The world's smallest monkey babbles like a human baby and taps trees for gum
Weighing just over 100 grams, the pygmy marmoset is the smallest monkey on Earth. It chews holes in Amazon tree bark and laps up the gum that oozes out. Its infants babble their way toward adult calls much as human babies babble toward speech, and paired adults gradually tune their trills to match each other.
The genus Cebuella holds two species, western and eastern, which look almost identical and are kept apart mostly by big South American rivers. They live in the western Amazon across Brazil, Colombia, Ecuador, Peru and Bolivia, usually in mature evergreen forest near water. A body barely 12 to 15 centimetres long trails an even longer ringed tail, and the animal can swivel its head 180 degrees. Evolution shrank this lineage unusually fast by slowing growth before and after birth.
Food comes mainly from gum. Using specialised teeth, a marmoset gnaws into suitable trees and vines, waits for sap to pool, then licks it up, while also ambushing insects such as butterflies drawn to the holes. Insect-like claws called tegulae let it cling to trunks while feeding. A group's range covers only 0.1 to 0.4 hectares and centres on one or two trees until they are tapped out, and neighbouring brown-mantled tamarins often raid the holes.
Groups of two to nine usually consist of a breeding pair and several litters of young. Twins are the norm; singles occur in 16% of pregnancies and triplets in 8%. Fathers carry infants on their backs, and older siblings help, sometimes with females temporarily halting their own ovulation to care for others' babies. About five caregivers appears to be ideal.
Communication is layered by distance: a trill for close contact, a J-call at middle range and a long call once the group spreads beyond 10 metres, each lower in pitch because deep sounds carry better through humid, leafy forest. In one study, three of four new pairs made their trills more alike within six weeks, a match still stable three years later. The species' biggest threats are habitat loss and the pet trade.
Source: Pygmy marmoset
