Email Calvin || Glossary || Book's Table of Contents || Calvin Home Page  


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.
Webbed Reprint Collection
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


 The brackets [ ] indicate the page numbers where a further explanation can be found.


1,500-year cycle  A minor climate cycle  that varies from 1,100 to 1,800 years long, seen in rocks dropped from floating ice in the North Atlantic.  It extends throughout both glacial times and the present interglaciation, though it sometimes skips a beat or two.  It is difficult to see this cycle in temperature or solar variations, but its most recent cycle corresponds to the Little Ice Age  between 1300 and 1865.  Some occurrences may be exaggerated into a Dansgaard-Oeschger cycle, those climate flips from warm-and-wet to cool-and-dry. [217]


Acheulian   In archaeology, a hominid  toolkit (of fewer than a dozen tools) arising about 1.8 million years ago and coexisting with the older Oldowan  toolkit for some time.  The Acheulian handaxe  (the name comes from the site in France where they were first discovered in the 19th century, St. Acheul) is the best-known exemplar.

adaptation   A body-behavioral feature that has altered so that it more or less matches an environmental feature, though seldom reaching the lock-and-key extent.  Curved finger bones are said to be an adaptation for hanging from tree branches while picking fruit.  The loss of such arboreal adaptations occurred millions of years after the appearance of such adaptations for upright posture as indented knees and a bowl-shaped pelvis.  Remember that behaviors and other functional changes can initially occur without obvious adaptations; bony changes only make some of them more efficient over the long run.

allele   Alternative versions of a gene .  Perhaps 20 percent of your expressed genes have a different allele on the other chromosome; that is, you are heterozygous for that gene and might switch to using it under some conditions.  One reason that children are unlike parents is that parents are often passing on their less-used allele.  Inbred strains have less heterozygosity.

ASL  No, it’s not American Sign Language but rather Above Sea Level, a map abbreviation that distinguishes elevations from Above the Surface, as in a radio tower 100 m high.

altruism   Doing something for another’s benefit, at expense to yourself – but not necessarily at the expense of your genes, as when you aid relatives.  Beyond kin selection is reciprocal altruism, sharing with nonrelatives that is often eventually reciprocated, though the system is weakened by freeloaders (“cheaters”).


bonobo   Pan paniscus, formerly called the “pygmy chimpanzee ,” and the last great ape species to be identified.  Until 1927, they were confused with the chimpanzee, Pan troglodytes – with the old common name arising because they were said to be the “chimpanzee of the pygmies,” living as they do on the left bank of the Congo River  in equatorial forests at about 21-22°E (they’re called the “Left Bank Chimps” for other reasons, too).  While bonobos are not particularly smaller, they are of a more slender body build than chimps.  Humans and the other hominids last shared a common ancestor with both Pan species about 5-6 million years ago, what we might call “Pan prior.”  The two Pan species diverged at about the beginning of the ice ages, 2.5-3.0 million years ago, roughly the same time that the australopithecines  spun off the Homo lineage.

bottleneck   In population biology, an occasion when genetic variability in a population was greatly simplified by the loss of alternative alleles – not because of selection against the lost ones but simply due to reduced choice in mates.  This happens when population numbers are greatly reduced for a time; the re-expansion then populates the world from the smaller range of surviving variation. [78]


cerebral cortex   The outer 2 mm of the brain’s cerebral hemispheres with a layered structure.  It isn’t requir­ed for performing a lot of simple actions but seems essential for creat­ing new episodic memories, the fancier associations, and many new move­ment programs.  Paleocortex, and archicortex such as hippo­campus, has a simpler structure and earlier evolutionary appearance than the six-plus-layered neocortex.

cheater detection   A feature of reciprocal altruism  theories, what you use to identify freeloaders who receive but rarely give back.

conveyor   An oceanographic term for the north-on-top, south-near-the-bottom loop of current in the Atlantic Ocean, which includes the Gulf Stream  and the North Atlantic Current . After sinking, it is called the North Atlantic Deep Water on the return loop.  It is also thought to extend through the Indian Ocean into the Pacific Ocean and equilibrate the large salinity differences that would otherwise develop between Atlantic and Pacific.  The far-northern downwelling sites for the conveyor are in the Greenland  and Labrador Seas, though thermohaline  circulation also likely occurs at mid-northern latitudes.  There is a southern upwelling site all through the southern oceans, promoted by the westerlies that circle the globe at the higher southern altitudes. [240, 247, 249, 265]

Coriolis effect   The tendency (thanks to conservation of momentum) of moving objects to turn left in the Southern Hemisphere and to the right up north, and not at all at the equator.  It contributes oceanic upwelling by moving the surface waters off to one side of the direction of the wind.  It also keeps the spread of heat from the tropics from proceeding directly to the poles, by turning it aside into the trade winds and creating eddies.  The Northern Hemisphere low-pressure updraft eddies are counter­clockwise because the near-surface air drawn into them turns to the right.  [67, 155]

creole  Children invent a new language – a creole – out of the words of the pidgin  protolanguage  they hear their immigrant parents speaking.  A pidgin is what traders, tourists, and “guest workers” (and, in the old days, slaves) use to communicate when they don’t share a real language; pidgin sentences are unstructured and short, while those in creoles have the features of universal grammar .


Dansgaard-Oeschger events   The abrupt warmings of 5-10°C seen throughout the last 117,000 years, superimposed on the more gradual trends of the orbital trends.  The D-O cycle  (abrupt warming and then abrupt cooling) is thought to occur as an exaggeration of some occurrences of the 1,500-year cycle.  The D-O’s are what I have been calling the flips from the cool-dry-windy-dusty mode into warm-and-wet.  [217]

DNA clock   The building blocks of the genes are DNA bases, arranged in a string whose sequence carries the information about what proteins to construct.  By comparing corresponding segments of DNA from two individuals, one can infer something about their degree of relatedness.  Because more extensive differences require more time to happen, inferences can be made about when the two individuals last shared a common ancestor.


exaptation   This was a term intended to cover cases where an organ with one original function got adapted to perform another function (such as the swim-bladders becoming lungs when the first marine creatures became terrestrial).  Previously, the term “pre-adaptation ” had been used,  but this form is objectionable if it suggests some degree of prescience.


founder effect   The great expansion from a small number of individuals discovering an empty niche .  Like the bottleneck  without the prior downsizing,  but still having the restricted range of variation.


gene   A unit of heredity, essentially that segment of a DNA molecule compris­ing the code for a particular peptide or protein. We also talk loosely of “a gene for blue eyes” and so forth (reification strikes again), but many a DNA gene is pleiotropic :  it has multiple (and sometimes very different) effects on its body; like that maxim about intervening in complex systems, “You can’t do just one thing.”

genotype   The full set of genes carried by an individual, whether expressed or silent alleles or junk DNA.  See phenotype  for some comparisons.  What makes living matter so different from other self-organizing systems is that a cell has an information center, the genes, concerned with orchestrating the many different processes going on within the cell, and in such a manner that copies of the cell tend to survive.

GPS                        The Global Positioning System uses several dozen satellites in orbits about 20,000 km up.  Signals from any four of them allow a GPS receiver to calculate the local latitude, longitude, and elevation above mean sea level.  Differences between successive fixes allow direction of travel to be inferred, together with speed.

grammar   In general use, synonymous with syntax  but sometimes used within linguistics more narrowly, for all the three-dozen little words such as the, with, before that locate objects in space and time.

great apes   All of the apes except the gibbon  and siamang .  African apes (gorilla , chimp , bonobo ) are all great apes, as is the now-only-in-southeast-Asia orangutan (it too probably originally evolved in Africa).

Gulf Stream   The section of the conveyor  that loops through the Gulf of Mexico, hooks around Florida, and travels up the east coast of North America and the Grand Banks, east of which its name changes to the North Atlantic Current .


handaxe   A misnomer in archaeological terminology, referring to a tear-shaped flattened stone tool seen starting about 1.4 million years ago and continuing to be made even 50,000 years ago.  Its function is unclear; the sharpened-all-around version (which makes a good “killer frisbee”) cannot be used as a handheld axe, though broken or tumbled versions might have been secondarily used for pounding and hacking functions. [145]

heat, latent  The heat that is inherent in water vapor , which you get back as measurable heat when water droplets form.  Similarly, when ice forms.

Heinrich events   A paleoclimate term for the major ice-rafting events, where great armadas of icebergs set sail from Labrador, probably because of a sideways collapse of the Hudson’s Bay ice mountain.  They drop rocks from their bottoms as they melt, all while drifting southeasterly toward the Bay of Biscay.  The Heinrich events are detected by the exotic rocks in layers of ocean-bottom cores in the Atlantic.  They are associated with the coldest periods seen in Greenland , but sometimes the southern oceans warm up somewhat during Heinrich events, perhaps because the conveyor  is totally shut down in the North Atlantic Ocean and little heat can be exported from the southern oceans.

higher intellectual functions               In my terminology, a suite of structured functionality that encompasses syntax , multi-stage planning, multivoiced music, chains of logic, games with arbitrary rules, coherence-seeking (finding patterns within apparent chaos) and similar aspects of structured thought.  They may all share a common neural machinery.  They are all aspects of cognition difficult to discover in the great apes  and there is some suspicion that they were largely absent before the appearance of behaviorally-modern Homo sapiens  about 50,000 years ago.

hominid   The paleoanthropology term for the “third chimpanzee  tribe” since the common ancestor 5-6 million years ago, of which we are now the only surviving species.  Hominid is used to designate the extinct australo­pithecine and Homo species, but not the chimpanzee and bonobo Hominoid is the term that covers all the apes, including hominids and humans, back to the common ancestor with Old World monkeys.  Hominin (avoided here, in agreement with Klein, 1999) is equivalent to hominid in all but purist usage.

Homo erectus   The longest-lasting hominid  species, first seen about 1.8 million years ago in Africa and Asia, and last seen about 50,000 years ago in China .  The African branch (likely older) is now called ergaster rather than erectus by purists.  Homo species such as rudolfensis go back to at least 2.4 million years ago in the East African Rift valley.

Homo heidelbergensis   First seen in Ethiopia about 600,000 years ago at Bodo, it was in Europe by 500,000 years ago, sometimes in association with the earliest hearths.  Its brain size , though smaller on average, was mostly within the modern range.

Homo sapiens  According to DNA dating, our species arose sometime in the ice age  before last, probably between 175,000 and the warm period at 125,000 years ago.  “Anatomically modern” is more-or-less synonymous but is meant to contrast with “behaviorally modern” humans beginning at about 50,000 years ago in East Africa, perhaps coinciding with the most recent “out of Africa” worldwide emigration episode.  The modernity  transition to Homo sapiens sapiens  may be earlier and more gradual within Africa.


innateness   “Hardwired by genes” is the general idea, but it is, more generally, a bit of behavior that arises without learning.  When the individual finds itself in a particular setting, out pops some complicated behavior.  Mating behaviors are innate; some things are too important to be left to learning.  But there isn’t a dichotomy between innateness and environmental causation; as epigenetic rules show, something innate may have, via environmental triggers, profound effects on future form and function.

inheritance principle  Darwin’s great but often misunderstood insight, that variation is not truly random.  (There would be a lot less skepticism about evolution if only people understood this.)  Rather than variations being done from some ideal or average type, small undirected variations are more often done (because they survive to reproductive age) from the more successful individuals of the current generation, exploring the solution space nearby (not jumping randomly to some­where truly unrelated) in the next generation.  If the jumps were large, the starting place wouldn’t matter (and the “randomness” skepticism would have some validity).  [23]

island biogeography   The peculiarities of animal and plant species when largely isolated, with just occasional interbreeding.  An “island” can also be a deep ocean basin, a high mountain valley, or a patch in a patchy resource distribution that prevents migration because of nothing appropriate to eat on the journey.  Islands often have a reduced number of species, so traditional predators or para­sites may be lacking by happenstance.  Species often arrive in small numbers, so founder effects (a special type of bottle­nec k) are a standard feature of island populations.  [87]

isotopic thermometers   An atom doesn’t always have a standard number of neutrons in its nucleus, and so some are a little heavier than others.  For example, most oxygen is an atomic weight of 16 but one “isotope ” has two extra neutrons for 18 total protons and neutrons.  The factory which churned out our oxygen atoms (our “local” supernova about 7 billion years ago) simply didn’t standardize them.  It makes little difference in ordinary chemistry (which is sensitive to the number of electrons, and thus the number of protons, but not to neutrons) but isotopes sometimes make a difference to scientific inquiries.  A molecule of water with oxygen-18 is a little heavier than the usual oxygen-16 water.  It doesn’t evaporate as easily and, if it does, it precipitates out more easily – and when the air is colder, the effects are even more pronounced.  So the ratio of oxygen-18 to oxygen-16 in an ice core, far from the site of evaporation, is something of a proxy for ancient air temperature en route.  The colder it is, the fewer oxygen-18 isotopes complete the journey from seawater to glacier.  The isotopic thermometer can be calibrated by borehole temperatures and by ancient snowlines. [226]


lapse rate  For every 1000 meter rise in elevation, ice age  air temperature dropped about 6°C.  Thus, if an ancient snow line was 500 meters lower, it was likely 3°C cooler then.

Little Ice Age   The minor cooling episode beginning about 1300 and lasting until about 1850, seen around the world.  While a worse time for Greenland  and Europe, it was a better time in East Africa.  It was preceded by about eight centuries of warming, known as the Medieval warm period.  They are the most recent of the events which make up the cycle which recurs every 1,100-1,800 years, whether in an ice age  or interglaciation.


meme   Richard Dawkins’s 1976 coinage, on the analogy (with a little aid from mime and mimic) to gene , for a cultural copying unit, such as a new word or melody that is mimicked by others.

mitochondrial DNA   Like the Y chromosome, the separate DNA of the mitochondria (the energy workhorses within cells) are not subject to shuffling during the formation of eggs and sperm, so that their changes over time are due only to point mutations.  Most regions of the mtDNA mutate at a slow, constant rate, allowing inferences about how long it has been since two species shared a common ancestor.  Your mtDNA is inherited only from your mother.

modernity   See Homo sapiens .

mutation   An alteration in the DNA base sequence of a gene .  The simplest version is a point mutation, where a single DNA base is changed.


Neandertals   A robustly-built European species, Homo neanderthalensis, arising perhaps 400,000 years ago, occasionally pushed out of Europe by ice into Asia; in Israel they overlapped anatomically-modern Homo sapiens  for almost 60,000 years.  They largely disappeared about 35,000 years ago when behaviorally-modern Homo sapiens spread westward out of Asia into Europe.  Their way of life subjected them to more bone fractures; they seldom survived until forty years of age; while making tools similar to overlapping species, there was little of the inventiveness that characterizes behaviorally-modern Homo sapiens.  They are named for the place where they were first found in 1856, a valley in Germany (“Neander Thal” in the German spelling of the time; the “h” has since been dropped from the German spelling of “valley” but not from the italicized species name).  The valley itself was named for the seventeenth-century German poet and composer, Joachim Neander, who sought his muse there – which makes for irony, because higher intellectual functions  like syntax  and structured music may have been lacking in Neandertals, just as suspected for anatomically-but-not-behaviorally-modern Homo sapiens.

neocortex  All of cerebral cortex  except for such places as hippocampus, the simpler layered structure that lacks the patterned recurrent excitatory connections and columnar structures that make the six-layered neocortex so interesting.

niche   The “outward project­ion of the needs of an organism” such as food resources, migration routes, camouflage from predators, suitable housing and sites for effective reproduction.  An empty niche is a proven niche space that is temporarily unoccupied by a tenant species.

North Atlantic Current   In casual usage, most people just say Gulf Stream .  More properly, an oceanographic term for the section of the conveyor  beginning northeast of the Gulf Stream section, the name changing east of the Grand Banks.  It continues east until turning north off Ireland and splitting into two main branches, the northern going up the Norwegian coast to sink in the Greenland  Sea.  The other branch turns west, goes south of Iceland, hooks around the southern tip of Greenland, and then sinks in the Labrador Sea.  Once sunken, it becomes the North Atlantic Deep Water (NADW) on the southbound return loop.  [241]


Out of Africa  and the Multiregional Hypothesis .  OOA refers to the most recent hominid  spread out of Africa and the Levant in the last ice age , somewhat before 50,000 years ago.  (There is also an earlier emigration out of Africa about 1.8 million years ago by Homo erectus , and perhaps another at 500,000 years by Homo heidelbergensis .)  The genetic evidence tends to point to the 50,000-year event as being a replacement, that earlier hominids such as Neandertals  (and remaining Homo erectus in east and southeast Asia) did not contribute any genes to the modern gene  pool.  The Multiregional Hypothesis argues that there are regional anatomical characteristics that suggest some interbreeding, while accepting that all regional varieties of modern humans are largely African.  DNA evidence has contradicted many hard-evidence groupings of paleontological relationships, such as the notion several decades ago that humans were as closely related to gorillas as to chimpanzees.  Whatever the importance of the Multiregional Hypothesis for modern human ancestry, similar issues cloud the interpretation of “the hard evidence” in many aspects of paleontology where there is no DNA or soft-tissue evidence available, only bones and their shapes.


Paleolithic   Just as Pleistocene  is a climate term, Paleolithic is an archaeology term for periods of stone toolmaking; they are both ways of subdividing the several million years before the present warm period featuring agriculture and civilizations.  The periods of “old stone tools” in Europe are subdivided into Lower, Middle, and Upper Paleolithic periods, with the most recent (“Upper”) starting perhaps 50,000 years ago when long blades appeared in Europe.  Archaeologists working in Africa in the 1920s created a different system, the Earlier, Middle, and Later Stone Ages.  The oldest stone tools date back to 2.6 million years ago in Ethiopia.  The ESA includes the Oldowan  and Acheulian  tool kits; the MSA starting about 250,000 years ago encompasses flake and blade tools, made from prepar­ed cores.  The LSA, starting somewhere between 40,000 and 20,000 years ago, has microlithic technology, often with holders for the small sharp edged material.  The MSA-LSA transition is often conflated with the Middle-to-Upper Paleolithic of Europe, but Africa may have made the transition earlier and more gradually.  Blade technology is clearly in place in Africa by 120,000 years ago, and likely earlier.

Pan  The genus of our closest living cousins among the apes, the chimpanzee  (Pan troglodytes) and the bonobo  (Pan paniscus).  Used alone, Pan means both species (and perhaps our common ancestor with them).  “Ancestral Pan” means the unnamed species between 5-6 million years (“Pan prior”) and the chimp -bonobo split about 2.5-3.0 million years ago; it is analogous in use to “bipedal ape” in our branch since the common ancestor.

parcellation   Fragmentation; breaking apart a population into smaller, isolated units (“parcels” or “patches”), as when rising sea level converts a hilly island into an archipelago of former hilltops.  See also island biogeography .

phenotype   Usually “body” but actually the entire constitution of an individual (anatomical, physio­logical, behavioral) resulting from the interaction of the genes with the environment.  As Richard Dawkins emphasized in The Extended Phenotype, this can even include such things as the way of making bird nests or beaver lodges.  Compare to genotype ; as Peter Schuster said in his Schrödinger Lectures, “One can say that the genotype carries a program that is executed in a suitable environment and thereby produces the phenotype. The most relevant evolutionary consequence of this separation of [legislative] and executive power is that all variations through mutation  and recombination  occur on the genotype whereas selection operates exclusively on phenotypes.”

phoneme   The units of vocalization distinguished by native speakers of a language.  Unlike ape calls and cries, phonemes are all meaningless by themselves, having meaning only in combinations (words).  It is important to realize that phonemes are categories that standardize.  For example, Japanese has a phoneme that is in between the English /L/ and /R/ in sound space.  Those English phonemes are mistakenly treated by Japanese speakers as mere variants on the Japanese phoneme.  Because of this “capture” by the familiar category, those Japanese speakers who can’t hear the difference will also pronounce them the same, as in the familiar rice-lice confusion.

Pleistocene   A climate term for the period starting about 2 million years ago, and usually subdivided into Lower, Middle, and Upper.  The Middle Pleistocene starts with the reversal of the earth’s magnetic field about 780,000 years ago and lasts until the beginning of the last warm period 130,000 years ago, with the Upper ending at 10,000 years ago.  The Quaternary comprises the Pleistocene and the Holocene  (the present warm period of the last 10,000 years).  Pleistocene is generally a term for the ice ages, but their beginning keeps creeping farther back toward 3 million years ago.

Pliocene   The period from 5 million years until 2 million years; the Miocene runs from 24 to 5 million years ago.

protolanguage   Any form of communication that contains arbitrary, mean­ingful symbols but lacks syntactic structure.  Forms of protolanguage include the communication of linguistically-trained apes and other animals, pidgins in their early stages,  the speech of nonproficient second-language learners, and that of children under two.

pyramidal neurons   The excitatory neurons of neocortex.  They typically have a tall apical dendrite receiving input synapses and a triangular-shaped cell body (from whence the name) from which their axon leaves, creating distant output synapses.  A better name would be “acacia neuron.”


quasispecies   The best adapted genotypes and their near neighbors.  When the fitness landscape has a lot of isolating hilltops and valleys, small differences may produce reproductive isolation.  The concept is best seen in virology, in how small genetic changes may allow a virus to escape the immune system’s efforts to eradicate it.  But it may also apply to human ancestors with high spontaneous abortion  rates modulated by environmental toxins, allowing locally adapted subpopulations to remain reproductively isolated when immigrants arrive.  Without such quasispeciation, immigrant genotypes would dilute out whatever local “progress” had been achieved.  [120]


recombination   (1) The shuffling of genetic material between an individ­ual’s two chromosome pairs that occurs just prior to the production of ova or sperm (the crossing-over phase of meiosis); and (2) the production of a new individual through the union of a sperm and an ovum from two parents at fertilization.  Both the mitochrondrial DNA  (mtDNA) and the Y chromosome genes escape shuffling and, because mtDNA comes only from a mother and the Y chromosome only from a father, fertilization does not change them either, making them more useful for DNA dating techniques.

refugia   Regions that, in the midst of major population downsizings, still provide the essential elements of the species’ niche  for small subpopulations.  Shorelines and mountain tops are often refugia locales, with a little bit more climate change resulting in the extinction of the subpopulation.  Europe has many fewer plant species than one might expect because so many were, in effect, pushed into the Mediterranean  during an ice age . [78]


Sahel                         In geography, it’s the African transition zone between the arid Sahara  and the tropical rain forests (15-20°N and 15°W-15°E).  The main countries included are Senegal, Mauritania, Burkina Faso, Niger, Nigeria, and Chad.  Though wet in the 1950s, the Sahel experienced an extended drought  starting in the late 1960s.  The Sahel droughts correlate with the sea-surface temperature cycles of the tropical Atlantic Ocean, which also determine the severity of hurricanes that reach North America.

speciation   The process whereby a new species arises as a regional variant of a parent population.  It usually involves a small population size.  They become unable to produce fertile offspring when mating with the parent population, thus preserving whatever adaptations they had acquired in their somewhat different niche . [120]

surface-to-volume ratio   It’s the reason why kids have to be bundled up even when their parents don’t.  The rate of temperature loss is proportional to surface area, but heat capacity is proportional to volume – and babies have a lot of surface area for their volume (weight).  In two dimensions, this is the perimeter-to-area ratio; for a circle, the perimeter is proport­ional to diameter and the area to diameter squared, so the rate of temper­ature change halves when the diameter doubles.  Herds coming to drink at a waterhole  bunch up; double the herd diameter with four times as many individuals, and while the perimeter doubles, the percentage exposed to traditional predators is cut in half.  (The “killer frisbee” over-the-top strategy shows how this simple protection scheme can be turned to a predator’s advantage.)  [139]

Stone Age   See paleolithic.

syntax   The set of rules and principles that determine how structured sentences are formed, as when phrases and clauses can be nested inside one another.  Each dialect has its own syntax, but the possibilities are not unlimited (as “universal grammar ” observes).


thermohaline  circulation  In oceanography, the circulation path determined by temperature and salt – downwellings due to surface-water density created by low temperature and high salinity.  Because dense water tends to eventually sink through less dense underlying layers, it contributes a vertical aspect to ocean currents.  The sinking waters do not always mix with the underlying layers.  Sometimes they slide down a continental slope to the ocean bottom (the most dense bottom waters are formed this way near Antarctica ).  Or they may become so dense from evaporative cooling (and evaporative augmentation of salt at the surface) that they plunge through the underlying layers.  More organized thermohaline circulation occurs in giant whirlpools at some places in the Greenland  Sea, 10-15 km across, slowly conveying surface waters to the ocean floor in a hard-to-see column.  [234, 239]






Copyright ©2002 by
William H. Calvin

The nonvirtual book is
available from
or direct from
 University of Chicago Press

  Book's Table of Contents  

  Calvin Home Page

All of my books are on the web.
You can also click on a cover for the link to

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

all regional varieties of modern humans are largely African.  DNA