Researchers show how social environment can have large impact on weight and health in mice

The genetics of nearby mice can have a large impact on one animal's weight and health, according to a report by Amelie Baud and Oliver Stegle of the European Bioinformatics Institute (EMBL - EBI) in Hinxton, United Kingdom, published on January 25th, 2017 in PLOS Genetics.

Researchers know that human and animal health can be influenced - both positively and negatively - by how individuals interact with each other on a daily basis. But studying those social effects can be challenging, as they are difficult to pick apart and quantify.

Social effects can be measured without looking at behaviours or other characteristics of nearby mice directly, instead examining only how the genetic makeup of one animal impacts the traits (called phenotypes) of another animal it lives with. This is called 'social genetic effects'.

For the first time, Baud and colleagues have quantified the contribution of social genetic effects to more than 100 different behavioral and physical phenotypes in laboratory mice. They compared the phenotype of one mouse with the genotypes of its cage mates, and found that social genetic effects explained up to 29% of the variation they observed in wound healing, anxiety level, immune function, and body weight. The study uncovers a surprisingly strong influence of the social environment, which has previously been overlooked in health studies.

This knowledge helps researchers clarify the contribution of different types of genetic and environmental factors on individual health. Using this approach to study social animals could greatly advance our understanding of social effects on health and disease in humans.

Furthermore, these factors may be an important component to understanding the genetics that underlie human traits with unclear causes. The scientists have demonstrated that ignoring social genetic effects can severely bias estimates of heritability in mice, suggesting that they may be an important source of the "missing heritability" in studies of complex traits in humans.