"Braun focuses on degus, small rodents tied to guinea pigs and chinchillas. The mother and father raise the degus in nature.
The Journal’s money quote:
When deprived of their father, the degu pups exhibit both short- and long-term changes in nerve-cell growth in different regions of the brain. Dr. Braun, director of the Institute of Biology at Otto von Guericke University in Magdeburg, and her colleagues are also looking at how these physical changes affect offspring behavior.
Bottom line: Degu pups without fathers are more aggressive and impulsive than others with two parents."