My next post was going to be about the legacy of nasty Normans, and the wrongs they inflicted on those poor Anglo-Saxons. But Norman/Saxon tensions have been around for a thousand years, so they can wait a few weeks longer.
Instead, I’m sitting here listening to Chrissie Hynde singing my favourite Pretenders song – “Hymn to Her”. It’s an eulogy to the essential female figures in her life. It’s a lovely song, and you could check it out on Spotify if you don’t know it (other music streaming services are available, of course).
I’m playing it, and writing this post in honour of an essential female figure in my life – Joy, my dear mum-in-law, who has recently died. Joy was adopted as a baby, and was passionately interested in tracking down details of her birth parents. She made great strides in finding out about her mother’s family, and met several of her cousins. I enjoyed doing the more historic research, digging out genealogical details of her rural Hampshire family.
But she always wondered who her biological father might be. So, we went down the route of genetic DNA profiling. It’s offered nowadays by many companies, using a saliva sample or the scraping from inside a cheek. The results when they arrived, weren’t what she expected at all!
When thinking about her today, it struck me that the mechanics of genes would be a perfect topic to write about in her honour. What better example of living history than the historical data we each carry around, in every cell in our bodies?
Shuffling of the (DNA) pack
To her surprise, Joy found that a large proportion of her recent genetic heritage came from Suffolk. Very little derived from Hampshire, her birth-mother’s home county, at all. Why would this be? Well, the way that most of the DNA sites work is by matching your DNA against that of other subscribers on their database. So, the geographical locations of your ancestors are based on the profiles of near-relatives and by extrapolation, from their ancestors.
But in reality, you can’t go back more than a few generations, before the DNA matches begin to break down. This is because of the way inheritance works. Here comes the little biology lesson.
Our cells hold 23 pairs of chromosomes, and each pair carries sets of genes, again in pairs. Each pair of genes are inherited, one from ma and one from pa. But the thing is, the particular gene you inherit for each set from your parents is totally random.
So, let’s say for a particular gene on a particular chromosome you inherited from your pa: it might be the one he inherited from his dad, or it might be the one he inherited from his mum. It’s totally down to chance. For every one of a new baby’s sets of genes, inheritance shuffles the DNA gene cards, passes one on, and throws the other card on the floor. So, over a very little time in historical terms, individual genes stand a large chance of disappearing altogether. Here’s a little video, kindly created by Mr. Albion, which shows how this works for a single set of genes.
Now multiply it by around 25,000 times, for the whole human genome!
One in ten
I recently went to the Excel Exhibition Centre in Docklands to have my COVID jab. In happier days, my previous visit there had been to a genealogy exposition – family history is big business. At that event, I sat in on a fascinating free lecture by a professor of genetics.
He asked us how many eight-times great grandparents we had. That’s ten generations, and takes us back in time to roughly around 1600 – when the first Queen Elizabeth was on her last legs. The answer, as all you computer scientists have no doubt already calculated, is 1,024 (genetic science is very binary).
Then he told us something that I found amazing. Of those 1,024 ancestors, on average, you only share genes in common with – 10 percent of them. So, you have nothing in common genetically at all with 900 or so, out of your thousand g-g-g-g-g-g-g-g grandparents. Such is the power of genetic shuffling.
So, you might take with a pinch of salt the claims of aristocrats that they are the spitting image of an ancestor in an ancient portrait. The chances are that they have very few genes in common with them at all.
“But hold on”, I hear the mathematicians amongst you say. “Your sums can’t be right, if each person with, say, British ethnicity has so many ancestors, this island would have sunk under the weight of some many millions of people!”. That is very true, and the answer helps explain how in some families strong likenesses prevail: marriage between cousins.
As soon as a cousin marries a cousin, the number of their offsprings’ ancestors halves, and the chances of any particular gene being passed on doubles. This causes an event called pedigree collapse. The same is of course true to a lesser extent, when second or third cousins marry. The amount of an individual’s pedigree collapse is expressed by biologists as a coefficient, depending on how many inter-family marriages have occurred in an individual’s genetic history. You do the maths, my head is spinning, so I’ll pass.
But marriage between cousins carries risks. Bad genes which carry high risk of disease are offset when paired with a healthy gene from an unrelated ancestor. But with cousins, you have a far higher chance of two copies of the same bad gene being inherited from both mother and father.
Fall of the Habsburgs
You have only to look at the sad case of Charles II of Spain, last of the Habsburg kings. He was physically disfigured, with a head, jaw and tongue so misshapen he couldn’t eat properly, and he constantly drooled. He was intellectually disabled, and couldn’t walk unaided. His inability to rule was a direct cause of the fall of the Habsburgs, as well the decline of Spain itself in the 17th century.
The cause of his terrible afflictions? Pedigree collapse, because the number of his ancestors was drastically reduced through inbreeding. His mother married her uncle. Both of his parents were products of marriage between cousins, and both sets of those cousins were in turn related.
In an effort to “keep the money in the family”, the Habsburgs unwittingly restricted the gene pool from which the next generation’s genes could be shuffled. That greatly increased the chances of inheriting pairs of “bad genes”, with not enough “good genes” in the mix to offset them.
Interestingly, biologists think the same type of pedigree collapse caused the health problems experienced by the Egyptian pharaoh Tutankhamen. He was unable to walk without assistance, had scoliosis of the spine, and suffered from several diseases. DNA testing of royal mummies indicate that his father and mother were brother and sister.
Under false pretences
When I was studying psychology at university, I went to a weekend seminar on social psychology. The program included a voluntary lecture – on the Saturday evening – entitled “Sexual practices in prehistory in relation to trimodal theory”. The lecture theatre was filled to capacity. Not that anyone was particularly interested in trimodal theory. Everyone just wanted the lowdown on caveman sex.
The professor took great pleasure in telling us that he had deliberately lured us away from the bar on a Saturday evening, with his titillatingly-titled lecture. He was actually going to tell us how primitive societies ensured healthy diversity in the tribe’s gene pool. The elders chucked young men out into the wilderness, and encouraged them to join neighbouring tribes and pair up with likely young females in the new tribe. This would ensure that not too much inbreeding occurred, and so would keep the tribes healthy.
How ironic that so-called primitive people observed the impact of inbreeding, and took steps to avoid it, but more so-called sophisticated societies didn’t or couldn’t see the connection.
A little white lie
Way back in this post, I told a little white lie. Yes I know, I should know better. Our cells hold 23 pairs of chromosomes, but actually only 22 pairs are the results of random gene shuffling. The last of the pairs is the one that determines the sex of the baby. Each chromosome of that pair comes intact from its mother and father.
Women always have a pair of what are labelled X chromosomes, but men have an X (inherited from his mother), and and Y (from his father). If the baby ends up with an X from mum paired with an X from dad, the baby will be a girl. However, if an X from mum is paired with a Y from dad, then the baby will be a boy.
This fact casts a sobering light on the fates of tragic queens like Anne Boleyn. She was disposed of because of her inability to produce male children. Ironically, the sex of their offspring was actually determined by the X chromosomes of King Henry!
But the great thing about the Y chromosome from a historian’s and geneticist’s viewpoint, is that its genes are never shuffled. So, it provides a virtually uninterrupted line from father to son across countless thousand years. I say “virtually uninterrupted” because random mutations can sometimes change its structure.
But nevertheless it can be studied much like surnames can, which are also passed from father to son, at least in most western cultures. And their history goes way back further in time than the earliest surnames. Scientists can use the Y chromosomes to track migrations of tribes as far back as 30,000 years in the past.
Another little white lie
Yes, another one I’m afraid. There’s another way inheritance is passed down through the generations, other than through genes and chromosomes. There is a special sort of genetic coding in our cells called Mitochondrial DNA. It’s only inherited from your mother. So, just as we can study the paternal line back through pre-history via the Y chromosome, scientists can study an uninterrupted line from mothers to daughters, for thousands of years.
Mr Adrian Targett
Let me introduce you to Adrian Targett, a history teacher from Cheddar in Somerset. A number of years back, he volunteered for an intriguing project. DNA had been extracted from a molar tooth from the skeleton of a prehistoric man, who had lived in Cheddar gorge around 7,000 years ago. Scientists asked local people for samples of their DNA (a cheek-scrape, I believe), to compare to that found in the prehistoric remains.
Incredibly, Mr. Targett shared a common female ancestry, through his maternal line, with our caveman. That’s over 300 generations in the past… What I found very endearing is first, Mr Targett is the very epitome of the virtues of staying local. And second, on learning this incredible fact, his wife said “that’s why he likes his steaks rare”.
The poignant thing is that, unless Mr. Target has sisters who can pass on his mother’s Mitochondrial DNA to their daughters, this ancient line within his particular family stops with him.
Royal Blood in the Queen Vic
Let’s finish on a fun note. Who can forget the moment in BBC’s Who Do You Think You Are? when Mick Carter, landlord of the Queen Vic in Eastenders (aka actor Danny Dyer), found he was a descendant of King Edward III of England? The program ended with him going home to his Essex mansion and telling his daughter, “I always knew you were a princess!”.
Well, to get this into context, let me tell readers that, if you are of predominantly ethnic English descent, it’s almost impossible that you are NOT a descendant of Edward III too. Chances are we all have a drop of royal blood. It helped that Edward and his wife, Queen Phillipa of Hainault, had 13 children, most of whom survived into adulthood.
A respected genealogist, Adam Rutherford, outlined the maths behind this assertion in his book A Brief History of Everyone Who Has Ever Lived. You’ve had enough science for one read, so I won’t go into the mathematical details. But I really recommend the book- an easier read than most scientific offerings on genetics.
Hiding in plain sight
I hope I’ve convinced you that, unwittingly, you carry around thousands – no, millions of years of history. Yes, genealogy plays a part in discovering our ancestors, but that’s really just delving into the dry written documents. They only record what people wanted to be recorded. Your bodies carry the real history, and it will be interesting to see how science will make that knowledge accessible to us in the years ahead.
I’ll finish by paraphrasing a quote from American author John Irving’s Cider House Rules. Doctor Wilbur Larch runs an orphanage in Maine for abandoned children. Every night the kind doctor turns off the dormitory lights with the words, “Goodnight, you Princes of Maine, you Kings of New England!”.
So, “Goodnight Joy, you Princess of England”.