What does “Optimism keeps us moving forward rather than to the nearest ‘high-rise ledge’” mean?

Question

There was the following sentence in Time magazine’s (May 28th) article titled “The Optimism Bias”:

Overly positive assumptions can lead to disastrous miscalculations – make us less likely to get health checkups, apply sunscreen, and more likely to bet the farm on a bad investment. But the (optimistic) bias also protects and inspires us: it keeps us moving forward rather than to the nearest high-rise ledge. Without optimism, our ancestors might never have ventured far from their tribes and we might all be cave dwellers, huddling together and dreaming of light and heat.

Does ‘high-rise ledge’ in the above sentence literally mean the ledge or balcony of today’s high-rise building, a steep cliff or rock facing ocean, or something else?

Why is moving forward is better than approaching or facing to ‘the high-rise ledge’? Is there special or negative meaning with “high-rise ledge” used here?

Answer 1

Suicides often jump from tall buildings: the "high-rise ledge" is a window ledge in a high-rise building, and the sentence is saying that optimism is what keeps us moving forward instead of killing ourselves.

There's a great phrase I first learned from John Irving's Hotel New Hampshire, and which later became a song by Queen: "Keep passing the open windows."

Answer 2

I suspect the author was thinking of optimism and pessimism. Implying pessimism by suggesting suicide by reference to tall buildings amounts to hyperbole dressed up as euphemism.