People today are living longer than at any point in human history.
Virtually every country enjoys a higher life expectancy than it did in the 19th century.
In 1870, the average person could expect to live for 30 years.
By 2015 that number had increased to 71, more than doubling.
The West was the first region to see an increase in life expectancy.
Scientific discoveries led to a growing awareness of germs and disease.
New medicines and treatments were developed, and people adopted more hygienic lifestyles.
Public health measures were a major factor.
During the 20th century, the average lifespan in the United States increased by more than 30 years, of which 25 years can be attributed to advances in public health.
Between 1900 and 1950, Europe's life expectancy grew from 43 years to 65 years.
However, this did not reflect the experience of the rest of the world, which largely remained impoverished and underdeveloped.
In 1950, Asia's average life expectancy was 42 and Africa's was 36.
In the following decades, living conditions in both continents improved, along with life expectancy.
As Asian economies grew, people had better access to health services, and greater quantities of food.
In Africa however, several countries did not see significant economic growth, but still enjoyed a growing life expectancy.
This was due to better access to medicines and vaccines.
As of 2015, the life expectancies of Asia and Africa were about 72 and 60 years respectively.
In all countries, some facts are universal, including higher mortality rates associated with childhood.
Therefore, life expectancy increases with age.
Economic conditions also affect life expectancy.
For example, in the UK, life expectancy among the wealthiest is several years higher than among the poorest.
This may reflect factors such as diet and lifestyle, as well as access to medical care.
And finally, women enjoy an advantage over men.
Females have a higher survival rate from birth to old age.
Of individuals aged 110, 90% are women.
In fact, for almost all animal species except birds, females have higher survival rates than males.
