2. Got Milk?

As soon as scientists first learned how to edit the genomes of animals, they began to imagine all the ways in which they might use this new power. Creating brightly coloured novelty pets was not a high priority, however. Instead, most researchers envisioned far more consequential applications, hoping to create genetically engineered animals that would save human lives. Welcome to the world of ‘pharming’, in which simple genetic tweaks turn animals into living pharmaceutical factories kitted out to cure our ills.

Many of the proteins that our cells naturally crank out make for good medicine. Our bodies’ own enzymes, hormones, clotting factors and antibodies are commonly used to treat cancer, diabetes, autoimmune diseases and more. The trouble is that it’s difficult and expensive to make these compounds on an industrial scale, and as a result, many patients face shortages of the medicines they need. Dairy animals, on the other hand, are expert protein producers, their udders swollen with milk. With the creation of the first transgenic mammals – first mice, then other species – in the 1980s, scientists landed on an idea: What if they put the gene for a human antibody or enzyme into some milk-producing wonder – a cow, goat or sheep? If the researchers put the gene in just the right place, under the control of just the right molecular switch, maybe they could engineer animals that produced healing human proteins in their milk. Then doctors could collect medicine by the bucketful.

Throughout the 1980s and ’90s, studies provided proof of principle, as scientists created transgenic mice, sheep, goats, pigs, cattle and rabbits that did in fact make therapeutic compounds in their milk. At first, this work was merely wowing boffinery, lab-bound thought experiments come true. That all changed with the invention of ATryn, a drug produced by the Massachusetts firm GTC Biotherapeutics. ATryn is antithrombin, an anticoagulant that can be used to prevent life-threatening blood clots. The compound, made by human liver cells, plays a key role in keeping our bodies clot-free. It acts as a molecular bouncer, sidling up to clot-forming compounds and escorting them out of the bloodstream. But as many as 1 in 2,000 people are born with a genetic mutation that prevents them from making antithrombin. These patients are prone to clots, especially in their legs and lungs, and they are at elevated risk of suffering from fatal complications during surgery and childbirth. Supplemental antithrombin can reduce this risk, and GTC decided to try to manufacture the compound using genetically engineered goats.

To create its special herd of goats, GTC used microinjection, the same technique that produced GloFish and AquAdvantage salmon. The company’s scientists took the gene for human antithrombin and injected it directly into fertilized goat eggs. Then they implanted the eggs in the wombs of female goats. When the kids were born, some of them proved to be transgenic, the human gene nestled safely in their cells. The researchers paired the antithrombin gene with a promoter (which, as you’ll recall, is a sequence of DNA that controls gene activity) that is normally active in the goat’s mammary glands during milk production. When the transgenic females lactated, the promoter turned the transgene on and the goats’ udders filled with milk containing antithrombin. All that was left to do was to collect the milk, and extract and purify the protein. Et voilà – human medicine! And for GTC, a new brand of liquid gold. The EU approved ATryn in 2006, and it immediately debuted as the world’s first transgenic animal drug.6 Over the course of a year, the ‘milking parlours’ on GTC’s 120-hectare farm in Massachusetts could collect more than a kilogram of medicine from a single animal.

Thus the humble goat – tin-can eater and petting-farm star – has added a new item to its résumé: pharmaceutical manufacturer. The universe of pharming is rapidly expanding; labs and companies around the world are working feverishly to stock their barns, fields and coops with animals that pump out medicines for ailments ranging from haemophilia to cancer.⁷ ATryn has already been joined by Ruconest, a drug produced in the milk of genetically engineered rabbits. Sold by the Dutch company Pharming, Ruconest treats hereditary angioedema, a genetic disease that causes painful bodily swelling.

Pharm animals, which push the boundaries of medical research and could save human lives, make GloFish look like child’s play; there is nothing frivolous about them. But that’s a double-edged sword. Making animals more useful also makes them more likely to be used. Genetic engineering allows us to exploit other species for new reasons and in new ways, expanding our supply of creature commodities. Of course, using animals for our own purposes isn’t new. Should we object because the technology is?

Scientists are working to coax all sorts of curative compounds out of animal bodies. Many of these substances are remedies for rare genetic disorders. When it came time to choose a target, two biologists at the University of California, James Murray and Elizabeth Maga, decided to use the tools of pharming to alleviate a much more pervasive problem: diarrhoea. The ailment’s global toll is enormous, with more than 2 million children dying of diarrhoeal disease every year. That’s a ghastly statistic, and if Murray and Maga can begin to make a dent in that number, their work will be the most far-reaching pharming project yet.

As it happens, human breast milk is a potent anti-diarrhoea elixir. The liquid is full of compounds that boost a child’s immune system and attack invading bacteria. Evidence now suggests that infants who are breast-fed have healthier digestive systems and are less likely to suffer from diarrhoeal diseases than those fed purely on formula. Some of these effects can last even after breast-feeding ends; infants who drink breast milk for the first thirteen weeks of life are less likely to come down with gastrointestinal problems during their entire first year.

One of the compounds responsible for these effects is an enzyme called lysozyme, a microbe destroyer that bursts bacterial cells like balloons, causing the cellular membranes to rupture and the disease-causing contents to spill out. Lysozyme is naturally present in the milk of all mammals, but it’s especially concentrated in human breast milk, which contains three thousand times as much of the enzyme as the milk of some other animals. (Infant formula, which is usually made from cow’s milk, has only trace amounts of lysozyme, at best.)

Murray and Maga want to extend the protective effects of breast milk to infants who don’t nurse or children who have grown too old for nursing. Their plan is to harness the power of pharming, engineering dairy goats that make extra lysozyme in their milk. The pair hopes that this genetically modified milk can be used to both prevent and treat childhood diarrhoea. Like the scientists at GTC, Murray and Maga set out to create their supergoats using microinjection.8 They squirted the human lysozyme gene into fertilized goat eggs and implanted the resulting embryos in surrogate mothers. One of the embryos grew into a little kid named Artemis, a transgenic female with a penchant for mulberry leaves.⁹ She lives out at the university’s goat barn, and one winter day, Murray took me to see her.

The barn is home to 150 assorted goats – representing a variety of wonderfully named breeds, including Alpine, Nubian, Toggenberg and LaMancha goats – but Artemis has pride of place, making her home in a private enclosure directly in front of the entrance. Artemis, now a fully grown adult doe, is mostly white, with some black markings around her eyes and the classic goat accessory: a long white beard. As soon as we reach her pen, Artemis sticks her head in Murray’s hands, waiting for him to stroke her ears. After Artemis matured, she became what’s known as the ‘founder female’ – by breeding her, Murray and Maga generated a whole line of transgenic goats.

Today, Artemis’s heirs are all over this facility, living in a line of wire-enclosed pens stretching out behind the barn. It’s been raining all morning, and many of the goats are still huddled underneath their small wooden shelters. As we walk down the slick, hay-strewn path, the animals begin to ‘baa’ and traipse over to us through the mud. I don’t think I’ve had a close encounter of this kind since my petting-farm days, and I’ve forgotten how endearing these animals can be, with their wide-set eyes, their oversized ears, and their eagerness for attention and affection. The goats jostle one another, poking their noses through the holes in the wire fence, angling for strokes from Murray and me. We happily oblige.

As we dole out our goat strokes, Murray points out the genetically modified animals. I’m glad he does, because they look just like all the other goats, and I never would have recognized them on my own. Eight of the transgenic females are pregnant, due to deliver a batch of new kids in the next month or two. With newborns to care for, these does’ udders will fill with lysozyme-rich milk. They’ll make up to two litres a day of the stuff, for about three hundred days after they give birth.

Murray and Maga have carefully analysed the milk from Artemis’s heirs and found that it does indeed contain elevated levels of lysozyme – 1,000 percent more than normal. They’ve also demonstrated that the milk has protective effects in pigs, which have a digestive anatomy that is similar to our own. Compared with piglets that suck down conventional goat milk, young pigs that get the special, transgenic stuff have lower baseline levels of coliform bacteria – including E. coli, a common cause of diarrhoeal disease – in their guts. They also had stronger immune systems and healthier small intestines. And when the researchers try to make the pigs sick, by feeding them a delicious E. coli–laden soy broth, the piglets slurping down the lysozyme-rich milk fared better.

These results are giving Murray and Maga confidence that the modified milk will do a human body good. In September 2011, they asked the FDA to review the milk from transgenic goats and officially rule whether it’s safe for human consumption, and they are still awaiting a verdict. And though Murray acknowledges that nothing can be 100-percent risk-free, he thinks that lysozyme is pretty close. The compound is well studied and naturally present not only in our milk, but also in our tears and saliva. As Murray points out, ‘You’ve been eating lysozyme since the day you first swallowed.’

Still, the two scientists aren’t sure whether the FDA will rule in their favour. For now, GloFish are the only transgenic animals available to the American public, and the federal government doesn’t seem eager to give the neon swimmers any company. Ironically, it’s the makers of useful transgenic animals – the ones designed to be sources of food or medicine – that are struggling to get the official stamp of approval. GloFish sailed through because they were totally trivial, designed purely to be pets. Of course, it is appropriate to subject an engineered animal intended for human consumption to a higher level of scrutiny, but as a result, these organisms can get stalled in a never-ending regulatory process. Even if the FDA approves their transgenic goat milk, there’s no guarantee that American doctors or patients will embrace it.

So Murray and Maga are hedging their bets and establishing a second herd of goats in Brazil, which is among a handful of countries – including Argentina, China and India – poised to become major powers in the world of agricultural biotechnology. Brazil is already a leading grower of genetically modified crops, and the country’s government is giving Murray and Maga’s colleagues at the Federal University of Ceará £2 million to create a herd of lysozyme goats. Once the goats are up and bleating, the international research team will start human trials in Brazil, studying the milk’s effects in healthy adults and then healthy children. If all goes well, they’ll move on to trials with those who might really be able to benefit from the milk: the infants and toddlers with diarrhoeal disease.

The team is headquartered in Fortaleza, along Brazil’s northeastern coast. The region is home to some of Brazil’s poorest towns and villages, where as many as 10 percent of children die before their fifth birthday. Transgenic goats’ milk may be a much-needed salve. Assuming the human trials are successful, Murray and Maga see the milk being used in several ways. Doctors could give it to infants who aren’t breast-fed, in order to help them develop healthy immune systems. Or they could prescribe it for toddlers who are no longer nursing, in order to keep their digestive system in tip-top shape. Or the milk could be used as a treatment itself – administered alongside rehydration therapy to infants, toddlers and older children suffering from diarrhoeal disease. As an added bonus, the milk would also provide some much-needed nourishment, combating the malnutrition, which often goes hand in hand with intestinal disease.10 The ultimate goal, Murray and Maga say, is to get their goats into towns and villages all over Brazil. Instead of keeping a herd of normal goats, families would raise transgenic ones, and anyone drinking the animals’ milk would benefit from the supercharged levels of lysozyme.

Keeping children alive seems like an unobjectionable endeavour, but doing so through genetic engineering makes many people uncomfortable. The anxiety comes in many forms. There are legitimate concerns about health risks, but these are easy to address – that’s exactly what human trials are for. The other objections are more philosophical – and harder to answer with cold, hard data.

Take, for instance, the worries about animal exploitation. The development of our new genetic tools has coincided with a growing concern for the rights and welfare of animals. In 1975, just as scientists were learning to mix and match DNA, Peter Singer published his famous treatise Animal Liberation. In it he railed against ‘speciesism’, arguing that our mistreatment of animals, and our exploitation of their bodies for food or research, was akin to the subjugation of women or racial minorities. Animal suffering matters, he said, and we have an obligation to minimize the pain and distress we inflict upon other species. It was the birth of the modern animal rights movement, and in the years since, activists have fought a variety of campaigns, lobbying governments to grant full legal rights to great apes and protesting companies that test cosmetics on rats or rabbits.

Those working to extend animal rights are motivated by a wide range of philosophies and goals, but one of the common themes is that animals have a basic intrinsic value – that is, that they are inherently valuable on their own, solely because they are living creatures with whom we share this Earth. On the other hand, when we use animals for food, or fibre, or drugs, we reduce them to their instrumental value, treating them as mere tools to be used or resources to be tapped.

Much to the chagrin of the animal rights crowd, biotechnology lets us turn animals into even better tools. Scientists can engineer lab rats guaranteed to suffer from the very medical afflictions – from diabetes to epilepsy – they want to study.11 And they have done so. In fact, such GM animals are taking over scientific laboratories. Since 1995, the number of ‘genetically normal’ animals used in UK labs has decreased slightly, while the ranks of genetically engineered animals have grown more than six-fold. In 2010, 43 percent of all lab procedures performed in the UK involved GM animals. Japan’s labs are home to 3.6 million genetically modified mice. With this genetic engineering, scientists bestow on animals the traits we, as a society, wish to exploit. As Richard Twine, the Lancaster University sociologist, notes of pharming, ‘Animals that have previously been defined as agricultural commodities are becoming pharmaceutical commodities. Biotechnology might be inciting new forms of commodification within human and animal relations. It’s potentially multiplying the uses to which profits can be made from different forms of animal life.’

An extreme example involves doctors’ longstanding hopes for using animals as organ donors in human patients. Worldwide, there’s an acute shortage of human donors – in the UK, 1,000 people awaiting new organs die every year – and animal organs could help fill the gap. Throughout the twentieth century, surgeons experimented with this kind of ‘xenotransplantation’, putting monkey parts into humans suffering from various diseases and defects. The most famous case came in 1984, when an infant with an underdeveloped heart received a replacement heart from a baboon. It was a daring experiment, but Baby Fae, as the infant was called, survived just twenty days with the new organ, and other recipients of monkey organs haven’t fared much better. In the 1990s, for example, two patients received livers from baboons; one lived for seventy days after the operation, the other for just twenty-six. And none of six patients who were given baboon kidneys survived longer than two months.12

The biggest barrier to successful cross-species transplants is rejection; our immune systems expertly, and correctly, identify implanted animal parts as foreign tissues and attack the new organs. Genetic engineering, however, may give us a way to create animal organs suitable for transplant into our own bodies. Using cognitively sophisticated monkeys and apes as organ donors has become taboo, so researchers are now focusing on pigs, which are widely farmed and have organs that are about the same size as our own. In fact, replacing defective human heart valves with pig valves has become a routine medical procedure. (This interspecies transfer of tissue, rather than a whole organ, is known as xenografting.) The surfaces of pig cells are adorned with signature sugars, which immediately tip our human immune systems off to the fact that something strange has entered the body. Surgeons can keep pig valves from provoking an immune response by treating them with a special preservative before they’re implanted in the human body. It works fine for this small piece of tissue, but it’s not feasible for entire organs, which must be fresh and viable when they’re transplanted. Enter genetic engineering: scientists have now created pigs in which the gene that codes for these distinct sugars is ‘knocked out’, hoping that organs from these pigs will pass more easily as native human tissue.

Using these knockout pigs as organ donors could save thousands of human lives, but it also means that we’d be turning sentient creatures into more suitable sacrificial lambs, engineering animals purely so we can later dismantle them. That’s instrumental in the extreme. Yes, we already break pigs into pieces to make our morning bacon, but genetic modification could expand the market for pig parts.

By and large, we accept the use of animals as objects and tools. Despite the growth of the animal rights movement, for instance, there aren’t many vegetarians. (Polls reveal that between 92 and 97 percent of Britons eats eighty kilograms of meat annually, up from seventy kilograms in 1980; the Danish eat a staggering 146 kilograms per person.) And what is a Rib Eye steak if not a reduction of an animal to parts, to its instrumental value? There are issues with farming, of course, especially the industrial-scale factory farming that is the norm today. But whatever our objections to the system itself, the truth is that most of us accept the idea that we can use an animal’s body to nourish our own.

For most of us, then, the real ethical question surrounding pharm animals comes down to the genetic engineering itself. Is there something about editing DNA and remixing biological material that is just inherently wrong? Monstrous mash-ups have long menaced the imagination, and critics of biotechnology worry that breaching species barriers violates the rules of God or nature or both. These concerns are magnified when researchers combine animal DNA with our own, by, say, putting a human gene into a goat.

Some scientists are doing a whole lot more than inserting a single human gene into another species – they’re creating human-animal ‘chimaeras’, whose bodies contain both human and animal cells. The difference between a transgenic animal, which has a single gene from a foreign species present in every cell, and a chimaeric animal, which has cells that come from two different species, can be visualized this way: Imagine a transgenic animal as one in which every cell is blue with a single red dot, while a chimaeric one looks more like a patchwork quilt, with some cells that are entirely blue and others that are entirely red. (To continue the analogy, a hybrid – created when the sperm of one species fertilizes the egg of another – would be a creature in which all cells are purple.)13 In a series of recent experiments, researchers at the University of Nevada, Reno, injected human stem cells – shape-shifting cells capable of becoming a variety of tissues – into sheep foetuses. As the lambs developed in utero, they incorporated these cells into their bodies, resulting in sheep that had hearts, livers and pancreases that were part sheep and part human.

These interspecies combinations are not popular with the public. In one survey, 53 percent of Europeans agreed with the statement ‘Mixing animal and human genes is unacceptable even if it helps medical research for human health.’ Why such opposition? Well, for one thing, combining human genes with those of other animals can raise uncomfortable existential questions, threatening our sense of uniqueness. If we can make our cells spring to life in a sheep or make a piece of our biological code work in a beady-eyed little rodent, what is it, exactly, that separates man from beast? In the US, one senator has even proposed a federal Human-Animal Hybrid Prohibition Act, noting that ‘human dignity and the integrity of the human species are compromised by human-animal hybrids’. Yet we rarely hear the flip side of this argument – that human-animal hybrids threaten the dignity of animals.

From an ethical standpoint, human-animal mixtures are especially tricky when they involve the melding of minds. Animal cognition has much in common with our own, but certain kinds of autobiographical memory, language, number sense and aspects of social cognition are unique to humans. At least, they are for the time being; scientists have already started manipulating genes involved in some of these capabilities. In 2009, German researchers engineered mice that carried a human version of FOXP2, a gene thought to be partially responsible for our unique way with words. (Mutations in the gene can cause speech and language disorders.) Giving mice the human FOXP2 variant changed the sound of the rodents’ squeaks and the shape and size of their neurons.

What if, instead of making sheep with human cells in their livers, the scientists at the University of Nevada had made sheep, rats or monkeys with a mass of human cells in their brains? Would these animals suddenly have a sense of justice? An ability to count? Would they be self-aware enough to realize that they were spending their lives as experimental subjects? If so, should we spring them from their cages? How many human brain cells and human behaviours would a sheep, rat or ape need to display in order to qualify for enhanced legal status, legislative representation and other rights? Neither fully animal nor fully human, these creatures would occupy an ethical no-man’s-land.

These sticky philosophical questions, among other concerns, led the UK’s Academy of Medical Sciences to conclude in a 2011 report that research that might make an animal’s brain more ‘humanlike’ should be subject to special scrutiny14. The working group of fifteen British scientists and scholars that put together the 150-page report, entitled Animals Containing Human Material, arrived at that conclusion after examining a whole host of scientific, ethical and regulatory issues. In the report, the group recommends establishing a national expert body to review research involving human-animal hybrids. This body should evaluate certain classes of research especially carefully, the working group said, including ‘[e]xperiments that could be expected to significantly alter the appearance or behaviour of animals, affecting those characteristics that are perceived to contribute most to distinguishing our species from our close evolutionary relatives’. The working group also concluded that some research should be totally off limits, at least for the foreseeable future. ‘A very narrow range of experiments should not, for now, be licensed because they either lack compelling scientific justification or raise very strong ethical concerns’, the report stated. Among these forbidden experiments are those in which substantial numbers of human brain cells are transplanted in non-human primates – our closest evolutionary relatives – as well as those in which animals may end up manufacturing human reproductive cells.

Not all human-animal mixtures create the same quandaries, however. Putting a gene for human lysozyme in a goat does not make that animal a person any more than putting a pig valve into a human heart makes that surgical patient a pig.15 Though both of these creatures are a mix of human and nonhuman animal, neither occupies some new, undefinable moral category. No one would seriously argue that a goat with a single human gene should get the right to vote or that a human with a pig part inside should be kept in a sty. As the Academy of Medical Sciences put it, ‘the great majority’ of experiments involving animals engineered to carry human genes ‘pose no novel issues’.

Even as we worry about breaching species barriers, biologists argue over just what it is that makes a ‘species’ in the first place. Though ‘species’ exist as rigid categories in our minds – and are a convenient way for us to label the natural world – they’re considerably more fluid in nature. After all, Darwin’s theory of evolution is based on the idea that there are smooth transitions, rather than sharp dividing lines, between humans and chimpanzees, between rats and rabbits. The genetic characteristics of a species are not set in stone; whatever it is that makes a human a human and a chimp a chimp is constantly evolving.

What’s more, genes from different species sometimes mingle in the natural world. Animals occasionally pursue torrid interspecies affairs, giving us ligers and tigons and zorses. (Oh my!) Different species of bacteria can spontaneously swap DNA in the wild or transfer novel genes into insects, worms and other animals. The parasite that causes Chagas’ disease, a chronic illness associated with heart and digestive problems, can slip its DNA into our own genomes, and pea aphids have borrowed genes from a fungus that turns the bugs’ bodies red. We may be able to change animals faster and in more profound ways than nature does on its own, but the point is that there’s nothing inherently sacred about a species’s genome – it’s an amorphous, ever-changing thing.

Still, there is logic, and then there is emotion. We don’t have to believe that the genome is sacred or that humans are divine to feel a sense of revulsion when we imagine a mouse with a human brain. This reaction is what ethicists call the ‘yuck factor’, and it’s what makes us recoil when we consider the prospect of drinking wastewater (even after it’s been decontaminated) or adopting a dog that glows neon red.

The bioethicist Leon Kass believes that we should pay careful attention to those visceral, gut responses to biotechnology. His essay ‘The Wisdom of Repugnance’ was initially intended as a missive against human cloning, but his arguments have since been applied to all sorts of biotechnologies, including genetic engineering. ‘In critical cases’, Kass wrote, ‘repugnance is the emotional expression of deep wisdom, beyond reason’s power fully to articulate it . . . Repugnance, here as elsewhere, revolts against the excesses of human willfulness, warning us not to transgress what is unspeakably profound’. Kass also argues that ‘repugnance may be the only voice left that speaks up to defend the central core of our humanity’.

As for the wisdom of repugnancy, a knot in the throat or a pit in the stomach may suggest that we’re approaching dangerous territory, that we need to consider our actions carefully. That doesn’t mean we should let disgust run the show. After all, as an emotion, disgust is not always grounded in the world of reason. For example, the Academy of Medical Sciences noted that while we’re uneasy about giving animals human faces, limbs, hair and skin, we’re far less perturbed by making animals look human on the inside. This discrepancy, the report’s authors concluded, ‘appears to be irrational . . . [O]ne can compare this distaste at the humanised appearance of an animal with the common reaction of unease at the sight of human disfigurement. This is a primitive reaction which has no inherent “wisdom”.’

Repugnance may be a good spark for public dialogue, but it shouldn’t be a substitute for it. Acting in an ethical manner sometimes requires rising above raw emotion. What if we had let the visceral disgust some people once felt at seeing an interracial couple be the final word on interracial marriage? A gut instinct shouldn’t be a death sentence, an emotional reaction a replacement for moral and ethical reasoning.

So if we discount the ‘yuck factor’, how are we to evaluate the genetic alteration of animals? Bernard Rollin, a philosopher at Colorado State University, proposes that we use a simple ethic: ‘conservation of welfare’. Simply put, he says, the principle holds: ‘If you’re going to modify a line of animals, the resultant animals should be no worse off from a welfare point of view – and preferably better.’

Some genetically engineered animals would certainly fail this test. The most infamous case is the ‘Beltsville pig’, engineered by the US Department of Agriculture’s research centre in Maryland to carry a gene for human growth hormone. The goal was to create a pig that gained weight faster, required less food and had a higher ratio of muscle to body fat. The resulting transgenic piggies were indeed leaner and required fewer calories to bulk up, but from the point of view of the animals’ own welfare, the modification was catastrophic. The list of these little piggies’ afflictions reads like a medical encyclopaedia: joint disease, kidney disease, heart disease, diabetes, weakened immune systems, diarrhoea, arthritis, ulcers, pneumonia, sexual dysfunction and more. The swine also had bulging eyes and thickened skin, and they were lethargic and uncoordinated.

Not all genetic tinkering causes such animal welfare disasters, however. The precise effects of our engineering depend on the particular gene we insert and the snippet of regulatory DNA to which we attach it. In pharming, for instance, scientists have been able to restrict the production of foreign proteins to an animal’s mammary gland by attaching it to a promoter active only in that part of the body. Our ability to limit a gene’s activity to this one organ may explain why, by and large, pharm animals do not suffer from any unusual health problems. For example, the FDA examined seven generations of the ATryn goats, and found no evidence of strange ailments or illnesses. These goats have utterly normal lives – they just spend their days unknowingly secreting human medicine in their milk.

According to the conservation-of-welfare framework, the ATryn goats are ethically acceptable and the Beltsville pig is not. And the Beltsville pig is wrong not because it was genetically engineered but because it suffered. This ethical framework considers genetic engineering to be value-neutral – biotechnology is merely a tool, and whether it’s a force for good or evil depends entirely on how we deploy it. As Rollin put it in his book The Frankenstein Syndrome, ‘It is simply false that all genetic engineering must harm animals. Unless one assumes that all species of animals exist currently at their maximal possible state of happiness or well-being of welfare, such a claim is not legitimate.’

In fact, Murray and Maga’s goats – which have not shown any deformities – may be even healthier than their nontransgenic brethren. With higher concentrations of bacteria-busting lysozyme in their milk, the transgenic goats have healthier udders and fewer signs of infection, according to early data.

Other scientists are engineering livestock specifically to make them more resistant to disease. Several labs, for instance, have created cows that lack prions, the infectious proteins that can cause mad cow disease, the scourge of the British beef industry. In one approach, researchers used a technique called RNA interference. Messenger RNA, or mRNA, is essential for protein production – it carries the gene’s instructions from the nucleus to the part of the cell where proteins are actually manufactured. Scientists have discovered that they can silence genes by injecting into a cell small molecules that destroy or disable mRNA while it’s in transit. The RNA is thus not able to deliver its instructions to the cell’s protein factories (it’s as though the letter gets lost in the post) and the protein is not produced. By designing molecules that target certain stretches of mRNA, scientists can silence specific genes and prevent the production of select proteins, such as prions. The prion-free cattle that result may be immune to mad cow disease. That would be a victory for animals and humans too, since as of 2000, more than 4.4 million British cattle had been killed as a precautionary measure against the disease.

Pharming continues to march forward. Biotech companies around the world are working on the next generation of transgenic dairy animals, capable of producing all sorts of crucial human antibodies, clotting factors and other therapeutic proteins in their milk. Several teams of Chinese scientists have engineered cows that make milk with special nutritional properties, such as elevated levels of heart-healthy omega 3 fatty acids or reduced levels of hard-to-digest lactose. Researchers in some labs are working on producing transgenic animal drugs in other bodily fluids, such as blood, urine and semen. (Apparently, a single boar ejaculation can contain a whopping nine grams of protein. Talk about a yuck factor.) A team of Japanese biologists got transgenic silkworms to spin cocoons containing human collagen.

A few researchers are putting their eggs in an entirely different basket: chickens. Thanks to our selective breeding for master layers, one hen can lay 330 eggs, each of which contains 3.5 grams of protein, in a single year. What if we gave these egg-making superstars jobs in the pharmaceutical industry? ‘The egg is very appealing’ for pharming, says Helen Sang, a developmental biologist at the Roslin Institute in Scotland. ‘It’s a nice little package that hens lay once a day and we don’t have to milk them or anything.’

Making transgenic chickens has proved to be more difficult than meddling with mammals, but recent progress means that these golden eggs may finally be ready to hatch. Sang and her colleagues, for instance, turned a flock of rust-coloured chickens into drug-making machines. They created two different kinds of transgenic poultry, one carrying the human gene for miR24, an antibody that could be used to treat skin cancer, and another with a stretch of human DNA that codes for interferon beta-1-alpha, a compound used to treat multiple sclerosis. The transgenic fowl laid eggs jam-packed with these therapeutic proteins; there’s enough in each egg to treat several patients for an entire year. The modification did not seem to hurt the chickens. ‘And you could purify it and show that it had the expected biological activity.’ The chickens made the human proteins only in their eggs. ‘We showed that we got, for example, human beta-interferon in egg white and it wasn’t synthesized anywhere else in the hen’, Sang reports. Before long, we could all be cracking eggs for the cure.

The latest techniques are also making it possible to edit animal genomes with unprecedented precision. ‘The way we’ve been making transgenics up until now is really kind of crude’, Alison Van Eenennaam, a geneticist at the University of California, Davis, confesses. ‘You inject a bit of DNA and hope like hell it integrates somewhere on the genome. There are new technologies that are coming along that will allow us to go in and make very specific edits to the genome.’ One approach relies on what’s known as ‘zinc finger nucleases’ – lab-made proteins that act as little molecular scissors, cutting a strand of DNA at a specific location. Doing so means that researchers can disable one particular gene or slip a transgene into the genome in just the right spot. Today, scientists are far better equipped to control how a foreign gene is inserted and expressed than they were in the 1980s, which may help us engineer animals with fewer unwanted side effects.

Meanwhile, the emerging field of synthetic biology – in which scientists engineer new genes, cells and biological systems from scratch – could eventually provide another way to design animals to our exact specifications. It’s a young field, but it’s moving fast; in 2010, the biologist J. Craig Venter announced that he had created a partially synthetic organism capable of replicating itself. Venter’s team engineered the single-celled organism by building a genome that contained genes derived from a common species of bacteria as well as some entirely novel man-made stretches of DNA. (These custom-designed genetic sequences spelled out coded versions of the researchers’ names as well as several famous quotations.) They inserted this genome into the cell of a different bacterial species, where it sprang into action, taking control of all cellular functions. Synthetic biology may yield new ways to build microbes – and, eventually, more complex life-forms – capable of producing drugs, biofuels and other valuable compounds. (Of course, all the animal welfare, environmental contamination and human safety concerns that accompany moving single genes around the animal kingdom are magnified a thousandfold when we consider the prospect of assembling an entire genome from scratch.)

Despite the scientific advances, political, economic and social factors will keep some nations from embracing genetic engineering. European governments seem poised to reject products made by engineered animals, and the outlook in the US is also iffy. In 2012, Canadian researchers were forced to abandon fifteen years of research on an eco-friendly pig after their funding ran out. Researchers at the University of Guelph in Ontario had engineered the animals – dubbed Enviropigs – to excrete less phosphorus, a common cause of water pollution, in their manure. When phosphorus makes its way into streams, lakes and rivers, algae populations explode; this algal overgrowth can poison the water and kill fish and other aquatic organisms. Despite the pigs’ potential, the scientific team was unable to find a company willing to bring them to market, and the animals were euthanized in May 2012. Animal rights activists had launched a campaign to save the pigs’ lives, and many people contacted the researchers offering to adopt the swine. But the scientists’ hands were tied; regulations simply don’t permit unapproved, experimental genetically modified animals to be released from a secure laboratory environment.

If other nations start approving, and possibly exporting, transgenic animal products, it will put pressure on other countries to be more accepting of genetically engineered organisms; governments that shun all GM organisms could see themselves left behind economically and technologically. Rejecting genetic engineering wholesale means losing the good along with the bad. When it comes right down to it, as Murray says, ‘I don’t think anybody in the world will turn down a drug from a transgenic animal if they need it or their loved ones need it. Or a transplant, if they need it.’

It’s easy to oppose biotechnology in the abstract, but when that technology can save your life, grand pronouncements about scientific evils tend to dissolve. Most of us would do a lot more than drink transgenic goat milk to have even one more day with our loved ones.

Or, in some cases, to spend more time with our beloved pets.