 Goodall said that as long as humans and wild animals are kept in close proximity in zoos, there is no way to prevent accidents from happening, but she believed that zoos "with the highest standards of care" could play an important role.Zookeeper Jack Hanna strongly defended the zoo's actions as the "correct decision", noting that a tranquilizer dart might have taken five or ten minutes to take effect and could have aggravated Harambe further.Primatologist Frans de Waal said he saw few options for the zoo