That's a mistake that a lot of people make. Choosing to do the tutorial would have warned about that. You really need to have some villagers researching at the research table so that your villagers will learn how to farm. Tap on the Tech button and tap on Harvesting on the tech screen. Then tap on "Info" and you'll see the different ways that your villagers can get food. You can also check out the other techs that way. That will give you a better idea of what to spend your research points on. I'd recommend buying level 2 of Harvesting first, though, so that your villagers will have a new food source.

Also, it's not a good idea to grow your population too much early in the game. First, you lose the productivity of the moms, and they can't research or gather food, and second, the babies eat as much as the adults, and you'll run out of food sooner.