While you may be able to hide your age with makeup and plastic surgery, don't think that your deception is foolproof. Researchers have now developed a technique to ascertain your age to within five years using only your saliva.
The new method, published in the journal PLoS One, could someday be used by forensic experts to pinpoint the age of crime suspects.
The researchers began by taking saliva samples from 34 pairs of identical, male twins between the ages of 21 and 55 years old. Eric Vilain, the lead researcher and director of the Center for Society and Genetics at UCLA, was originally interested in studying sexual orientation differences in identical twins. He wanted to see if environmental influences?diet, stress, exposure to toxins, etc.?caused any epigenetic changes that could contribute to the twins' sexuality differences.
Vilain and his team focused their attention on methylation, a chemical process where a methyl group (a carbon atom bonded to three hydrogen atoms) attaches to a gene and affects how it turns on or off. Unexpectedly, the team found that the degree of methylation in certain areas of the genome increased with the age of the twins. They repeated their experiments with a population of singletons and found the same pattern.
The scientists then identified the two genes that had the strongest age-related link to methylation, and used them to build a predictive model. When they plugged in data from the saliva samples, they were able to predict people's ages to within five years.
Recently, scientists learned that they could use carbon-14 dating to accurately determine, give or take a year, the birth year of people born since the atomic tests of the Cold War (pdf). That method, however, uses tooth enamel, which is harder to get than saliva. Moreover, the technique will no longer be valid once the level of carbon-14 in the atmosphere returns to its baseline level (in a few decades).
In previous studies, scientists noticed significant DNA methylation differences in people with age-related diseases. Knowing this, Vilain notes that the new research could prove to be a valuable tool in health care. "Doctors could predict your medical risk for a particular disease and customize treatment based on your DNA's true biological age, as opposed to how old you are," he said in a prepared statement.
The technique needs to be replicated and confirmed before it can be used in real crime scene investigations. Future research should also look into whether the method can be adapted for other tissue samples, like hair and skin. Vilain and his team are now studying how biological age relates to health. They are looking at whether people with lower biological ages live longer and suffer fewer diseases than their peers with higher biological ages.
Source: http://www.cbsnews.com/stories/2011/06/24/scitech/main20074051.shtml
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