Book Summary: “Understanding Human History” by Michael Hart

Title: Understanding Human History
Author: Michael Hart
Scope: 4 stars
Readability: 3 stars
My personal rating: 4 stars
See more on my book rating system.

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Topic of Book

Hart outlines early human history and argues that levels of intelligence account for different levels of development by each ethnicity.

If you would like to understand history in a new way, read my book From Poverty to Progress: How Humans Invented Progress, and How We Can Keep It Going.

My Comments

I do not agree with Hart’s theory that intelligence is the main factor in accounting for different levels of development between ethnicities. He does, however, give an excellent account of different ethnic groups around the world and their pre-historic migrations.

If living in a cold, hostile environment leads to higher levels of intelligence, why aren’t the Eskimos, Aleuts, Inuits, Sami, Chuckchis and Nenets who all live in the Arctic the most intelligent people in the world? Nor do I believe that cold temperatures are the most important determinants of a harsh environment that forces the evolution of human intelligence. The Ancient Romans, Greeks and Middle Easterners seem to have done fine despite living in moderate climates.

Key Take-aways

Hart argues the following:

  • The differences in average intelligence that evolved between the human races have been a major factor in the course of human history and prehistory.
  • Intelligence is key to survival of humans in harsh environment.
  • Twins studies clearly show that intelligence is largely heritable.
  • Unrelated adults who are raised in the same family have no correlation in intelligence.
  • High intelligence enhances many other abilities.
  • Ethnicities who inhabited cold, northern regimes have higher average intelligence (Europeans, East Asians, Mongols and Turks). This hostile environment forced them to evolve higher levels of intelligence. This higher intelligence enabled them to evolve more complex societies.
  • Throughout history, most of the instances of people from one region attacking and conquering substantial portions of another region have involved “northerners” invading more southerly lands.

Important Quotes from Book

Since there are already many books on world history, the reader may wonder why I have chosen to write another one. The answer is that most such books are unsatisfactory because they omit a crucial factor in human history.

Historians have come to appreciate the critical role that scientific and technological advances have on human affairs. However, although it is now common for world histories to mention such advances, they usually do not delve very deeply into their causes.

In general, all such advances arise from human intelligence, and in particular from the application of the superior intelligence of one or more unusually talented individuals.

How did that high human intelligence arise? The answer comes from Darwin’s theory of evolution. At some point in the distant past, the average intelligence of our ancestors was much lower than the average intelligence of humans living today. It is through the process of Darwinian evolution — and that alone — that the high intelligence needed to produce technological advances has arisen.

In particular, groups that resided for many millennia in regions with cold winters gradually — through the process of natural selection — evolved higher average intelligence than the groups living in milder climates.

As a result, the peoples living in Northern Asia and Europe now have mean IQs of about 100, while the peoples living in sub-Saharan Africa have average IQs of around 70, and those living in a broad intermediate zone (stretching from North Africa across southern Asia and into Indonesia) have average IQs in the 80-90 range. At least four different types of evidence confirm these differences in intelligence:

1) The results of numerous IQ tests taken over a period of more than 80 years, not just in the United States but in many other countries.

2) Measurements of the average brain size of the members of various racial groups.

3) The poor performance (on average) of blacks in Europe and America in economic matters, contributions to mathematics and science, and in games of intellectual skill, such as tournament chess and duplicate bridge.

4) The extreme backwardness of the countries in the secluded zone of sub-Saharan Africa before they had contact with either Islamic or European civilization.

The differences in average intelligence that evolved between the human races have been a major factor in the course of human history and prehistory. Any theory that ignores those differences, or denies their existence, will therefore be unable to explain various major aspects of history.

When genes replicate, their “children” are identical to the original genes. But although human beings reproduce, they never replicate: human children are not copies of their parents. Genes make copies of themselves; human beings do not, nor do members of any other sexually reproducing species.

Still, virtually all modern scientists agree that Darwin’s central insight — evolution by means of natural selection — was correct.

Nevertheless, lots of people have never really accepted the theory of evolution. The most obvious of these are religious fundamentalists, many of whom openly dispute the theory. A more important group, however, consists of the numerous persons who say (and think) that they accept the theory of evolution, but who in fact shrink from accepting the implications of that theory. Among those unwelcome implications are:

1) Human beings are animals

2) Evolution is a completely amoral process.

3) A person’s physical capabilities and limitations are strongly influenced by his genes.

4) A person’s mental attributes (i.e., his individual abilities and proclivities) are also influenced by his genes — not rigidly determined, but strongly influenced. The notion that we are entirely products of our environments is therefore false.

5) The observed behavioral differences between the sexes are strongly influenced by our genes — again, not rigidly determined, but strongly influenced. Even less welcome, perhaps, are these other implications of the theory:

6) Whenever two populations within a species are reproductively isolated, they will diverge from each other genetically. If they are in different environments, this will occur by natural selection; but it will occur by genetic drift even if the environments are the same.

7) The process of evolution did not stop with the emergence of Homo sapiens, nor with the emergence of Homo sapiens sapiens (the branch of that species to which all living humans belong). Rather, evolution has continued and has produced visible differences between human groups whose ancestors evolved in different regions.

8) There is no reason to suppose that the visible differences we see between the regional variations of human beings are the only differences that exist between them. On the contrary, it would be very surprising if that were the case.

A race (or subspecies, or variety, or breed) might be defined as a large group of individuals — all of them members of the same species — who have formed a partially or completely isolated breeding population for a significant period of time, and who consequently differ statistically from the rest of the species in various heritable traits by which they can be recognized.

Perhaps the best known example of a species that includes various breeds or subspecies is the domestic dog, Canis familiaris.

It is clear that high intelligence does not, by itself, ensure an individual’s success.

Nor is high intelligence — or even average intelligence — necessary for an individual to function capably in everyday life… As long as their job or occupation does not require a high degree of abstract reasoning, such persons are able to perform their duties in an adequate manner.

However, although high intelligence is neither necessary for functioning in ordinary circumstances, nor sufficient by itself for marked success, it is not unimportant. In the first place, there are certain tasks for which high intelligence is an absolute requisite. For example, one can hardly imagine a person of average intelligence teaching a course in quantum mechanics

In the second place, high intelligence enhances most other abilities. Even when a job or task can be performed adequately by someone of average intelligence, it can usually be performed better by a person of higher intelligence.12 This holds for such varied tasks as planting crops, composing music, or waiting on tables. It is even true for many menial tasks.

Finally, high intelligence plays a crucial role in inventions. Every aspect of our modern world and its technology had to be invented, and virtually none of those innovations were obvious. It seems highly probable that throughout history (and prehistory) all the important inventions and innovations were made by persons who were far above average intelligence.

Perhaps the most straightforward way of measuring the heritability of IQ is by comparing the IQs of identical twins who were reared separately. Although such pairs (called “monozygotic apart” or “MZA” in the literature) are quite rare, because of their theoretical importance they have been sought out and carefully studied. Every study shows a high correlation between the IQs of MZAs, with the correlations ranging from 0.69 to 0.78.

These results should be compared with the correlation between the IQs of ordinary siblings reared together which is only 0.49.17 (Such pairs share half of their genes in addition to having been reared in very similar environments.) Even in the case of fraternal twins reared together, the correlation of the IQs is only about 0.60.18 That is a high figure, but still a good deal lower than for identical twins reared apart, which suggests that genetic factors are more powerful than environmental ones in shaping a person’s IQ.

Another approach is to compare the correlation between the adult IQs of ordinary siblings who have been reared apart (which is about 0.47) with the correlation between the IQs of unrelated adults who were reared together (which is nearly zero).

The empirical data, however, makes it very clear that we do know the answer. Both genetic and environmental factors affect a person’s intelligence, with the influence of heredity being somewhat larger than that of his upbringing and environment, perhaps considerably larger.

The essential points of this chapter can be summarized rather easily. Basically, many of the old common-sense views about intelligence that used to be widely accepted (and would probably be readily accepted today if racial concerns did not make us self-conscious) are compatible with recent scientific studies.

In primitive speech (such as many animals possess):

• The vocabulary is small.

• Each sentence consists of a single word.

• There are no grammatical rules.

On the other hand, in a fully-developed language (or “syntactic language”):

• There is a large vocabulary.

• Multi-word sentences (sometimes quite lengthy ones) are common.

• There are rules for expressing:

a) Negatives.

b) Conditional or hypothetical statements.

c) The distinction between the subject and the object of a verb.

d) A full range of tenses, including past, present, future, future perfect, pluperfect, and so forth

In the course of human history and prehistory there have been many inventions of great importance, including agriculture, metalworking, printing, firearms, antibiotics, and computers. But none of those was nearly as important as the invention of speech.

It is speech — syntactic language — that truly separates us from all other animals.

It has often been noted that human beings living in civilized states appear to follow a dual code of morality. Within our own society, cooperation is highly valued, and killing another person is a grievous sin. However, when we are engaged in a war with another nation, not only are we permitted to kill members of that nation, but we are encouraged to do so. Indeed, those who are conspicuously successful in wreaking havoc and destruction upon that other nation are highly praised and considered to be heroes.

Nor is this dual code something that exists only in civilized states. It appears to be equally present in primitive tribes and bands. Within a band, the standard of proper behavior involves helpfulness and cooperation. But that code holds only within the band. Members of unrelated bands can be attacked, plundered, or killed without incurring the disapproval of one’s fellow band members.

Although I have been referring to this collection of attitudes as a “dual code of morality,” upon consideration one can see that at heart these attitudes really comprise a single standard, which might be expressed as: “Do what is best for your own group.”

Racial differences in physical traits are real, widespread, and often of great importance.

Contrary to the claim of some ideologues, physical differences between the races are not confined to a few “superficial” traits. On the contrary, differences between racial groups include resistance to various diseases, and also appear in a wide variety of physical traits and systems, including the reproductive system, the bones, the eyes, the muscles, and the blood. Nor are the observed genetic differences without importance; on the contrary, some of the differences have large — even lethal — consequences.

I would suggest, however, that the existence of racial differences in intelligence is not a moral question at all, but merely a factual question.

The attempt to turn factual questions into moral questions is the essence of dogmatism, and has long been a hindrance to scientific progress.

The evidence [for racial differences in IQ] is so overwhelming that even scholars who stoutly maintain that environmental factors can completely explain the difference in test scores between the two groups admit that the difference exists.

Arguments that there is a strong genetic component in:

A) The magnitude of δ has changed very little in the eight decades since it was first observed.

B) The low average intelligence of blacks is a worldwide phenomenon.

C) None of the environmental theories that have been suggested adequately explains δ.

Studies have been made of the results by dividing the students into four groups depending on their parents’ income. For both blacks and whites, average test scores rise sharply with increasing parental income. However, within each of the four income groups, the black average is at least 144 points lower than the whites. (Until very recently, the difference between a perfect test score and an absolute bottom was 1200 points.) Furthermore, blacks whose parental income exceeded $70,000 a year (the highest of the four categories) have on average obtained lower SAT scores than whites whose parental income is less than $20,000 a year (the lowest of the four categories).

These results appear to refute the notion that the low test scores of blacks are caused entirely — or even mostly — by their relative poverty.

In the second place, when we compare blacks and whites whose parents are from the same SES (socioeconomic status, as measured by a combination of affluence, occupation, and education) the difference in mean IQs between the races does not fall to nearly zero — as predicted by extreme environmentalism — but is still about 9 points, or more.  At first sight, this would suggest that genetic factors are responsible for only 9/15, or 60% of the difference in IQ scores. In fact, it indicates that genetic factors are responsible for at least 60% of the difference, since they might also be responsible for much of the difference in parental SES. (The first, incorrect inference is an example of the “sociologist’s fallacy.”8)

D) Even the best planned and most lavishly funded “early intervention” projects have failed to bring the average IQs of adult blacks up to, or close to, the white level.

The largest and most carefully studied such program was the Minnesota Transracial

Adoption Study.

Note that in each racial category the children in the study scored much higher than is usual for children of that racial group. Plainly, the enriched environment was highly beneficial. Nevertheless, when the children were tested again at age 17, most of the improvement in IQ scores had vanished…. In particular, the average score of the black adoptees was 89.4, which is only 4.4 points higher than blacks in the general population, and more than ten points less than whites in the general population. Note that for the adoptees in the study, the gap between the mean IQ scores of 17-year-old whites and blacks was over 16 points — every bit as large a difference as found in the general population.

E) The differences between the environments of American blacks and whites have not resulted in any black inferiority in physical skills.

F) Since genes have caused so many physical differences between the races, it is implausible that they have not caused any mental differences.

G) Blacks, on average, have smaller brains than whites.

H) Most of sub-Saharan Africa was extremely primitive before it came into contact with the West two centuries ago.

I) It appears that not a single major invention of the last 20,000 years was made in sub-Saharan Africa.

K) While environmentalists often attack the evidence that δ is due to genetic factors, they rarely offer any direct evidence of the alleged equality of black and white native intelligence.

Indeed, the overall evidence in favor of this conclusion is so great that no one would dispute the point if it was not an issue that aroused strong emotions on ideological grounds.

The evolution of sufficiently high intelligence was therefore an essential preliminary for the invention of agriculture. The sequence of historical events suggests that an average IQ of about 79 was needed for the independent invention of agriculture, even in a region with a warm climate and abundant rainfall. This single factor explains why agriculture was not invented a million years ago — nor 100 kya, nor even 50 kya — even though plants and animals suitable for domestication had been available throughout the Pleistocene Era. It also explains why agriculture did not originate spontaneously in tropical regions such as India, Indonesia, or SSA (sub-Saharan Africa).

Jared Diamond’s theory cannot explain why MesoAmerica developed faster than Sub-Saharan Africa, despite SSA have more advantages (more domesticatable plants and animals).

Middle East

[The reason why Middle East fell behind Europe and China once they acquired agriculture]  is that it was the higher average intelligence of the northern peoples (the Europeans and the Mongoloids) that enabled them to catch up with and surpass the Middle East.

Ancient Greece

[The reason for Ancient Greece] were due to the high native intelligence of the Greeks. This suggestion is also partly correct. It appears that the Indo-European tribes who were the immediate ancestors of the Greeks had, on average, substantially higher IQs than the Egyptians, Minoans, Sumerians, and the various Semitic peoples in the Middle East.

The best explanation for the Greek phenomenon lies in a combination of genetic and geographic factors. The peoples living in the cold regions of Europe had, over a period of many millennia, evolved higher average intelligence than the peoples living in the Middle East. However, because of the mild climate in the Middle East, and the availability of a large assortment of useful domesticable plants and animals, the inhabitants of the Middle East developed agriculture long before the peoples of northern Europe. The early advent of agriculture and cities in the Middle East enabled them to make major progress during the Neolithic Era and the early historic era, and to get a big jump on the rest of the world in technology and in intellectual matters. In time, the superior genetic endowment of the Europeans would enable them to overcome that head start. However, between European groups, the one most likely to advance first was the one which had the earliest opportunity of learning from the civilizations of the Middle East and Egypt. Because of their geographic location, the Greeks were the first European people to come into contact with those civilizations.

Ancient China:

Originally, the inhabitants of northern and southern China were very different racially.1 Southern China was settled by σ-3 who entered from Southeast Asia, whereas northern China was settled by M-1 (Mongoloids), who entered from the north. (See Map 10-1 and sections 11-4 and 12-6.) The two groups differed in appearance and in average IQ. The M-1 had already evolved a high intelligence before their entrance into China, and the cold winters of northern China tended to continue that process.

After agriculture was introduced into northern China (about 6400 BC) the North China Plain became capable of supporting a high population. From then on, the people of the North China Plain enjoyed a combination of (a) high average intelligence, (b) a large region of very fertile soil and adequate rainfall, and (c) nearby regions into which they could expand.

It was this unusual combination that explains the rise, spread, and remarkable size of the Chinese population. As the population of the North China Plain increased, excess population kept overflowing into the rest of northern China, resulting in a large, relatively homogeneous population with a high average IQ. Because the geographic barriers within northern China are relatively minor, movement was easy, which resulted in relatively little linguistic variation within the region.

Eventually, the north Chinese spread into southern China, and gradually most of the southern Chinese have been assimilated into the dominant culture.

Because of substantial interbreeding between the two groups, the original differences in appearance and intelligence between the northern and southern Chinese have become muted in the course of the last two millennia.

On an overall basis, Chinese civilization is the only one that rivals European civilization.

The Chinese — virtually unaided by outsiders — created a complex and complete civilization, with a smoothly functioning government, and multitudinous achievements in technology, construction, literature, the arts, and philosophy. They had a wide variety of skilled craftsmen; they maintained large, powerful armies; and they created a school system, a network of roads, an elaborate (and delicious) cuisine, and all the other attributes of a sophisticated civilization.

Between 600 and 1300 AD, China was clearly more prosperous than the West… the interval 600-1300 AD was atypical. For most of recorded history — and for most of the last ten thousand years — China has been well behind the Western world in both technology and the arts. The relative backwardness of China is apparent in such important fields as agriculture, writing, astronomy, mathematics, metalworking, and cloth making.


From the linguistic and genetic data, it appears that there were three main migrations of HSS into India:

1) An early migration (before 50 kya) by σ-1 from the Middle East.

2) A second migration (about 8 kya), by Caucasoid, Dravidian-speaking farmers from the Middle East.

3) A third migration (about 3.5 kya), by Caucasoid, Indo-European-speaking tribes (the Aryans) coming from Afghanistan and/or Iran.

Note that the only large empires ruled by native Indians were the Mauryan and Gupta empires, and that these endured for a combined total of less than 400 years. Note also that in its entire history India has never conquered, or even invaded, any sizable territory outside the Indian subcontinent.

The caste system in Hinduism originally had a racial basis. The Aryan invaders relegated the darker-skinned people whom they had conquered to the lowest of the four main castes (the Sudras, or workers), while reserving the three higher castes for themselves.

The average IQ in India is considerably lower than in China or Europe. If we assume that a very high level of the talents measured by intelligence tests is essential for major breakthroughs in mathematics, science, and invention, but not as crucial for artistic achievements, it would explain why Indian civilization was able to produce so much of the latter, but so little of the former. It seems likely, therefore, that this is the best of the three explanations.

Northern Asia

By about 30 kya the M-1 or Mongolids (the Asian branch of the Mongoloid race) and the M-2 (or pre-Amerindians) had separated from each other (see section 12-4). The Mongolids are the most cold-selected branch of the human race and, with the possible exception of the European Caucasoids, the group with the highest average intelligence. The Mongolids eventually split into two main groups, which are genetically very similar to each other.

1) The Southern Mongolids. At an early stage, this group migrated southward into northern China. The North Chinese and some closely related peoples are descended from them.

2) The Northern Mongolids (hereafter abbreviated NM). This group remained in Mongolia and Siberia, although some of them later migrated into other areas.

The NM have never been very numerous; however, because of their military prowess they have had a great impact on the peoples dwelling south and west of them. It is probable that an important element in that military prowess was the high average intelligence that the NM evolved during their long stay in a region where the winters were so brutally cold.

Three thousand years ago, less than 1 percent of the world’s population spoke Altaic languages; and even today, less than 1. percent do. It is therefore not surprising that the Altaics have not made a large contribution to the arts and sciences.

What is surprising is the extent of their military conquests. Most history books agree that the Mongol conquests of the 13th century were astonishing in their magnitude, and that by 1280 Kubilai Khan ruled the largest empire in history. What is rarely mentioned, though, is that the territory ruled or occupied by Altaics in the late 17th century was even larger, and far more populous than Kubilai’s realm had ever been (see Map 39-3).

In 1700, the Ottoman, Mughal, and Manchu dynasties were all flourishing, and most of Central Asia and Siberia was also occupied by Altaic-speaking peoples.

The three large Altaic-ruled empires contained a majority of the world’s population!

How can we explain the Altaics astonishing expansion? The Chinese, Indians, Arabs, and Europeans whose lands they had conquered were at least as advanced technologically as the Altaics, and outnumbered them enormously. The simplest explanation is that the average intelligence of the Altaics was very high (which is consistent with the theoretical calculations summarized in Table 17-1) and that this high intelligence manifested itself as a combination of very capable soldiers and extraordinarily able leadership.

Sub-Saharan Africa

A major factor in the history of SSA has been the very low average intelligence of its inhabitants. Average IQ scores, as measured by conventional tests, vary from country to country, but are typically around 70 (see Table 15-2). As there is no reason to believe that they have fallen significantly in historical times, it seems likely that average IQs in SSA have been that low for many millennia.


Why was Europe the site of the earliest transition to modern times?

For most regions (the chief exception is China) the answer is obvious: The people living there were not, on average, as intelligent as the inhabitants of Europe; consequently, those regions lacked the supply of exceptionally talented persons necessary to produce the important discoveries and inventions that characterize the modern age and the transition into it.

Broad Trends in History

Throughout history, most of the instances of people from one region attacking and conquering substantial portions of another region have involved “northerners” invading more southerly lands. The European conquests of third-world countries in recent centuries are the most obvious examples of this, but the pattern existed long before modern times.

China, for example, has never been attacked by any of the populous countries south of it, but it has been repeatedly attacked from the north. India, despite its large population, has never invaded the countries north of it, but rather has been repeatedly invaded from the north and northwest.

Note also that the three Indian dynasties which came closest to ruling the entire subcontinent (the Mauryas, the Guptas, and the Mughals) all originated in the north.

The Greeks were not the original inhabitants of Greece, but were invaders who entered from the north about 2000 BC. Although the Greeks later founded many colonies.

The ancestors of the Romans entered Italy from the north, probably in the second millennium BC.

The Arab conquests are the only major counter-example to the general rule… However, Arab control of Southwest Asia only lasted for a few centuries. It ended when the region was invaded by Turkish tribes (from Central Asia) and by the Mongols (from northern Asia), who between them ruled most of Southwest Asia for over nine hundred years.

The most extensive conquests of pre-modern times were those made by the Mongols.

The obvious — and, I believe, the correct — explanation for the military superiority of the northerly peoples is the higher average intelligence of those peoples compared with the inhabitants of more tropical regions.

The meagerness of contributions from Southeast Asia, Australia, and SSA during the Neolithic Era and pre-modern times is also apparent… This was true even in the Late Paleolithic

Why didn’t the northern peoples dominate the tropical ones earlier?

Since the higher average IQ of the northerners originated in prehistoric times, why was it not until recently that they gained control of the more tropical regions? Two factors seem to be involved:

The first factor was that the peoples residing in the Middle East and central China had originated agriculture earlier than the northerners did. This had occurred  because the milder climate there made the introduction of agriculture easier than in more northern climates; and in addition, the Middle East had a large number of plants and animals that were both useful and easily domesticated. As a result, the Middle East and central China obtained a large head start on the more northern peoples.

The second factor was that in pre-modern times it was hard to move armies over large distances. It was not until fairly recently that the growth of technology enabled the Europeans to project their power far overseas; until then, most of the backward regions of the Earth were protected by geographic barriers, and by the sheer distance.

If you would like to understand history in a new way, read my book From Poverty to Progress: How Humans Invented Progress, and How We Can Keep It Going.

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