Well, I don't believe karma exists. That's not important though. Don't confuse that with self-effacement. Its existence or non-existence is something of a moot point. Firstly, there is no way to differentiate the illusion of karma and actual karma. It would come to us perfectly camouflaged. Secondly, even if it were proved, it would have no material affect on decisions. People already act in their own best interests. Doing good things, believing the universe will reward you for it, sets up for a nice catch-22. It would essentially turn every good, deliberative act into a selfish one, escaping nothing of what was not already present in our nature. You could even argue that karma takes away the morality of being good. Selflessness is described by absence and not gain. Thirdly, its nature makes us ignorant of all the rules that govern its nature.

I would be more interested in knowing where it started.

Are the rocks on Mars subject to karma? Those tide pools of sulfuric acid on Jupiter's icy moon Europa? What happens in those environments is governed by chemistry and physics alone. I do not think (though I could be wrong) that a rock falling 300 meters on a lifeless planet needs balancing.

Are the animals on the serengeti subject to karma? They make decisions based on their physical needs, but these are hardly moral decisions. Does karma govern non-moral decisions? I do not think (though I could also be wrong) that a hyena disemboweling a giraffe needs any more balancing than the instinct to survive already provides. Among hyenas, karma would only be dishing out cruelty. In fact, as every animal is capable only of selfishness, karma would result in an ever escalating cycle that would definitely and necessarily kill every living thing not capable of doing good. Every living animal on the serengeti would be there in defiance of karma.

There would be a three-billion-year-plus defiance until nature could finally produce an animal capable of receiving good things from this karma (unless it sat there waiting, in latency, ignoring the cruelty of hyenas and lions and baboons and everything that ever lived). Then we have human beings.

And we are to sit here in judgment for things hyenas and baboons can ignore? It does not seem fair that human beings get picked on by karma and hyenas can go on disemboweling with complete immunity. We both walked the same grass fields 100,000 years ago. Why should our morality give us a disadvantage to those cruel, heartless beasts when we were in competition for the same foods?

So perhaps, in its ethereal fairness, it casts a blind eye to those evils that both men and hyenas do to survive. Perhaps it was our good that helped us find shoes and arrows and tents, but still, only rewarding the moral good of our species still disadvantages us as evil is more potent than good. And if karma can only reward the good in imperceptible and impotent ways, then why even have it? The bad would necessarily go unpunished and the positives would be mere insults in the face of overwhelming evil.

Why support such an injustice as karma? (I said that to be ironic)

I only agree with the statement of Heraclitus, a man's character is his fate. What we do has consequences already. What is the purpose in adding more?