Life expectancy has increased dramatically over the past century due to advances in medicine, public health, nutrition and standard of living. In the early 20th century, average life expectancy in developed countries was around 50 years. Today it is over 80 years and still rising. But how long can this increase continue? What is the maximum human lifespan and how old will humans live in the future?
Current average life expectancy
According to the latest data from the World Health Organization (WHO), global average life expectancy at birth in 2019 was 72.6 years. The highest life expectancies are in developed countries like Japan (84.5 years), Switzerland (83.6 years), Singapore (83.5 years), Australia (83.4 years) and Spain (83.4 years). The lowest life expectancies are in some sub-Saharan African countries like Central African Republic (54.4 years), Chad (54.2 years) and Sierra Leone (54.1 years).
Within countries, women tend to live longer than men on average. For example, in the United States in 2020, female life expectancy was 80.5 years compared to 75.1 years for males. The reasons for this gender gap are not fully understood but may include genetic factors, hormones, lifestyle differences and the lower prevalence of cardiovascular disease in premenopausal women.
Life expectancy trends
Historical data shows that life expectancy has been increasing steadily in most parts of the world over the past century. The rate of increase was fastest in the early-to-mid 20th century due to improvements in child mortality, sanitation, nutrition and antibiotics. In the US, life expectancy jumped from 47 years in 1900 to 68 years in 1950.
From 1950 onwards, the rate of increase in life expectancy has slowed in developed nations but continued to rise at a steady pace of 2-3 additional years per decade on average. Developing nations lagged behind for most of the 20th century but life expectancy has accelerated there as well over the past few decades with improved access to vaccines, medicines, technology and education.
Some scientists believe we are approaching a plateau where maximum human lifespan is near its upper boundary. Others argue that there is no evidence yet that we are close to a limit, and technology may continue to push the lifespan envelope further. Public health initiatives to reduce smoking, obesity and accidents could also extend average lifespans.
Record human lifespans
The oldest confirmed lifespan for a human being was Jeanne Calment of France, who lived 122 years from 1875 to 1997. Only a handful of verified cases of humans reaching age 115+ are known. The current world’s oldest living person is 118-year-old Kane Tanaka of Japan.
While maximum human lifespan records continue to inch higher, these supercentenarians are outliers. The validated age of the world’s oldest person has not increased significantly in decades. Some scientists argue that 122 years may be close to the upper limit of human longevity. However, this remains controversial with other experts pointing out these record lifespans have continued to be broken over time.
Biological factors limiting lifespan
There are several biological factors that limit the human lifespan:
– Telomeres – The DNA at the end of chromosomes shortens with each cell division. When telomeres become too short, cells can no longer divide and renew tissues. Telomere length is therefore correlated with lifespan.
– Cell senescence – Damaged cells eventually stop dividing altogether but remain metabolically active, secreting inflammatory and immune-altering factors that contribute to age-related diseases.
– Stem cell exhaustion – Loss and dysfunction of stem cells impairs the body’s ability to regenerate tissues and organs.
– Mitochondrial mutations – Errors accumulate in the mitochondria which can lead to impaired energy production in cells.
– Protein aggregation – Misfolded proteins accumulate into aggregates (amyloid plaques) that disrupt cell function.
– Genomic instability – Accumulated DNA damage from factors like radiation, free radicals and replication errors can lead to cancer.
Prospects for increasing the maximum human lifespan
What is the likelihood that scientific and technological advances could break through the biological barriers and push maximum human lifespan significantly higher in the future?
Some scientists are optimistic. They point to interventions such as:
– Pharmacological enhancement of telomerase activity to maintain or extend telomeres.
– Clearing senescent cells to revitalize tissues and organs.
– Therapies to stimulate stem cell populations.
– Mitochondrial enhancements and anti-oxidants.
– Novel anti-amyloid drugs to prevent protein aggregation.
– Advanced diagnostics to detect cancers early.
– Gene therapies to potentially reverse aging processes.
Other experts argue that longevity research progress has generally been disappointing so far. Most drugs that work in animal models have failed in humans. They believe major lifespan expansion may be infeasible and 120-125 years will remain our ceiling.
There are also some who question whether radical lifespan extension would really be beneficial for individuals or society. As lifespan increases, so does the risk of age-related diseases like dementia that could lower quality of life. Overpopulation could be a challenge if people live significantly longer.
Predictions for life expectancy in the future
Given the general trend of steadily rising life expectancy over the past century, most experts predict this will continue to some degree, but there is uncertainty around how much further we can push lifespan boundaries. Here are some predictions from longevity researchers:
Conservative predictions
– Average life expectancy will increase at a modest pace of 1-2 years per decade in developed nations, reaching the late 80s or 90 years by the end of the 21st century. [1]
– Maximum human lifespan will only increase marginally from 122 years to around 125 years (an outer limit of 130 years) due to biological constraints. [2]
– Novel therapies may add 2-5 years but radical life extension beyond biological norms will not be possible. [3]
Moderate life extension predictions
– Average life expectancy could climb more rapidly, reaching 100 years by 2100. [4]
– A small proportion of the population may live past 125 years with advanced biomedical technologies. [5]
– 1 in 10,000 individuals living to 140 years by the end of the century. [6]
Optimistic “longevity escape velocity” forecasts
– Human trials of telomerase gene therapies within 10-20 years, increasing healthspan by 20-30 years. [7]
– Robust rejuvenation therapies by mid-century, allowing life expectancy of 120-150 years. [8]
– Those born after 2050 may have indefinite lifespans. [9]
– Incentives created for “longevity mega-projects” on the scale of the Moon mission. [10]
– 1 in 1,000 people reaching age 150 and 1 in 10,000 reaching 200 years old by 2100. [11]
There is a wide range of opinions on this topic among experts reflecting different views on the plausibility of life extension technologies as well as ethical considerations. Societal age demographics could look very different by the end of the century depending on which trajectory comes closest to the mark. But most agree that average lifespans are likely to continue increasing at least modestly, so our children or grandchildren may live significantly longer than we do today.
Conclusion
– Historic trends show steady growth in life expectancy over decades due to improvements in medicine, public health and living standards.
– Current biological limits mean maximum human lifespan is unlikely to exceed 125 years. However, some scientists believe new therapies could break through these barriers.
– Most experts predict average life expectancy will keep rising at varying paces, reaching late 80s to 100 years by 2100. A minority hold more radical views of potential indefinite life extension.
– There is ongoing debate around how much lifespan expansion is realistic or desirable for individuals and societies. Outcomes will depend on scientific progress and how we choose to utilize future technologies.
– Living significantly longer than today will fundamentally transform human culture and civilization, if the optimists are proven right. But extreme longevity may also introduce unforeseen challenges we will need to overcome.