Just Doubt !!

I learned Psychology in my first semester at ABAC and found something about needs theory that made me doubt. In pschology , needs can seperate in to two kind. First is biological needs. Second is social needs.
One of favourite activities in our life is eating. Do you known that eating food is one of biological needs ? and why we count it as biological needs ? The meaning of biological needs are physiological requirements that are critical to our survival and physical well-being. After read the meaning of biological needs , can you understand why food is one of it ? Ok! if you can't got it ! I'll explain that. The reason that we count food as biological needs is if we have no food to eat , we'll die. Things that we count as biological needs are food , water , sex , Oxygen , sleep and the last one is avoid pain.
Social needs are needs that are acquired through learning and experienced. Forexample of social needs are achieve , form social bonds , have fun , relax.
Things that I interested is something and some activities can count as social needs and biological needs. For example , we may drink not only to satisfy biological needs but to make social contact with each other well. For this kind of needs , I don't know which thing that we use to compel it. There isn't has an explanation of this in any place. That's make me doubt !!
I forgot to tell you something. All of this am just doubt but really I'm no need to know that because am a law student not a book writter or a psychiatrist. JUST DOUBT!!