A groundbreaking new study published in Science suggests that genetics play a far more significant role in determining lifespan than previously estimated. For decades, scientists believed that longevity was only around 25% heritable, with the remaining 75% attributed to environmental factors like diet and lifestyle. However, recent research indicates that lifespan may be as much as 55% genetically determined.
The Flawed Foundation of Past Estimates
The discrepancy arises from how previous studies were conducted. Early longevity research relied heavily on data from populations where extrinsic mortality – deaths caused by accidents, infections, or other external factors – was high. This skewed the results, making genetics appear less influential than they actually are. The problem is that if someone dies in a car crash at 25, that doesn’t tell you much about their potential lifespan if they had lived to 80.
Distinguishing Between Internal and External Causes of Death
Researchers led by Uri Alon at the Weizmann Institute of Science reframed the question by separating deaths into two categories: intrinsic mortality (from biological aging and genetic mutations) and extrinsic mortality (from external causes). When computer simulations eliminated all external factors, the heritability of lifespan nearly doubled. This suggests that if people lived in a world without accidents or disease, the genetic component of longevity would be much more apparent.
The Rising Heritability with Declining Extrinsic Mortality
The study reinforces this idea by analyzing data from twins born across different eras. As medical advances reduced premature death from external causes, the observed heritability of lifespan increased steadily from one generation to the next. The trend is clear: as extrinsic mortality decreases, the genetic influence on lifespan becomes more pronounced. This means that for people born today, with significantly lower rates of accidental or infectious deaths, genetics are likely to play a dominant role in how long they live.
The Implications for Future Research
While some researchers note that people still die from both types of causes, the new estimate of 55% heritability is more relevant for modern populations. Understanding these intrinsic genetic factors is now a priority for scientists studying aging. The ultimate goal is to develop therapies that mimic the biological advantages of centenarians – those who live to 100 and beyond – and make them accessible to everyone.
As Sofiya Milman, a longevity scientist at the Albert Einstein College of Medicine, puts it: “We’re hoping to create therapies that will mimic those intrinsic factors… and make them accessible to people who didn’t win the genetic lottery.”
In essence, the latest findings underscore that while lifestyle choices matter, genetics may ultimately hold the key to extending human lifespan.
