Quick Answer
If humans stopped experiencing biological aging while retaining normal vulnerability to injury and disease, life expectancy would rise dramatically but would not become infinite. Population growth would become a major constraint if people continued having children at today's rates. Medicine, retirement, inheritance, housing and political institutions would all have to adapt to people remaining physically young for much longer.
Aging is a collection of biological changes rather than a single clock. To make a human truly ageless, many processes involving cellular damage, cancer suppression, immune function, tissue maintenance and metabolism would have to behave differently. For this thought experiment, assume those aging processes remain under control while ordinary accidents and acute diseases still exist.
Death would still happen
Ageless is not the same as indestructible. A person could still die from a severe accident, infectious disease, poisoning or violence. If the probability of death from those causes stayed constant every year, lifetime survival would improve greatly but would not guarantee endless life.
Population becomes the central problem
If fewer people died from aging but birth rates stayed similar, populations would accumulate. Within a few generations, housing, food, energy and land demand would rise sharply. Societies would likely change reproductive norms or expand their resource base through technology.
Retirement would make little sense
A career lasting forty years would become a small fraction of a person's life. Education could become continuous, careers could change repeatedly, and the concept of a fixed working age could weaken. Pension systems based on a short working period followed by a long retirement would require fundamental redesign.
What happens to wealth?
Inheritance would slow because parents could remain alive for centuries. Wealth could become more concentrated across long-lived individuals unless tax and inheritance systems changed. On the other hand, people could accumulate skills and capital over much longer periods, potentially creating new forms of entrepreneurship and expertise.
Established scienceModern human populations already demonstrate that lower mortality can change age structure dramatically. An ageless population would push that demographic effect much further because the normal biological endpoint of old age would be removed.
The psychological effect
A person expecting centuries of life might make different decisions about education, relationships, careers and risk. But individual psychology is difficult to predict, so claims that everyone would become wiser, happier or less ambitious would be speculation rather than established consequences.
Removed by assumption
Biological aging
Still possible
Accidental death
Much higher
Population pressure
Fundamentally disrupted
Retirement model
The bottom line
The largest consequence of ageless humans would not be a single medical miracle. It would be a demographic and institutional transformation. Humanity would have to rethink reproduction, work, inheritance, housing and the meaning of a lifetime.