It is only now are we starting to understand who we really are as modern science starts to catch up to our complex biology and ancestry, we remodel our story once again. But we’re only at the beginning stages of this long investigation connecting our history to our future. Our longheld assumptions around speciation, race and skin colour are thrown out the window, part of the cultural narrative we have created to work out what it means to be human. At the heart of our humanness, we are storytellers, but these stories clash deeply with the facts of our DNA. In this fascinating insight into our genetic makeup, Adam Rutherford talks to us about our evolutionary twists and turns, why DNA testing sites are speculative at best, how CRISPR will change our lives and how his work with renowned sci-fi director Alex Garland has been the greatest professional relationship of his life.

Why do you think the world of genes has become and, in a sense, always has been so political?

I have been developing this idea over the last few years that the misunderstanding of genetics has become the ultimate identity politics. There’s the casual end of this, which is people doing ancestry tests because they want to discover that they were Vikings to explain why they have blonde hair and blue eyes, but at the far end of the scale you have neo-Nazis and the Alt-Right trying to use these personalised commercial genetic tests to demonstrate their racial purity. I don’t recommend this to anyone, but I sometimes hang around on neo-Nazi websites just to see what the conversations around genetics, and it’s a very big thing to use these tests to prove how ‘white’ and northern European they are. It’s also quite amusing when they realise that actually, they have Slavic or Middle Eastern genes.

Certain demographics like the Jewish people have a very mobile messy history. Do you think it’s easier to tell a story through a religious denomination or certain demographic?

Yes, I do use the word ‘messy’ quite a lot, but humans are terrible model animals for understanding inheritance because we are so messy, and there is so much culture to unpack in trying to understand our ancestors. But you are absolutely right that Jewish history has made its people qualitatively different due to forces of immigration and multiple diasporas. But also something that doesn’t get talked about as much is forced Christianisations, re-adoption of Jewish cultural heritage, and then there are weird phenomena like the so-called ‘Ashkenazi intelligence’ where there are supposedly more Nobel Prize winners, chess grandmasters and orchestral conductors have come from Ashkenazi Jewish backgrounds.

I think it’s around 25 percent of Nobel Prize winners that are Jewish.

Sure. One of my friends at UCL calculated that the highest predictor of Nobel Prize winners in the science categories was having a Hungarian Jewish mother.

You mentioned that you have surfed Alt-Right websites to look at their discussions about pure genes and so on, but your book would suggest that it is impossible to claim such a pure genetic line, and our footprints tell a messy story of a species that has been ‘mobile and horny’ as you put it. Could you elaborate on this idea?

Humans are very good at two things: sex and mobility. Genes are even more mobile than people because you can transfer your genes without even remaining in the same place. I do use the word ‘messy’ quite a lot, but humans are terrible model animals for understanding inheritance because we are so messy, and there is so much culture to unpack in trying to understand our ancestors.

But we are also very bad at thinking about long-term history.The idea of how tribal we are and how associated we are with a specific culture is very ingrained in human psychology. So there is a natural conflict between this idea that we are a part of this family, this cultural or religious identity and the idea that actually a number of ancestors we must have, because everyone has two parents, and the amount of mobility there is in our past. So the notion of purity – racial or religious – is nonsensical when you begin to look at how family trees actually work in real people over generational time.

“The notion of purity – racial or religious – is nonsensical when you begin to look at how family trees actually work in real people over generational time.”

Even with clumsy racial identifiers like skin colour; we now know that the variation of skin colour predates Homo sapiens by probably 600,000 years. When we talk about Homo sapiens we are really talking about 200,000 to 300,000 years ago, as an African originated species, but we now know that around 900,000 years ago, within Africa there existed variations in skin colour genes that would have the effect of some of these creatures having pale skin while some had darker skin and the full spectrum in between. We very casually talk about white-skinned Europeans or African Americans and East Asians, and we do see natural variation in skin tones, but the origin of those is deeper than the origin of Homo sapiens themselves.

I find it hard to separate the behavioural science side of things from the genetics. What I mean by that is how the narrative we have built up around race and other things sits so well alongside the science of genes?

I think it is much to do with how tribal we are as a species. We naturally group and defend those groups over others, which you can see in our cousins the great apes in a more obvious way. So it is biologically part of our history to have some level of ethnocentrism and for people to want to identify as a member of a close-knit community.

The problem is this idea of timescale. History is very sparse beyond a few generations so it is difficult to actually claim tribal membership over more than a few generations and so we construct these narratives. A classic example of this in contemporary America is identifying as African American. Being black in America is an important identifier, not least because of the amount of racism that black people in America and the world over are subject to, but from a genealogical point of view, two black people in America are more likely to be genetically different from each other than white people are to either of the black people or white people are to each other. It’s very difficult to assess that because most African Americans are the descendants of slaves, and we have very little information on where those slaves were seized from over the last few centuries, but if one of your ancestors was taken from East Africa and the other was taken from West Africa, even though superficially they have dark skin and can be identified as black in America, genetically they are incredibly distinct.

“I argue in the book that we should probably sequence everyone’s genomes at birth.”

I’m going to pose quite a controversial question to you. Do you think the hundreds of thousands of years of hyper migration across continents has been good for us and secondly, hypothetically if we had stayed more separate would we see fewer mutations and genetic diseases today?

That’s a good question but a hard one. In answer to the first part of that, good is a term that is difficult to quantify scientifically; the longevity of our species is increasing, the infant mortality rate is decreasing, however, we measure it globally, but are we happier? That is a question that I am not, and I don’t think that science as a whole, is very well equipped to answer. In terms of the success of the species in increasing its reproductivity, if that is the measure of what is good, then yes – outbreeding is better for the health of an organism that inbreeding. So spreading over the world, leaving Africa and taking with us a diversity of genes that allowed us reproductive success and cognitive development, is an asset of human behaviour. The more we move, the more we have sex and the more evolutionary success we will have.

In terms of the second part of that question, we respond in an evolutionary sense to our local environment more than anything. Sickle cell disease is a great example of this, which has evolved in people who have a recent evolutionary history in malarial zones, the reason being that sickle cell trait is protective against malaria. So if you take that as an example, we have responded in a very geographically specific way. It’s sort of a vicious circle but there is evidence that when we started farming, particularly yams is one theory, we cleared forests so there was more standing water, therefore meaning more mosquitoes and other vectors that will bear these diseases. So we have a very geographically related evolution in response to our local environment.

Let’s move to more present-day issues: there has been this surge of DNA testing in recent years, with companies like 23andMe and where you get results of your genetic makeup and then that dictates everything down to what you should or shouldn’t eat. You have said that this sort of DNA home testing should be treated with caution because while it has become this huge industry, the science of genetics is essentially probabilistic. Can you give us your thoughts on the advantages and disadvantages of this area? 

I do find it a problematic area. As you alluded to, it’s because genetics is probabilistic and not deterministic.

If you mark genetics as merely the understanding of heritage, sex and families then what you are dealing with is a science that is really only 20 years old sitting alongside a cultural idea that it is as old as time – the study of our families, who we have sex with and what is passed down from generations before is thousands of years old.

A lot of the reason why we think like this is that the history of the field has led us into this intellectual cul-de-sac. We discovered the first disease genes in the 1980s because they were the easiest ones to identify, and they were Huntington’s disease, cystic fibrosis and Duchenne muscular dystrophy among a few others. The reason we spotted them first is that if you have an expansion of the gene Huntington then you will get Huntington’s disease. So those ones actually turned out to be the outliers in terms of how genetics relates to our existences, but it also reinforced this historic cultural notion that we’ve had for thousands of years which is a deterministic view of biology – that if I’ve got this then I will be like this. I’ve got the gene for football skills or the gene for this personality trait that’s how people talk. It just doesn’t work like that.

And then you’ve got an 8-year-old who is bought by a football club for $10 million.

Exactly, and that’s where it gets really pernicious because the less scrupulous companies offer exactly that – I’ll tell you what sport your child is good at based on their DNA. That’s fucked up.

We spoke with the physician Siddhartha Mukherjee and he said, “What I do see happening is a kind of personalised form of eugenics in which you can potentially sequence the genes of your unborn child and make decisions about that child in the future.” What would you say to that?

I think the principle is correct, that we can have further and further understanding of the DNA of our unborn children, and I think it is something that we should be concerned about but not in the immediate future.

I get a lot of questions about ‘designer babies’ because it is a genuine concern for people. The truth is that we do not understand the genetics of eye colour, and it is impossible to predict the eye colour of your children based on the eye colour of the parents. So I use this as an example when I talk about how, if we are thinking about designer babies and how we are going to select for a bunch of blonde-haired, blue-eyed children, as is the major concern in the eugenics type of conversation, we’re actually not capable of doing that.

At the more complex end of the scale, in the last six months, the first two disease genes have been manipulated and corrected by CRISPR. One of those is sudden cardiac arrest, which we sometimes see when footballers drop down dead on the pitch, and that’s a heavily genetically influenced condition. The other one was linked to the blood disorder beta-thalassemia. These two were chosen because they tend to be single base pair mutations in specific genes that we have a reasonable understanding of, and therefore if you could correct them you might be able to eradicate that disease from a familial line. Now these are significant studies and they are a step in this direction, but even so, these are still very experimental, they are poorly understood, and they are not really correcting the disease at all; we are talking about a bundle of cells in which a small proportion of the disease gene has been corrected.

I know all of this sounds like I’m saying, “Hey, relax folks, everything is going to be fine.” These are serious issues but I just think that we are well ahead of ourselves worrying about how significant they are going to be in the future because the technology is simply nowhere near where we think it is. I think the media overplay it a lot.

“In the last six months, the first two disease genes have been manipulated and corrected by CRISPR.”

Do you have any personal hunches about what the future will bring us as an understanding of our DNA and who we are as a species? Do you think a discovery equivalent to gravitational waves in physics could come about?

That’s a great question. Physics has been looking for grand unifying theories for several thousand years, and they have come up with some broad descriptions of the universe but they are still looking for that grand unifying theory. In biology, we have our four grand unifying theories: cell theory (all life is made of cells), universal genetics (all organisms are encoded by DNA), chemiosmosis (all organisms are powered in the same way by the process of metabolism), and natural selection underwrites the whole business. All of those pillars of biology were established over the course of 100 years starting in the mid-19^th century.

I think we are at a stage in biology, and science as a whole, where we have infinite detail to work out but the major landmarks in our understanding of life are in place. I would be very surprised if anyone significantly overturned any one of those theories. Whoever did do that would be very rich and have Nobel prizes falling at their feet if they did. Having said that, woe betides any scientist for saying that we are done now.

In terms of understanding human diversity, which also includes disease, migration and current human existence, I do think we are in the details phase. I argue in the book that we should probably sequence everyone’s genomes at birth. The caveat to that is we have none of the security or ethical constraints that need to be in place for it to be a reality, but what I am saying is that the only real way to understand human diversity is having data. Like you said, we are the data. So in that sense, I think the pursuit of more and more data on human genetics is essential.

I want to end the interview on your work in film. You have worked as a scientific advisor on various Alex Garland films like Ex Machina, which some people say is the best sci-fi movie in the last decade, and Annihilation, which I am dying to see. Talk to me about working on ideas that are so supernatural and speculative, and crossing the line between the fantasy and what is real.

For starters, I’ve now seen the final cut of Annihilation, which comes out in February, and I actually think it is a better film than Ex Machina.

Working with Alex has been the greatest joy of my professional life. He’s a very intelligent guy, thorough and meticulous and he really cares about the idea, whether it’s artistic or scientific because he’s very scientifically literate. I’ve worked on other films where you are just there to make the science more robust or ‘not ridiculous’ is how it is often phrased. There’s a line from 2012, one of those disaster movies that are dumb as bricks but really fun, where they were trying to describe the earth collapsing. A white-coated Indian scientist looks at the screen and says, “The neutrinos are mutating!” So that has kind of become a thing with Alex because we want to make sure that there are no ‘mutating neutrinos’ in the script or anything that is so absurd that it’s going to make people go, “What the fuck was that?”

I often have some quite ridiculous conversations with Alex on things like the nature of consciousness or the nature of genetics. I’d be in the supermarket and he’d ring me up talking about one line in the script and we would then have a half hour conversation about it. That to me is what the creative process should be like; that’s when it works best when you spend a lot of time just talking about an idea. Even if it only relates to one line of the script, the fact that you have this discussion that sits behind it means that whatever the criticism that comes – and people like these films or they don’t – you know that they are based in intellectual rigour. I suppose that’s the best you can hope for because once you release them into the wild you have no control over what people think about them; no matter how great you might think they are, someone else might find them boring or hate them. But I think one of the things you always try to avoid, whether with films or books, is people saying that it’s wrong, so at least we can say that it’s not.

A Brief History Of Everyone Who Ever Lived by Adam Rutherford is available to buy now through Orion Publishing

Original imagery by Stefan Oboski