Where did karma started?

Karma, good or bad, doesn't exist. It's a concept of asian religions, like Hinduism, which believe in rebirth cycle. They believe that you should collect good karma by doing good deeds in life so you would rebirth into a better being after death and continuing this cycle eventually free from the rebirth and obtain nirvana, ultimate state of good feeling.The whole concept is wrong though, since it implies that there are inferior beings, inferior humans, and it keeps the Caste System working in India. All beings are the same in value, no are higher than others, and rebirth is only a myth they like to believe in. So is nirvana and so is karma.

You should do good in life of course, but you don't need the concept of karma for that. Since you cannot rebirth into a new life, you should even more make your only life worth it, do good to people around you, and they will do good to you. That feels sincerely more nice than the idea of imaginary nirvana.