Fecal Proteomics Reveals Orangutan Juveniles Nurse Until at Least 6.5 Years
Key Finding
A study using fecal proteomics has shown that wild Bornean orangutan juveniles continue to consume breast milk until at least 6.5 years of age, confirming one of the longest breastfeeding periods among mammals.
Method
Researchers applied fecal proteomics to fecal samples from wild Bornean orangutans in the Danum Valley Conservation Area, Sabah, Malaysian Borneo. Over a period of 2 years and 7 months, they collected samples from identified individuals.
Milk-specific proteins were detected in all 20 samples from individuals under 6.5 years old, providing direct evidence of continued milk consumption.
Additional Observations
Comparison of milk-specific proteins with biological defense proteins and probiotic intestinal bacteria proteins suggests that higher milk consumption is associated with stronger biological defenses and higher presence of probiotic bacteria.
Implications
The prolonged breastfeeding period likely supports the high survival rate of orangutan offspring and contributes to their slow reproductive strategy. It also indicates that populations of this critically endangered great ape recover very slowly from declines, emphasizing the need for habitat protection.