What is life expectancy? Definition and examples

Life expectancy refers to the number of years we expect a person to live. We can use the term for a person, group of people, town, region, whole country, or even other organisms. In most cases, a national statistical organization determines and publishes these figures. We also call it ‘expectancy of life.’ Some people use the term ‘expected lifespan.’

People’s life expectancies vary according to location and gender. They also vary according to time. For example, during the 19th century, the lifespans in Europe were between 30 and 40 years. Now, they range from 80 to 85 years in the advanced economies, i.e., the rich countries.

The life expectancy of each country depends on factors such as national health services and financial status. Lifestyle, child mortality, occupation, armed conflict, and nutrition are also affecting variables.

Life expectancy – all species

We can use the term for all organisms; not just humans. Scientists say that organisms with long lifespans probably have genes that code for slow aging. In other words, they have good cellular repair.

The Arctic whale (bowhead) is by far the longest-living mammal; it can live more than 211 years.

The mayfly, on the other hand, only lives 24 hours. It has the shortest life expectancy among creatures that are not microscopic, i.e., they’re visible with the naked eye.

Life Expectancy
According to Wikipedia: “Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, its current age and other demographic factors including gender.”

Life expectancy getting longer

People’s lifespans have been getting longer since the Age of Enlightenment. The ‘Enlightenment’ was a philosophical and intellectual movement that existed in Europe during the 18th century.

However, over the past 200 years, people’s life expectancy has doubled in some countries.

According to the ONS (Office of National Statistics), in 1841, life expectancy in the UK was of 40.2 years for men and 42.2 years for women. By 2015, it rose to 79.09 and 83 years for men and women respectively.

The World Health Organizations (WHO) says that globally women live on average 4.6 years longer than men.

Life expectancy – GDP per capita

There is a close link between GDP per capita and life expectancy. Countries with a high GDP per capita have longer life expectancies than those with a low GDP per capita.

GDP stands for Gross Domestic Product, i.e., a country’s total production of goods and services within a set time. To get GDP per capita, we divide GDP by the country’s total population.

Life Expectancy at birth of six countries
This chart has WHO data on life expectancy at birth. The figure is for both genders for a period of 65 years across 8 countries. People’s lifespans have been getting longer.

Life expectancy in business

In business, life expectancy is relevant for insurance, annuity contracts, and retirement plans.


Companies with insurance services will calculate lifespans to minimize their liability risk.

Insurance companies will look at certain factors to determine individual risk factors. They will take into consideration factors such as medical history, lifestyle, and occupation.

A librarian, for example, has a smaller risk of ‘dying on the job’ than a bullfighter or test pilot.

All these factors influence people’s risk of experiencing or suffering an adverse event. The higher the risk, the greater the chances are of an insurance claim.

Annuity contracts

In some cases, companies may offer a single-life annuity payment plan. In other words, payments continue until the person dies.

An annuity is a terminating stream of fixed payments. Companies pay out annuities over specific periods.

Retirement plans

When considering a retirement plan, calculating a person’s life expectancy is important. The pension company has to estimate how long it will have to continue paying out money.

When the pension involves a couple, it will take into consideration both their lifespans.

Video – life expectancy of animals

Why do animals have such different lifespans? Why do mayflies die when they are just one day old but whales live for over a century.?