The reason how I converted all of the heathens (including) rascals was when ever I had Females who could have kids I would make them have kids I would just have the men work. I have always had a big population not only to get work done faster but to have a lot of divine energy to get the high ranking powers such as earthquake. When ever I had a hut that could have been built I would everyone the farmers scientists and healers build the hut to get it done quickly to get my population up. When I ran out of kids I made one using grant youth. You should always have a child even if you have found all the collectibles. Especially when you start the game always have at least one child. Missing collectibles really hurts and it could mean the difference between life and death for your tribe. Well, maybe not life and death but it will certainly make the game harder. I am just saying when ever you can increase your population you should do it.