20 years ago, the world was stunned by the creation of Dolly the sheep. Scientists have since tried their hand at copying other animals, from mice and racing mules to dogs and a fighting bull.
Cloning is and has always been a highly controversial procedure that raises a slew of ethical issues, including animal welfare. Last year, the European Parliament voted to ban the cloning of all farm animals and the sale of cloned livestock, their offspring, and products derived from them. The suggestions go far beyond a directive proposed by the European Commission in 2013 that targeted a ban on cloning only five species.
Since Dolly's birth 20 years ago in Scotland, technologies to influence DNA have greatly developed, says Joachim Boldt of the University of Freiburg. Genetic technology today "offers new options that far surpass the possibilities of simple cloning," he says, adding that genetic sequencing is faster and cheaper these days. Scientists speculate about the chance to not only cure diseases, but to "improve the human immune system to such a degree that it can no longer be overcome by viruses or bacteria." But the new technologies increasingly raise ethical questions, too, Boldt says. "To shape our entire genetic identity - is that what we want?"