In 1997, scientists announced they'd created a healthy sheep cloned from another ewe's mammary gland cell. Two decades on, the technique is being refined and applied to new challenges.
It took years of attempts before scientists were able to clone a mammal from an adult cell. And with that success came plenty more questions.
Every single Cavendish banana plant worldwide is genetically identical. This vast monoculture sets them up for disastrous disease outbreaks. But researchers have ideas on how to protect the crop.