There are many disagreements in the world of research, but few debates will get as heated as those surrounding animal testing. Many scientists and research advocates contend that animal experiments are crucial for learning about basic biology and disease mechanisms, and are necessary for testing the safety and efficacy of new medicines and chemicals. They point to many potent medicines that exist thanks to animal testing. Opponents, meanwhile, contend that subjecting animals to experiments for human gain is ethically unjustified. What’s more, many argue, such research is often misleading because it compares apples and oranges: results from animal studies often don’t translate to humans because the animals are just too different.
Animal welfare activists have long insisted that researchers jettison research on animals for alternative methods, such as human stem cells grown in a dish, computer modelling, or expanded clinical trials. But it’s only in the past few years that most of these tools have become truly good enough for prime-time use. Now, many researchers are embracing these alternatives. As Dr Donald Ingber, director of Harvard University’s Wyss Institute for Biologically Inspired Engineering, says, “It’s coming to a tipping point.”
Tallying the precise number of animals used in research is difficult, because countries record animal experiments differently. But estimates suggest that the count is more than 100 million animals each year worldwide. The majority are used in basic research and breeding to create specific genetic modifications. A smaller percentage of animals are used to test the effects of drugs or chemicals. More than 95 per cent of all animals used in research are mice, rats, birds and fish, but other species enter the mix, too. For example, some 60,000 monkeys like macaques are used in experiments in the US, Europe and Australia.
It’s hard to deny that research on animals has advanced human health. In the 19th Century, for example, French biologist Louis Pasteur used animal experiments to understand how microorganisms can cause disease, and later to develop a vaccine for rabies. Animal studies were also crucial in understanding how insulin is produced and in developing ways to supplement it in people with diabetes. Penicillin was proven effective in mice, blood transfusions were perfected in rabbits, and kidney transplants were tested in dogs and pigs.
There’s no shortage of recent examples, either. Experiments in which macaques were infected with SIV, the monkey version of the AIDS-causing HIV virus, were crucial in creating antiretroviral medicines and in developing strategies for a potential HIV vaccine. Deep brain stimulation, used by some 20,000 people with Parkinson’s disease, relied on rat and monkey models to understand how the disease affects a part of the brain called the basal ganglia and how surgically implanting a stimulator could improve patients’ motor symptoms. And brain-machine interfaces that allow paralysed people to perform everyday tasks, such as bringing a coffee cup to their lips, are being developed with the help of experiments in monkeys.
A dying breed?
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