Growing Old Faster

Inequality speeds up the body’s clock

Early-life social disadvantage can leave long-lasting effects on the body. Research led by Yayouk Willems highlights that inequality shapes how fast we age.

People who grow up and live under different social conditions do not just experience different opportunities. They may also age at different biological speeds. Summarizing 140 studies across 23 countries, a new international meta-analysis shows that social inequality is consistently linked to faster biological ageing as measured in our epigenome. Understanding how and why these differences emerge over the lifespan is a central question for psychologist Yayouk Willems. She wants to understand why people’s (mental) health trajectories diverge across the lifespan. This interest led her to do a PhD at the Netherlands Twin Register in Amsterdam, where she studied the lives of twins to understand the interplay of genes and environment, and on to a postdoctoral position in the Biosocial Research Group led by Laurel Raffington at the Max Planck Institute for Human Development. Here she investigates how social conditions influence our epigenome, and in doing so, shape health and wellbeing across the lifespan. Building on this work, she spearheaded a new study in Nature Human Behaviour revealing that social inequality is associated with faster biological ageing as measured in the epigenome.

Epigenetic clocks as a measuring tool

How can we measure whether social inequality becomes biologically embedded? In recent years, new biomarkers have emerged to study this: so-called “epigenetic clocks.” These biomarkers estimate a person's biological age based on their epigenome. Researchers look at the epigenome through DNA methylation, which consists of small chemical tags on the DNA that influence whether genes are switched on or off, without altering the genetic sequence itself. These patterns shift in predictable ways over the course of a lifetime.  Epigenetic clocks summarize numerous epigenetic signals to calculate a biological age, which can deviate from a person's calendar age. For example, two people can share the same birth year and yet not be ageing at the same rate. The difference is not always visible. It unfolds quietly, at the level of cells and molecules and our epigenome, shaped in part by the conditions of everyday life. Increasingly, researchers are finding that inequality may leave traces in the body itself, influencing how quickly it wears down over time. 

Since the first epigenetic clock was developed more than a decade ago, numerous new epigenetic clocks have emerged, each based on different methodological approaches. The first clocks (also referred to as “first generation epigenetic clocks”) aimed to predict a person's actual chronological age as accurately as possible—an important breakthrough, but one with limited ability to predict health outcomes. The second-generation clocks were trained to better capture mortality risk and health outcomes. Most recently, third-generation clocks have been developed: rather than estimating a biological age, these clocks measure a person's pace of ageing, that is, how rapidly the body is deteriorating across multiple organ systems.

Tracking inequality in the body

A large meta-analysis, conducted at the Max Planck Institute for Human Development, in the Biosocial Research Group led by Laurel Raffington, with shared first authors Yayouk Willems and Ada Rezaki, in collaboration with Dan Belsky from Columbia University, now systematically examines which of these clocks are most sensitive to social inequality. The study pools 140 individual investigations involving nearly 66,000 participants from 23 countries. A meta-analysis brings together the findings of many different studies in a systematic way. This provides a bird's-eye view that reveals robust patterns running through many data sets.

The patterns: people who experience socioeconomic disadvantage as measured by their education level and or income tend to exhibit accelerated biological ageing compared to their better-off counterparts. This association proves remarkably stable across different countries and age groups. The strongest and most consistent associations with social inequality are found in third-generation clocks, followed by those of the second-generation clocks. The early first-generation clocks are considerably less sensitive. 

Traces of biological ageing begin early in life

Particularly striking is how early these effects appear: children exposed to socioeconomic disadvantage already show signs of accelerated ageing. Epigenetic measurements could thus serve as a kind of ‘molecular bridge’ between childhood experiences and health outcomes decades later. Experiences such as financial insecurity, limited access to education, or poor quality housing may become embedded in the body over the long term, before any illness becomes visible. That said, many epigenetic clocks were originally developed for adults, which is why their validity in children continues to be studied.

When discrimination becomes biologically embedded

It is not only economic disadvantage that leaves its mark. Racial discrimination also has measurable effects on biological ageing. For this part of the analysis, the study relies exclusively on data from the United States. Black Americans show greater signs of accelerated biological ageing compared to white Americans. People of Hispanic heritage show similar, if somewhat smaller, effects.

These measurements reflect at the molecular level what has long been known at the societal level: those who experience racial discrimination are more likely to demonstrate biological signals that are negative indicators of health. Since all relevant data comes from the United States, the researchers explicitly call for more internationally comparative studies.

From observation to change

Despite the strength of these findings, the meta-analysis does not establish clear cause-and-effect relationships. Moving beyond correlations will require targeted experiments that follow people over long periods of time. Some of these investigations are already underway: researchers—including the same members of the Max Planck Biosocial Research Group—are analyzing data from a randomized controlled trial in the United States in which low-income families received unconditional cash transfers. The aim is to determine whether such measures change the epigenome.

Still, this meta-analysis shows that social conditions are consistently associated with differences in biological ageing, suggesting they may become biologically embedded over time. As such, epigenetic clocks provide a new perspective on the long-term consequences of social inequality.

Full citation:  

Willems, Y. E., Rezaki, A. D., Aikins, M., Bahl, A., Wu, Q., Belsky, D. W., & Raffington, L. (2026). Social determinants of health and epigenetic clocks: a systematic review and meta-analysis of 140 studies. Nature Human Behaviour. Advance online publication. https://doi.org/10.1038/s41562-026-02477-6

[These authors contributed equally: Willems, Y.E., Rezaki, A.D.]