I think she brought up a good conversation piece. I am often intrigued by the age of the ancient people and prophets, not that I doubt them but curious how they came to be. Honestly, I did talk about it with my friends in the religious circle. They can be a few things:
They lived up to the normal age but their counting of the years may be different. Obvuously, no Gregorian calendar which is a very recent thing.
They could use the moons instead of years. Our natives would measure time by the moons. If it was moons, then 900 years would be 900 moons, which is 84 years, and more like today old age. They might live shorter life, of course.
They could be miracles also - God purposely allowed them to live long lives to do His work on earth. But if that was, it would be quite unusual - how would the people related to them with such an old age? It is all left to our imagination.
Those are what I could think of.
I have no problem with the parting of the Red sea, for example. I think it was a miracle unlike what the movie makes of it - a low tide and tsunami.