Many scientists have believed that giraffes are solitary creatures, preferring to spend their time alone instead of with others. But observations of giraffes and their behavior in recent years has suggested that these animals may be more social than we once thought. For example, scientists Zoe Muller and Stephen Harris claim that giraffes may even help each other care for one another's newborns.

Which finding, if true, would most directly support Muller and Harris's conclusion?