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• A survivorship curve is a graph that shows the number of individuals surviving at each age interval vs. time.
• These graphs can be used to compare the life histories of different populations.

Survivorship curves can be divided into three types.

• In type II curves, mortality is essentially constant over the course of a person's life, and death can happen at any time. A type II or intermediate survivorship curve can be found in many bird populations.
• Early ages have the highest mortality rates in type III survivorship curves, but species that live to advanced ages have significantly lower mortality rates. Type III creatures generate a huge number of progeny but give them little or no care. Because very few creatures survive their younger years, trees and marine invertebrates have a type III survival curve. Those that do survive to old age are more likely to live for a long time.

• In the early and middle years of a type I curve, mortality is modest, and it mostly affects the elderly.
• Organisms with type I survivability often generate few offspring and provide appropriate care to them, boosting their chances of survival.
• The type I survivorship curve is found in humans and most mammals.