Rhesus macaques (also known as rhesus monkeys) are native to India, China, and much of southeast Asia. They are found in a wide range of habitats, including arid, open terrain, woodlands, mountains, wetlands, and agricultural and rural areas. Rhesus macaques are brown or grey in color and have pink, almost hairless faces. They are about 1.5 to 2 feet tall; adult males weigh approximately 15 lbs, females rarely exceed 12 lbs. They can live up to 25 years. The rhesus macaque has been used extensively in medical and biological research, even the space program.