Which primate is the world’s smallest by average body mass?

Madame Berthe’s mouse lemur is the world’s smallest primate by average body mass.

This tiny lemur weighs about 30 grams on average, though individual weights vary. Its scientific name is Microcebus berthae, and it is named after the Malagasy conservationist and primatologist Berthe Rakotosamimanana. Like other mouse lemurs, it has large eyes suited to nocturnal activity and a long tail that helps with balance.

The species is endemic to Madagascar, where it inhabits dry deciduous forests, especially in the Kirindy region. It feeds on fruit, insects, gums and other small food items. Its small size makes it vulnerable to habitat loss, particularly when forests are cleared or fragmented.

People sometimes confuse it with the pygmy marmoset, which is the smallest monkey. Mouse lemurs are lemurs, not monkeys, and lemurs are naturally found in the wild only on Madagascar and nearby islands. “Smallest primate” can depend on whether researchers compare average mass, minimum recorded mass or body length, but Madame Berthe’s mouse lemur is the standard answer by average body mass.