“On the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much - the wheel, New York, wars and so on - whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man - for precisely the same reasons."

                                                                                             -       Douglas Adams

Oh! So you think man is the most successful creature on earth?

Well, is that even a question! Of, Course man is!

Why would you say that? If you define success as being the most numerous, then I guess we are far behind most of the organisms.

We are the most intelligent creature on earth.

What gives you the authority to choose intelligence as the criteria to measure success? If smell were to be the criteria, then a dog would surpass you.

Okay may be you are right about intelligence, but I say, we can destroy all life if we want to. Set off all the nuclear bombs or so. No other animal can do that.

Well if a virus infects all the phytoplankton in the ocean, there would be no one to produce oxygen. It would be as devastating to life as the nuclear bomb. That makes the phytoplankton or the virus as successful as you. Both hold the fate of life in its hands, as much as man does. On the contrary, if all the humans were to be killed, nothing bad would happen to life on earth except for the few parasites that depend on us.

Okay, let me put it in another way. I can kill any animal in the world. I am at the top of the food chain, even though I may not want to eat it after I kill.

True. Given the right circumstances, for instance a gun, you could kill any animal. But I would equally argue, given the circumstances, a lion could kill you too. Moving along your definition for success; if a mouse happens to push a brick from a ten storied building with you underneath would make the mouse the most successful animal in the world.

Alright then, if not humans then who is? Someone has to be at the top place.

The question is more like asking someone where a circle starts and ends. If every step is completely necessary for a process, how can you classify one as more important than the other? Which do you think is more important, the heart, brain or the artery that feeds the brain; when you will die instantly if I take out any of these?