A half-baked idea that PETA could bake longer in the oven. Lions eat lots of other cute animals like zebras and antelope. Make an effort to convert them to vegetarianism. The human diet consists of a smaller percentage of meat; lions eat pounds of meat a day. Think of all the lives that could be saved. Then move on to other carnivores; preach to the tiger next.
But maybe we are going off the deep end. In his book, Star Maker, Olaf Stapledon put forth a consideration in his science fiction novel that even rocks may be a life form with an extremely slow metabolism. One human year could be equivalent to a thousand years to a rock. In that case, walking on the earth may be inhumane. Is the cycle of life a vicious cycle?