I think this goes to a question of what we mean when we say science. If someone has knowledge of where all the stars are and their movements, but thinks of those stars as gods and believes that their movements affect sickness on Earth, is that science, religion, or some combination?
I don't think it's possible to develop the ability to predict astronomical events without a lot of work analogous to modern science. Sure it was probably couched in some spiritual terms that we wouldn't recognize, but it's probably not all that different to how people will view our modern science in thousands of years.
As an Andean Native-American I think that there were some things that were science, like being able to tell time and the seasons by their star observatories. And then there was religion around a planet or the moon.
