The plaintiffs of a historic lawsuit seeking legal rights for chimpanzees finally made a public appearance—not in court, but in a study on the mechanics of walking on two feet.

The study, published Tuesday in the journal Nature Communications, describes how two chimps trained to walk upright move more like humans than expected, perhaps hinting at the evolutionary origins of our own gait.

It hints at so much more. The research was conducted on Hercules and Leo, two 7-year-old chimps kept at the Stony Brook University laboratory of anthropologist Susan Larson. Earlier this summer, these two chimps received worldwide attention when activists with the Nonhuman Rights Project argued in a New York courtroom that Leo and Hercules should legally be