Scientists have found that human beings age at a molecular level in two accelerated bursts – first at the age of 44, and then again at 60.
In a study published in the journal Nature Aging, scientists at Stanford University and Nanyang Technological University in Singapore followed 108 participants over several years to observe aging changes in their molecules — RNA, proteins and participants’ microbiomes.
The scientists found that human aging does not happen in a gradual, linear way. Rather, the majority of the molecules they studied showed accelerated, non-linear changes at the ages of 44 and 60.
Xiaotao Shen, an assistant professor in microbiome medicine at Nanyang Technological University and first author of the study, told CNN that the results show “we are not becoming old gradually.” Some points in time are particularly important for our aging and health, he added.
For example, the ability to metabolize caffeine notably decreases – first around the age of 40 and once more around 60. Components involved in metabolizing alcohol also diminish, particularly around the age of 40, Michael Snyder, chair of the department of genetics at Stanford and an author of the study, told CNN, referring to the two waves of aging.
Snyder added that, anecdotally, “people often get muscle injuries and see their fat accumulation hit in their 40s (related to lipid metabolism), and definitely sarcopenia (muscle loss) hit people in their 60s — this is a very big deal.”