Passage Two
Throughout history, humans have suffered from a condition that they have never been able to escape—ageing. Some researchers, however, believe we may be thinking about it in the wrong way. They say we should start treating ageing itself as a disease—one that can be prevented and treated.
Their hopes are founded on recent discoveries that suggest biological ageing may be entirely preventable and treatable. From a biological preventive, the body ages at different rates according to genetic and environmental factors. Tiny errors build up in our DNA and our cells begin developing faults that can grow into tissue damage, which leads to ageing and ageing—related diseases.
One of the leading figures in human life research, Aubrey De Grey, explains in an interview that their goal is to develop a set of therapies for middle-aged and older people that will leave them physically and mentally equivalent(相当的) to someone under the age of 30. “Of course, without wiping their memories,” he adds. But he doesn’t think that is will be possible to stop ageing altogether. He sees a future where “rejuvenation technologies” can be applied to old people in order to revert their cells to what they were like when they were in their youth, buying them extra time. The idea is that someone who is treated at the age of 60 will be biologically reverted to 30. But because the therapies are not permanent fixes. Their cells will end up becoming 60 years old again in another 30 years time.

Humans age at different rates due to _____ reasons.