Fun with Science Club®


			Not all mice are created equal. Beth Tyler 05.03.01 Bully mice have more sisters than brothers and get less attention from mom. Not all mice (Mus musculus) are created equal. As in human societies, mice communities have some males that start fights and try to dominate other males. Five scientists thought that the early life of a male mouse influenced his future behavior. To test this hypothesis, they raised some mice litters. They watched many male mice from birth and made systematic observations on how much attention they got from their mother and how many brothers and sisters they had. When the male mice were adults (about 2 months after they're born), the scientists put some strangers together and made systematic observations on their behavior. These scientists were mostly interested in how aggressive a mouse was towards the other mice. They measured aggression by the number of times one mouse attacked another mouse. Then, the scientists compared their observations on aggression to their observations on early family life. They discovered two things about the most aggressive male mice: first, they came from litters where there were more sisters than brothers; and second, their mothers gave them less attention.


			Barnard, C. J., J. M. Behnke, A. R. Gage, H. Brown, and P. R. Smithurst. 1998. Maternal effects on the development of social rank and immunity trade-offs in male laboratory mice (Mus musculus). Proceedings of the Royal Society of London: Biological Sciences, 265: 2087-2093.