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William H. Calvin, A Brain for All Seasons:  Human Evolution and Abrupt Climate Change (University of Chicago Press, 2002). See also

copyright ©2002 by William H. Calvin
ISBN 0-226-09201-1 (cloth)    GN21.xxx0     
Available from or University of Chicago Press.
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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

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To:                  Human Evolution E-Seminar
From:             William H. Calvin
34.35729°S   18.47400°E    1m ASL
                        Cape of Good Hope
The turning point that wasn’t

Speaking of pumping, tides must be the original stroke-after-stroke device.  Tidal fish traps show you how our ancestors could have gone fishing along this coastline, even without spears or fish hooks.  If the tide flushes into a gully, all they had to do is to pile up some boulders to half the height of high tide, making a sill across the gully entrance.  It doesn’t have to hold back the water effectively, only the larger fish that aren’t quick enough to notice the falling tide.  Now the pump has a fallback.  And so some fish will remain behind the dam, high and drying, there for the taking on your daily visit.

     While the evidence for such things along the southern coastline probably doesn’t go back more than several thousand years to when the pastoralists arrived, this is the sort of thing that even bipedal apes might have been able to do.  There are many natural examples, called tide pools, that trap small fish and crabs every day.  These could have served as examples and indeed you can block up the low points of natural tide pools to enlarge them, giving you the idea for how to approach the problem on the larger scale of a little inlet.  One can easily imagine people piling up rocks to fill in the low points of the entrance.  Groups would have zealously guarded the good gullies, perhaps even settling down for a while.

     The cold current keeps the ocean here about 11°C, in contrast to the 20°C waters east of Cape Agulhas.  And so the modern version of the fish trap is the tidal swimming pool, sometimes seen in the beaches of the western Cape Town suburbs.  A particularly high tide flushes out the shallow pool with new water every two weeks.  The sun then warms up the trapped water enough for you to swim comfortably.  And maybe you’ll encounter a fish, too, looking for a way out.  It’s too bad that there isn’t some way for the tides to pump the water higher and higher with each tidal extreme, with a ratchet tracking it up.  You have to wait for biological evolution before such ratchets happen.

     There are a series of caves facing out onto the Indian Ocean east of here, such as Nelson’s Bay Cave and Klasies River.  Klasies is particularly important, as it has remains of anatomically-modern (except for chins) Homo sapiens from before 100,000 years ago, back into the last major warm period.  Its tools are the usual Middle Stone Age types, and the bones include a lot of eland and penguins, together with some Cape buffalo and wild pigs.  Nelson’s Bay Cave, a deep cave somewhat above the high-water line which we explored several days ago, has layers from the last ice age and into our present warm period; their tools included projectile weapons, and, judging from the bones they discarded, they had gotten good at bringing home the bacon and dealing with the ill-tempered Cape buffs, among the most dangerous animals in Africa.


This southwest corner of Africa is about as far south of the equator as Los Angeles is to the north of the equator.  However, L.A. doesn’t have ostrich wandering the bush or shoreline-patrolling baboons snatching your unguarded picnic basket.  Indeed, this place looks like a high mountain plateau, treeless with heathers and high winds. You expect to feel breathless due to the thin air but it is located at sea level.

     The lighthouse is on another point just a kilometer east, Cape Point, which is much higher and looks down on the Cape of Good Hope.  The ocean stretches west to Argentina and south to Antarctica.  Bartholomeu Dias reached here in 1488 in the intrepid Portuguese caravels inspired by Prince Henry the Navigator.  John II of Portugal named the cape Cabo da Bõa Esperança, Portuguese for Cape of Good Hope (the “hope” refers to trade prospects with China), when his explorers returned and presented their map.

     That the Cape of Good Hope wasn’t named something else sixty years earlier by a Chinese admiral, Zheng He, is one of the major ironies of history.  The Cape is not, by a half degree, the southernmost extent of Africa (that’s Cape Agulhas farther east, where the ocean’s name officially changes from Indian to Atlantic.  Agulhas would not have impressed a sailor very much, being just another protrusion of a wandering shoreline, important only in retrospect while tabulating latitudes.

     But when you round the Cape of Good Hope going west, the water turns cold, kelp beds line the shore, and the sea coast stretches away to the north, seemingly forever.  You know that you’ve turned a corner.  The Chinese sailors would have wondered where it led, and might have gone on to discover Europe.  But it appears that they didn’t make it quite this far.

     Between 1405 and 1433, so-called “treasure fleets” sailed from China to explore India and the East African coast.  The scale of the venture, hundreds of ships at a time, makes European exploration pale by comparison.  The Portuguese, later that same century, were far less ambitious than the Chinese but they succeeded.  Three ships, led by Vasco da Gama, eventually rounded this cape in 1497 and then continued on to India in 1498.

     So why didn’t the Chinese discover Europe, and beat the Europeans to the Americas and Australia?  Politics.  China’s explorations were suspended before their ships ever turned the corner into the Atlantic Ocean.  Back home, power shifted to a traditionalist faction that wanted to distance China from the outside world.  The eunuchs in the government who supported exploration fell into disfavor.  By a century later, the act of venturing abroad in a multimasted ship, even to trade, had become a criminal offense in China.  They even abolished mechanical clocks after leading the world in clock construction technology.

     For an equivalent, you have to imagine an ultraconservative takeover of the U.S. that, for some reason, frowned on both airplanes and computers, with Seattle and Silicon Valley in deep depression and the conservative radio talk show hosts beginning to look liberal in comparison to the people in power.  The short-sighted in China set the stage for Europe’s 400-year domination of coastal Asia, when it might have been vice versa.

     As Jared Diamond is fond of pointing out, various European countries did equally stupid things but, since Europe was never politically unified in the way that China was, there was always some European country to keep exploring when others stagnated.  As the story of Christopher Columbus shows, sometimes an Italian explorer unable to find financial support back home could even persuade a Spanish king (probably competing with the Portuguese) to bankroll an expedition.

     Evolution is full of stories like this treasure fleet tale.  What species gets there first can make a enormous difference for a long time afterwards.  And getting there first depends on whether populations are unified or fragmented.  This is one aspect of what Stephen Jay Gould likes to refer to as “contingency” in evolution.  Grand principles are perhaps there to be found (such as the six essentials for a Darwinian process), but they are not likely to substitute for the hard-to-learn details about the happenstance of history.



Notes and References
(this chapter
corresponds to 
pages 111 to 115 of the printed book)

Copyright ©2002 by
William H. Calvin

The nonvirtual book is
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or direct from
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All of my books are on the web.
You can also click on a cover for the link to

Conversations with Neil's Brain:  The Neural Nature of Thought and Language (Calvin & Ojemann, 1994)

The Cerebral Code:  Thinking a Thought in the Mosaics of the Mind (1996)

How Brains Think:  Evolving Intelligence, Then and Now (1996)

Lingua ex Machina:  Reconciling Darwin and Chomsky with the Human Brain (Calvin & Bickerton, 2000)

The six out-of-print books are again available via Authors Guild reprint editions,
also available through (click on cover):

Inside the Brain

The Throwing Madonna:  Essays on the Brain

The River That Flows Uphill


The Cerebral Symphony

The Ascent of Mind

How the Shaman Stole the Moon