In a University of Chicago lab, a rat left free to roam learned to open a tube and release a trapped cagemate, and when researchers added chocolate as a rival temptation, the rat opened both at much the same speed, then ate less of the chocolate than it would - Space Daily

What the report says

Space Daily revisits a widely cited University of Chicago rat experiment first reported in Science in December 2011 by Inbal Ben-Ami Bartal, Jean Decety and Peggy Mason. In the study, a free rat was placed near a cagemate confined inside a clear restrainer that could be opened only with effort. Most rats in that condition eventually learned to open the door, while openings were rare in controls involving an empty tube, a toy rat or a rat already free behind a divider.

The article focuses on the study’s best-known twist: when researchers offered both a trapped cagemate and five chocolate chips in separate restrainers, the rats opened both at similar speeds later in testing and ate fewer chips than rats with chocolate alone. Space Daily notes that this supports a real behavioral difference, but not the simplified version often repeated online; the published data do not show that rats consistently freed companions before eating.

The report also emphasizes limits and later challenges. The original authors considered alternatives such as curiosity, agitation or distress relief, and did not fully distinguish whether rats were easing another animal’s distress or their own. Subsequent work by Alan Silberberg’s group argued that the behavior may reflect a desire for social contact rather than empathy, while other experiments using water-based distress setups found results more supportive of helping.

Space Daily concludes that the experiment remains important but unsettled. Follow-up work suggests familiarity and social experience strongly shape whether rats open for others, meaning the findings should be used cautiously, especially when drawing comparisons to human generosity.