The Economist had a special report on marriage a few months back with a bit on cousin marriage around the world. They had an interesting conclusion.
> Two academics, Bilal Barakat and Stuart Gietel-Basten, point out that when women usually have five surviving children, a woman can expect to have 25 male cousins. When the average number of children falls to two, that same woman will have just three male cousins, some or all of whom might be younger than she is, and thus ineligible as marriage partners. The marriage squeeze will be even tighter in cultures that insist, for example, that a woman marry not any old cousin but her father’s brother’s son. Eventually, cousin marriage will be crushed not by medics but by mathematics
But not much more than 2 children surviving through marriage age. That would mean a total population explosion in less than a century. Definitely wasn't ever the norm: population used to be more or less constant through mid-XVIII century.
It seems to be a thing in various continental European regions. I'm most familiar with seeing it done in French. From Wikipedia:
>Capital or small capital Roman numerals are widely used in Romance languages to denote centuries, e.g. the French xviiie siècle[26] and the Spanish siglo XVIII mean "18th century". Slavic languages in and adjacent to Russia similarly favour Roman numerals (XVIII век). On the other hand, in Slavic languages in Central Europe, like most Germanic languages, one writes "18." (with a period) before the local word for "century".
And the famous Mexican beer Dos Equis gets its name because it was created in 1897 and was celebrating the soon to be 20th century (XX, Dos Equis in Spanish).
Weird things happen because the the number of surviving children isn't uniform. Where that hit home for me was during the great depression the median family was small. Most families were using various types of birth control and illicit abortions were rampant. However most children came from larger families... because large families were really large.
And poor.
Hint my dad had two brothers. One of my dad's brothers fathered six kids. My dad three and his other brother one.
So families sizes of 6:3:1
The majority of my grandmothers grandchildren came from a family with 6 children. Those six have 14 children. My dad and other uncle have two grandchildren total, one each.
My paternal grandfather had 12 surviving children, by two wives. The first, my grandmother, died in childbirth. The second was the nanny. Me, I've had no children that I know of.
My grandpa married his second cousin, it was already frowned upon in 1935 but not unheard of. One improvement factor was transportation - the bicycle was invented not much before, and it was expensive. But a bike or a train ticket allowed you to know people beyond the rural village you lived. It's been even said that the inventor of the bicycle was the 2nd greatest feminist, because he improved the availability of suitable grooms, nobody needed to marry the violent moron next plantation anymore.
Royalty is literally defined by marrying into your own family — essentially all royal families in Europe are a single large family with varying degrees of chin and haemophilia :)
This is probably more true than many realize. There’s a great history re-enactment series on BBC called Victorian Farm, Edwardian Farm, etc (I believe they’ve done more) and before technological innovations laundry was the largest time-sink in a woman’s life. Watching the labor involved was a horrible revelation for me.
Why is it horrible? Their work was valuable at the time. It’s only horrible if we choose to not see the value they provided; IMO It’s not any more or less horrible than the husbands whose largest time sink was deep in the coal mines or on the streets sweeping horse manure. I don’t know about you, I’d be annoyed at someone feeling bad for me having to do my work. I’m grateful for our ancestors putting whatever effort necessary to keep society going.
Also, it was an employment opportunity for many maidens, ie., not yet married women who needed some income might do laundry for people of greater means.
Alison Wolf's book, "The XX Factor," examines time use diaries to gather data about which domestic tasks women spent the most time on, and the conclusion that she ultimately comes to is that while washing machines did make the process of washing laundry more efficient, the end result of these efficiency gains isn't that women spent less time doing laundry, but that people started doing laundry more often. So the washing machine made us more hygienic, but it didn't really free up a lot of time for women who performed those sorts of domestic tasks.
One Alison Wolf's main conclusions is that the inventions that actually resulted in women spending less time on domestic tasks were mainly those relating to cooking and food preparation (such as TV dinners and fast food in the 1950's), because the result of a x10 efficiency gain in food preparation isn't that people start eating x10 as many meals, but that the same number of meals get produced with 10% of the time investment.
There's a much bigger and longer story than this. Roughly speaking, it's my understanding that the catholic church suppressed this in Europe from roughly 1000 years ago, essentially as a way to counter alternative power centres.
Here's a famous article about Iraq, where this did not happen:
I think that someone could write a very reasonable sounding evolutionary psychology article about why the guiding hand of natural selection intervened and stopped cousin marriage due to higher rates of genetic abnormalities. However, in this case they'd be wrong in that the Catholic Church intervened directly and conciously and put a stop to cousin marriage.
Finding out that a phenomenon is not due to evolutionary psychology requires careful historical research and that's hard work. Making up evolutionary psychology ideas though takes no time and can make for a great clickbait article.
It seems clear evolution has uniformly negative opinions of brother-sister couples.
But cousins are more interesting, because the biological downside of having some ill (or just thick) grandkids must be balanced against the upside of having a tight clan, without divided allegiances, to fight off other clans.
A friend reported going to the wedding of German first cousins who married. The groom opened his speech with, "just in case you're still wondering, yes it's legal".
No, they were not the British royal family.
And apparently it was quite an uncomfortable moment.
I relate the story as something which would have been quite normal once, whilst legal now, is fairly taboo. I'm not sure why, although obviously feel and appreciate the taboo.
"No, they were not the British royal family." - LOL.
It's not just Britain, royal families all over Europe often needed "reseeding" from abroad as need dictated and the family trees got quite intertwined as a result. During the "Great War" of 1914-1918 King George V, Kaiser Wilhelm II and Tsar Nicholas II were all cousins. To be fair, parts of my family tree get a little ahem complicated and resemble bushes.
Nowadays, our royals are branching out and diluting the blood in a very healthy move. Gawd bless em all.
unfortunately for the larger-than-normal percentage of children born with birth defects and genetic abnormalities, first cousin marriage is extremely common in pakistan:
another example of what happens when you have a relatively small population group that marries and reproduces only within their own community, repeatedly for 1000+ years, there's a large number of genetic disorders which disproportionately affect ashkenazi jews:
to the extent that ashkenazi are strongly encouraged by their family doctors to go for special genetic screening, as a routine part of family planning.
The excess risk of defects etc is about 2%. That's a lot! That is many thousands of kids that are suffering unnecessarily. If the governments in cousin marriage permissive countries actually had to pay the cost of looking after these disabled people, cousin marriage would be out the door very quickly.
There was also a study looking at the genomes of a large consanguineous pedigree. The amount of pathogenic genome changes seen was shocking, amazing that the phenotypes were normal or mild... that is a gift you will pass on to all your descendants.
The present study revealed a higher incidence of certain diseases in consanguineous population with a high significant increase in the prevalence of common adult diseases such as diabetes mellitus, cancer, blood disorders, mental disorders, heart diseases, asthma, gastro-intestinal disorders, hypertension, hearing deficit, G6PD and common eye diseases. This confirms the role of genetic factors across the full spectrum of disease and not only for Mendelian disorders."
A positive correlation between inbreeding and numerous health outcomes has been reported in several studies. Indeed, unions between relatives are generally associated with an increased risk of abortions, stillbirths (Al-Awadi et al. 1986; Hussain 1998, 1999; Hussain et al. 2001), perinatal mortality (Stoltenberg et al. 1999), and congenital malformations (Abdulrazzaq et al. 1997; Chéhab et al. 2006; Yunis et al. 2006).
Consanguineous marriages are also recognized as being associated with higher risk for autosomal recessive diseases than in the general population (Taillemite et al. 1985; Alwan and Modell 1997; Kumaramanickavel et al. 2002) by favoring the expression of recessive deleterious alleles. Many reports have highlighted a positive association between inbreeding and a number of recessive single gene disorders like achromatopsia (Tchen et al. 1977), Leber's congenital amaurosis, xeroderma pigmentosum (Mokhtar et al. 1998), and metabolic defects like aminoacidopathies and mucopolysaccharidoses (Jaouad et al. 2009). However, some authors believe that a long practice of inbreeding over several generations leads to the elimination of deleterious recessive mutations from the population gene pool (Khoury et al. 1987).
Extremely common is a bit of an understatement ... it's practically enforced... to the point that women from the UK are kidnapped and forced to marry cousins and uncles back 'home'.
Due to cultural sensitivities, the authorities often turn a blind eye on the widely prevalent practice.
No, we've understood heredity for a very long time, and sex between siblings or between parents and children has always been a taboo. Cousin marriage, however, is not particularly harmful (https://www.psychologytoday.com/blog/animals-and-us/201210/t...).
"The real reason we stopped marrying cousins is:..."
Perhaps in the majority groups in the West. Certain communities in the UK still widely practice cousin marriage and suffer hugely in genetic abnormalities. They are not constrained by transport, it is a cultural thing that has not yet been updated.
It's noteworthy that it's simultaneously socially unacceptable to criticize Pakistanis for their preference for first cousin marriages, despite the undeniable harm caused by it, and yet it's also socially unacceptable for whites to have the much less incestuous preference for just marrying other whites, despite the absence of harm:
The first article you link to is a BBC news article that says exactly what you claim it is socially unacceptable to say. In the second article, the only people getting outraged are those who've been referred to as "inbred". You can hardly expect them to take kindly to that description.
> Baroness Flather said because of 'inbreeding', members of the ethnic group are 13 TIMES more likely than the rest of the UK population to have disabled children.
> The Pakistan-born peer has called on the Government to take steps against the issue of unions between close relatives in Muslim communities, which she called an "outdated, un-British custom".
...
> She also accused Britain of a "cowardly reluctance to tackle damaging social practices within certain ethnic minorities".
> In what has been described as a brave attempt to break a taboo she said there was a fear of "accusations of racial prejudice" which has made the issue "unsayable".
> She added: "That is certainly what happened over the disgraceful sex-grooming scandal in Rotherham, in which the civic authorities, including the police and social services, tried to cover up the systematic abuse of more than 1,400 vulnerable girls by predatory gangs of Pakistani heritage men."
Though close relatives marrying is bad for the children's health, it's actually a slight benefit for the grandchildren, great-grandchildren, etc.
Why that's true: The reason inbreeding is bad is that the child is at risk of inheriting two copies of a nasty recessive mutation, in a region of their genome where both versions came from the same recent ancestor. However, if the child goes on to successfully reproduce, it's more likely that they had zero copies than two--and in that case the grandchildren have zero copies, which is good for them.
The condition itself is often (though not always) caused by a recessive mutation, which consanguineous marriages--ever popular in Pakistan--significantly increase the risk unmasking:
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The issue there is probably with the practice being common and repeated through many generations. The risk of generic abnormalities is not particularly high for cousin marriage.
yes, a single instance is not extremely risky from a statistical perspective, it's when the children of first-cousin marriages repeat the practice for several dozen generations... some really bad things can crop up.
Even that's not enough, you need a small population, small number of children each generation, and for harmful mutations not to be weeded out. A wild Frog species that has 100 eggs could have regular 'first-cousin' marriages without significant issues beyond infectious diseases.
Humans unfortunately tend to accumulate negative mutations more easily. Though the upside of lack of predation etc is not something I would want to pass up personally.
I haven’t yet read the scientific article that it’s based on, but the OP points out that there’s about a 50 year lag between the move to cities and a decrease in cousin marriage, so there was probably some cultural component.
Oh, certainly. Any culture takes time to develop a taboo like that. It's especially hard to damn the behavior of your own parents when their union led to your own existence. Only when everybody who was married has died will there really be a change.
"2. We could reasonably travel more than 10 miles from home in a day."
No, this is not the reason. Plenty of societies had very strong norms against cousin marriage centuries ago -- from memory below 1 percent in colonial new england?
Others did not. Sometimes because they were just far from the enforcers of such norms. But often for deliberate reasons of keeping family and property together. Saddam Hussein wasn't short of private jets, but was very concerned about losing power, and blood relatives are more reliable. And about 50 percent of his countrymen feel the same way.
It's not particularly harmful in terms of heredity (roughly the same "danger" as a woman having a kid at 40 in societies where it is not common).
Interesting factoid: Freud was married to his first cousin.
It's partly because of misunderstood heredity dangers, but mostly because of increased social pools. (Cousins used to be very socialized with each other, but strangers of opposite sex had minimal opportunities for meaningful interactions.)
While isolated instances of first cousin marriage aren't especially harmful, contrary to what some comments here suggest, if done across successive generations, these unions can produce a catastrophic unmasking of harmful recessive alleles, and the nations with the highest rates of consanguineous marriages also often have the highest rates of birth defects (see p. 22): https://www.marchofdimes.org/materials/global-report-on-birt...
However, while the dangers of inbreeding depression are common knowledge, it's worth pointing out that outbreeding depression exists as well. Where lies the ideal balance between these two extremes? Surprisingly, it appears to be marriages between third or fourth cousins, if you use fecundity as a proxy for general offspring health: https://www.sciencedaily.com/releases/2008/02/080207140855.h...
A third or fourth cousin is a person with whom you share first cousin grandparents or great grandparents--essentially a distant relative, or simply put, someone of your own "race," which is quite at odds with the "hybrid vigor" claims often made to tout interracial marriage. Apparently just marrying any old white person (if you're white) gives you all the hybrid vigor your offspring need.
I have some doubt that the generations are that cleanly separated when doing genealogy. The if nothing else the youngest and oldest children of a couple can be 20+ years apart. The same person could easily show up as someones great grandparent (3) and their great great grandparent (4).
> if nothing else the youngest and oldest children of a couple can be 20+ years apart.
This isn't relevant to generations. My youngest sister is 21 years younger than I am. But we are both part of the same familial generation. My children and her children will also be part of the same familial generation. (This is irrespective of the fact that my sister is a millennial and I am not.)
> The same person could easily show up as someones great grandparent (3) and their great great grandparent (4).
In the case of the graphic, I suggest that they put each person at the highest possible place in the hierarchy and then simply extended the relationship line down in cases like this.
Now fast forward 200 years and that clean separation you describe starts looking like a tangle as you and your sister marry people from different 'generations'.
Basically, if you want to understand how people actually behave you need to exclude the living as their relationships are going to be more complex than such neat abstractions suggest. It's only with dead people that you can really understand their life story after-all someone can get married at 25 and again at 95.
What is your definition of "generation," and why do you refer to it as an abstraction? We are referring to generations as a structural parent-child term, where people on the same tier of the tree share the same generation. This is not the same as saying "Generation X/Y/Z" and so forth, which is a different meaning of the word entirely.
I am deriving the second definition from the first.
Basically, as you start looking at the family tree that actually represents humanity the idea of generation breaks down, do you mean the shortest route from you to someone in ~100,000 BCE or the longest route to some person in ~100,000 BCE. You could say your mother's mother's mother's ... or your father's father's father's but even then the length of the chain going back that far stops being equivalent.
The only thing that becomes meaningful on such a scale is simply generation as unit's of time.
> I am deriving the second definition from the first.
That doesn't make any sense.
The first definition is a parent-child tree relationship. The second definition is a way to characterize the social atmosphere of a given span of twenty-some years. They are structurally different definitions that are not reconcilable.
I have an aunt that’s two weeks younger than I. Another aunt from that same mother is only six or seven years older than I. The fact that my Mom got started young with me is a contributing factor.
Indian family trees in certain communities are like this. And in general, due to keeping in touch, or remaining in one particular geographic area, one hears stories like this quite commonly in India.
Are you talking about the graphic? I would guess they imposed some order on it, but I also sort of expect that the sort of thing you talk about doesn't happen all that frequently in different branches of a family tree.
No need to doubt the visualization, rare cases like that blend into the visual noise. And in fact, in the most ancient generations, where this problem would be more prominent, you can see far less delineation of the generations.
They can cluster the individuals (green) into hierarchical circles cleanly, then add a line that jumps over one generation, which would not be visible at the resolution of the plot.
> Two academics, Bilal Barakat and Stuart Gietel-Basten, point out that when women usually have five surviving children, a woman can expect to have 25 male cousins. When the average number of children falls to two, that same woman will have just three male cousins, some or all of whom might be younger than she is, and thus ineligible as marriage partners. The marriage squeeze will be even tighter in cultures that insist, for example, that a woman marry not any old cousin but her father’s brother’s son. Eventually, cousin marriage will be crushed not by medics but by mathematics
https://www.economist.com/news/special-report/21731490-pract...