A number of studies at the National Institutes of Health Intramural Research Program use rhesus monkeys to examine the impact of environment on early childhood development, such as maternal attachment.
Earlier this year PETA, the animal rights organization, initiated a request through the Freedom of Information Act to obtain materials -- including these photos -- from the NIH. PETA claims these studies are abusive and not scientifically justified. The NIH says the purpose of these animal studies is to help scientists develop more effective human mental health treatments.
These photos were provided to PETA by the NIH and were taken between 2009 and 2012.