The West African country of Sierra Leone has the shortest life expectancy for men - just 39 - while Afghanistan fares badly for both sexes, with men and women living to 41 and 42 years respectively.
Those figures come from the World Health Organization, which announced its annual health statistics Thursday on the year 2007, the latest available.
The data showed that some countries have made remarkable progress in increasing life expectancy since 1990 - partly by ending wars, partly through successful health initiatives.
Eritrea increased its average life expectancy during that period by 33 years to 61 for men, and by 12 years to 65 for women. In Liberia, the figure for men jumped 29 years to 54, and rose 13 years to 58 for women. Angola, Bangladesh, Maldives, Niger and East Timor also increased their average life expectancies for both men and women by full 10 years.
In the United States, the life expectancy was on the rise for both sexes, but not so dramatically: up to 76 from 72 years for men, and to 81 from 79 for women.
Other countries, meanwhile, showed a sharp decline since 1990, especially in Africa.
In Zimbabwe, a yearslong economic crisis and rampant inflation have created serious shortages of food and medicine and forced medical workers to flee the country. Those factors are among the reasons that women's life expectancy fell by 19 years to 44 and the men's average fell 12 years to 45.
The southern African nation of Lesotho recorded a 16-year drop for both men and women to 43 and 47 respectively. In the nearby kingdom of Swaziland, women live to 49 year on average, a drop of 14 years, while men's life expectancy declined by 12 years to 47.
Botswana, Congo, Kenya, South Africa and Zambia also reported significant drops in life expectancy for both sexes.
In Russia, the average life expectancy for men dropped to 60 from 64 years since the time of the Soviet Union. For women the drop was less marked, to 73 from 74 years.
The figures are only one of over 100 health indicators that WHO tracks in its 193 member states. Others include mother and child mortality; prevalence of diseases such as HIV, malaria and tuberculosis; access to doctors and medical facilities; and health expenditure per person.
Some of these indicators form part of the U.N.'s so-called 'Millennium Development Goals,' which the global agency hopes to achieve by 2015.
WHO said the trend for deaths in young children was promising overall, with a global drop of 27 percent since 1990. Some 9 million children under 5 years old died in 2007, compared to 12.5 million in 1990.
"The decline in the death toll of children under five illustrates what can be achieved," said WHO's director of statistics, Ties Boerma.
The increased use of insecticide-treated mosquito nets for malaria, oral rehydration therapy for diarrhea, better access to vaccines and improved water and sanitation in developing countries are proving particularly effective, he said.