Physicist here, been with the same company for almost 25 years, developing measurement equipment. We have a lot of older scientists and engineers. My impression is that there's no correlation between age and resistance to innovation. Some of the oldest engineers are the ones pushing the hardest for trying new things.

Other possible explanations for the longevity of workers include: 1) It's rewarding, interesting work. If it's not directly improving peoples' lives, at least it's improving something. 2) It's based on principles that are hard to learn and don't change very rapidly, such as math and physics. The engineers who are given the hardest math and theory problems to solve tend to have the grayest hair. 3) The people who know the value of their domain knowledge and experience are also capable of controlling the pace of work so they don't burn out.