To see if a rat could be motivated to help a stranger of a different strain, albino rats were housed for two weeks with a black-hooded rat, and then re-housed with another albino rat before being tested with black-hooded strangers. These rats, which had known only one black-hooded individual during their lifetimes, freed trapped black-hooded strangers. These tests suggest that rats do not need to be familiar with an individual to display empathy-driven helping behavior, but that they do need to be familiar with the strain of a rat.
To determine if this strain familiarity is needed for a rat's own strain, newborn albino rats were fostered with black-hooded mothers and littermates. These albino rats were raised in an environment in which they were denied any exposure to rats of their own strain. When tested, these rats helped trapped black-hooded strangers but not albino strangers.
"Rats are apparently able to categorize others into groups and modify their social behavior according to group membership," Bartal said. "Genetic similarity or relatedness to another individual really has no influence at all."
"Rats are not born with an innate identity or motivation to help their own type," Mason said. "It's only through social interactions that they form bonds that elicit empathy and motivate helping. There are no mirrors in nature, so what they see forms their identity."
With these behavioral patterns established in an animal model, the researchers are optimistic the underlying biological mechanisms of helping and group categorization can be explored, and that these results can inform future studies in other social species, including humans.
"Exposure to and interaction with different
|Contact: Kevin Jiang|
University of Chicago Medical Center