Genes and the Environment — Steve Jones / Serious Science

when I think about genes in the environment I often think about William Shakespeare because Shakespeare wrote a play called The Tempest and the plot of this play involves a shipwreck on an island and on this island there lives a little devil whose name is Caliban and the people who were shipwrecked tried to be kind to this little devil and he turns out to be completely awful he won't cooperate with them he won't help them he's just a nuisance and in great big aspiration one of them says to Caliban on thy foul nature-nurture will never stick in other words you were born so awful that nothing we can do to change your environment will make you better and that's a very common fallacy when we're talking about genetics the nature-nurture controversy not many people know that the nature-nurture phrase comes from Shakespeare and Francis Galton who was in some senses the founder of human genetics was completely convinced absolutely convinced as was almost everybody else that everything was in your nature the way you were born okay and he did he wasn't he was understanding the good scientist here he made mistakes but all scientists do he wrote a book called hereditary genius in which he pointed out that for example if your father had been a judge and his father had been a judge and his father had been a judge it was quite likely you'll be a judge but he went further than that he went up to Newcastle on time which is on a big river where people used to have rowing races and he found indeed that people who were champion rowers their fathers turn tends to be a champion rower the grandfathers didn't the great-grandfather's did and he did this for various attributes and he found this happened again and again and - this - for him this proved that everything was in your nature in your biology and that nothing you could do to change the environment would make any difference now of course he was completely wrong there okay one of the things which is absolutely passed down from one generation to the next often for many generations is money most people who are millionaires in the modern world are millionaires because their parents are millionaires that isn't true everybody in this technological age which had been true for a long long time and there's no genes for money so the mere the mere existence of a hereditary pattern is a very weak insight to whether something is genetic or not but many people still don't see that if you type in to Google the words scientists find the gene for you get last time I did it something like sixty three thousand hits okay and given there's only twenty three thousand genes that's quite impressive but they're silly scientists find the gene for language scientists find the gene for unhappiness scientists find the gene for musicality scientist find the genes for height all these things but the most dangerous word in the science of genetics is the gene for something okay because genes are just boring bits of DNA they work in an environment and without the environment they wouldn't be doing anything and that's the extraordinary thing about knowing a certain amount about genetics for the public that makes the environment seem less important for geneticists it makes them seem more important I often talk about a classic example of this which is cat genetics oh I have many examples from cat genetics and one of them has to do with black cats and white cats now we all know about black cats and we know about white cats Charles Darwin actually found something interesting about white cats that all blue-eyed white cats are death don't we found that and the reason for that is that white cats cannot make the pigment that's called melanin and that's the pigment which we've all got which is if you've got dark hairs got melanin is the gotalk skin you got matter in it but he was it's also in your brain and your ears and various other places so a black cat can make melanin in a kind of production line a biochemical production line which starts with simple chemicals and puts them together to make this complicated Pigman okay if one of the machines in that production line has broken down and if the machinery will go up to that broken point and then : kill no further and you'll have a white cat okay so that's simple but sometimes what happens is that the machine hasn't broken down it's just been slightly damaged so it doesn't work very well and then you get some rather strange patterns in cats the one I'll talk about is called the Siamese cat I don't know what you call it in Russian but it's a cat which has got a black nose ears and tail and if it's a male cat it's got black testicles as well thank you and the Siamese cat is a genetic mutation it's a change in the DNA in the genes we know exactly what's gone wrong we know where it's gone wrong we know the exact DNA base in the DNA chain we know exactly what's gone wrong there if we do breeding experiments with other cats the pattern follows exactly the rules that Mendel found with peas so it's genetic and very very happy to accept that it's certainly genetic it's certainly true but crucially it's also environmental because the reason on the cat has got that strange pattern is that the enzyme that does the job of making melanin can do its job well in the cold parts of a cat's body where there's less spare energy running around and bashing the biochemical process but it does the work job much less well in the warm part of the cat's body that's the main body mass which is one or two degrees warmer more than the Python the nose the ears and the tail and the testicles which of course are both literally and metaphorically the coolest part of any male body they're black as a result and if you want to make a dark colored Siamese cat you can do it by breeding for many generations from dark-colored Siamese cats or you can take assign these kitten and you can keep it in a cold room and it'll be much darker if you want to make a light colored Siamese cat you can take a Siamese kitten and keep it in a warm room and it would be much lighter if you want a very expensive black cat take a Siamese kitten and keep it in a refrigerator and it may be a black cat so that the Siamese characteristic is absolutely genetic but also absolutely environmental and the two are working together and that happens again and again and again and we can see it happening in a dramatic way in our own lifetimes when I was born which is 75 years ago depressing but true fact I was born at the end of the Second World War and then after the war there weren't any real famines but there were certain food shortages and there were what we call rationing they were of course much worse in Russia and they were Western Europe much was in Germany too but people were forced to eat a very simple diet and in retrospect it was a very healthy diet very little sugar very few cakes and so on no almost no butter all this kind of thing and so people would generally rather thin since then things have changed dramatically in the in in those days and indeed in the 19th century and indeed in Russia in the 19th century if you read Tolstoy and so on it turns out that one of the defining characters of the of the ruling class the rich the worth that they were fat the peasants were starving they were thin and the same was true here here in Britain if you read Charles Dickens many of his always rich characters in London of the 19th century they wore top hats and they had cigars than they were obese the poor people were the poor people were thin we've now seen an astonishing reversal of that and when I give lectures of this to my UCL students here I look at them and they're a highly intelligent and very middle class group and to a person that I don't think is a fat person in the class but if I go to a working class part of London obesity is a big problem in America it's a major problem life expectancy in the United States is dropping fast and the reason for that is is obesity why is there obviously because food has basically become free in the 1930s in America it took a working working man and it would have been a man more than half his working week to get enough money to buy food for himself his wife and two children now it takes him on average less than day to do that as long as he buys cheap nasty sugary fatty food so that food is now everywhere universally available and so people eat that food and they get fat and in fact we know a lot about the genetics behind that there are strong there is strong evidence very strong evidence that the individuals with particular genes if they eat a lot of food become fat but those genes only ever manifest their effects in a place where food is cheap it's a Siamese cat phenomenon if there's no food it doesn't matter if you've got genes that make you fat because you're not going to get enough food but the effect is big and these genes have been very surprising place where they work they don't work in the intestine or the liver to change your metabolism most of them don't instead they work in your brain they're a pit nearly all of them are appetite genes we have all kinds of hormones that that change our feelings of hunger insulin actually is one in fact the first hormone ever found I have to put an advertisement again in Finn University College London was found here just about two hundred yards away down there and that was actually an hormone called ghrelin which was an appetite hormone discovered in 1903 okay and we all know the feeling of hunger we're hungry so we go to McDonald's either in Paris or London or Moscow and we buy we buy some junk food and we eat it I don't eat either I bet you don't either but people eat it and they say oh that was nice wasn't it I think God not for me thanks but you don't then go again and buy another cheeseburger and another milkshake or a third one because you have other hormones that come in and say you've eaten enough these are what we call satiety whole hormones stop eating you could hunger hormones and stop eating columns okay occasionally very occasionally people are born who don't make these hormones they so they're always hungry is one of them that's called leptin and one birth in 50,000 or 100,000 of children who were born with no leptin and so as babies they're always hungry and they're not just pretending they're they are screamingly hungry and so of course they scream and they yell and make a fuss and their parents of course are very upset by this so they give them too much food and they become morbidly obese now we fortunately we can actually treat this with injections of leptin but that's the nature-nurture thing these genes for obesity or not obesity these hunger genes have been around since humans evolved but they've only become a problem in the last 20 or 30 years when food has become free effectively so that's nature and nurture working together and there's a second subtlety which people really don't like to think about which is these genes work in your mind okay and they were definitely work in your mind and people find that very disquieting that your appetites are changed by your DNA well I say well it's a hormone there's another hormone it shows the nature-nurture thing very well and works in your mind and that's testosterone that's that that's the hormone of course that makes us men the wonderful creatures that we are women have it too in much smaller doses with that's why some elderly women grow mustaches as they grow old women have a little bit but men have a lot more and testosterones are not is nasty stuff it makes it mix men live shorter lives it makes them much more liable to infectious disease because testosterone suppresses the immune system and it makes them much more likely to get involved in in being murdered okay so it says testosterone changes your behavior and we know very well the way it doesn't you know a lot about the biochemistry bodybuilders for example who use testosterone to get big muscles they tend to die for male reasons they're murdered they died in car crashes they commit suicide that kind of thing so testosterone works on your on your mind but one of the things it definitely does is to is to change your propensity for violent behavior all over the world men murder at ten times the rate of women the murder rate in Britain is fairly low it's not as low as in Singapore the murder rate in cut in Colombia in South America is a hundred times the murder rate in Singapore the murder rate in the United States is five times the rate of the murder rate in Britain okay now the testosterone is exactly the same in both places but in Colombia there are drugs there are gangs there are weapons this poverty there's unemployment there's violence and this puts part of the population at genetic risk they're known as men they have genes that put them at risk of murder if they're placed in a murderous environment if you want to get rid of murder you do what the people in Singapore and in Britain have done you get rid of guns you cannot get a gun in this country a pistol it's impossible ditto in Singapore you try to improve living conditions you try to reduce unemployment and all this works so you're solving a genetic problem by changing the environment and that it probably is the take-home most important message you could take from the modern world of human genetics

Channel: Serious Science

Views: 3,197

Keywords: science, lecture, Serious Science, Steve Jones, Genes and the Environment, genes, genetics, biology, nature vs. nurture, nature, nurture, environment, obesity, Siamese cats, DNA, metabolism, hunger, ghrelin, appetite hormone, leptin, testosterone, murder rate, genetic problem, hereditary pattern, heritability, hereditability, descendant, Frances Galton, Hereditary genius

Id: WsEaUX4e6C0

Length: 14min 12sec (852 seconds)

Published: Thu Apr 16 2020