The eighteenth-century philosopher Jean-Jacques Rousseau considered civilised humans to be in some way degenerate: a pale, flabby diversion from the original, noble state of the savage. Other, humanist philosophers have seen human ‘domestication’ as a positive advance, removing us from a more brutal ancestral condition. The discussion around human self-domestication has become mired in political and moral interpretations. Biological ideas are always subject to misuse in this way, but there’s no moral dimension to evolution. What happens happens because natural selection favours adaptations that are performing well, at that moment, in that particular environment, and sieves out the rest. What was good for our ancestors may not be so good for us now. They were neither worse nor better than us, from a moral perspective. We got better at living with each other, in close proximity, simply because that worked, not because it was morally superior. We wouldn’t suggest that the dog is morally superior to the wolf, or the cow to the aurochs, or domesticated wheat to its wild cousins.
The physical changes seen in humans over time, and which seem to reflect a reduction in aggressive tendencies and an increase in tolerance, echo what’s seen in domestic animals – but also chime with differences between some wild species. Bonobos are close cousins of chimpanzees – but they’re much less aggressive and more playful. Their development, compared with chimpanzees, is also delayed – bonobo infants tend to be less fearful and more dependent on their mothers. There’s less difference in skull shape, and in the size of canine teeth, between the sexes in bonobos than there is in chimpanzees. Crucially, these anatomical changes seem to have appeared as incidental by-products of selection for sociability, just as they did in the domesticated silver foxes. It seems that a process akin to ‘self-domestication’ has actually been quite widespread in mammalian evolution – wherever increasing social tolerance has proven useful to evolutionary success.
While some philosophers have talked about self-domestication in humans representing some sort of escape from the normal rules of evolution, and from natural selection in particular, the presence of a similar suite of characteristics in other – non-domesticated – animals shows this to be quite wrong. Natural selection is still hard at work, even when it’s pro-social, non-aggressive, cooperative behaviour that’s being selected for. Once again, humans aren’t such a special case as we sometimes imagine ourselves to be. Normal rules apply.
And when it comes to the animals we’ve domesticated, it seems that we may have struck it lucky – we’ve just harnessed a natural potential by taming those animals, securing them as our allies. That potential may be more developed in some animals than others – depending on how their society and their interactions with members of other species has evolved – perhaps explaining why it’s easier to domesticate wolves than wolverines, and horses compared with zebras. And humans – we’ve always been ripe for self-domestication. Apes are social creatures. We found success in living in denser groups; we became even more sociable. There was no stopping us. We do this puppyish, youthful, playful, trusting thing better than anyone else. And when the Neolithic came along, with the potential to support expanding human populations, our ancestors thrived in that new environment of their own making. As the population boomed, and people started living in closer quarters than ever before, selection for social tolerance would have become even stronger. The people of Catalhöyük literally lived on top of each other in their small citadel of mud-brick houses. Today, life in huge, dense cities is only possible because we’re so socially tolerant, because we’ve domesticated ourselves. But of course, it’s not only our environment that we’ve changed.
The legacy of the Neolithic
Humans exert a profound effect on the physical environment, not just locally, but globally. The conventional view is that anthropogenic climate change – caused by humans – began during the Industrial Revolutions of the eighteenth and nineteenth centuries. Since then, we’ve been burning fossil fuels in increasing quantities, pushing up the level of carbon dioxide in the atmosphere, and warming the planet. But in fact, our impact on global climate started much earlier – back in the Neolithic. Antarctic ice cores provide a record of ancient levels of carbon dioxide and methane in the atmosphere, and for most of the past 400,000 years the concentrations of these gases has fluctuated in predictable natural cycles. But then the pattern changed – 8,000 years ago for carbon dioxide, and 5,000 years ago for methane. The levels of these gases began to rise when they should have been dropping. The timings correspond with the beginning of the Neolithic in western and eastern Asia, and with the spread and intensification of agriculture. The shift from foraging to farming had a profound impact on the landscape, as forests were cleared to make way for fields – and carbon dioxide was released into the atmosphere. It’s possible that this delayed the onset of a glaciation that would otherwise have seen ice sheets descending once more over the Northern Hemisphere. In this period of climatic stability, then, our civilisations grew up and flourished. But now we’ve undoubtedly gone too far – we’re not just tinkering with global climate, we’re prodding it hard, and we don’t fully understand the long-term consequences of that. If a few thousand humans armed with stone tools could inadvertently warm the climate enough to delay an Ice Age, what damage could more than 7 billion of us do?
Human-induced, anthropogenic climate change represents a clear and present threat, not only to us, but to many other species. But set against that pressing necessity to cut greenhouse-gas emissions is the need to feed a whole world full of people. And our numbers just keep growing. Before the Neolithic, the global human population was just a few million at most. The advent of farming supported a population boom, so that, by 1,000 years ago, it’s estimated that there were around 300 million people on the planet. By 1800 that number had risen to a billion.
During the twentieth century, the human population burgeoned from 1.6 billion to 6 billion. Food production needed a huge boost, and got it – in the form of the Green Revolution. Between 1965 and 1985, average crop yields increased by more than 50 per cent. The rate of population growth peaked in the 1960s and is now declining, and the number of humans on the planet seems set to stabilise at around 9 billion, in the middle of this century. But we’re still looking at a billion more mouths to feed by 2050. It’s enough to spark a mild Malthusian panic.
We seem to need another ‘Green Revolution’ – but in fact the first one was far from being a sustainable solution: the boost to productivity came at a high cost. Grain for grain, agriculture is now more energy-hungry and more dependent on fossil fuels than it was before that not-so-green revolution. Agriculture is responsible for around a third of global greenhouse-gas emissions – through the clearing of tropical forests, from methane emanating from the rear ends of livestock, as well as that produced by microbes in flooded rice fields, and nitrous oxide wafting up from fertilised soil. There are other problems too: more expensive seeds and a growing emphasis on monoculture and cash crops threaten the livelihoods of poor farmers. Heavy use of agrochemicals has also taken its toll on both human health and wildlife. Changes in land use, together with pesticides, have decimated insect populations. The environmental and health costs of nitrogen contamination from fertilisers are even estimated by some to outweigh the economic gains in agriculture. But perhaps just as importantly, although the Green Revolution boosted food production, it never solved world hunger. This is where it gets insanely complicated, and highly political, because we’re already producing enough food for everyone – just not in the right places, or at the right prices. International trade in food generates profits for increasingly large and powerful corporations, but doesn’t get food to where it’s needed most. There’s been a recent expansion of land pressed into agricultural use, but this has been largely to provide meat, oil, sugar, cocoa and coffee for the rich. We’re also wasting an obscene amount – a full third of the food we produce. Meanwhile, the poorest people – in both developing and developed countries – still don’t have access
to the nutritious food they require. Our global food system clearly needs a major overhaul if we’re to have a hope of feeding everyone, sustainably.
The key to solving world hunger is unlikely to come simply from driving productivity on large-scale commercial farms – which already produce huge surpluses. Some 90 per cent of the world’s farms are smaller than 2 hectares – so supporting smallholders to become more productive is crucial to achieving global food security. Focusing on yield alone is likely to lead to more problems with spiralling energy costs, increased greenhouse-gas emissions, loss of habitats and biodiversity, and contaminated water. Ecologists argue that the best way forward is not through intensification and the use of agrochemicals, but through sustainable ‘agro-ecological’ methods which are designed to maintain soil and water quality, and to support – rather than to poison – pollinators. We need bees – more than they need us.
GM could be part of the solution. We’ve seen how a dietary staple could be transformed into something which delivers a much-needed vitamin, in the form of Golden Rice. We now have the tools to make crops that are also better at extracting nutrients, naturally resistant to diseases and drought. We may soon be able to breed flu-resistant chickens and pigs. The prize seems tempting enough – bringing us another step closer to global food security – but of course the technology is still mired in controversy.
Moving parts from one organism to another – including organ transplants in humans – has always caused consternation. In the past, grafting of fruit trees even met with some ethical objections. In the biblical law laid out in the Talmud, dating to the third century BCE, there’s a specific prohibition against grafting one type of tree on to another: ‘Grafting apple with wild pear, peach with almond or red date with sidr [another date tree], in spite of their similarity, is forbidden.’ It was also forbidden to breed together two different kinds of animals. It seems that concern about transgressing the species boundary goes back a long way, and even grafting within a species was condemned by some. The sixteenth-century botanist Jean Ruel called grafting an ‘insitione adulteries’ – an ‘adulterous insertion’. And John ‘Johnny Appleseed’ Chapman – the man who transported canoe-loads of pips to set up apple-tree nurseries at the frontier in early nineteenth-century North America – railed against the practice. He’s quoted as saying: ‘They can improve the apple in that way, but that is only a device of man, and it is wicked to cut up trees in that way. The correct method is to select good seeds and plant them in good ground and only God can improve the apple.’ There are echoes here with contemporary objections to genetic modification – which, after all, is grafting at a molecular level.
It can be quite easy to fall into the trap of viewing species as monolithic, unchanging. The fact that we don’t tend to see one species changing into another over the short time frame of a human life helps to cement that idea. But of course species are not immutable. That’s the lesson of evolution – which we see in fossils, in the structure of living organisms, and in their DNA. And actually there are instances when we do see changes within a human lifetime, or even more quickly. Bacteria reproduce and evolve extremely fast. The appearance and spread of resistance to antibiotics amongst bacteria represents a fast, recent – and hugely troubling – evolutionary change. But it’s possible to see ‘real-time’ evolutionary changes in animals, too, especially where environments have undergone dramatic change – and through selective breeding. Experiments like that of Belyaev with his silver foxes show just how fast those changes can be. And Darwin focused on describing variation and change under domestication in the Origin precisely because he knew that this represented evidence of the mutability of species that everyone would be familiar with. Once he’d covered that ground, laying out the evidence for the effects of artificial selection, he could move on to describing how unthinking, natural processes could produce a similar effect: how natural selection could work to create the diversity of life on earth.
A species is in constant flux. Even without novel mutations, the frequency of particular types of gene in a population changes over time: through genetic drift and natural selection – and introduction of DNA from other species. It’s the interaction between the members of a species and their environment which produces this dance – some variations do better than others. Mutations, when they do occur, introduce new possibilities into the mix – although they’re not the only source of novelty. Sexual reproduction, which involves a shuffling of DNA as gametes are produced, as well as the creation of novel pairs of genes when maternal and paternal chromosomes come together in the fertilised egg, creates variation out of existing genetic material. A changing environment also exerts new pressures. That environment is not only physical but biological – it includes all the other species that an organism interacts with.
We’ve been influencing the development of our domesticated species through altering their biological and physical environments for centuries. We’ve moved them around the globe. We’ve managed the mates they’ve found to breed with. We’ve protected them from predators, and ensured that they have a good supply of food. We’ve affected their DNA profoundly, but everything we’ve done before (apart from radiation breeding) has been about indirectly altering genomes. Gene editing, of course, offers us the potential to directly modify genomes.
The recently revealed hybrid nature of so many species, including us – and our domesticated allies – has been a genuine revelation. Even geneticists have been surprised at how permeable the ‘species boundary’ has turned out to be. It certainly provides us with a novel context for thinking about the ethics of transferring genes from one species to another.
There does seem to be something of a shift occurring within the Green Movement – away from a blanket rejection of genetic modification, and towards the possibility that this technology could represent a useful and environmentally sensitive tool. Tony Juniper, conservation biologist and a former director of Friends of the Earth, has publicly recognised the potential of GM. Speaking on BBC Radio 4’s Today programme in March 2017, he sounded a cautiously positive note, talking about the potential for using gene-editing techniques to ‘accelerate the process of selective breeding’, spreading useful alleles within a species. But Juniper was also open to the possibility and potential of some transgenic – between-species – alterations. ‘You [could] take genes from the wild relatives of domesticated plants,’ he commented, ‘and … apply those into crop varieties more effectively … helping to solve various problems including climate-change impact, soil damage, [and] water scarcity.’ Some people are even starting to talk about ‘GM organic’. It would be an extraordinary twist of fate indeed if GM became part of the new, truly Green revolution.
But the ethical considerations around genetic modification go further than the potential biological problems. There’s the question of who is carrying out the task, and profiting from it. There are also real concerns about food sovereignty, about forcing a new technology on to people who don’t want or need it. On the other hand, pestresistant Bt Brinjal and vitamin-enriched Golden Rice might offer genuine options to support poor, smallholder farmers. Obstructing those opportunities – especially if that’s done without really knowing what the farmers and their communities want – could simply end up preserving the status quo, ensuring that only the rich countries of the Northern hemisphere benefit from new technological advances. A less paternalistic approach, supporting the poorest farmers to make their own, informed choices, seems fairer.
The geneticists at the Roslin Institute – with their research into gene editing in chickens – aren’t interested in persuading people to accept this technology, but they’d love them to be better informed, and then to make up their own minds. They’re not cultish or evangelical about GM in the least. I think that this is something fundamentally important about the science and technology that’s explored and developed in universities – compared with private corporations. There’s much less room for vested interests. Most scientists in
universities are doing what they do because they believe it’s good for humanity, and they tend to be quite self-critical, self-effacing and fairly resistant to exaggerating claims – even when funders encourage them to do so. I’m sure that’s a source of intense frustration for the more business-minded and profit-focused managers in our higher-education institutions, but it’s absolutely essential. Publicly funded scientists shouldn’t be working to maximise profits. They should be free to follow where curiosity leads them, and to explore possibilities which could work for the common good.
None of the geneticists I’ve met have presented GM as a panacea, but they think it might have some useful applications, and they’re keen to work in partnership with farmers in developing countries to explore its usefulness. Mike McGrew at the Roslin Institute was most animated when he was talking about the potential for gene editing in conservation – but he was equally excited by one of his projects in Africa, funded by the Gates Foundation, focusing on improving flocks of chickens in challenging environments. He was also firm about the need to work on this technology in clear sight and through real engagement with communities. He talked about another project he was involved in – trying to make a dairy cow resistant to the parasitic disease, trypanosomiasis, in Africa, moving a gene from another species into the cow. ‘You have to tell people what you’re planning to do ahead of time and ask if people find that acceptable … we shouldn’t impose our values on other cultures.’
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