Oh, please, we're talking about prehistory here. How do you think the food got into your mouth in the first place? I don't think these people had much problem with getting their hands dirty. And I really don't imagine it being easier to get food into a kid's mouth with your tongue than with your fingers. I don't know about you, but my fingers are much more dexterous. Not to mention that it's going to come back out again anyway (we're talking about babies here, right?) and you're going to have to catch it and stick it back in. I don't see the mouth being the most efficient method of dealing with this.