How'd they learn to eat?

[hEaLiNgViSiOnAnGeLicMiX]

Here's something I thought of when I was eating lunch today. Now, we all know the first person on earth have children, meaning that they lived up to be atleast 13/14 (when they hit puberty) but here's a thing. How did that person live up to be so old? Obviously, he/she ate. Now here's my question: When that person felt hungry for the first time in his/her list? How did he/she know, that by shoving something into their mouth and swallowing it, would cure that hunger? I dunno, it's an odd question, but it's making my brain bleed. Post some opinions if you've got any