EDGE 14 April 23, 1997
THE THIRD CULTURE
"WHY DID HUMAN HISTORY UNFOLD DIFFERENTLY
ON DIFFERENT CONTINENTS FOR THE LAST 13,000 YEARS?"
A Talk with Jared Diamond
I've set myself the modest task of trying to explain the broad pattern
of human history, on all the continents, for the last 13,000 years.
Why did history take such different evolutionary courses for peoples
of different continents? This problem has fascinated me for a long
time, but it's now ripe for a new synthesis because of recent advances
in many fields seemingly remote from history, including molecular
biology, plant and animal genetics and biogeography, archaeology,
THE REALITY CLUB
[Jared Diamond is travelling until May 5th. Responses to his talk
will be published shortly thereafter along with his rejoinder.]
THE THIRD CULTURE
"WHY DID HUMAN HISTORY UNFOLD DIFFERENTLY
ON DIFFERENT CONTINENTS FOR THE LAST 13,000 YEARS?"
A Talk with Jared Diamond
JARED DIAMOND is Professor of Physiology, UCLA Medical School, a
MacArthur Fellow, and the author of The Third Chimpanzee
(Winner, British Science Book Prize and The Los Angeles Times Book
Prize), and the recently published Guns, Germs, and Steel
the Fates of Human Societies
; (W.W. Norton, Jonathan Cape).
JOHN BROCKMAN: The biggest question that Jared Diamond is asking
himself is how to turn the study of history into a science. He notes
the distinction between the "hard sciences" such as physics, biology,
and astronomy and what we sometimes call the "social sciences,"
which includes history, economics, government. The social sciences
are often thought of as a pejorative. In particular many of the
so-called hard scientists such as physicists or biologists, don't
consider history to be a science. The situation is even more extreme
because, he points out, even historians themselves don't consider
history to be a science. Historians don't get training in the scientific
methods; they don't get training in statistics; they don't get training
in the experimental method or problems of doing experiments on historical
subjects; and they'll often say that history is not a science, history
is closer to an art.
Jared comes to this question as one who is accomplished in two scientific
areas: physiology and evolutionary biology. The first is a laboratory
science; the second, is never far from history. "Biology is the
science," he says. "Evolution is the concept that makes biology
In his new theories of human development, he brings together history
and biology in presenting a global account of the rise of civilization.
In so doing he takes on race-based theories of human development.
"Most people are explicitly racists," he says.
"In parts of the world so called educated, so-called western
society we've learned that it is not polite to be racist,
and so often we don't express racist views, but nevertheless I've
given lectures on this subject, and members of the National Academy
of Sciences come up to me afterwards and say, but native Australians,
they're so primitive. Racism is one of the big issues in the world
today. Racism is the big social problem in the United States."
So why are people racists? According to Jared, racism involves the
belief that other people are not capable of being educated. Or being
human that they're different from us, and they're less than
human. It was through his work in New Guinea for the last 30 years
that convinced him that it's not true. "'They' are smarter than
we are," he says. But perhaps the main reason why people resort
to racist explanations, he notes, is that they don't have another
answer. Until there's a convincing answer why history really took
the course that it did, people are going to fall back on the racist
explanation. Jared believes that the big world impact of his ideas
may being in demolishing the basis for racist theories of history
and racist views.-
JARED DIAMOND: I've set myself the modest task of trying to explain
the broad pattern of human history, on all the continents, for the
last 13,000 years. Why did history take such different evolutionary
courses for peoples of different continents? This problem has fascinated
me for a long time, but it's now ripe for a new synthesis because
of recent advances in many fields seemingly remote from history,
including molecular biology, plant and animal genetics and biogeography,
archaeology, and linguistics.
As we all know, Eurasians, especially peoples of Europe and eastern
Asia, have spread around the globe, to dominate the modern world
in wealth and power. Other peoples, including most Africans, survived,
and have thrown off European domination but remain behind in wealth
and power. Still other peoples, including the original inhabitants
of Australia, the Americas, and southern Africa, are no longer even
masters of their own lands but have been decimated, subjugated,
or exterminated by European colonialists. Why did history turn out
that way, instead of the opposite way? Why weren't Native Americans,
Africans, and Aboriginal Australians the ones who conquered or exterminated
Europeans and Asians?
This big question can easily be pushed back one step further. By
the year A.D. 1500, the approximate year when Europe's overseas
expansion was just beginning, peoples of the different continents
already differed greatly in technology and political organization.
Much of Eurasia and North Africa was occupied then by Iron Age states
and empires, some of them on the verge of industrialization. Two
Native American peoples, the Incas and Aztecs, ruled over empires
with stone tools and were just starting to experiment with bronze.
Parts of sub-Saharan Africa were divided among small indigenous
Iron Age states or chiefdoms. But all peoples of Australia, New
Guinea, and the Pacific islands, and many peoples of the Americas
and sub-Saharan Africa, were still living as farmers or even still
as hunter/ gatherers with stone tools.
Obviously, those differences as of A.D. 1500 were the immediate
cause of the modern world's inequalities. Empires with iron tools
conquered or exterminated tribes with stone tools. But how did the
world evolve to be the way that it was in the year A.D. 1500?
This question, too can be easily pushed back a further step, with
the help of written histories and archaeological discoveries. Until
the end of the last Ice Age around 11,000 B.C., all humans on all
continents were still living as Stone Age hunter/gatherers. Different
rates of development on different continents, from 11,000 B.C. to
A.D. 1500, were what produced the inequalities of A.D. 1500. While
Aboriginal Australians and many Native American peoples remained
Stone Age hunter/gatherers, most Eurasian peoples, and many peoples
of the Americas and sub-Saharan Africa, gradually developed agriculture,
herding, metallurgy, and complex political organization. Parts of
Eurasia, and one small area of the Americas, developed indigenous
writing as well. But each of these new developments appeared earlier
in Eurasia than elsewhere.
So, we can finally rephrase our question about the evolution of
the modern world's inequalities as follows. Why did human development
proceed at such different rates on different continents for the
last 13,000 years? Those differing rates constitute the broadest
pattern of history, the biggest unsolved problem of history, and
my subject today.
Historians tend to avoid this subject like the plague, because of
its apparently racist overtones. Many people, or even most people,
assume that the answer involves biological differences in average
IQ among the world's populations, despite the fact that there is
no evidence for the existence of such IQ differences. Even to ask
the question why different peoples had different histories strikes
some of us as evil, because it appears to be justifying what happened
in history. In fact, we study the injustices of history for the
same reason that we study genocide, and for the same reason that
psychologists study the minds of murderers and rapists: not in order
to justify history, genocide, murder, and rape, but instead to understand
how those evil things came about, and then to use that understanding
so as to prevent their happening again. In case the stink of racism
still makes you feel uncomfortable about exploring this subject,
just reflect on the underlying reason why so many people accept
racist explanations of history's broad pattern: we don't have a
convincing alternative explanation. Until we do, people will continue
to gravitate by default to racist theories. That leaves us with
a huge moral gap, which constitutes the strongest reason for tackling
this uncomfortable subject.
Let's proceed continent-by-continent. As our first continental comparison,
let's consider the collision of the Old World and the New World
that began with Christopher Columbus's voyage in A.D. 1492, because
the proximate factors involved in that outcome are well understood.
I'll now give you a summary and interpretation of the histories
of North America, South America, Europe, and Asia from my perspective
as a biogeographer and evolutionary biologist all that in
ten minutes; 2 minutes per continent. Here we go:
Most of us are familiar with the stories of how a few hundred Spaniards
under Cortés and Pizarro overthrew the Aztec and Inca Empires.
The populations of each of those empires numbered tens of millions.
We're also familiar with the gruesome details of how other Europeans
conquered other parts of the New World. The result is that Europeans
came to settle and dominate most of the New World, while the Native
American population declined drastically from its level as of A.D.
1492. Why did it happen that way? Why didn't it instead happen that
the Emperors Montezuma or Atahuallpa led the Aztecs or Incas to
The proximate reasons are obvious. Invading Europeans had steel
swords, guns, and horses, while Native Americans had only stone
and wooden weapons and no animals that could be ridden. Those military
advantages repeatedly enabled troops of a few dozen mounted Spaniards
to defeat Indian armies numbering in the thousands.
Nevertheless, steel swords, guns, and horses weren't the sole proximate
factors behind the European conquest of the New World. Infectious
diseases introduced with Europeans, like smallpox and measles, spread
from one Indian tribe to another, far in advance of Europeans themselves,
and killed an estimated 95% of the New World's Indian population.
Those diseases were endemic in Europe, and Europeans had had time
to develop both genetic and immune resistance to them, but Indians
initially had no such resistance. That role played by infectious
diseases in the European conquest of the New World was duplicated
in many other parts of the world, including Aboriginal Australia,
southern Africa, and many Pacific islands.
Finally, there is still another set of proximate factors to consider.
How is it that Pizarro and Cortés reached the New World at
all, before Aztec and Inca conquistadors could reach Europe? That
outcome depended partly on technology in the form of oceangoing
ships. Europeans had such ships, while the Aztecs and Incas did
not. Also, those European ships were backed by the centralized political
organization that enabled Spain and other European countries to
build and staff the ships. Equally crucial was the role of European
writing in permitting the quick spread of accurate detailed information,
including maps, sailing directions, and accounts by earlier explorers,
back to Europe, to motivate later explorers.
So far, we've identified a series of proximate factors behind European
colonization of the New World: namely, ships, political organization,
and writing that brought Europeans to the New World; European germs
that killed most Indians before they could reach the battlefield;
and guns, steel swords, and horses that gave Europeans a big advantage
on the battlefield. Now, let's try to push the chain of causation
back further. Why did these proximate advantages go to the Old World
rather than to the New World? Theoretically, Native Americans might
have been the ones to develop steel swords and guns first, to develop
oceangoing ships and empires and writing first, to be mounted on
domestic animals more terrifying than horses, and to bear germs
worse than smallpox.
The part of that question that's easiest to answer concerns the
reasons why Eurasia evolved the nastiest germs. It's striking that
Native Americans evolved no devastating epidemic diseases to give
to Europeans, in return for the many devastating epidemic diseases
that Indians received from the Old World. There are two straightforward
reasons for this gross imbalance. First, most of our familiar epidemic
diseases can sustain themselves only in large dense human populations
concentrated into villages and cities, which arose much earlier
in the Old World than in the New World. Second, recent studies of
microbes, by molecular biologists, have shown that most human epidemic
diseases evolved from similar epidemic diseases of the dense populations
of Old World domestic animals with which we came into close contact.
For example, measles and TB evolved from diseases of our cattle,
influenza from a disease of pigs, and smallpox possibly from a disease
of camels. The Americas had very few native domesticated animal
species from which humans could acquire such diseases.
Let's now push the chain of reasoning back one step further. Why
were there far more species of domesticated animals in Eurasia than
in the Americas? The Americas harbor over a thousand native wild
mammal species, so you might initially suppose that the Americas
offered plenty of starting material for domestication.
In fact, only a tiny fraction of wild mammal species has been successfully
domesticated, because domestication requires that a wild animal
fulfill many prerequisites: the animal has to have a diet that humans
can supply; a rapid growth rate; a willingness to breed in captivity;
a tractable disposition; a social structure involving submissive
behavior towards dominant animals and humans; and lack of a tendency
to panic when fenced in. Thousands of years ago, humans domesticated
every possible large wild mammal species fulfilling all those criteria
and worth domesticating, with the result that there have been no
valuable additions of domestic animals in recent times, despite
the efforts of modern science.
Eurasia ended up with the most domesticated animal species in part
because it's the world's largest land mass and offered the most
wild species to begin with. That preexisting difference was magnified
13,000 years ago at the end of the last Ice Age, when most of the
large mammal species of North and South America became extinct,
perhaps exterminated by the first arriving Indians. As a result,
Native Americans inherited far fewer species of big wild mammals
than did Eurasians, leaving them only with the llama and alpaca
as a domesticate. Differences between the Old and New Worlds in
domesticated plants, especially in large-seeded cereals, are qualitatively
similar to these differences in domesticated mammals, though the
difference is not so extreme.
Another reason for the higher local diversity of domesticated plants
and animals in Eurasia than in the Americas is that Eurasia's main
axis is east/west, whereas the main axis of the Americas is north/south.
Eurasia's east/west axis meant that species domesticated in one
part of Eurasia could easily spread thousands of miles at the same
latitude, encountering the same day-length and climate to which
they were already adapted. As a result, chickens and citrus fruit
domesticated in Southeast Asia quickly spread westward to Europe;
horses domesticated in the Ukraine quickly spread eastward to China;
and the sheep, goats, cattle, wheat, and barley of the Fertile Crescent
quickly spread both west and east.
In contrast, the north/south axis of the Americas meant that species
domesticated in one area couldn't spread far without encountering
day-lengths and climates to which they were not adapted. As a result,
the turkey never spread from its site of domestication in Mexico
to the Andes; llamas and alpacas never spread from the Andes to
Mexico, so that the Indian civilizations of Central and North America
remained entirely without pack animals; and it took thousands of
years for the corn that evolved in Mexico's climate to become modified
into a corn adapted to the short growing season and seasonally changing
day-length of North America.
Eurasia's domesticated plants and animals were important for several
other reasons besides letting Europeans develop nasty germs. Domesticated
plants and animals yield far more calories per acre than do wild
habitats, in which most species are inedible to humans. As a result,
population densities of farmers and herders are typically ten to
a hundred times greater than those of hunter/gatherers. That fact
alone explains why farmers and herders everywhere in the world have
been able to push hunter/gatherers out of land suitable for farming
and herding. Domestic animals revolutionized land transport. They
also revolutionized agriculture, by letting one farmer plough and
manure much more land than the farmer could till or manure by the
farmer's own efforts. Also, hunter/gatherer societies tend to be
egalitarian and to have no political organization beyond the level
of the band or tribe, whereas the food surpluses and storage made
possible by agriculture permitted the development of stratified,
politically centralized societies with governing elites. Those food
surpluses also accelerated the development of technology, by supporting
craftspeople who didn't raise their own food and who could instead
devote themselves to developing metallurgy, writing, swords, and
Thus, we began by identifying a series of proximate explanations
guns, germs, and so on for the conquest of the Americas
by Europeans. Those proximate factors seem to me ultimately traceable
in large part to the Old World's greater number of domesticated
plants, much greater number of domesticated animals, and east/west
axis. The chain of causation is most direct in explaining the Old
World's advantages of horses and nasty germs. But domesticated plants
and animals also led more indirectly to Eurasia's advantage in guns,
swords, oceangoing ships, political organization, and writing, all
of which were products of the large, dense, sedentary, stratified
societies made possible by agriculture.
Let's next examine whether this scheme, derived
from the collision of Europeans with Native Americans, helps us
understand the broadest pattern of African history, which I'll summarize
in five minutes. I'll concentrate on the history of sub-Saharan
Africa, because it was much more isolated from Eurasia by distance
and climate than was North Africa, whose history is closely linked
to Eurasia's history. Here we go again:
Just as we asked why Cortés invaded Mexico before Montezuma
could invade Europe, we can similarly ask why Europeans colonized
sub-Saharan Africa before sub-Saharans could colonize Europe. The
proximate factors were the same familiar ones of guns, steel, oceangoing
ships, political organization, and writing. But again, we can ask
why guns and ships and so on ended up being developed in Europe
rather than in sub-Saharan Africa. To the student of human evolution,
that question is particularly puzzling, because humans have been
evolving for millions of years longer in Africa than in Europe,
and even anatomically modern Homo sapiens may have reached
Europe from Africa only within the last 50,000 years. If time were
a critical factor in the development of human societies, Africa
should have enjoyed an enormous head start and advantage over Europe.
Again, that outcome largely reflects biogeographic differences in
the availability of domesticable wild animal and plant species.
Taking first domestic animals, it's striking that the sole animal
domesticated within sub-Saharan Africa was [you guess] a bird, the
Guinea fowl. All of Africa's mammalian domesticates cattle,
sheep, goats, horses, even dogs entered sub-Saharan Africa
from the north, from Eurasia or North Africa. At first that sounds
astonishing, since we now think of Africa as the continent of big
wild mammals. In fact, none of those famous big wild mammal species
of Africa proved domesticable. They were all disqualified by one
or another problem such as: unsuitable social organization; intractable
behavior; slow growth rate, and so on. Just think what the course
of world history might have been like if Africa's rhinos and hippos
had lent themselves to domestication! If that had been possible,
African cavalry mounted on rhinos or hippos would have made mincemeat
of European cavalry mounted on horses. But it couldn't happen.
Instead, as I mentioned, the livestock adopted in Africa were Eurasian
species that came in from the north. Africa's long axis, like that
of the Americas, is north/south rather than east /west. Those Eurasian
domestic mammals spread southward very slowly in Africa, because
they had to adapt to different climate zones and different animal
The difficulties posed by a north/south axis to the spread of domesticated
species are even more striking for African crops than they are for
livestock. Remember that the food staples of ancient Egypt were
Fertile Crescent and Mediterranean crops like wheat and barley,
which require winter rains and seasonal variation in day length
for their germination. Those crops couldn't spread south in Africa
beyond Ethiopia, beyond which the rains come in the summer and there's
little or no seasonal variation in day length. Instead, the development
of agriculture in the sub-Sahara had to await the domestication
of native African plant species like sorghum and millet, adapted
to Central Africa's summer rains and relatively constant day length.
Ironically, those crops of Central Africa were for the same reason
then unable to spread south to the Mediterranean zone of South Africa,
where once again winter rains and big seasonal variations in day
length prevailed. The southward advance of native African farmers
with Central African crops halted in Natal, beyond which Central
African crops couldn't grow with enormous consequences for
the recent history of South Africa.
In short, a north/south axis, and a paucity of wild plant and animal
species suitable for domestication, were decisive in African history,
just as they were in Native American history. Although native Africans
domesticated some plants in the Sahel and in Ethiopia and in tropical
West Africa, they acquired valuable domestic animals only later,
from the north. The resulting advantages of Europeans in guns, ships,
political organization, and writing permitted Europeans to colonize
Africa, rather than Africans to colonize Europe.
Let's now conclude our whirlwind tour around the
globe by devoting five minutes to the last continent, Australia.
Here we go again, for the last time.
In modern times, Australia was the sole continent still inhabited
only by hunter/gatherers. That makes Australia a critical test of
any theory about continental differences in the evolution of human
societies. Native Australia had no farmers or herders, no writing,
no metal tools, and no political organization beyond the level of
the tribe or band. Those, of course, are the reasons why European
guns and germs destroyed Aboriginal Australian society. But why
had all Native Australians remained hunter/gatherers?
There are three obvious reasons. First, even to this day no native
Australian animal species and only one plant species (the macadamia
nut) have proved suitable for domestication. There still are no
Second, Australia is the smallest continent, and most of it can
support only small human populations because of low rainfall and
productivity. Hence the total number of Australian hunter /gatherers
was only about 300,000.
Finally, Australia is the most isolated continent. The sole outside
contacts of Aboriginal Australians were tenuous overwater contacts
with New Guineans and Indonesians.
To get an idea of the significance of that small population size
and isolation for the pace of development in Australia, consider
the Australian island of Tasmania, which had the most extraordinary
human society in the modern world. Tasmania is just an island of
modest size, but it was the most extreme outpost of the most extreme
continent, and it illuminates a big issue in the evolution of all
human societies. Tasmania lies 130 miles southeast of Australia.
When it was first visited by Europeans in 1642, Tasmania was occupied
by 4,000 hunter/gatherers related to mainland Australians, but with
the simplest technology of any recent people on Earth. Unlike mainland
Aboriginal Australians, Tasmanians couldn't start a fire; they had
no boomerangs, spear throwers, or shields; they had no bone tools,
no specialized stone tools, and no compound tools like an axe head
mounted on a handle; they couldn't cut down a tree or hollow out
a canoe; they lacked sewing to make sewn clothing, despite Tasmania's
cold winter climate with snow; and, incredibly, though they lived
mostly on the sea coast, the Tasmanians didn't catch or eat fish.
How did those enormous gaps in Tasmanian material culture arise?
The answer stems from the fact that Tasmania used to be joined to
the southern Australian mainland at Pleistocene times of low sea
level, until that land bridge was severed by rising sea level 10,000
years ago. People walked out to Tasmania tens of thousands of years
ago, when it was still part of Australia. Once that land bridge
was severed, though, there was absolutely no further contact of
Tasmanians with mainland Australians or with any other people on
Earth until European arrival in 1642, because both Tasmanians and
mainland Australians lacked watercraft capable of crossing those
130-mile straits between Tasmania and Australia. Tasmanian history
is thus a study of human isolation unprecedented except in science
fiction namely, complete isolation from other humans for
10,000 years. Tasmania had the smallest and most isolated human
population in the world. If population size and isolation have any
effect on accumulation of inventions, we should expect to see that
effect in Tasmania.
If all those technologies that I mentioned, absent from Tasmania
but present on the opposite Australian mainland, were invented by
Australians within the last 10,000 years, we can surely conclude
at least that Tasmania's tiny population didn't invent them independently.
Astonishingly, the archaeological record demonstrates something
further: Tasmanians actually abandoned some technologies that they
brought with them from Australia and that persisted on the Australian
mainland. For example, bone tools and the practice of fishing were
both present in Tasmania at the time that the land bridge was severed,
and both disappeared from Tasmania by around 1500 B.C. That represents
the loss of valuable technologies: fish could have been smoked to
provide a winter food supply, and bone needles could have been used
to sew warm clothes.
What sense can we make of these cultural losses?
The only interpretation that makes sense to me goes as follows.
First, technology has to be invented or adopted. Human societies
vary in lots of independent factors affecting their openness to
innovation. Hence the higher the human population and the more societies
there are on an island or continent, the greater the chance of any
given invention being conceived and adopted somewhere there.
Second, for all human societies except those of totally-isolated
Tasmania, most technological innovations diffuse in from the outside,
instead of being invented locally, so one expects the evolution
of technology to proceed most rapidly in societies most closely
connected with outside societies.
Finally, technology not only has to be adopted; it also has to be
maintained. All human societies go through fads in which they temporarily
either adopt practices of little use or else abandon practices of
considerable use. Whenever such economically senseless taboos arise
in an area with many competing human societies, only some societies
will adopt the taboo at a given time. Other societies will retain
the useful practice, and will either outcompete the societies that
lost it, or else will be there as a model for the societies with
the taboos to repent their error and reacquire the practice. If
Tasmanians had remained in contact with mainland Australians, they
could have rediscovered the value and techniques of fishing and
making bone tools that they had lost. But that couldn't happen in
the complete isolation of Tasmania, where cultural losses became
In short, the message of the differences between Tasmanian and mainland
Australian societies seems to be the following. All other things
being equal, the rate of human invention is faster, and the rate
of cultural loss is slower, in areas occupied by many competing
societies with many individuals and in contact with societies elsewhere.
If this interpretation is correct, then it's likely to be of much
broader significance. It probably provides part of the explanation
why native Australians, on the world's smallest and most isolated
continent, remained Stone Age hunter/ gatherers, while people of
other continents were adopting agriculture and metal. It's also
likely to contribute to the differences that I already discussed
between the farmers of sub-Saharan Africa, the farmers of the much
larger Americas, and the farmers of the still larger Eurasia.
Naturally, there are many important factors in
world history that I haven't had time to discuss in 40 minutes,
and that I do discuss in my book. For example, I've said little
or nothing about the distribution of domesticable plants (3 chapters);
about the precise way in which complex political institutions and
the development of writing and technology and organized religion
depend on agriculture and herding; about the fascinating reasons
for the differences within Eurasia between China, India, the Near
East, and Europe; and about the effects of individuals, and of cultural
differences unrelated to the environment, on history. But it's now
time to summarize the overall meaning of this whirlwind tour through
human history, with its unequally distributed guns and germs.
The broadest pattern of history namely, the differences between
human societies on different continents seems to me to be
attributable to differences among continental environments, and
not to biological differences among peoples themselves. In particular,
the availability of wild plant and animal species suitable for domestication,
and the ease with which those species could spread without encountering
unsuitable climates, contributed decisively to the varying rates
of rise of agriculture and herding, which in turn contributed decisively
to the rise of human population numbers, population densities, and
food surpluses, which in turn contributed decisively to the development
of epidemic infectious diseases, writing, technology, and political
organization. In addition, the histories of Tasmania and Australia
warn us that the differing areas and isolations of the continents,
by determining the number of competing societies, may have been
another important factor in human development.
As a biologist practicing laboratory experimental science, I'm aware
that some scientists may be inclined to dismiss these historical
interpretations as unprovable speculation, because they're not founded
on replicated laboratory experiments. The same objection can be
raised against any of the historical sciences, including astronomy,
evolutionary biology, geology, and paleontology. The objection can
of course be raised against the whole field of history, and most
of the other social sciences. That's the reason why we're uncomfortable
about considering history as a science. It's classified as a social
science, which is considered not quite scientific.
But remember that the word "science" isn't derived from the Latin
word for "replicated laboratory experiment," but instead from the
Latin word "scientia" for "knowledge." In science, we seek knowledge
by whatever methodologies are available and appropriate. There are
many fields that no one hesitates to consider sciences even though
replicated laboratory experiments in those fields would be immoral,
illegal, or impossible. We can't manipulate some stars while maintaining
other stars as controls; we can't start and stop ice ages, and we
can't experiment with designing and evolving dinosaurs. Nevertheless,
we can still gain considerable insight into these historical fields
by other means. Then we should surely be able to understand human
history, because introspection and preserved writings give us far
more insight into the ways of past humans than we have into the
ways of past dinosaurs. For that reason I'm optimistic that we can
eventually arrive at convincing explanations for these broadest
patterns of human history.