Heritability of intrinsic human life span is about 50%
A new study estimates human lifespan to be approximately 50% heritable, a figure higher than some previous analyses. This finding sparked Hacker News's interest in the nuanced definition of 'heritability' itself. The discussion quickly evolved into a debate over the relative importance of raw longevity versus 'healthspan'.
The Lowdown
The article, despite its paywall, reports a finding that approximately half of an individual's intrinsic human lifespan is heritable. This revised estimate challenges earlier, lower figures and sparks significant discussion on the interplay between genetics and environmental factors in longevity. The study likely utilizes advanced modeling and twin cohort analyses to arrive at this updated percentage.
- The research suggests human lifespan is about 50% heritable, meaning roughly half the variation in lifespan within a population is attributable to genetic differences.
- This estimate is presented as a correction or refinement of previous studies, often based on twin data, which might have underestimated the genetic component.
- The findings prompt a deeper consideration of what 'heritability' truly signifies in a complex trait like lifespan, moving beyond a simple genetic determinism and acknowledging environmental influence.
The core takeaway is that while genetics play a substantial role, a significant portion of an individual's lifespan remains influenced by non-genetic factors, such as lifestyle and environment.
The Gossip
Heritability Hurdles & Methodological Murkiness
Commenters dive deep into the definition of heritability, noting its context-dependency and potential for misinterpretation. Many question the reliability of twin studies, especially concerning shared environments potentially inflating estimates, while others find the 50% figure a welcome rectification of previous mental models. The general consensus points to the difficulty in truly isolating genetic influences from a complex web of environmental factors.
Healthspan Hails, Lifespan Wanes
A dominant theme is the assertion that 'healthspan' (the period of life spent in good health) is far more significant than mere 'lifespan.' Users emphasize that quality of life, physical capability, and avoiding debilitating conditions are more valuable than simply existing for a longer duration. This perspective highlights the importance of lifestyle choices over purely genetic predispositions for a fulfilling later life.
Evolutionary Enigmas & Practical Ponderings
Discussion surfaces around the evolutionary purpose of extended human lifespans, particularly post-reproductive years, with the 'grandmother hypothesis' being a popular explanation for the value of older individuals within a tribe. Users also ponder the practical utility of knowing lifespan heritability, questioning its applicability to individual choices and societal implications, including the balance between individual longevity and faster species evolution.