People living in tropical areas are likely to die more than seven years younger than those in other regions, the first findings of a global research project show.
The State of the Tropics study, run by 13 institutions across 12 countries, reported that people living in the world's tropical zones in 2010 had an average life expectancy of 64.4 years.
This was 7.7 years less than those living in non-tropical areas, according to the broad-ranging research project, which was initiated by Australia's James Cook University.
Overall mortality in the region was affected by disease, conflict, poverty and food insecurity, the study said. Investment in social services, such as health and education, as well as access to water, sanitation and medical technology, were also important factors.
According to the report, central and southern Africa had the worst adult mortality rates, with 377 in every 1,000 people who lived to 15 years old dying before they reached 60.
That compared with an average of 240 in every 1,000 across the tropics and 154 in every 1,000 for the rest of the world.
Australia has the largest tropical area among developed nations. University vice-chancellor Sandra Harding said a person in the north typically died 2-1/2 years earlier than one in the cooler south.
The study estimates that all continents except Europe and Antarctica are partly in the tropics and 144 nations or territories are either "fully or partly in the tropical region".
By 2050 about half the world is expected to live in the tropics, a vast area encompassing swathes of Australia, South and Southeast Asia, Africa and the Middle East, Central and South America, the Caribbean and Oceania.
The report found that life expectancy in the tropics had increased in the past six decades, with people living 22.8 years longer than in 1950.
Southeast Asia saw the biggest improvements in life expectancy in the 60 years to 2010, adding 26.7 years to the average life span, compared with a global average increase of 20.2 years in the same period.
Infant mortality in the tropical areas also decreased, from 161 deaths per 1,000 live births in 1950 to 58 per 1,000 in 2010, though this was still much higher than the 33 per 1,000 rate in the rest of the world.