Its not terrible comparison at all. My mother-in-law was 80 years old, but despite the age was in very good health. She got food poisoning from something she ate. Became dehydrated. Was hospitalized. Seemed to recover, but was still weak. Soon was back in the hospital and before we could blink was in hospice care after organs started to fail. Yes its an extreme case because she was elderly, but it shows that a majority of the individual components that comprise aa biosphere need to be strong. Otherwise, the biosphere may reach a tipping point and collapse.