We wanted to know: If you could flip the telomerase switch on and restore telomeres in animals with entrenched age-related disease, what would happen? Would it slow down aging, stabilize it, or even reverse it?

It was akin to a Ponce de León [the Spanish explorer looking for the Fountain of Youth] effect. When we flipped the telomerase switch on and looked a month later, the brains had largely returned to normal.

One of the most amazing changes was in the animals’ testes, which were essentially barren as aging caused the death and elimination of sperm cells. When we restored telomerase, the testes produced new sperm cells, and the animals’ fecundity was improved – their mates gave birth to larger litters.