If you own Asian elephants and have been struggling with the issues of urging them to breed in captivity (and who can't relate to that problem, nowadays?), you'll want to take note of this interesting little study out of the University of Sheffield in the UK: researchers investigating birth and longevity data for elephants dating back to the 1940s have discovered that among elephants, teenage mothers are likely to have bigger families, but also die younger, compared to elephants who postpone motherhood into their 20s or beyond.
Although elephants can live into their 70s, the same as humans, they have a much smaller fertility window — for an Asian elephant, pregnancy is possible as early as age five, yet fertility peaks around age 19 and declines thereafter. Older elephants can still have offspring, of course, but the older the mother is, the greater the chance her offspring will be unhealthy.
The researchers determined that: “elephants that gave birth twice in their teenage years had calves three times more likely to survive to independence than those born to mothers who had their first young after the age of 19. Therefore, although having calves as a teenager reduced a mother's lifespan, early reproduction was favoured by natural selection because those mothers raised the largest families in their lifetime.”
(In strictly evolutionary terms, it doesn't matter how long you live or how much enjoyment you derive out of life; all that matters is “How many healthy surviving offspring do you leave behind when you do finally die?”)
In all seriousness, the study of elephant reproductive strategies is important because, like all megafauna, elephants find it ever-harder to live in the wild, as human developments encroach on their former territories. So if we want to prevent the species from going extinct, we need to increase the healthy birthrate among captive elephants, since their cousins in the wild probably can't maintain their population by themselves.