Some of us claim we are Humanists. That’s our identity. However, the fundamental question as to how we came to be human goes unanswered many times.

It is as wide open a question as what one means by God. Every one of the believers has a different answer to this fundamental question. A question shouldn’t be that open for interpretation. It is almost certain that any simple answer is wrong. It is not even incorrect.

So, how did we come to be human?

To answer that question isn’t easy. (No one said it was.) That is the first myth we need to break. It is a complex question which deserves a lot of our respect. It takes some time to understand and answer.

Firstly, we need to delve into the origin of life on this planet. How did life come about on this planet and how did, as a consequence, humans come to exist?

The first signs of life on Earth date back to 3.5 to 3.46 billion years. It is important to remember that there is no evidence of life before that on our planet. We find traces of life in the form of bacterium which lived and died leaving their fossilized remains. Where some left their “shells”, others left behind traces of their activities; those that powerful microscopes can reveal.

But bacteria are complex beings by themselves. Although just a few millimeters across they are gigantic as far as the molecules they embody. Viruses are an order smaller than bacteria. Then why can’t viruses be the elements of life?

The simple answer to that is that viruses are not “complete” beings. They cannot do anything on their own. The essential function of reproduction is piggy-backed on to other organisms. They deceive others to perform the functions that they themselves lack the ability to do. Bacteria do those functions on their own. Usually, viruses attach themselves to the self-replicating mechanism of other organisms so that they can replicate. Viruses don’t eat or breathe. And as a consequence viruses don’t produce energy from their own activities, unlike bacteria.

So, we take bacteria as the fundamental elements of life on this planet. In fact they are the most dominant group on this planet. Their living mass as a whole on this planet hasn’t been superseded ever since they first appeared on this planet 3.5 billion years or so back. The plant and animal mass of this planet falls far short of bacteria’s total mass even today. They are prolific beings. And they cannot be wiped out by any catastrophe, whereas plant and animal life is deeply vulnerable.

The surface to volume ratio of a bacterium is such that the equation of life favors them as millimeter (microscopic) organisms. The ratio falls as any being increases in size (hence volume.) This ratio is so favorable that between 3.5 billion years and 570 million years ago, the only organisms that existed on this planet were the various unicellular organisms. The oxygen and food intake favors bacteria more than a multicellular organism, hence life didn’t seek anything more. There was no reason to.

In the Cambrian age, from 570 million years ago, we find evidence of multicellular organisms. We do not know why the Cambrian age is special. Maybe there was an upsurge of oxygen during that period. (This is the period right after the snowball earth.) This is not to say that the bacterium didn’t have the evolutionary capabilities to form colonies of multicellular organisms until then. There is evidence that the required mutations for such a transformation had taken place much before, a couple of billion years before the actual multicellular beings came about. But why then didn’t the multicellular organisms form?

Not just because there was now a reason to break the “golden” ratio that we mentioned before. There wasn’t a need to break that ratio before the Cambrian age. The life form was already dominant in the way of bacteria. Why would the less “stable” multicellular organisms form? There isn’t any evolutionary or survival advantage. In fact, multicellular organisms helped maintain the proper buoyancy and hence were evolutionarily desirable.

Once that came about there was a proliferation in both plant and animal life on the planet. The Cambrian period of the Earth, which lasted only about 30 million years (about 570 to 540 million years) -- a geological blink of an eye -- saw the explosion of multicellular life. Insects, worms, crustaceans, etc. formed and dominated the earth (or tried to). They never really superseded the bacteria -- nothing ever did -- but the fossil records show rich number of them from the Cambrian period.

Four factors give the illusion of randomness: Mutations, genetic mixing, natural selection and planetary cataclysms. In fact, they are random. None can be foreseen. Evolution essentially is blind. Each of these factors needs further elaboration.

Natural selection weeds out the characteristics in beings that do not impart in them any benefits for survival. There is no ‘end design.’ There is no grand architect. There isn’t any intelligence in the design.

The bacteria – the cells in any organism, whether unicellular or multicellular – continue to mutate and evolve. Essential mutations take place at the cell level even today. It is the selfish gene, as Dawkins put it.

People had difficulty seeing man evolve from a chimpanzee. A chimp has 99 percent of the proteins and DNA (Nucleic acid sequences) similar to that of man. Though this fact is made much of, the real difficulty should be to see a unicellular bacterium evolve into mammoth beings such as the dinosaurs. We find plenty of evidence for all this of course. No one in their right mind can deny that dinosaurs lived and walked this earth. Their remains are found abundantly everywhere on this planet.

Like the dinosaurs, millions and billions of species came and went. They were driven to extinction because of changing environments. Environs are as dynamic as the species that live in them.

Those that couldn’t adapt, and were hence ill-fit to live, were eliminated. We humans have contributed to the extinction of many a species in the name of our own survival. The vanishing of big game on continents as humans invaded them is proof aplenty. There is evidence that we literally drove them off the cliffs.

There are countless episodes of violence, deceit, and valor in our history as humans. Yet we are not the dominant beings on this planet. Bacteria are.

But the fundamental question as to how bacteria came about on this earth is still not answered. We just said that viruses which are smaller are not organisms. Then where did the bacteria come from? We can summarize the answer in one word: Panspermia.

Panspermia “seeds disseminated everywhere.” For us this hypothesis means that life came to earth from elsewhere; specifically from space; by some means; and that life didn’t spawn on this planet. The planet, in fact, is not the womb, it’s just a home.

This isn’t an outlandish proposal. The more we delve into it, the more sense it will begin to make. For the basic molecules of life to come together, there should exist the right conditions. Scientists are in agreement, if not totally, that such conditions never existed on earth. Comets, with their water and amino acids, probably are better suited. Mars, our earth’s sister planet, is, for example, better suited than earth itself for life to form.

The popular notion of the search for life on Mars is to look for little green men. Scientists don’t look for them. Martian soil is sterile and barren. It took scientists some time to figure out that the rocks hold the key. They are now looking for traces of bacteria on and in rocks. Bacteria probably still live in these rocks and underground. However, they could be buried kilometers underneath the surface of the Martian soil. This is difficult to get to, to say the least.

It has already been shown that Mars had water. This was important because water is one of the essential elements of life. At least the carbon based life depends on it. But we do not know if water was essential, or there was anything else for such a cell to form. For now the search continues. We continue to send probes to Mars every year.

The mechanism of transplantation of life from Mars to earth is well understood and shown to be quite plausible. Bacteria can go into deep hibernation for prolonged periods. A Martian stone spewed into space because of volcanism or meteorite strike could have carried life. Such a rock could have fallen onto earth. Earth was atmospherically receptive at one time to accept without damage such a stone. A meteorite, which fell in the Antarctic continent a few thousand years ago, and discovered in 1984, showed signs of life along with the tell-tale spectrographic signature that it came from Mars.

That’s as mythical as one can get when we talk of our origins as humans: that our life on this planet came from elsewhere. The rest is quite well supported by evidence.

From very humble beginnings we all evolved. The point is not to be ashamed of our humble background (We should admit it with pride.) Bacteria are quite complex and sophisticated “animals.” They encapsulate our very being. We have billions of cells in our bodies.

The mitochondrion, the nucleus that gets passed from mother to child and never from the father, is a cell trapped by the bacteria. This capturing of “foreign cells” has made evolution a revolution. It put evolution on a fast track. Cohabitation -- or as scientists call it Endosymbiosis -- speeds up evolution. So does sexual reproduction.

The genetic material contained in the animal cell undergoes mutations. By sharing chromosomes from both the mother and the father the combinations explode. Such a zygote is better prepared to fight other bacteria and viruses, and be weeded out by natural selection if found unfit to survive.

There is ample evidence that a fast track evolution happened on this planet. But the culmination was never intended to be a human being; there was no intentionality on the part of evolution. Evolution represented as a tree with the leaves as the surviving species with the top leaf of the tree representing a human is totally wrong.

An appropriate picture is that of a unicellular organism forming the tiny stem representing 3.5 billion ago. The thin stem continues on till 570 million years ago. On this stem stands a bush. The bush levels and crops up to the present. Humans share the top with millions of other species. We aren’t unique after all. Humans used intelligence as a survival tool; the other species specialized in other ways. Intelligence won out. By sheer chance humans stumbled on it.

It isn’t surprising that the compelling story of how we came to be humans can only be retold by humans.

Prasad N. Golla is an entrepreneur and researcher in the technology realm. He holds a Ph.D. and couple of Masters degrees in Engineering, and also has a M.B.A. He is adjunct faculty in SMU, Dallas. Prasad is a resident cartoonist and a member of the board of directors of North Texas Skeptics. He lives with his wife and son in Plano, Texas.