05 October 2021

Charles Darwin adored his first cousin - love Vs scientific fear of inherited disease?

As I discussed, Charles Darwin (1809-82) was sick all his life, but he had no idea why. It wasn’t until 2013 that John Hayman solved the problem in Charles Darwin’s Mitochondria. Charles’ ill­ness, his brother's, mother's and others on the mother’s side showed a gen­etic pattern of maternal in­her­it­ance that was the hallmark of mitochon­d­rial mutations. The symptoms were severe depression, an­xiety, nau­sea, vomit­ing, visual hallucinations, headaches and cardiac pal­pitations.

Emma and Charles Darwin loved each other and had 10 children together, 
even though they were first cousins. 7 of their children grew into healthy adults.

Charles inherited any weaknesses his own parents had PLUS he also chose to marry, of all the possible women, his own first cou­sin Emma Wedg­wood. It was therefore important for Prof Hayman to dis­cov­er what happened to the next generation. Hayman showed that Charles Darwin’s children were unaffected.. since defective mit­o­chondria can only be in­her­ited from the mother. And Emma Wedgwood was genetically clean!

Now back to 1832. Charles Darwin set out on a 5-year, around-the-world voyage on the naval ship HMS Beagle. As the ship exp­lored the oceans and coasts of the Southern Hemisphere, it dropped Darwin off at various ports, for his expeditions. There Darwin collected thousands of specimens of extinct and still-living plant and animal species.

In 1838, 2 years after disembarking from the Beagle, Darwin fell deeply in love. Emma was an intelligent young woman, an excel­lent pianist who had studied briefly with Chopin and the grand-daughter of Josiah Wedgwood, the famous potter who’d made his fortune making gorgeous porcelain.

Yet at the same time that Darwin was falling for Emma, he didn’t feel at all ready for marriage. In his note book Darwin wrote of his fears about giving up bachelorhood. “If I married tomor­r­ow: there would be an infinity of trouble & expense in getting & furnishing a house, morning calls, awkward­ness, loss of time every day”. Thinking about Emma and imag­in­ing marriage as slavery, Darwin scribbled two lists: ‘Not Marry’ included freedom to go where one liked and loss of evenings. ‘Marry’ included charms of music & female chit-chat. If only Prof John Hayman could advise Darwin back then!

Emma was shocked when Darwin proposed. She’d had no idea that they had been courting, thinking instead that they were friendly relat­ions who enjoyed occasional fireside chats. But she was 30 and still single, so she accepted his proposal quickly.

In Jan 1839, they married. Though the love between Darwin and Emma proved unshakable, Darwin knew that Emma’s grandfather Josiah Wedgwood was his grandfather too!

On the Origin of the Species by Means of Natural Selection (1859).
Darwin understood the consequences of inter-breeding.

Charles and Emma Darwin eventually had ten children. Mary died 3 weeks after her birth. 10-year-old Annie died of a res­pir­at­ory dis­ease, probably tuberculosis. 18-month-old Charles died of scarlet fever. The other children lived to normal adult­hood.

Of course many C19th children died in the weeks after birth, even in families that were not impoverished. Antibiotics were unknown. Raising only seven out of ten children to mat­urity might have been about average for middle class British families then. Darwin fretted anyway that his dec­ision to marry his first cousin was the cause of his child­ren’s weaknesses. And of all men on the planet, Darwin should have known bet­terIn the years before his marriage, he’d long been investig­ating the consequences of inter-breeding!

Analysing his specimens and writing books about them was Darwin’s life role. He had long developed the ideas that would comprise his break­through work, the 1859 On the Origin of Species by Means of Natural Sel­ection. In it Darwin prop­osed that all of the complex plants and animals of the modern world were the progeny of only a few simple organisms that existed eons ago. The deviation of modern organisms’ morphology from that of their pre-historic prog­enitors was a result of Natural Select­ion, the ability of organisms with certain genotypes to survive and thrive in the environment, more than their siblings. As the surviving organisms created progeny, their characteristics helped define the species.

Buttressed by the huge specimen library that Darwin collected before his travels, Origin of Species re-aligned Western thought about life on earth. Meanwhile other scientists and religious lead­ers responded with ideas of their own. Origin was such compelling reading that it quieted the some­times acrimonious conversation.

12 years after Origin was published and 32 years after the Darwins married, Charles released Descent of Man, and Selection in Relation to Sex (1871). It applied Darwin’s theory of evolut­ion to the human species, and boldly proposed that humans and mod­ern apes shared a common ancestor. It also outlined how the mating preferences of an­imals within a species could influence natural sel­ection. A year later, Darwin’s The Expression of the Emotions in Man and Anim­als (1872) catalogued a wide range of gestures and behaviours shared by animals and hum­ans. The presence of nearly identical ges­t­ures across species sug­gested that the species’ emotional experiences were similar.

Charles Darwin's state funeral, Westminster Abbey, April 1882. 
Wood engraving. wellcome collection

The Darwins’ marriage lasted 43 happy years, despite him having been so ill. Regardless of how many scientific symposia Darwin was invited to attend, he rare­ly agreed to spend a night away from Emma - she tended to his every need, enabling Darwin to work at home peacefully. The memor­ies of anx­iety, grief and joy were indelibly inscribed on his brain when he worked inside his study. Did his love for Emma colour his later scientific writings?

Darwin was buried with a grand state funeral in West­min­ster Abbey. Being enshrined with the great stars of British science was a well-deserved honour; to this day his work profoundly influences all of the biological sciences. Thank you to Rebecca Coffey's journal paper.





21 comments:

Hels said...

Hayman gave an unclear response. "Charles Darwin’s 10 children were in general a sickly lot; one died in infancy, one in childhood, and their first daughter died at 10. Their illnesses do not seem to be related to one another and not related to the illness of their father. As well as other symptoms, the children suffered from various infections. Their sicknesses may have at least in part been due to the consanguinity of their parents (Charles and his wife Emma were first cousins) as there may be increased susceptibility to infection in the children of such partnerships".

Deb said...

Even though close relatives in my family married each other, I would never marry a first cousin, under any condition. That would be gross.

Parnassus said...

Hello Hels, I find the marriage of two relatives of almost any definable degree to be repellent. I realize that in British and European literature and history this is quite common, but does not alter my opinion. Even if the relative is not a blood one, say in cases of adoption, this feeling still goes. This seems to be an even more general taboo. I think that while some people will choose partners from their close circle of friends, most do not, despite the advantages of propinquity (although I have no statistics on the subject).
--Jim

Rosemary said...

I own a "Darwin tobacco" jar that came to me via my grandmother whose aunt married into the Darwin family. Should you are interested in the story you can read more about it here:-
https://wherefivevalleysmeet.blogspot.com/2019/10/the-story-of-my-tobacco-jar.html

mem said...

What a great post . Thankyou . I find it amazing that when you consider where society was at in regards to education and religious conviction , that Darwin wasn't tarred and feathered . It gives me hope that people ,are on the whole capable of rational thought which we certainly needed at the moment . As for the issues of marrying close relatives, it doesn't surprise me that this happens . After all the people we are attracted to are often people with whom we share an outlook or values . It stands to reason that someone who is genetically related to us might share these values and so be attractive to us . Its one of the reasons I think that making the identity of donor eggs and sperm is SO important. People have the right to know who they actually are in the biological sense . I don't feel a repulsion to cousins marrying but its interesting that so many people do . Maybe its something we are primed to because it is best for us to avoid this situation . Look at the Hapsburg family . Not a pretty situation .

Anonymous said...

It is certainly very strange that he married his first cousin, with his knowledge and suspicions. In spite of his various medical maladies, how much enlightenment he brought to the world. I wonder if his theories began the slow decline of religion in the world, with science clashing against religion.

Hels said...

Deb

I asked my grandparents why there were marriages between close relatives in both their families. Grandma said 1] because they could only check potential partners in their own towns or neighbouring towns, not distant cities that had non-relatives. And 2] if a new spouse had been chosen sight unseen, they could only trust the choice if he/she was family. hmmm

Hels said...

Parnassus

I looked up with nations banned marriages between first cousins and there were very very few eg China has a relatively modern ban. In fact in many societies close relatives marrying was seen as strengthening communal ties.

Except for the US where 24 states prohibit marriages between first cousins!

Not sure about your social taboo theory. Boys and girls who were close friends in high school and marry in adulthood were seen as ideal couples.

Hels said...

Rosemary

what a great story, thank you. There were many members of Darwin's family who might have owned the tobacco jar, and passed it down the generations. Do you know the approximate year in which the jar was made?

Hels said...

mem

the Hapsburgs were a perfect example, yes. They carefully married their children onto close cousins, reaching across from Austria and Spain in each generation. This kept the high quality Hapsburg genes going, and even more importantly retained power and wealth in the family. However we know how that model ended :(

The very educated Darwin certainly knew better, as you say.

Joseph said...

Helen I value the family details that you wrote in your first post on the Darwins.

Erasmus Darwin was a very close friend of Josiah Wedgwood, prominent abolitionist and founder of the pottery firm. Josiah Wedgwood. So close were the two families that Josiah’s granddaughter, Emma Wedgwood, married Erasmus’ grandson, Charles Darwin. Sir Francis Galton, grandson of Erasmus and cousin of Charles Darwin, was another extraordinary polymath in that family.

Hels said...

Andrew

Darwin was a truly clever scientist, and even if he didn't yet understand the details of mitochon­d­rial mutations, he had been long committed to investig­ating the consequences of inter-breeding. So how did one of the world's most insightful scientist make his (relatively) elderly wife pregnant _every_ _single_ year till her menopause?

The first time I thought about Darwin dividing religion and science was when religious opponents of evolutionary theory tried to eliminate Darwin’s theory from science courses, based on the Book of Genesis. You are right.. the division has never been repaired.

Hels said...

Joseph

marriages between close relatives, over more than one generation, apparently created two very different results. On one hand there was an increased risk of autosomal recessive genetic conditions, as Darwin and most scientists ever since have known. On the other hand, the intelligence genes were also magnified in those who lived to adulthood. Darwin's father, uncles and sons were all successful doctors, astronomers, mathematicians, military leaders and composers.

bazza said...

The Westermarck Effect hypothesises that those brought up in close proximity from birth until the age of six experience a kind of sexual avoidance. Some research on this was carried out in Israeli kibbutzim which supported the theory. So, although marriage between cousins presents a risk of genetic defects it is back to the old nature vs nurture debate. A relative of mine who was a genetic counsellor, told me that among some Turkish families, close intermarriage is encouraged to "keep the family wealth intact"!
CLICK HERE for Bazza’s fondly fulsome Blog ‘To Discover Ice’

DUTA said...

Love and passion are dominant. All the other factors, even wealth, become secondary.

I tend to believe in 'no smoke without a fire', and there are problems with "inter-breeding" as you call it. Just as there are problems with ethnically mixed marriages.

In Israel, for instance, there's constant debate between those with european roots and those with oriental roots. Kids resulting from these
mixed marriages ask: where am I in all this? Well, they're usually told, they're orientals as the dominant gene in a mixed marriage is the oriental one.
Love and passion overcome it all.

Luiz Gomes said...

Boa tarde minha querida amiga. Eu tenho um caso de um casamento assim na família. Meus avós paternos eram primos de primeiro grau.

Hels said...

bazza

The Westermarck Effect is new to me, something that I will need to read up in the journals. But with dangerous autosomal recessive disorders in a family, there was no nurture/nature issue. There was nothing that could be done to protect the children, at least in Darwin's time.

Nowadays if cousins are thinking of having babies, they really should get genetic counselling _beforehand_.

Hels said...

DUTA

mixed marriages seem to refresh the family's genetic history and are therefore a great idea. All my mother's family came from adjoining small cities on the Sea of Azov and probably didn't refresh the gene pool for several generations.

Hels said...

Luiz

marrying cousins was very common in many societies and still is greatly valued, in places like Pakistan. The spouses' shared values hopefully promote happier and more stable marriages.

Hilary Melton-Butcher said...

Hi Hels - Darwin was an extraordinary man of his era - and gave us so much to learn from - he must have had the ability to memorise so much - I really need to read more about him. Cheers Hilary

Hels said...

Hilary

he was a stunning thinker. wasn't he? He was at the meeting point of science and philosophy.
The discovery of natural selection came after thousands of years of thinkers, and had great power for explaining adaptive changes. Its nature was not a force like those written up in the laws of physics, so Darwin was open to change, additions and improvements.