Why do we use non-human primates?

Monkeys and apes are our closest relatives in the animal kingdom, and because of their high cognitive abilities and complex social behaviour, biomedical research using these animals requires additional justification and high welfare standards.

Due to the high degree of genetic, anatomical and physiological conservation, non-human primates can be the best models for understanding human biological processes. They may be used to understand normal or abnormal structure and function or determine the efficacy of treatments where no other suitable animal models exist. Their use has led to a number of valuable medicines and treatments. 

Whilst genetic similarity to humans is high in non-human primates, it is also high in less developed species; for instance, we share 96% of our DNA with mice, 70% with fruit flies, and indeed 50% with crops such as bananas. In different species the same gene may be expressed in different ways or interact in different ways with other genes. Having genes in common may help with comparing and understanding some biological processes but is of limited relevance with respect to assessing welfare, social needs etc.

Despite their close relatedness, research with non-human primates is not widespread and is only undertaken when other mammals are clearly inadequate. They are used to study brain disorders such as Parkinson’s disease and obsessive compulsive disorder. The brain is an incredibly complex organ, and while we can study some brain function in tissue culture, computer models and rodents, the study of advanced behaviour (both normal and abnormal) requires a human-like brain. Our only option is therefore to study these processes in non-human primates, such as marmosets and rhesus macaques.

The majority of non-human primates used in biomedical research are either marmosets or rhesus macaques. We must justify the use of these species to ourselves, our Ethics Committee, and to the Home Office and the Animals in Science Committee, providing proof that there is no alternative. It is not legal in the UK to carry out research using great apes (for example chimpanzees and gorillas). 

Information adapted from AnimalResearch.info

What do we study?

We use primates to study a limited number of potentially serious conditions that affect the health of many millions of people in the UK alone. Ultimately, this will aid the development of new treatments to transform the lives of those affected by these conditions. In all cases, we only use animals where absolutely necessary and where, for ethical and practical reasons, it is not possible to carry out the research in humans.

We use non-human primates – marmosets and macaques – to study how advanced behaviour is controlled by the brain. 

Mental health research

Our marmoset work provides a fundamental understanding of the processes behind the symptoms of psychiatric disorders including depression, obsessive compulsive disorder and anxiety. The current range of potential treatments for many of these psychiatric disorders is relatively restricted and their success rates are limited and highly variable. Basic research is essential to identify new treatments by analysing the cellular activity and chemical processes within regions of the brain that control those complex behaviours impaired in psychiatric disorders. 

Brain manipulations often involve the permanent implantation of tiny metal tubes known as cannulas that permit direct delivery of drugs into specific brain regions in awake marmosets. Once implanted, the cannulas do not bother the animals. This allows researchers to determine the causal effects on behaviour of temporary alterations in the chemical function of these regions. The drug infusion procedure only takes a few minutes while marmosets are held gently by a handler very familiar with them. The drug effects are only temporary.

Understanding reward and risk

Our macaque research is aimed at underpinning our knowledge of how the brain functions in healthy individuals and how malfunctions can have potentially serious health implications. In particular, the work concerns how we use information about reward and risk for making crucial decisions and has relevance to issues as widespread as obesity, drug addiction, schizophrenia and Parkinson’s disease. A better understanding of how reward and risk affect our decisions could lead to significant health benefits in the long term.

Image: Marmoset