Philip, to answer your question about my experiences in the village and how they might fit into my essentially scientific world view --
I saw what I saw. It is a fact, correct? Do I know what it means? No. Would the villagers' possible interpretation of evil spirits or a bad omen have been correct? I am agnostic on that. Again, I don't know the answer. My Christian missionary friends in the nearby town, however, felt that there was a battle for souls going on over Western Kenya. I don't know how they would have interpreted the situation with the "dogs" in my yard, but it might have either been 1) they were indeed evil spirits, or 2) they were merely dogs and the locals were superstitious, which was itself evidence of inherent evil. They would have been unsurprised by the strangeness of my experience because they'd had odd experiences too.
I lived in both Kenya and Zimbabwe and associated with all sorts of people, but was mainly either with African university professors and intellectuals, or out in the village. Most westerners I knew sheltered themselves among the ex-pats and USAID/Embassy people. They didn't understand what was going on. To them, it was all aid, economics, and how to get people to plan their families. Many were highly critical of the people and the country, and some were fearful -- some of it founded, of course, but a great deal out of misunderstanding. This is what happens if you stay on the surface. I have likened Africa to going to the La Brea Tar Pits in Los Angeles: the grass looks like a regular park if you stick to the sidewalks, but when you walk on the grass, you find that the tar is seeping up and is all over your shoes. The bucolic scene is really an illusion. This is what it's like. It may have a veneer of modernity and Christianity, but the old life is still there, the old beliefs are still there, and it sticks to you.