Population Question

A question to those in the know who might happen to read this weblog:

It's prompted by this thread on a BB I'm a member of, and specifically by something I was thinking about in this particular post. Actually, thinking about it, the question (as I've thought about it) probably goes back around 10 years, back to the days when I used to hang out in uk.rec.ufo (back in the days when usenet was generally fun and usable).

So, here's the background summary (which isn't really the question as such, but gives it some context): Fans of the Extraterrestrial hypothesis, as an explanation for UFO sightings, almost always tend to be of the opinion that the distance problem is a non-problem due to the fact that any visiting race is older than us and, obviously, have solved the problem of travelling at speeds greater than the speed of light.

But why should it be so? Why should we assume that humans are a youthful race in our galaxy (let's keep it simple and just think in terms of our galaxy)? Why can't it be that we're one of the first forms of intelligence to emerge?

This is where I got to thinking about the question I wanted to ask: assuming, for a moment, that life only forms in the vicinity of metal-rich stars (a safe assumption based on the available evidence, right?), this would mean that life would be forming around Population I stars. When I raised this in the thread I mention above someone got to wondering about the relative age of the Sun to other Population I stars. It was then that I realised I didn't know the answer to such a question. It was my understanding that the Sun was about as old as the oldest Population I stars but, when I went and did a little bit of searching, I couldn't find a clear answer.

So, after all that waffle, here's my question to anyone who might know: how old are the oldest known Population I stars, especially in comparison to the Sun? Is the Sun an "elder" member of Population I or is it a more youthful member?

Note that I'm aware of the accepted age of the Sun, and I'm also aware of the accepted life expectancy. It's the age in relation to all known Population I stars that I'm wondering about.

Anyone got any good pointers for an interested layman?