Essentially, it goes something like this
· A scientist, or group of scientists, becomes interested in explaining one aspect of how the natural world works. (This comes easily for scientists, as well as most people, people are curious...)
· Both intentionally and unintentionally, scientists conduct observations. (Some observations may be commonsense or centuries old (i.e., the tides), others may require specialized experience (variation in scutellar hair number on different strains of Drosophila)
A hypothesis is constructed based on all the pertinent observations.