Non-human Primates: A Brief Introduction To Their Biological Characteristics

Non-human primates are animals that are closely related to humans in terms of genetics or phenotypes. They are also commonly used in non-clinical safety evaluation studies. Among them, cynomolgus monkeys are the most widely used, followed by rhesus monkeys and marmosets. In this article, we will give a simple introduction to the biological features of some common non-human primates.

Cynomolgus monkey

Also known as crab-eating macaque or long-tailed macaque, it is the most frequently used non-human primate in toxicology research. It belongs to the same family as rhesus monkey, but it has a smaller body size, which means less drug consumption. It also has the advantages of low aggressiveness and non-seasonal breeding. Cynomolgus monkeys have fur colors ranging from reddish-brown to gray, and their tails are longer than their bodies. The males are larger than the females, and have much bigger upper canine teeth. Cynomolgus monkeys are mainly found in Southeast Asia, and there are two groups: 1) Insular, from the Philippines and Indonesia; 2) Indochinese, from Vietnam, Cambodia, Laos, Thailand and Malaysia.

Rhesus monkey

Also known as rhesus macaque, it has thick fur that is brown to reddish-brown. It is bigger than cynomolgus monkey, and has a shorter tail. Its face and perineal area are hairless, and have a red to pink color. Like cynomolgus monkey, the males are larger and have bigger upper canine teeth. Rhesus monkeys are distributed in most parts of Asia.

Common marmoset

It is a New World monkey that is native to Brazil. It has a mixture of brown, gray and yellow fur. It has distinctive white ear tufts, a white forehead, and a long striped tail. Unlike the Old World monkeys (such as macaques), it has a broad and flat nose, with nostrils facing sideways. It also lacks ischial callosities (thickened skin on the sitting bones, which are hairless and nerveless in Old World monkeys). Common marmosets do not have obvious sexual dimorphism (differences other than reproductive organs, such as body size). They have a shorter lifespan and smaller body size than cynomolgus and rhesus monkeys.

Baboon

It is often used in reproductive biology, evolutionary biology and ecology studies. In the 1960s, baboons were rarely used in US laboratories. In the 1970s, with the support of NIH, baboons began to be bred in captivity. Until now, baboons have become very popular and widely used. Baboons have obvious sexual dimorphism, including larger body size and canine teeth in males. In addition, the ischial callosities of male and female baboons are different, the former are fused, while the latter are separate. Female baboons reach puberty at 3-4 years old, and breed all year round. The perineal skin of female baboons changes color and swells, indicating hormonal changes and ovulation cycle, and they can accept mating from male baboons. 

Tamarins

New World monkeys, Tamarins are members of the Callitrichinae subfamily, which are native to the Amazon, Guyana, Colombia and Central America. They are different from the Old World monkeys (such as macaques) in having wide and flat noses, side-facing nostrils, and no ischial callosities (thickened skin on the sitting bones). Tamarins are very small monkeys, weighing between 0.23 and 0.25 kg. They have long and striped tails, and distinctive white ear tufts. They have no obvious sexual dimorphism (differences between males and females other than the reproductive system). Tamarins usually breed twice a year, and often have dizygotic twins. 

Non-human primates include many species of monkeys, and their biological characteristics are very complex. Due to limited time, we will not elaborate on them. This article is written by Prisys Biotechnology, a leading company in biopharmaceutical development and manufacturing. We provide high-quality and innovative solutions for non-clinical safety evaluation, clinical trials, and commercial production of biologics.