I tend to agree with the evolutionary theory. The one that emerged from the works of Alfred Wallace and Charles Darwin. They basically stated that life is an infinite competition, where only the fittest survive.

Here is how Wikipedia describers the theory of the evolution:

In biology, evolution is the process of change in the inherited traits of a population of organisms from one generation to the next. The genes that are passed on to an organism’s offspring produce the inherited traits that are the basis of evolution. Mutations in genes can produce new or altered traits in individuals, resulting in the appearance of heritable differences between organisms, but new traits also come from the transfer of genes between populations, as in migration, or between species, in horizontal gene transfer. In species that reproduce sexually, new combinations of genes are produced by genetic recombination, which can increase the variation in traits between organisms. Evolution occurs when these heritable differences become more common or rare in a population.

There are two major mechanisms that drive evolution. The first is natural selection, a process causing heritable traits that are helpful for survival and reproduction to become more common in a population, and harmful traits to become more rare. This occurs because individuals with advantageous traits are more likely to reproduce, so that more individuals in the next generation inherit these traits. Over many generations, adaptations occur through a combination of successive, small, random changes in traits, and natural selection of those variants best-suited for their environment. The second is genetic drift, an independent process that produces random changes in the frequency of traits in a population. Genetic drift results from the role probability plays in whether a given trait will be passed on as individuals survive and reproduce. Though the changes produced in any one generation by drift and selection are small, differences accumulate with each subsequent generation and can, over time, cause substantial changes in the organisms.

So basically it all started around 4 billion years ago, with the first self replicating RNA molecule. This molecule could replicate itself over and over again, as long as it could find the necessary substances on the environment around it.

This in turn triggered a competition for the natural resources, and self replicating RNA molecules that developed traits that would make this replication process more efficient went ahead.

For example, suppose that at one given generation one of those RNA molecules developed a way to replicate itself that required only half of the resources that normal RNA molecules required. Obviously this particular trait would favor this new breed of RNA molecules, they would replicate faster, and would therefore have higher chances to survive.

Over the time the normal RNA molecules would disappear because they would not able to compete with the new ones.

Then imagine at some point, the genetic drift would cause one molecule to develop a protective skin. Again this mutation, that appeared pretty much randomly, would give the new RNA molecules significant advantages over the others, and soon they would dominate the whole environment (or the whole Earth!).

So on and so forth. If you combine the mechanisms of natural selection and genetic drift, with billions of years to spawn different combinations of traits and to filter only the most efficient ones, it is really possible to come up with very complex organisms, as complex as men or other mammals.

I agree with that.

The question that I can’t answer, and neither can scientists and evolutionary theorists, is how and why the first self replicating RNA molecules appeared on Earth.

Before them all we had were minerals and other primordial elements. Why someday one molecule would just decide that perhaps it would be cool if it could make a copy of itself?

That is the key to the “Where do we come from?” question. Once we have a self replicating organism in place, the evolutionary theory explains the rest until our days. But what and how this first self replicating organism emerged?

Perhaps someday science will manage to explain it, but until then one cannot exclude that it might have been something related to a divine, mystical or extraterrestrial power!