What are the hidden costs of civilisation? Could civilisation be behind disease, mental illness, climate change, and religious fundamentalism? Spencer Wells thinks it might just be. Maria Armoudian speaks to Wells about his book Pandora’s Seed: The Unforeseen Cost of Civilisation.
Spencer Wells is an Adjunct Professor in the Department of Integrative Biology at the University of Texas. He is the author of Pandora’s Seed: Why the Hunter-Gatherer Holds the Key to Our Survival.
Before we get into your general theory, could you firstly give us a refresher on genetics?
So each of us is carrying around inside nearly every cell in our body, a blueprint, basically a way to make another version of yourself. This is your instruction set, it tells your body how to make the proteins and how the cells behave together and so on. And this information is passed on from one generation to the next. The reason your kids tend to resemble you more than people you are not related to is because you are passing on your DNA to them and so their instruction sets are very similar to yours. But as it has been copied to be passed on, think of it like a long text, you are going to make a mistake occasionally and so these changes, we call them mutations at the genetic level ultimately create all the variation we see in the world and they allow us to track ancient human migrations because as people move, as our ancestors moved over tens of thousands of years around the world they carried these changes in their DNA with them and passed them on and so we can study those changes. And not only at the kind of ancestry side of things, so simply you know where did these markers arise, these genetic changes, and who they were passed on to, but also, they encode things that are actually functional. So what is clear is we have actually been changing quite a bit, relatively recently in the grand scheme of things, there have been studies that have been done showing that we have actually been adapting to this culture we have created in the last ten thousand years which is really within the blink of an eye in an evolutionary sense, you know it is only a couple of hundred generations. Our DNA has actually changed substantially in that span of time and the question is: why?
You talked about mutation and we talk about natural selection, how do they fit together?
Like I said, mutations are these random changes, typos if you will, that occur as your DNA is being copied to be passed on through the generations. They are random, they occur as a relatively low rate – about one hundred in every genome in every generation, so each child has around one hundred changes relative to their parents that have never been seen before for the most part. So that is what mutation is, it is how we generate the variation we see around us, so we don’t all look alike and that is due to these small genetic changes that occur.
So you mentioned in the book for example opposable thumbs, colour vision…
Right, and so once the variation arises due to this process called mutation then it is either neutral, it has absolutely no effect on the organism, the likelihood of surviving, or whatever it might be, and so it can drift around and increase somewhat in frequency or disappear. Some changes are bad and so they are selected against, so this means you are not going to reproduce as effectively as other organisms. And some are actually good and so they get selected for and they increase in frequency in the population. As I mentioned before, we have seen a lot of those occurring over the last ten thousand years or so.
So the ones that are bad is that what you called the junk DNA?
Well junk DNA is a catch-all term for part of the genome that we don’t really understand yet. So if you think about the way the genome is arranged, we have got about 22-23,000 genes that code for protein. And this is actually a very small number compared to what people thought as recently as ten years ago when we were guessing there might be as many as 100,000 or even more genes. And it is not that much more than the number of genes that we se in fruit flies for instance. So we have a relatively small number of genes and billions of nucleotides of genomes. So a lot of it is kind of empty space in between the genes and we have referred to that as junk DNA but it basically means that we don’t know what it does, it is turning out to probably have some function.
I was wondering if it was related, because in the very next paragraph of the book you talk about cancer. I was wondering about the relationship?
It might be related to cancer, again, we are just figuring all this stuff out. It turns out there was a kind of three-dimensional structure to the DNA in your cell nucleus in the genomes. The junk DNA probably plays a very important role in that and so how the genes are kind of aligned next to each other and how they are turned on and off, and so it could conceivably have a lot to do with cancer, we just don’t know yet.
So now when we track the changes that you see based on the archaeological sites and you said in your book that suddenly you see between 80-50,000 years ago that there are no records of humanity. So you have thought that the species was maybe even on the brink of extinction at that point. Tell us about this.
This really coms out of the study of human genetics, it is not something that really comes from paleoanthropology and archaeology. As I say in the book, we don’t se a lot of archaeological evidence but maybe it is because we haven’t found it yet, maybe we are not looking in the right places. But what we do see very clearly in the DNA is a remarkably low level of variation. And so I talk about these mutations that occur and that is what produces the variation. We have a lot less variation than we should. I mean we are a population of around seven billion people spread all over the world and we should have a fair amount of genetic variation, and in fact we have a quarter, a tenth, as much genetic variation as other species of large apes, so chimps, gorillas, orangutans. And you know we think about these species as being endangered or being on the verge of extinction themselves, in fact we were nearly on the verge of extinction going back about 70,000 years ago, and that is the reason why we have so little variation because we lost it as we went through this bottleneck event – a reduction in population-size. And so we came back from that and we expanded around the world but starting from a relatively small number of people, it might have been as few as 2000 living around 70,000 years ago.
That is when agriculture is introduced?
No, agriculture was introduced about 10,000 years ago. And so we had expanded around the world living in a way our ancestors had always lived and in the way that most species on Earth live, which is as hunter-gatherers. So we are finding game and hunting it and we are picking up roots and collecting berries and nuts and so on. And around 10,000 years ago we had basically reached the far ends of the Earth and the population had probably stabilized at roughly the level that the land could support with us living as hunter-gatherers. We were coming out of the end of the last Ice Age starting around 15,000 years ago, the population was again at a relatively steady state. And then we crunched back into the last Ice Age, it was about a one-thousand-year period where we effectively went back into the Ice Age conditions again. And during this time, we effectively exceeded the carrying capacity of the land as hunter-gatherers and we had to come up with a way of producing more food, and the innovation which made total sense at the time was to plant seeds. So, you can grow wheat, you can grow rice, you can grow corn and this happened at lots of places around the world at roughly the same time and it is probably because there was a food crisis.
In and of itself that is interesting, that it happened in lots of different places all over the world.
It is. It is almost as if somebody got on the internet and started tweeting about this, you know, ‘Hey if you are worried about finding food plant some seeds’. There was no way of communicating, the thinking is there was probably some kind of global climatic crisis that led to this event all over the world.
So your argument is that this is kind of a turning point for humanity and it has carried with it both some positive consequences and some negative consequences which were unintended. Talk about that.
Yeah, well that is the argument that I make in the book. As I said, it made total sense at the time, it is a solution that anybody would come up with. The problem is, once we have left these really tough climatic conditions and went back into what we today call the Holocene, this period of really nice weather, the population started to explode. And so the total world population around ten thousand years ago was maybe five million people spread all over the world. And as I said, it is seven billion today and growing to nine maybe ten billion by the middle of the century. That has been produced in effect by developing agriculture ten thousand years ago. And so it has lots of knock-on effects, I mean people started living in cities and we had to domesticate animals because we couldn’t hunt enough of them, there were not enough wild animals living out there for us to get the protein we needed. And that introduced communicable diseases. So most of the infectious diseases that we think about – small pox – those were introduced for the most part due to the domestication of animals and people living in close contact with these animals. The increase in population I argue in the book also had some psychological effects on us. So when we are living as hunter-gatherers we are living in relatively egalitarian societies, there is not a lot of social hierarchy, there is no need for government, you are talking about a few dozen people, maybe as many as one hundred and fifty or so, but when you are living in cities with thousands of people, even millions today you have got to have some way of controlling those people and channelling their energy, focussing on tasks that need to be done for the good of society. And this is a good thing for societies as a whole, but for individuals I argue, if you think about the average factory worker in Victorian England you become a cog in the wheel and this has a psychological knock-on effect. So people who had been effectively mentally free for millennia were suddenly chained to their work place, chained to one particular location in close contact with lots of people that they didn’t know very well, and I would argue that it has reflected today in the increasing rates of mental illness for instance.
You said that each of these major diseases has roots in this mismatch between our biology and the world we have created..
Again this was a radical shift in lifestyle. No organism as far as we know has ever done anything like this and been successful at it. So it has allowed us to produce lots of people and keep those people fed, but it has had these longer-term knock-on effects, unintended consequences that have come out of it.
Now what do you think that the genetic impact is, since you were looking at the genetic basis of this?
Well, what we can see very clearly in the human genome is that there has been a lot of adaptation, a lot of selection acting on the genome in the last ten thousand years and it really probably is a consequence of us adapting to these profound cultural shifts: shifts in lifestyle, shifts in food sources towards foods that are rich in carbohydrates – milk is a great example, so we see a very strong signal of recent selection around the lactase gene, this is the gene that encodes the protein that allows you to digest the sugar in milk. In most societies and historically in human history people lost the ability to digest milk sugar lactose once they hit two-three years old, and in some communities people who domesticated sheep and goats and cattle around seven to eight thousand years ago, they had a mutation in their DNA to retain that ability to digest lactose into adulthood. And we can see evidence of very strong selection around that gene in those populations within the last ten thousand years. And so producing this culture has produced changes in us.
What are these things you call macro-mutations?
If you think about anything that is really complex, so the example that Darwin talked about in the Origins of Species was the eye. A really complex organ, it is difficult to imagine how any non-functioning partial semblance of an eye could be selected for. You think about ‘Oh god, you have got to have the lens and the nerve cells have got to be arranged in such a way to make it all work’. You can’t imagine, a priori, thinking about something so complex could have arisen through tiny little changes in the DNA. And so there was a geneticist named [Richard] Goldschmidt in the early twentieth century who suggested, well in some cases maybe you have got mutations that have a huge effect and they produce something like an eye almost instantaneously with a single change. And maybe that is how we get these very highly adapted complex organs. Now that is not widely accepted, but it is a theory and there are some examples where you see changes that have a huge effect on the organism. FOXP2 is a good example where you have a gene where if you have a single letter change in the DNA sequence you can actually knock out your ability to speak, you can’t put sentences together, you have no sense of grammar, and so this is a tiny change that has a huge effect on the organism and its behaviour. So in some cases there probably are mutations that are analogous to Goldschmidt’s macro-mutations, but in many other cases probably they are relatively small changes, relatively small effects and you just get selection for the sequential steps which lead ultimately to the very complex organs.
Lets back up just a little bit. So we have had this introduction of agriculture and it has had the ability for people to live a little longer, and then we had medicine come in…
Well actually surprisingly, what is very interesting about the lifespan is that people were living longer as hunter-gatherers than they did in these early Neolithic farming communities. And in fact human lifespans didn’t increase substantially until the twentieth century. So the average Neolithic farmer was living around as long as the average factory worker in Victorian England in the nineteenth century. So it is really only with modern medicine that lifespans have increased substantially.
So what happened then is that the introduction of agriculture did not contribute to living longer but it produced more people yet it brought about all these other problems that you mentioned like the added diseases because of the close proximity to animals, and then mental illness. The other thing also was the types of food, wheat, more corn…
Yeah more carbs. Cheap, easy to produce sources of calories, in effect, and that has an immediate effect in things like the number of cavities that you see in the skeleton material. So you look at hunter-gatherer populations prior to the development of agriculture they got a tiny, tiny fraction of their teeth with cavities, less than five percent. After the introduction of agriculture, or after the development of agriculture, it goes up to 25-30 percent and that is because of the increase of simple carbohydrates in the diet and the sugar that lead to cavities.
And then you look at the increasing rates of mental illness, the World Health Organisation says by 2020 mental illness will be the second most important cause of death and disability in the world after hypertension, high blood pressure. This is huge, and ten percent of America is on antidepressants.
We know that there are connections to civilisation and mental illness but we don’t know exactly what it is in civilisation necessarily, I think there are a lot of theories about that.
No, we don’t know for sure. I mean I argue that it is this kind of cultural cacophony, the idea the average hunter-gatherer if they see someone they want to introduce themselves and talk about how they might be related and so on, engage with them as a person. And yet you think about life in a modern city and it would be impossible to do that with everyone you encounter. Think about people sitting in the subway trying to avert eye contact, you are standing in an elevator staring at the numbers rather than talking to each other – it is profoundly unnatural given our biology. And so that really is the point of the book that we have created this culture that has been tremendously successful but in many ways, it is a mismatch with our biology.
The last two things that you connect to the unforeseen costs of civilisation is of course climate change which is a very obvious development from overpopulation and overuse of energy and resources. But also fundamentalism. Talk about those two things.
The fundamentalism connection is a bit more tenuous than the others, but the argument that I make is that as society developed and we had to develop hierarchies we also developed formalised religions. Hunter-gatherers again don’t have these formalised systems of religion – they are what we call animists and they tend to believe there maybe one great God, but there are spirits everywhere, you are walking in the land that is inhabited by the spirits of your ancestors and so on. And religion became much more formalised and co-opted, I argue, when we had to develop governments and we had to develop ways of convincing people to band together and work toward a common good and so on. When we started living in these villages and ultimately cities, it appeared only during the Neolithic, and part of the extension of this I argue is that it has kind of dehumanised people and it is possible of course to see people who are not in your religious group as being separate from you and not like you in some way. It allows you to do things that perhaps you wouldn’t normally do without that ability to disconnect from them as individuals and as human beings and fundamentalism, I argue is one of those things, it is a reaction to this world where some people feel that they are not invested in the future, they have no place in the society that is developing, the secular world if you will, the futuristic world and they are rebelling against that. And through religion they are able to disconnect themselves from people as individuals and simply view them as entities that they can be opposed to, and that of course leads to some of the horrible acts that are committed in the name of fundamentalism.
Clearly we can’t go back to being hunter-gatherers, it is just not going to happen. So where do we go from here?
It is tough to say. I think the key – and it is not really saying anything new – but it is really trying to find a way to live within our means.
When you say this you don’t mean what some people mean by living within our means, you mean living within our biological, sustainable means?
Exactly. We have been on this kind of era of expansionist, manifest destiny, use as much as you can, accumulate as much excess as you can for 70,000 years in part when we were expanding around the world and it has really accelerated since we developed agriculture 10,000 years ago. And we have fooled ourselves into thinking that this could go on forever and in fact we are realising now particularly with things like climate change that that can’t go on forever. Is it possible for every country to live like the average American does today with gas-guzzling cars and huge amounts of energy expenditure? Of course it is not, we realize that. But how do you create that future where everything is sustainable, it means that we have to give up some things and we have to live within our means.
This interview was originally aired on the Scholars’ Circle. To access our archive of episodes and download this interview click here.