"Does photosynthesis occur in moonlight?" and "What’s the best way to treat insomnia?" BBC Click Radio presenter Gareth Mitchell answers life's big questions
Right now the future of meat is still just a small white blob in a Petri dish. "We're not quite there yet," admits Professor Mark Post, a physiologist at Maastricht University in the Netherlands. "We have made big improvements, but it still looks like wasted muscle because we don't exactly know how to beef it up."
For tissue engineers like Post, the ultimate goal is to create synthetic meat that looks and tastes as good as the real thing. The idea may not sound appetising to all, but producing synthetic meat might one day become a necessity. According to the UN, the world population passed the seven billion mark on 31 October 2011. By 2050, there will be nine billion people on our planet.
Humans rely on animals for meat and dairy products, which puts a significant strain on Earth's already stretched resources and real estate. Livestock systems currently occupy 30 per cent of the planet's terrestrial surface area (excluding ice-covered regions) and 228 million tonnes of meat is produced every year. To meet future demand, the UN's Food and Agriculture Organization estimates that annual global meat production will need to double to 463 million tonnes by 2050.
Although trends suggest that the needs of North America and Western Europe will remain fairly stable, there will soon be a surge in demand – driven by developing nations like China. "As countries get wealthier, it tends to mean that people want to improve their diet to what's perceived to be higher quality products, including meat," explains Dr Philip Thornton of the International Livestock Research Institute in Nairobi, Kenya.
Animals also contribute to climate change. Rearing livestock accounts for 18 per cent of greenhouse gas emissions – more than the transportation sector – largely due to the release of methane from digestion and indirectly through human activity, such as clearing forests to provide land for grazing.
Thornton notes that there's an important difference between species, as those producing white meat, such as poultry and pigs, are more environmentally friendly than ruminants – grazing animals like cows, which give red meat. "Ruminants are the worst in terms of the amounts of greenhouse gases emitted per kilo of meat or milk."
Synthetic meat could therefore reduce the demand for livestock, helping to feed the world and combat climate change. in a more science-fiction scenario, the technology for growing our own meat could even provide a source of protein for astronauts on long space missions or those colonising other worlds; in the early 2000s, a NASA-funded project produced edible lab-grown muscle from goldfish.
Growing meat is not a new idea. In 1932, for instance, Winston Churchill wrote: "Fifty years hence, we shall escape the absurdity of growing a whole chicken in order to eat the breast or wing, by growing these parts separately under a suitable medium."
They may be 30 years behind schedule, but scientists are now finally starting to grow edible muscle in the lab. "People call this in vitro or cultured meat," says synthetic meat pioneer Dr Vladimir Mironov.
Mironov says that some automatically dismiss the idea because they don't understand how it's made. "It's Monsanto syndrome. When you use the word 'engineered', people automatically assume you use genetic engineering, which is not the case – it's organic technology." He points out that we already eat plenty of synthetic food in the form of things like bread and yoghurt.
Unlike GM food, the DNA in cultured meat would remain untouched (unless there was a demand for designer meat), and it wouldn't suffer the genetic instabilities that affect cloned animals. Instead, the technology now being developed in the lab would imitate nature. It would replicate how meat normally develops, but without including the rest of the body.
The synthetic meat is cultured by isolating stem cells from a living animal and encouraging them to divide and develop into muscle. Mironov's recent research took place at the Medical University of South Carolina in Charleston, US, and he calls his meat 'Charlem' – short for Charleston-engineered meat. Charlem is originally derived from turkey stem cells, although the culturing process is similar for other animal species.
Once scientists have managed to create something that resembles real meat, the next step will be to manufacture enough to supply consumers. Petri dishes and other lab equipment is sufficient for small-scale experiments, but mass production would require large vats, and meat would need to be grown in sterile conditions to prevent contamination from bacteria and disease. These large 'bioreactors' would provide scalability. "You must produce not just kilograms, but tonnes of this stuff," says Mironov. "If you want industrial production, it must be scalable."
But there are still plenty of technical challenges to overcome before cultured meat is ready for mass production. For example, Mark Post's blob of muscle needs exercise. The muscle fibres anchor themselves to a scaffold as they grow, putting them under natural biophysical tension, which conditions the muscle and pumps up the protein content. Post also zaps them at regular intervals – a 10-volt electric shock every second – to stimulate contraction, like a microscopic abdominal trainer.
Mironov, meanwhile, uses a scaffold made of chitosan micro-beads that expand and contract with swings in temperature. Both types of scaffold are designed to be edible or degradable – chitosan is extracted from fungi or crustaceans, for example. But at the moment, both these exercise regimes would require too much energy to be cost-effective at an industrial scale, so the researchers are also looking at other options.
Another challenge is to grow meat in three dimensions in order to make something substantial, like a chunky steak. Lab-grown meat is marinated in a culture medium that contains oxygen and nutrients such as amino acids, sugar and minerals. This means the size of the meat is limited by the diffusion of these molecules between the muscle and the culture medium. Blood vessels are needed to supply the middle of tissues with nutrients, to keep the cells in the centre alive. Cultured meat is therefore currently limited to layers only 0.1-0.3mm thin, and scientists will need to include a network of blood vessels to make bigger meat.
Given these size limits, Post predicts that the first product made from synthetic meat will be either a hamburger or a sausage, where you could grind-up the muscle before it's added to food. His meat is derived from pig stem cells, and the first banger will be pretty pricey: a 2lb sausage would cost €300,000 (£263,000) to create. If Post can bulk-up the muscle, he could then create a lean pork chop.
Mironov suggests that synthetic meat could also be 'functional foods' that are engineered to be better for you. This would mean including ingredients that suppress appetite and help you lose weight, using less saturated fat or adding 'nutraceuticals'. you could, for instance, add extra omega-3 fatty acids, although you would have to be careful not to add too much and make chicken nuggets that taste like fishfingers.
Cultured meat could also find a market in those who oppose animal slaughter, yet still enjoy the taste of meat. The Vegetarian society supports the idea, although it stresses that food containing cultured meat will need to be clearly labelled if the synthetic stuff were indistinguishable from the real thing.
"Vegetarians and vegans would welcome in vitro meat to the extent that they believe it will reduce the amount of animal suffering and exploitation," says Dr Matthew Cole, a sociologist and co-founder of Vegatopia, an organisation that promotes ethical veganism.
Nonetheless, many people can't stomach the idea: in a 2005 survey by the European Commission, 54 per cent said they would 'never' approve of growing meat from cell cultures to reduce animal slaughter. To make it more palatable, advocates will have to alter public perception. "There would need to be a huge campaign to make in vitro meat acceptable, to convince people that it was safe, and it wasn't a 'frankenfood'," says Cole.
He adds that there's another issue to consider: to what extent are animals exploited in the process of developing the technology? For example, the culture medium that scientists use to grow synthetic meat often contains foetal calf serum, which comes from dead cows. Although researchers acknowledge this makes them hypocrites for now, it may be a temporary yet necessary evil until they can afford to switch to serum-free cultures, which are currently prohibitively expensive. For some animal rights supporters, however, this crosses an ethical line in the sand.
Cultured meat also has sociological implications, says Cole, as it will probably enter the market as an expensive high-end product. "There are problems of inequality, at least initially, in the same way that wealthier consumers can now buy welfare-friendly meat and pay a premium to feel better about their conscience."
Less well-off consumers simply won't be able to afford the moral high ground in terms of animal rights and the other advantages of cultured meat – healthier food and a lower environmental impact. "We already have a solution, and that's veganism – it's democratic, it's cheap, it's available to everyone," says Cole.
Even if wealthy consumers force the market to eventually drive down the price of synthetic meat, it could still take several decades before it's cheap enough for poorer countries. Philip Thornton points out that, if it did become popular, there would also be a flip side: the synthetic stuff would eat into the traditional market, affecting the incomes of livestock producers and ultimately make real meat more expensive.
For now, there's one question that's on everyone's lips: How will it taste? According to Post, his lab-grown prototype isn't worth a nibble. "You're just eating a relatively expensive experiment," he says. So far the only person to have tried was a russian TV journalist, who took a piece out of a Petri dish and popped it in his mouth before Post could say "you are not allowed to eat in the lab." The journalist described the prototype as chewy and tasteless.
"Meat is a dozen different types of cells, all of which you've got to grow together," notes biologist Professor Brian J Ford, author of The Future of Food. Although it's mostly muscle cells, meat also contains adipocytes, which store the fat that gives meat much of its flavour. so initially the taste would have to come from artificial flavourings.
How soon until we see 'real' cultured meat on the menu? it will depend on funding. Animal rights group PETA – the People for the Ethical Treatment of Animals – hopes to encourage research by offering a $1 million prize to the first scientist to sell synthetic chicken in the US by 30 june 2012. The chances of winning PETA's prize by the deadline look slim, but Post reckons that the technical challenges could be overcome within the next 20 years.
Over that time, cultured meat could be given a more appealing name, one that would help consumers get over the 'yuck factor' that some will associate with meat grown in vats. "You squeeze the modified sweat glands from the underbelly of cattle, then you keep it until it goes off," says Ford, describing how we make cheese. "I think the yuck factor is in our minds. When the product is there, it's not going to matter as much as the marketing people think it might."
Growing muscle in the lab is an impressive feat of tissue engineering, but Ford says that scientists will need to culture various kinds of cells together before synthetic meat is ready for mass consumption. "You've got to have the right blend of constituents. But once it's done, it will be exactly the same as meat."
JV Chamary is features editor of Focus