What difference would it have made if our life span was shorter or longer?

If our lifespans were shorter, we would probably mature, mentally and physically, much faster. We’d have to be ready to bear children by probably age ten or earlier. This is shown, to a less extreme degree, by the fact that marriage happened much earlier on average several centuries ago when our lifespans were shorter.
We would evolve faster. Species that go through many generations in a short amount of time, like fruit flies, evolve at a much faster rate than humans do. This means that we would be more closely adapted to a modern lifestyle than we are now. As it is now, scientists guess our brains and bodies are optimized to live the lifestyle our ancestors lived about 10,000 years ago.
And if our lifespans were longer, just the opposite would be true.

If we were shorter lived, we’d complain about how short life is. If we were longer lived, we’d complain about how short life is.

If we lived on average to 175 – 200 years, we’d probably have to work until we were 140 or so. we’d probably have a much slower pace, like turtles or reptiles that live long lives.

Life is too short no matter how you slice it.

The longer your lifespan the more experience you’ll get.

You can get a lot of experience in a few years if you try a lot of different things .

If one lives too long he gets bored while living a short life won’t be good either because you’d want more time to do what you learned .

I have a fantasy fiction story on a back burner, which includes a race of people who typically live for about 800 years, and will remain fit and healthy for most of that time. Every now and again, they are driven to completely change their lives in some way, like a total change of career, or they just up and leave their homes and go to settle somewhere else. It’s like they re-invent their lives every 100–200 years.

Doesn’t matter how long we live, if our conditions during that time are bad.

If life were shorter, women wouldn’t go through menopause ..that would be nice. Either way, I think a lot would change though ..as @Mariah stated.

I think the quality is more important than quantity though.

I don’t think it’d make a bit of difference, because we would have nothing to compare with.. in either case we’d bitch because life was so short. We’re more aware now simply because the life span variates thus we can compare, but except for the young, everyone will agree that it’s just not long enough.