It WAS as if someone had turned back time. Paws that once faltered gripped objects with renewed strength. Hearts and livers regained their youthful vitality. The hazy memories sharpened. And according to Steve Horvath’s experiments, the the biological age of his rats had been halved. “He was stunned,” he says.
Horvath, an anti-aging researcher at the University of Los Angeles, California, and colleagues saw these startling effects in 2020 after injecting older rats with blood extract from younger rodents. And they are not alone. A growing number of laboratories are reporting findings indicating that we may have been thinking about aging incorrectly.
Rather than being the result of accumulating wear and tear over time, aging could be driven by the forces that build our bodies in the womb and maintain them after birth. In youth they help us, but not turning them off brings the deterioration of old age. This new vision offers a deeper understanding of what aging really is and the possibility of slowing it down or even partially reversing it.
While the processes that drive aging are a matter of debate, biogerontologists agree on one thing: what it looks like: the progressive decline in physical function that most creatures experience over time. They have cataloged the cellular changes that accompany this decline, including the crumbling ends of chromosomes, damaged and unstable genomes, and changes in the way cells perceive nutrients.
For many years, biologists have favored the idea that these distinctive features were the result of damage such as that caused by reactive molecules called free…
