Researchers have discovered a new "epigenetic clock" that assesses how age affects human tissue.
A scientist used "a natural process by which DNA [is] altered over time," called methylation, to develop the age-revealing biological clock, Forbes reported.
"Time clocks" have been discovered before in hormones, saliva, and telomeres, but none were able to accurately pinpoint the age of a diverse set of organs and tissue, News Medical reported.
"To fight aging, we first need an objective way of measuring it. Pinpointing a set of biomarkers that keeps time throughout the body has been a four-year challenge," Steve Horvath, a professor of human genetics at the David Geffen School of Medicine at UCLA and of biostatistics at the UCLA Fielding School of Public Health said. "My goal in inventing this clock is to help scientists improve their understanding of what speeds up and slows down the human aging process."
Using this method, the team found that women's breasts tended to age more rapidly than the rest of their bodies. This could explain why breast cancer is more common than any other types of the disease. They also noticed that cancerous tissue was usually 36 years older than surrounding tissue, Forbes reported.
The researchers looked at 8,000 different DNA samples; they were able to find 353 DNA markers from various organs that changed over the course of a lifetime. Using this information the team was able to create a statistical model.
"[It is the] first-ever accurate age predictor that works across most tissues and cell types," Horvath said, Forbes reported.
Horvath also looked at pluripotent cells, which have been reverted back to their embryonic state, which allows them to become almost any type of tissue cell and "divide indefinitely," News Medical reported.
"My research shows that all stem cells are newborns," Horvath said. "More importantly, the process of transforming a person's cells into pluripotent stem cells resets the cells' clock to zero."
"The big question is whether the biological clock controls a process that leads to aging," Horvath said. "If so, the clock will become an important biomarker for studying new therapeutic approaches to keeping us young," he said.
Horvath's final discovery was that the clock's speed was affected by age.
"The clock's ticking rate isn't constant," he said. "It ticks much faster when we're born and growing from children into teenagers, then slows to a constant rate when we reach 20."
