The island of Madagascar, located 250 miles (more than 400 km) off the coast of East Africa, was one of the last large tracts of land to be colonized by humans.
Although, at present, Madagascar is also unique in its biodiversity.
But long ago, it lost all of its large vertebrates, including giant lemurs, elephant birds, giant tortoises and hippos.
A human genetic study published in Current Biology on November 4 reports that the disappearance of these large vertebrates is linked to the first large-scale human expansion on Madagascar about 1,000 years ago.
To learn more about the origins of the Malagasy people, a multidisciplinary consortium launched a project called Malagasy Genetics and Ethnolinguistics (MAGE) in 2007.
Over the course of 10 years, local and international Malagasy researchers have visited more than 250 villages on the island to sample human cultural and genetic diversity.
In the new study, the researchers scrutinized how different segments of human chromosomes share local ancestral information as well as genetic data from computer simulations.
Taken together, they deduce that the Malagasy’s Asian ancestors were isolated on the island for more than 1,000 years and had an effective population size of just a few hundred people.
A small group of Bantu-speaking Africans arrived on Madagascar about 1000 years ago, ending the isolation of their Asian ancestors.
Since then, the population has continued to grow rapidly.
They suggest that the growing population has led to extensive changes in the Malagasy landscape and the disappearance of all the large vertebrates that once lived there.
These findings can also provide new insights into how past population changes have led to changes in entire ecosystems.
