, in The Feeling of What
Happens, is not explicitly structured, though I think it amounts to the same
thing. He certainly shows us
another way to describe the big step up, and rather elegantly at that:
we slip and say that consciousness is a distinctively human quality, we are
thinking of extended consciousness at its highest reaches, not of core
consciousness, and we should be forgiven for the arrogance: extended
consciousness is indeed a prodigious function, and, at its peak, it is uniquely
Extended consciousness goes beyond the here and now of core
consciousness, both backward and forward…. If core consciousness allows you to
know for a transient moment that it is you seeing a bird in flight or that it is
you having a sensation of pain, extended consciousness places these same
experiences in a broader canvas and over a longer period of time.
Extended consciousness still hinges on the same core "you," but
that "you" is now connected to the lived past and anticipated future
that are part of your autobiographical record.
Rather than just accessing the fact that you have pain, you can also
survey the facts concerning where the pain is (the elbow), what caused it
(tennis), when you last had it before (three years ago, or was it four?), who
has also had it recently (Aunt Maggie), the doctor she went to…, the fact that
you will not be able to play with Jack tomorrow. [pp.195-6]
focus is not on the higher intellectual functions (indeed, he treats language
only briefly). But note that his
enhanced detail and time span of extended consciousness likely could not be
achieved without an equivalent in thought of Bickerton’s long sentences.
I’ll bet that in Damasio’s extended consciousness, you still need
phrases and clauses that can have a life of their own and combine in different
ways. In short, extended
consciousness likely needs syntax’s structuring aspect, even without overt
planning or speech, just to keep mental life from blending everything like a
summer drink. And getting muddled
when more than maybe three concepts have to juggled at the same time.
Now that I’ve explained what I mean by structured thought and life
without it, let me turn to the two remaining questions:
What are the gene-specified neural mechanisms coming into play?
And what are the roles played by speciation and by cultural spread -
might culture alone suffice to explain the Mind’s Big Bang, even with old
Let me briefly tackle the culture-alone possibility. Most things are nature and nurture, genes and
and chances are that the 40,000-years-ago happening is both a change in gene
combinations and cultural spread amplifying it.
But sometimes, as with the invention of reading and writing 5,000 years
ago, culture alone likely did the whole job, building on preexisting genes
already in use. What someone needs
to do is to rough out a culture-alone candidate for the rapid emergence of
syntax and complex thought, against which we can judge the new-gene-combination
candidates that we so readily concoct. I’m
trying to do just that for a book manuscript in progress, but there isn’t time
here to flesh it out. So I’m
going to stick to giving you two examples of how subtle genetic changes might
have triggered the efflorescence of tool-making and art-making, and then
consider how speciation prevents backsliding and conserves progress.
What brain mechanisms might kick in,
of the simplest changes you can make is in a behavioral predisposition:
Loner vs gregarious. Propensity
to share food. Liking to dig.
Liking to throw. Hoarding. Acquisitiveness
is the concept which I have applied (it’s somewhere in Lingua ex Machina)
to how the human infant builds a language machine by listening for patterns.
First, infants begin forming up categories for the common speech sounds
they hear, not whole words so much as the little units we call phonemes, less
than a tenth of a second in duration. Categories
allow them to generalize across speakers, so that the mother’s /ba/ sound and
the father’s somewhat deeper /ba/ sound are treated the same despite their
differences. By about a year of
age, babies stop hearing many of these differences, having standardized them.
a year of age, babies are discovering patterns in the strings of phonemes and
acquiring six to nine new words every day, just from the examples they hear
(long before they begin speaking them). The
words acquiring meaning, the phonemes remain meaningless.
You can say kids are like ‘sponges’ soaking up words but that’s too
passive a notion, one of the reasons I prefer the more active ‘acquisitive’
as the characterization.
kids have pyramided words atop the phonemes, and now have compound structures
made from building blocks. But then they do it again, discovering patterns in the
strings of words they hear and inferring the grammar of that particular
language: ways of making plurals
and past tenses and nested phrases. This
happens between the ages of 18 and 36 months.
Then they’re off detecting patterns on even longer time scales, that of
the collection of sentences we call a story.
They infer that a satisfying story has a beginning, middle, and a wrap-up
and then they start demanding proper endings for their bedtime stories.
you can talk about this as separate instincts for acquiring phonemes, words,
syntax, and narrative - or you can try out an overarching principle.
Mine is that it is just repeated instances of pattern-finding
acquisitiveness, spanning longer and longer time windows.
It may, of course, turn out to be something of both the general and the
specific, but what’s interesting is how much you can buy by just pyramiding
‘acquisitiveness’ concepts four times over.
It’s a pyramid, about like compounding atoms into molecules, molecules
into crystals, and then making goblets out of the crystals.
by kids is why there might be more than just cultural spread involved when
converting to widespread syntax, perhaps 40,000 years ago.
Yes, I can see acquisitiveness for words per se having been around for a
million years or more. But
pyramiding to syntax and then narratives in the preschool years, well before
much plan-ahead or accurate throwing develops, happens so reliably in most
modern kids that it makes me wonder if that higher-order acquisitiveness is an
additional adaptation, perhaps backstopped by a speciation-like event. That’s one possibility for the efflorescence, not a syntax
gene but minor changes in language development via acquisitiveness changes of
some sort, maybe just by change timing of staging in development.
let me briefly address another suggestion, Steven Mithen’s 1996 notion of
connecting mental modules as a source of the mind’s big bang.
It’s in The Prehistory of the Mind but let me quote the summary
that Ramachandran made:
“[Mithen] claims that before the big bang there were three different
brain modules in the human brain that were specialized for ‘social or
machiavellian intelligence,’ for ‘mechanical intelligence’ or tool use,
and for ‘natural history’ (a propensity to classify).
These three modules remained isolated from each other but around 50,000
years ago some genetic change in the brain suddenly allowed them to communicate
with each other, resulting in the enormous flexibility and versatility of human
the proprietor of about the only neural-circuits theory for how novel
long-distance cortical interconnections might improve dramatically (and without
any further brain enlargement or reorganization, at that), I find Mithen’s
notion appealing (though not his specific compartments; he seems to have
learned his neuroanatomy from Jerry Fodor).
better interconnections fits very well with the second half of my 1996 book, The
Cerebral Code. It addresses the
subject of rapid, on-the-fly communications between distant cortical areas -
and how to make a big improvement in them.
The problem is how to do long-distance communication in the cortex
without a slow learning procedure for each new novel combination.
suggested that the improved interconnections between areas briefly occur when
the anatomically-incoherent corticocortical interconnections (lots of jumble and
blur) finally become temporarily coherent via a physiological workaround
involving sufficient redundancy. With
such a plainchant chorus of sufficient size all singing the same little
spatiotemporal melody, you can recover that novel spatiotemporal firing pattern
at the other end and pass it on (see chapter 7 of The
Cerebral Code) to a
third cortical area, also unaltered. And
even loop back to the original area, with it immediately (without a learning
process) able to recognize the message.
common code in neocortex would sure make life easier for novelty.
And a Darwinian process of the kind I describe in the Cerebral Code
which is where the populations come from that act like choirs -
sure helps eliminate the nonsense and make the good even better.
ability to routinely handle novelty, dependent on finally reaching a
critical mass that allows recovery of the original pattern from the blur and
jumble, might well have contributed to the aforementioned Big Step Up.
It would have allowed novel parts, such as phrases and clauses, to
each be maintained in their own cortical workspace -
while still contributing to a whole somewhere else, such as a sentence
with syntax. A contingent plan, a
chain of logic, or a multivoiced musical appreciation also have independent
parts contributing to a whole -
and often a whole that must be contrasted to other wholes, even compete with
multiple possibilities quickly.
So I wonder if it wasn’t the whole suite of higher intellectual
functions that emerged so dramatically 50,000 years ago, not just syntax or
complex thought. Other things, like
buffers and speech speed, and certainly augmented imitation abilities, might
have helped. Indeed, mirroring
novel sequences, as in learning how to dance by mimicry, may have been the key
to spreading structured language around the world so quickly, just as a cultural
and the Emergence
Higher Intellectual Functions
Higher Intellectual Functions
step up, remember, is from protolanguage with lots of vocabulary and novel short
sentences, not all of the way up from the associative memory abilities of
chimpanzeelike creatures. But the
inflammation of protolanguage into red-hot syntax may not be the complete
answer. As I noted earlier, kids today are extremely acquisitive of
phonemes, then words, then syntax, and then narrative.
This suggests that some behavioral adaptations have been operating,
perhaps with the aid of ratchets that protect against backsliding.
let me revisit the old what’s-a-species issue.
You can have physiological speciation (poor interbreeding between
populations) without the obvious gross anatomical changes that paleoanthropologists
would be comfortable labeling a new species. As Ian Tattersall points out, there
have likely been many times more “physiological” speciation events than we
could infer from the bony-anatomy ones seen in the fossils.
is speciation good for, anyhow? It
preserves progress. It keeps things
from backsliding, that’s what. To
understand speciation, think small. Accumulating
some physical differences is much easier in an isolated small population with no
gene flow into it, say on an island. The
local environment can really “select for” those variants which fit it.
Similarly, sexual selection’s peculiarities like peacock tails can also
get going most easily in small situations.
when the climate improves, facilitating travel, some immigrants arrive from a
larger population elsewhere. This
dilutes whatever adaptations might have been achieved locally (which is one
definition of “progress”). “Genes
for cooperation,” for example. might have increased to involve half of the
small population but then the percentage backslides with the dilution.
The locals become more average.
That’s adaptation. Speciation is quite another matter, sometimes due to chromosomal peculiarities as in the horses, sometimes to shifted breeding seasons as in the Grand Canyon squirrels, sometimes to mate selection peculiarities such as males that don’t dance well enough to get an invitation to mate. The high spontaneous abortion rate in humans (80 percent of all conceptions are flushed in the first six weeks -- the rate is very low in domestic animals like horses and cattle) holds a lot of possibilities for speciation because if something raised it to 98% between groups, that would effectively create a barrier between the populations.
you have to distinguish between the evolution of physical differences in a
regional population (that’s “adaptation”) and the reproductively isolating
mechanisms which occasionally preserve those physical differences (that’s
“speciation”) from the usual back-and-forth mixing.
One usually doesn’t produce the other, but sometimes they coincide.
It’s much like trying to cross a two-way street, waiting for gaps in
the traffic. A gap in one lane
doesn’t help much, so you await simultaneous gaps before crossing.
It is when adaptation and speciation coincide that life undergoes sustainable change (though most new species promptly go extinct, just because small populations are more likely to be wiped out in the downsizing caused by the next drought). It’s the disruption of reproductive continuity that allows regional physical differences to accumulate, protecting them from dilution, much as a ratchet prevents backsliding.
two populations become reproductively isolated (“the species has split into
two”), then they tend to compete with one another.
Yes, they might ignore one another like two ships passing in the night,
just a wave in passing, or they might even cooperate in some matters, but if
they utilize much the same resources (food, nesting places) and have similar
predators and parasites, then one of the species is likely to fare somewhat
better than the other. That’s all
that “competition” really means - though, of course, competition between
populations can also include the bloodier forms.
that’s the sort of thing that might have preserved innovations at the Big Step
Up. While some modern mental
abilities become apparent in art and toolmaking between 50,000 and 35,000 years
ago, it’s not clear yet how fast they spread - whether
there was enough time for gene flow to operate, as in the two Out of Africas, or
whether cultural spread did the job. Furthermore,
the Y chromosome data suggests a population bottleneck about 50,000 to 40,000
raising the possibility of some late genetic change affecting higher
intellectual function -
so that the creative explosion might have been spread, in part, by gene spread.
Maybe new genes appeared on the scene 50,000 years ago.
Maybe not, too – we’re always happy to credit some new gene,
but as Ajit Varki points out, it’s even more likely to be the loss of
an allele than the addition of one. But
the committee changes, the committee of genes regulating early brain development
trajectories and staging, from whence comes the behavioral propensities, and the
bigger cerebral choirs, or whatever.
our modern life of the mind is less than 50,000 years old, however, it does raise some interesting
questions. The efficiency notions
surrounding evolution often lead to generalities about how evolution produces
“well-tested” parts -
this despite all of the evidence from medicine about how poorly “designed” a
lot of important things are, such as the female reproductive tract.
when innovations are still young, then all bets are certainly off.
We don’t expect reading to work well because writing has only been
around for 5,000 years. Five
thousand years is only fifty centuries and, at four generations per century,
that’s a mere 200 generations since writing was invented (and was only
implemented in only a few percent of the population, until recent centuries).
No time for adaptations, much less speciation to prevent backsliding.
It’s surprising that 85% of kids who try to read succeed so easily.
That’s all culture operating on some multifunctional brain circuitry.
50,000 years is only 2,000 generations and that sure isn’t much time either,
but at least a physiological speciation or two seems possible in that period.
The time back to the common ancestor with the chimps and bonobos is,
fortunately, a hundred-fold greater span of five million years. A lot more speciation is possible to protect progress from
backsliding, and a lot more multiple use could have developed in brain circuits.
Larson and the other cartoonists have fun imagining that the other animals think
too, but I suspect they’re profoundly wrong, that structured thinking
about novelty is one of the aspects of human uniqueness.
And one that evolution hasn’t yet tested very well, one that is clunky -
and perhaps dangerous, both to ourselves and the other inhabitants of our
©2000 by William H. Calvin, University of Washington, Seattle (firstname.lastname@example.org)
[i] “These results indicate that male movement out of Africa first occurred around 47,000 years ago. The age of mutation 2, at around 40,000 years ago, represents an estimate of the time of the beginning of global expansion. ” Russell Thomson, Jonathan K. Pritchard, Peidong Shen, Peter J. Oefner, and Marcus W. Feldman, “Recent common ancestry of human Y chromosomes: Evidence from DNA sequence data,” Proc. Natl. Acad. Sci. USA, Vol. 97, Issue 13, 7360-7365, June 20, 2000.
Ian Tattersall, Becoming Human (1998).
Richard Leakey, The Origin of Humankind (BasicBooks, 1995).
Oliver Sacks, Seeing Voices (University of California Press, 1987).
William H. Calvin is a theoretical neurobiologist, Affiliate Professor of Psychiatry and Behavioral Sciences at the University of Washington in Seattle. He is the author of ten books, mostly for general readers, about brains and evolution. The most recent is his book with Derek Bickerton, Lingua ex Machina: Reconciling Darwin and Chomsky with the Human Brain (MIT Press, 2000). His web site starts at faculty.washington.edu/wcalvin.
William H. Calvin, The Cerebral Code (1996)
William H. Calvin and Derek Bickerton,