Butterworth looked at me, one eyebrow still up. "I understand the philosophical point, Howard. However, in the real world, we are here to propagate our species. It is simply not possible to do that with a zero footprint. I would be happy to stop killing raptors, if the raptors could be persuaded to stop trying to eat colonists." He smiled. "Failing that, we and they will continue to interact in the ways that competing species have always handled such situations."