There are two kinds of life
span. One is maximum life span, the greatest age reached by any
member of a species. In humans this is currently about 120 years.
(The oldest confirmed recorded age for any human is 122 years).
The other is average life span, the average age reached by members
of a population.
Life expectancy is the number of remaining years an individual can
expect to live, based on his or her current age and average life
spans. Life expectancy generally quoted is the ''at birth'' number
which is an average that includes all the babies that die before
their first year of life as well as people that die from disease,
war, etc. For example, the Life Expectancy table at the University
of Texas shows ''at birth'' the life expectancy was 25, but at the
age of 5 it jumped to 48. So life expectancy changes with your
age.
Mozambique has the lowest life expectancy for its population at
39.2. Japan is the highest at 82.7 and the US is 38th at 78.2
years.