Humans have evolved different defences against malaria depending on where they live, scientists have found.
About half the world's population is exposed to the disease, which kills more than 500,000 people each year.
A study, conducted over 10 years across 11 countries, looked for specific mutations known as markers in genes that result in resistance against malaria in almost 12,000 people.
Laboratory head at the Walter and Eliza Hall Institute in Melbourne, Dr Ivo Mueller, said the study found there is a close evolutionary interplay between malaria and human populations.
"It is a complex interaction between the parasite and the human genome," he said.
"Part of this study was done in Papua New Guinea, but most of these mutations that we found are actually not found in Papua New Guinea because people there never acquired these mutations.