Roughly half of the howler monkeys in the research preserve have died or remain unaccounted for. Scientists had been studying them for more than 30 years. 

The seven primates came into contact with a dye that was used on their mothers, documents reveal.

A spending bill approved by a House committee would require the agency to “accelerate” the replacement of nonhuman primates in laboratories starting in October.

Rhesus monkeys engineered to express a human gene reportedly show delayed brain development and better short-term memory. Fellow scientists are raising ethical red flags.

A combination of public opposition, intense regulations, and rising costs in the EU make conditions in China and elsewhere attractive for studying monkeys.

The stem cell–derived transplants were stable for 24 months and led to wide-ranging behavioral improvements in the monkeys.  

A study finds two species of guenon monkeys in Tanzania have been mating and producing fertile offspring for generations.

Researchers engineered a system for bioluminescent imaging that is as much as 1,000 times stronger than existing methods.

The male proboscis monkey’s large nose probably evolved in response to female preference and competition between males.