Scientists Discover Parts of Our Bodies Age at Different Rates

Some people age faster than others, but the discovery of a DNA body clock by UCLA researchers now shows that different parts of our bodies age faster than others. The discovery offers important insights into the aging process — and what we might be able to do about it.
This isn’t the first time that biologists have developed a mechanism for assessing age. Earlier “biological clocks” have been derived from data drawn from saliva and hormones. More crucially, there are our telomeres to consider — those fraying tips of our chromosomes that have been linked to cellular expiry dates, and by virtue, our individual rates of aging.
But the new research, which was conducted by 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, is the first to show an internal clock able to accurately assess the age of various human organs, tissues, and cell types. And remarkably, certain parts appear to age faster than others.
To create the clock, Horvath studied DNA methylation, a naturally occurring process that chemically alters DNA. And indeed, scientists are increasingly learning that many manifestations of aging are caused by epigenetic factors — those changes to our DNA that happen after we’re born. As an epigenetic process, methylation is a crucial component of normal development and cellular differentiation. It can suppress the expression of viral genes and other biological nonsense that accumulates over time. Regrettably, it also plays a crucial role in aging and the development of nearly all types of cancer.
For the study, Horvath looked at 121 different sets of methylation-specific data, including 8,000 samples of 51 types of tissue and cells taken throughout the body. He took this information and charted how age affects DNA methylation levels from pre-birth all the way up to 101 years. The resulting DNA clock, which is essentially a statistical model, was compiled by honing in on the 353 markers that change with age and are present in our bodies.