The human Y chromosome contains only 86 genes, compared to 20,000 genes on the 45 other chromosomes. While most mutations defining Y-DNA haplogroups lie in non-coding regions of the Y chromosome, a few other take place in actual genes. One of the most important among these genes is SRY (sex-determining region). In rare cases when the SRY gene is translocated to the X chromosome, it causes the XX male syndrome (a person with two X chromosomes who should be a woman but is actually a man). Likewise, XY individuals with defects or deletions in the SRY gene end up with female characteristics (Swyer syndrome). Mutations in that SRY genes are therefore bound to have serious effects on the carrier. It is perhaps not a coincidence then that several of the most successful Y-chromosomal haplogroups are defined by a SRY mutation. This is the case for:
- Haplogroup BT (SRY1532.1, aka SRY10831.1) : the entire branch of humanity that split from haplogroup A some 70,000 years ago, when Homo Sapiens first decided to leave Africa and colonise Eurasia. Some of the earliest descendants of BT were haplogroups C and D, who colonised most of Asia and Oceania, and probably also entered Europe.
- Haplogroup E (SRY4064, aka SRY8299) : the most successful of all African male lineages, which also spread around the Middle East and Europe during the Neolithic.
- Haplogroup O2b (SRY465) : a major male lineage in Japan, Korea and Manchuria. It is associated with the Yayoi colonisation of Japan from Korea from 500 BCE.
- Haplogroup R1a1 (SRY10831.2!, aka SRY1532.2! => reversion of the BT mutation above) : a lineage which underwent one of the most spectacular expansions in human (pre)history soon after the SRY mutation emerged, conquering half of Europe and a big part of Asia, from Anatolia to Siberia and India. Note that R1a lineages lacking the SRY1532.2! mutation (R1a* defined by the M420 mutation) are almost extinct today.
- Haplogroup R1b-M167 (SRY2627) : the most common R1b subclade in Catalonia.
Here are other apparently important mutations in the coding region of the Y-chromosome.
- Haplogroup DE (M1, aka YAP) is defined by the Y-chromosome Alu Polymorphism (YAP) insertion, the most well-known unique event polymorphism (UEP), estimated to have occured 65,000 years ago.
- Haplogroups J (12f2.1) and D2 (12f2.2) are defined by the same 12f2 STS polymorphism, linked to the deletion of the L1PA4 element in the HERV15yq2 sequence block. The HERV gene stands for Human endogenous retrovirus. Recombinations in HERV15 have been linked to changes in fertility.
- Haplogroup R (M207, aka UTY2) : the most successful male lineage in western Eurasia is defined by a mutation in the UTY gene (ubiquitously transcribed TPR gene).
- R1b-M222 (USP9Y+3636) : the presumed lineage of Niall of the Nine Hostages, found chiefly in northern Ireland and southern Scotland. Defects in the USP9Y gene can cause azospermia and infertility. We can therefore assume, considering the quick expansion of this haplogroup since the early Middle Ages, that the USP9Y+3636 mutation improved fertility (more swimmers) in men who have it.
- Haplogroup T* (M184, aka USP9Y+3178) : the defining mutation of the whole haplogroup T is also on the USP9Y gene.
The effect of Y-DNA on behaviour
The phenotypic effects of the Y chromosomes are still unclear, apart from conferring distinctly male characteristics. There are many attributes which distinguish men from women. Some are physical (hairiness, more muscle, taller body, squarer jaws, etc.), but many are purely behavioural (aggressiveness, dominance, ambition, rational/logic thinking, problem-solving, inventiveness, seduction/courting tactics, etc.).
The success of some lineages in specific environments may lie in mutations increasing one of several of these attributes. Human societies vary greatly depending on their geographic environment (hot, cold, fertile land, dessert), and their stage of historical development (hunter-gatherers, Neolithic, metal age, feudal society, modern society). Behavioural traits that are successful in one particular geographic and socio-historical environment may be at a disadvantage under different conditions.
I believe that this may be why some haplogroups have prospered at specific time and place in history. Men living in a warlike and highly hierarchical Bronze-age society, where chieftains have many wives or concubines, will have more chances of success if they carry genes that make them more aggressive and socially dominant. In a society where elaborate courtship is determinant in men's reproductive success, aggressiveness may end up being detrimental. Concretely that may be why R1a1a prospered during the Bronze Age and societies where it is dominant today are still more aggressive than average (Russia, Pakistan) and have a culture in which male courtship is not preponderant. I have noticed that populations with high levels of haplogroup J2a (Italy, Greece, Turkey, Lebanon, Jewish community) are typically merchant cultures, in which men are known for being smooth talkers, shrewd negotiators (haggling culture), and perhaps skilled seducers too. That may have something to do with mutations in haplogroup J2a. J1 people are also quite commercial-minded, though appear more aggressive and less the Casanova types.
I have noticed before a correlation between industriousness and haplogroup R in Europe and O in East Asia. Overall it is probably the whole macro-haplogroup NOP (including Q and R) that predisposes men to a higher level of activity. One consequence of this is that countries or regions with high levels of combined haplogroups N, O, Q and R tend to be more productive, and therefore usually richer than others. It doesn't work at the individual level though, because individual wealth depends on many other factors, such as income equality, wealth redistribution, individual intelligence, skills (e.g. money management) and traits of character (e.g. parsimony). It also depends heavily on the political and economic system in place in that country. That is why Eastern Europe became considerably poorer during the Communist era, but is now catching up with Western Europe (at least countries with high levels of haplogroups R and N).
Adaptations of male fertility to the local environment and climate
I have long been intrigued by the fact that some haplogroups seem to have prospered in one specialised environment. Here are some examples:
- Haplogroup N appears to be particularly well-adapted to very cold climates (northern Scandinavia, Finland, Baltic, northern European Russia, Siberia). N is actually the predominant haplogroup pretty much everywhere in Eurasia above the Arctic Circle. This is odd considering that many other haplogroups (I1, R1a, R1b, Q, C3, O...) could have colonised the Arctic region, but for some reason it is always N that makes the majority of the population. This may simply have to do with a mutation that makes sperm more resistant to extreme cold in men belonging to haplogroup N. That would explain why, in the long term, even Baltic people with no Uralic connection an hardly any Mongoloid admixture (Lithuanians, Latvians) ended up with such high percentages of N. It may simply be an adaptation to the local climate.
- Haplogroup E doesn't seem to do well in colder countries. E1b1b colonised most of Europe as far as the British Isles during the Neolithic, but didn't survive well (definitely less well than the indigenous I1 and I2). That may be for the opposite reason that I cited above for N, namely that spermatozoa of men belonging to haplogroup E may be more resistant to heat, but less resistant to cold.
- Haplogroup J1-P58 is found mostly in very hot desert environments, and is not as common in other climates in places conquered by the Arabs during the expansion of Islam. For example, J1-P58 is less common in Lebanon than in Algeria, despite being closer to Saudi Arabia.
- Haplogroup BT (SRY1532.1, aka SRY10831.1) : the entire branch of humanity that split from haplogroup A some 70,000 years ago, when Homo Sapiens first decided to leave Africa and colonise Eurasia. Some of the earliest descendants of BT were haplogroups C and D, who colonised most of Asia and Oceania, and probably also entered Europe.
- Haplogroup E (SRY4064, aka SRY8299) : the most successful of all African male lineages, which also spread around the Middle East and Europe during the Neolithic.
- Haplogroup O2b (SRY465) : a major male lineage in Japan, Korea and Manchuria. It is associated with the Yayoi colonisation of Japan from Korea from 500 BCE.
- Haplogroup R1a1 (SRY10831.2!, aka SRY1532.2! => reversion of the BT mutation above) : a lineage which underwent one of the most spectacular expansions in human (pre)history soon after the SRY mutation emerged, conquering half of Europe and a big part of Asia, from Anatolia to Siberia and India. Note that R1a lineages lacking the SRY1532.2! mutation (R1a* defined by the M420 mutation) are almost extinct today.
- Haplogroup R1b-M167 (SRY2627) : the most common R1b subclade in Catalonia.
Here are other apparently important mutations in the coding region of the Y-chromosome.
- Haplogroup DE (M1, aka YAP) is defined by the Y-chromosome Alu Polymorphism (YAP) insertion, the most well-known unique event polymorphism (UEP), estimated to have occured 65,000 years ago.
- Haplogroups J (12f2.1) and D2 (12f2.2) are defined by the same 12f2 STS polymorphism, linked to the deletion of the L1PA4 element in the HERV15yq2 sequence block. The HERV gene stands for Human endogenous retrovirus. Recombinations in HERV15 have been linked to changes in fertility.
- Haplogroup R (M207, aka UTY2) : the most successful male lineage in western Eurasia is defined by a mutation in the UTY gene (ubiquitously transcribed TPR gene).
- R1b-M222 (USP9Y+3636) : the presumed lineage of Niall of the Nine Hostages, found chiefly in northern Ireland and southern Scotland. Defects in the USP9Y gene can cause azospermia and infertility. We can therefore assume, considering the quick expansion of this haplogroup since the early Middle Ages, that the USP9Y+3636 mutation improved fertility (more swimmers) in men who have it.
- Haplogroup T* (M184, aka USP9Y+3178) : the defining mutation of the whole haplogroup T is also on the USP9Y gene.
The effect of Y-DNA on behaviour
The phenotypic effects of the Y chromosomes are still unclear, apart from conferring distinctly male characteristics. There are many attributes which distinguish men from women. Some are physical (hairiness, more muscle, taller body, squarer jaws, etc.), but many are purely behavioural (aggressiveness, dominance, ambition, rational/logic thinking, problem-solving, inventiveness, seduction/courting tactics, etc.).
The success of some lineages in specific environments may lie in mutations increasing one of several of these attributes. Human societies vary greatly depending on their geographic environment (hot, cold, fertile land, dessert), and their stage of historical development (hunter-gatherers, Neolithic, metal age, feudal society, modern society). Behavioural traits that are successful in one particular geographic and socio-historical environment may be at a disadvantage under different conditions.
I believe that this may be why some haplogroups have prospered at specific time and place in history. Men living in a warlike and highly hierarchical Bronze-age society, where chieftains have many wives or concubines, will have more chances of success if they carry genes that make them more aggressive and socially dominant. In a society where elaborate courtship is determinant in men's reproductive success, aggressiveness may end up being detrimental. Concretely that may be why R1a1a prospered during the Bronze Age and societies where it is dominant today are still more aggressive than average (Russia, Pakistan) and have a culture in which male courtship is not preponderant. I have noticed that populations with high levels of haplogroup J2a (Italy, Greece, Turkey, Lebanon, Jewish community) are typically merchant cultures, in which men are known for being smooth talkers, shrewd negotiators (haggling culture), and perhaps skilled seducers too. That may have something to do with mutations in haplogroup J2a. J1 people are also quite commercial-minded, though appear more aggressive and less the Casanova types.
I have noticed before a correlation between industriousness and haplogroup R in Europe and O in East Asia. Overall it is probably the whole macro-haplogroup NOP (including Q and R) that predisposes men to a higher level of activity. One consequence of this is that countries or regions with high levels of combined haplogroups N, O, Q and R tend to be more productive, and therefore usually richer than others. It doesn't work at the individual level though, because individual wealth depends on many other factors, such as income equality, wealth redistribution, individual intelligence, skills (e.g. money management) and traits of character (e.g. parsimony). It also depends heavily on the political and economic system in place in that country. That is why Eastern Europe became considerably poorer during the Communist era, but is now catching up with Western Europe (at least countries with high levels of haplogroups R and N).
Adaptations of male fertility to the local environment and climate
I have long been intrigued by the fact that some haplogroups seem to have prospered in one specialised environment. Here are some examples:
- Haplogroup N appears to be particularly well-adapted to very cold climates (northern Scandinavia, Finland, Baltic, northern European Russia, Siberia). N is actually the predominant haplogroup pretty much everywhere in Eurasia above the Arctic Circle. This is odd considering that many other haplogroups (I1, R1a, R1b, Q, C3, O...) could have colonised the Arctic region, but for some reason it is always N that makes the majority of the population. This may simply have to do with a mutation that makes sperm more resistant to extreme cold in men belonging to haplogroup N. That would explain why, in the long term, even Baltic people with no Uralic connection an hardly any Mongoloid admixture (Lithuanians, Latvians) ended up with such high percentages of N. It may simply be an adaptation to the local climate.
- Haplogroup E doesn't seem to do well in colder countries. E1b1b colonised most of Europe as far as the British Isles during the Neolithic, but didn't survive well (definitely less well than the indigenous I1 and I2). That may be for the opposite reason that I cited above for N, namely that spermatozoa of men belonging to haplogroup E may be more resistant to heat, but less resistant to cold.
- Haplogroup J1-P58 is found mostly in very hot desert environments, and is not as common in other climates in places conquered by the Arabs during the expansion of Islam. For example, J1-P58 is less common in Lebanon than in Algeria, despite being closer to Saudi Arabia.
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) increased its frequency by a fraction of a percent at each generation. Over 50,000 years , or even 10,000 years for that matter, haplogroup C would have almost entirely replaced D in most communities. Haplogroup D could have survived only in specific isolated communities where a founder effect among the first settlers gave them 100% of D and 0% of C to start with. In Japan's case, a new special ins/del mutation for D1b was selected early (about 45,000 years ago) and allowed that lineage to survive.