Wevin Crown

Hello, I'm interested in the relationship of the ratios of pregnancy length, amount of time before the infant is independent of the parent and the average life span. For example, a dog is pregnant for 9 weeks, the puppy weens for 8-12 weeks, and then lives for 10-12 years. Does anyone know which animals (humans included - i know it's difficult to decide when a child is independent from it's parents) have the longest/shortest pregnancy in relation to life span. Also, which animal spends the most/least time dependent on it's parents in comparison to it's life span. Thanks!