If you have managed to feed all your tribers, you may spend extra food to reproduce them. For every two pieces of any food (perishable, non-perishable or treats) spent, you get one new triber from the general pool. Place the triber pawns on the bottom space of your tribe board. They will be available for you from the next season on.
If you’ve used treats to reproduce, remember to add 1 Happiness Point to your score for every treat used.