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Sex Differences in Intelligence: The Developmental Theory
In Sex Differences in Intelligence , Dr Richard Lynn refutes the belief that males and females are equally smart. He presents the findings of his extensive research showing that, on the contrary, the average intelligence of young girls is higher than that of young boys. It is only in school-age students that boys and girls have approximately the same intelligence, while in adults the average intelligence of men is four IQ points higher than that of women. Lynn supports his Developmental Theory with a review of well over a hundred studies conducted by himself and a host of other reputable scientists. The book discusses the reasons for the higher average intelligence of men among adults. One of these is that men have a larger average brain size than women. He refutes the contention of some feminists that brain size has no relation to intelligence. He argues that men have evolved higher average intelligence than that of women because this enhances their ability, in competition with other men for territory or status, to obtain women and thus pass on their genes. Another evolutionary explanation for men having a higher IQ lies in sexual selection such that females normally prefer to accept males with high intelligence as mates because they view them as potentially better providers for themselves and their children. This path-breaking book will revolutionise the understanding of sex differences in intelligence.
- GenresPsychology
160 pages, Kindle Edition
Published December 8, 2021
About the author
Richard Lynn
47 books89 followersBritish Professor Emeritus of Psychology, who is known for his views on racial and ethnic differences.
Lynn was educated at Cambridge University. He has worked as lecturer in psychology at the University of Exeter, and as professor of psychology at the Economic and Social Research Institute, Dublin, and at the University of Ulster at Coleraine.
Most of his books are about the differences of IQ between different etnicities.
Lynn was educated at Cambridge University. He has worked as lecturer in psychology at the University of Exeter, and as professor of psychology at the Economic and Social Research Institute, Dublin, and at the University of Ulster at Coleraine.
Most of his books are about the differences of IQ between different etnicities.
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Displaying 1 - 5 of 6 reviews
December 29, 2021
Only a 4 because most of the text is a dry, technical laying out of evidence supporting the thesis--primarily that there is an adult male IQ advantage over females of 4 points, and thus that the very common claim that there is no difference in general intelligence between the sexes is false.
February 16, 2026
Authoritative take on a difficult topic by the dean of living intelligence researchers.
Diversity. Equity. Inclusion. DEI – it is the mantra of the present generation. Richard Lynn, at something over 80, the dean of living intelligence researchers, has been the bête noire of the politically correct since long before they invented the terms woke, cancel culture and the like.
Lynn knows the literature in the field inside and out. He cites all of the significant authors and works, going out of his way to include references to the people who disagree with him. He treats them with courtesy, and politely points out where they err.
The other authors tend to overlook inconvenient facts, sometimes perhaps by accident, but often in the interest of saving their careers. Steven Pinker pointed out two decades ago in his The Blank Slate how dangerous it is to hold wrong opinions on matters concerning intelligence.
Lynn offer us a little bit of evolutionary history to explain why men and women are different. It applies as well to differences among human breeding populations, the topic of many of his previous books. The differences in intelligence between the sexes are much less significant among peoples whose evolutionary history did not lead through migration to cold climates and to agriculture.
The hominid line remained in Africa long after it split from chimpanzees seven million years ago. Early on we learned to walk upright, use makeshift tools, throw things, and grasp things with our opposable thumbs. The hemispheres of our brains evolved to follow the right/left specialization of our hands. We developed shared attention – the ability to have two people focus on the same object at one time with the intent of doing something or sharing knowledge about it.
A couple of million years ago those hands started to use sticks and rocks as tools, then to chip primitive tools from stone. About the same time we tamed fire. New species of hominids continued to evolve, some of such as the Neanderthals and the Denisovans migrated into Eurasia. As their culture became more complex, there was an increasing need to pass acquired knowledge down to children by showing them how to chip stones, make fires, make dwellings and the like.
One hundred and fifty thousand years ago, in other words, very recently, Homo sapiens evolved speech. Now we were able to communicate verbally about our objects of shared attention.
Mothers were able to ask others in the tribe, sisters, older children and their own mothers, for help with the children. With the help of others, women were able to bear children every two years instead of the six years’ spacing characteristic of ape mothers. Homo sapiens’ numbers grew. In this was presumably also the time at which the battle between the sexes moved to an oral battleground. Women were able to verbalize what they wanted. See [[ASIN:0345408934 Mother Nature]] and [[ASIN:0674060326 Mothers and Others]].
Our numbers grew. Homo sapiens expanded north out of Africa perhaps 70,000 years ago. We pushed the other species of ape men into extinction in Eurasia. About 15,000 years ago we spread from Siberia to Alaska and populated the Western hemisphere. Simultaneously we initiated the New Stone Age, with a much broader stick, stone and bone toolset. We put handles on our axes, stone tips on our spears and arrows, invented bows and harpoons, started to make pottery, invented needles to make clothing and so on.
We discovered that it was useful to drop the seeds of fruit trees and edible grasses along the way as we wandered. About 10,000 years ago we had advanced to the point where we could stay put and grow what we needed to eat. We started to settle in villages.This was the dawn of agriculture. We simultaneously learned to herd animals.
Tribes had been so closely related that relaxed sexual practices of such as those of today’s tribal Africans, Indians and Eskimos didn’t matter. Our ancestors swapped partners with abandon. Any kid born was welcome to the tribe. Women seem to have liked it this way. Benjamin Franklin lamented that colonial women who were taken captive by the Indians very often didn’t want to return.
With agriculture, paternity became an issue – a man wanted to leave something to his kids, and he wanted to be sure that they were his. There was a significant change in the relationship between men and women. People now came in contact with enough others that they became accustomed to dealing with strangers. The people around them were no longer close kin. They became wealthy enough that there was something to inherit when a man died.
Women were now more often obliged to stick with one partner. That partner was the biggest choice they’ve made in life – his ability to provide determined her status and her well-being. Whereas tribal women can feed themselves by scratching the ground and growing yams, manioc and taro, women in agricultural communities in colder climes depended on their men for food and protection. It was of course reciprocal. Women played essential roles in growing, preparing, and cooking food, making clothes, tending the children and so on.
The emergence of the patriarchy – man’s control over women’s sexuality and sustenance – meant that women had to persuade men in order to get what they wanted. As every man knows, they have evolved to be quite adept at this.
This concludes my argument in concurrence with Lynn’s observation that sex differences in intelligence are greater among Europeans and Asians and among other human populations.
The book includes a vast number of meta-analyses of scholarship by other researchers. It includes table after table of figures showing how averages between men and women differ by measurement after measurement. Though some differences are by absolute measure – such as the number of cubic centimeters and male and female brains – most of the differences are cited in standard deviations, a measure that may not be readily understandable to the average reader. Lynn’s graphics are useful in helping the reader understand what the numbers mean.
This work is a milestone of scholarship, not merely the capstone of a long career of making his own contributions to the field of intelligence research, but a summary of the state-of-the-art in all of intelligence research.
There have not been significant improvements in the techniques of statistical analysis over the past 20 years or so. The big new insights in intelligence research are more in the realms of genetics, epigenetics, nutrition and environmental factors such as pesticides and so on. In other words, one can be fairly confident that what Lynn is laying out here is not likely to change vastly any time soon to reflect new research. We will become better at explaining why it is, but what it is is well known.
Two writers who have made significant recent contributions to the study of intelligence are Robert Plomin in [[ASIN:B08BT69SZK Blueprint]] and Richard Haier with [[ASIN:110746143X The Neuroscience of Intelligence ]]. Though, as Lynn states, their stated opinions about sex differences do not necessarily agree with his, their research would point the same direction.
A five-star work. If Amazon gave awards for bravery he would get five stars as well for that.
Diversity. Equity. Inclusion. DEI – it is the mantra of the present generation. Richard Lynn, at something over 80, the dean of living intelligence researchers, has been the bête noire of the politically correct since long before they invented the terms woke, cancel culture and the like.
Lynn knows the literature in the field inside and out. He cites all of the significant authors and works, going out of his way to include references to the people who disagree with him. He treats them with courtesy, and politely points out where they err.
The other authors tend to overlook inconvenient facts, sometimes perhaps by accident, but often in the interest of saving their careers. Steven Pinker pointed out two decades ago in his The Blank Slate how dangerous it is to hold wrong opinions on matters concerning intelligence.
Lynn offer us a little bit of evolutionary history to explain why men and women are different. It applies as well to differences among human breeding populations, the topic of many of his previous books. The differences in intelligence between the sexes are much less significant among peoples whose evolutionary history did not lead through migration to cold climates and to agriculture.
The hominid line remained in Africa long after it split from chimpanzees seven million years ago. Early on we learned to walk upright, use makeshift tools, throw things, and grasp things with our opposable thumbs. The hemispheres of our brains evolved to follow the right/left specialization of our hands. We developed shared attention – the ability to have two people focus on the same object at one time with the intent of doing something or sharing knowledge about it.
A couple of million years ago those hands started to use sticks and rocks as tools, then to chip primitive tools from stone. About the same time we tamed fire. New species of hominids continued to evolve, some of such as the Neanderthals and the Denisovans migrated into Eurasia. As their culture became more complex, there was an increasing need to pass acquired knowledge down to children by showing them how to chip stones, make fires, make dwellings and the like.
One hundred and fifty thousand years ago, in other words, very recently, Homo sapiens evolved speech. Now we were able to communicate verbally about our objects of shared attention.
Mothers were able to ask others in the tribe, sisters, older children and their own mothers, for help with the children. With the help of others, women were able to bear children every two years instead of the six years’ spacing characteristic of ape mothers. Homo sapiens’ numbers grew. In this was presumably also the time at which the battle between the sexes moved to an oral battleground. Women were able to verbalize what they wanted. See [[ASIN:0345408934 Mother Nature]] and [[ASIN:0674060326 Mothers and Others]].
Our numbers grew. Homo sapiens expanded north out of Africa perhaps 70,000 years ago. We pushed the other species of ape men into extinction in Eurasia. About 15,000 years ago we spread from Siberia to Alaska and populated the Western hemisphere. Simultaneously we initiated the New Stone Age, with a much broader stick, stone and bone toolset. We put handles on our axes, stone tips on our spears and arrows, invented bows and harpoons, started to make pottery, invented needles to make clothing and so on.
We discovered that it was useful to drop the seeds of fruit trees and edible grasses along the way as we wandered. About 10,000 years ago we had advanced to the point where we could stay put and grow what we needed to eat. We started to settle in villages.This was the dawn of agriculture. We simultaneously learned to herd animals.
Tribes had been so closely related that relaxed sexual practices of such as those of today’s tribal Africans, Indians and Eskimos didn’t matter. Our ancestors swapped partners with abandon. Any kid born was welcome to the tribe. Women seem to have liked it this way. Benjamin Franklin lamented that colonial women who were taken captive by the Indians very often didn’t want to return.
With agriculture, paternity became an issue – a man wanted to leave something to his kids, and he wanted to be sure that they were his. There was a significant change in the relationship between men and women. People now came in contact with enough others that they became accustomed to dealing with strangers. The people around them were no longer close kin. They became wealthy enough that there was something to inherit when a man died.
Women were now more often obliged to stick with one partner. That partner was the biggest choice they’ve made in life – his ability to provide determined her status and her well-being. Whereas tribal women can feed themselves by scratching the ground and growing yams, manioc and taro, women in agricultural communities in colder climes depended on their men for food and protection. It was of course reciprocal. Women played essential roles in growing, preparing, and cooking food, making clothes, tending the children and so on.
The emergence of the patriarchy – man’s control over women’s sexuality and sustenance – meant that women had to persuade men in order to get what they wanted. As every man knows, they have evolved to be quite adept at this.
This concludes my argument in concurrence with Lynn’s observation that sex differences in intelligence are greater among Europeans and Asians and among other human populations.
The book includes a vast number of meta-analyses of scholarship by other researchers. It includes table after table of figures showing how averages between men and women differ by measurement after measurement. Though some differences are by absolute measure – such as the number of cubic centimeters and male and female brains – most of the differences are cited in standard deviations, a measure that may not be readily understandable to the average reader. Lynn’s graphics are useful in helping the reader understand what the numbers mean.
This work is a milestone of scholarship, not merely the capstone of a long career of making his own contributions to the field of intelligence research, but a summary of the state-of-the-art in all of intelligence research.
There have not been significant improvements in the techniques of statistical analysis over the past 20 years or so. The big new insights in intelligence research are more in the realms of genetics, epigenetics, nutrition and environmental factors such as pesticides and so on. In other words, one can be fairly confident that what Lynn is laying out here is not likely to change vastly any time soon to reflect new research. We will become better at explaining why it is, but what it is is well known.
Two writers who have made significant recent contributions to the study of intelligence are Robert Plomin in [[ASIN:B08BT69SZK Blueprint]] and Richard Haier with [[ASIN:110746143X The Neuroscience of Intelligence ]]. Though, as Lynn states, their stated opinions about sex differences do not necessarily agree with his, their research would point the same direction.
A five-star work. If Amazon gave awards for bravery he would get five stars as well for that.
February 8, 2024
At first glance, the title of this book may seem controversial in the post-modern, liberal, 21st century. Indeed, even the contents of the book may seem controversial, if you subscribe to the ideology of "dogmatic Wokeism". However, if you are reading this book without subscribing to dogmatic nonsense, you will easily find that there is almost nothing controversial about the book.
Namely, the book's is a presentation of the author's Developmental Theory which postulates, or rather problematizes the findings on what he calls Equalization Theory that there are no differences (or at least not substantial) sex differences in intelligence. According to the findings presented in this book, there are differences in that in infancy and up to 5 years of age, girls are on average more intelligent than boys, that there are no differences between 6-15 years of age, and that after 16 years of age and continuing through adulthood, men are more intelligent than women by approximately 4-5 IQ points. The majority of the book reads like a literature review of evidence and technical data confirming these findings, but also includes studies which go against those findings, thereby escaping a confirmation bias.
Nothing so far is controversial. Sex differences in intelligence (and not only in intelligence) exist, are evident and are not problematic, and only dogmatic ideological warriors would claim otherwise. It is not a problem that the differences exist - it is a completely different question whether such differences should have socio-political impact and that can and should certainly be discussed. But that is anyways, beyond the point of this book. Even most of the evolutionary explanations which Richard Lynn produces in this book are fairly reasonable, and though I have no background in any evolutionary science, they all seem quite adequate explanations. Nevertheless, those may be debated, but the essence of the book - the main hypothesis will still remain valid.
There was, though one point in the book which did seem problematic, at least to me - but I have to add, as a non-native speaker of English this may very well be a language issue, rather than any issue with the statement itself. The author makes the following claim: "The likely evolutionary explanation of earlier maturation of girls is that it is advantageous for them to begin reproducing in early puberty when they are sufficiently mature to have babies and look after them". If I understand correctly, the author suggests that girls in early puberty (which is between the ages of 8 - 10 or 11) are mature enough not just to reproduce but also to look after the babies, which - if correctly understood - is highly problematic.
Aside from that, it is an easy to read book, quite interesting and can be easily read within a day. I, thus highly recommend the book.
Namely, the book's is a presentation of the author's Developmental Theory which postulates, or rather problematizes the findings on what he calls Equalization Theory that there are no differences (or at least not substantial) sex differences in intelligence. According to the findings presented in this book, there are differences in that in infancy and up to 5 years of age, girls are on average more intelligent than boys, that there are no differences between 6-15 years of age, and that after 16 years of age and continuing through adulthood, men are more intelligent than women by approximately 4-5 IQ points. The majority of the book reads like a literature review of evidence and technical data confirming these findings, but also includes studies which go against those findings, thereby escaping a confirmation bias.
Nothing so far is controversial. Sex differences in intelligence (and not only in intelligence) exist, are evident and are not problematic, and only dogmatic ideological warriors would claim otherwise. It is not a problem that the differences exist - it is a completely different question whether such differences should have socio-political impact and that can and should certainly be discussed. But that is anyways, beyond the point of this book. Even most of the evolutionary explanations which Richard Lynn produces in this book are fairly reasonable, and though I have no background in any evolutionary science, they all seem quite adequate explanations. Nevertheless, those may be debated, but the essence of the book - the main hypothesis will still remain valid.
There was, though one point in the book which did seem problematic, at least to me - but I have to add, as a non-native speaker of English this may very well be a language issue, rather than any issue with the statement itself. The author makes the following claim: "The likely evolutionary explanation of earlier maturation of girls is that it is advantageous for them to begin reproducing in early puberty when they are sufficiently mature to have babies and look after them". If I understand correctly, the author suggests that girls in early puberty (which is between the ages of 8 - 10 or 11) are mature enough not just to reproduce but also to look after the babies, which - if correctly understood - is highly problematic.
Aside from that, it is an easy to read book, quite interesting and can be easily read within a day. I, thus highly recommend the book.
February 15, 2025
⭐⭐⭐⭐Really Good.
December 28, 2023
Where are all my reviews?
Displaying 1 - 5 of 6 reviews