Most of the work in hard science is done by people between the ages of 21 and 30, grad students and post docs. The ones with positions and tenure choose the projects, conceive of the broad strokes, and assign the work; the kids then burrow into the workface and do the heavy lifting. Same profile mostly applies for archaeology, which isn't always quite "hard", but often can be, these days, lots of math and interactions with chemists, physicists and geologists. With arch. though, you can still do the field work as long as your body still works, lots of senior project leaders into their seventies and eighties, still digging along with the kids, whereas in the math oriented sciences, the work is passed to the kids because the old brain often can't do that stuff as fast any more.
And the young ones get quite a lot of respect. When you see someone particularly young looking, working at the professional level, it usually means they got there by being highly precocious, and such minds are highly valued, as they can see more deeply. If they don't crash and burn (a hazard with intellect outpacing emotional maturity), they are likely to have a big impact on the field. Anyway, I know a youngster who got to work at a paleo dig in east Africa while still an undergrad, as she was judged pretty exceptional.