In Palo Alto in the heart of Silicon Valley, hedge fund manager Joon Yun is doing a back-of-the-envelope calculation. According to US social security data, he says, the probability of a 25-year-old dying before their 26th birthday is 0.1%. If we could keep that risk constant throughout life instead of it rising due to age-related disease, the average person would – statistically speaking – live 1,000 years.

I get ~ 1,400 years, as the "half life," but I see what Yun did. And that takes into account that 25 year olds have already gotten most of their risky behavior behind them. Your auto insurance rates dropped when you turned 25 for good empirical reasons.

Of course, these calculations don't mean anything because we don't have anywhere near enough of a baseline yet to make that sort of extrapolation plausible.