That is a given. Conversely the pain and death of individuals equals life for each and every species. All must die that all may live. It is the true balance of nature. That balance allows only one animal to practice compassionate death, or relaxation of painfull death to others.
Humanity is such an animal.
However our emotional relaxation of those rules, can never allow other natural deaths to become the norm. Death in nature by desease,starvation, or over predation know little of rights or welfare. We can not change nature. It deserves the best we as a species can offer, but neither death or pain will ever be wiped from her slate. She uses them both to make each individual stronger, so the species will individualy become stronger.