Example taken and adapted from Wikipedia: in a stationary population where 51% of people die at the age of 5 and 49% dies at the age of 70, the life expectancy at birth (defined in the sentence immediately before the [2]) is 36 years 10 months, whereas the median lifespan is 5 years. Life expectancy is the “same as mean, or average lifespan” in stationary populations no matter how skewed the distribution of death ages is—the reason why it isn’t in real populations is that mortality rates change with time.
Example taken and adapted from Wikipedia: in a stationary population where 51% of people die at the age of 5 and 49% dies at the age of 70, the life expectancy at birth (defined in the sentence immediately before the [2]) is 36 years 10 months, whereas the median lifespan is 5 years. Life expectancy is the “same as mean, or average lifespan” in stationary populations no matter how skewed the distribution of death ages is—the reason why it isn’t in real populations is that mortality rates change with time.