The origins quest is a millennium enterprise: since the human being is capable of wondering, the question of this origin, as well as that of the various alive forms which abound on the planet Earth, did not stop tormenting him.

During centuries, answer to these questioning was brought by simple religious dogmae and impervious to the criticism. Only one century ago, hardly, when the question of the origin of life was able to settle in scientific terms. It was not without hard battles, echo of which continues today in the fight of some dogmatic fractions against the recent, imperfect and fragile contributions of the contemporary biology. There are still many those that refuse the bestiality of the human being, its commonness, in a sense.

This attitude often meets itself at those even which studied the origin of the life. Observing this one confined on a single planet, they limited their analyses to conditions reigning over this planet only. They deducts that the appearance of primitive forms of life from the inanimate material had to take on a probability so weak as it held of the miracle. If such an attitude was able to be a justifiable time, knowledge accumulated mainly these last two decades make her void. he ensued from these old conceptions the idea that the Earth was doubtless the only planet inhabited in the universe, the attitude certainly " ecologically correct " which fitted very well into a vision of the world limited to a single planet value of which was so glorified: to modify the Earth, touch the biosphere showed then to constitute a crime against the entire universe!

We shall see that in fact the problem of the origin of the life on Earth can not be thought any more in strictly local terms, by fixing a quota for alive phenomenon in a single planet. The appearance of the life, as several indications seem to indicate it to us, is a global phenomenon which concerns a wide region, if it is not totality, of our galaxy. It is so in the space that will begin our history of the life, far away from the Earth. One of consequences, and it is not the least, of our way of envisaging the history of the life is that this one must be widely spread in the universe.

I would here like warning the reader: I not claimed to be able to write in a definitive way the history of the life, I tell only a history, who seems to me to be the one that agrees best with the known facts and reasonings which one can validly hold. Tomorrow maybe, the other observations will reduce to nothingness the interest of the scenario which I propose, or either will come to confirm it. The important is to succeed in understanding that scientific knowledge is not a motionless construction but a dynamics, a movement in which I aspire to be only a point of departure for all what wonder about the mystery of origins.

I tried to facilitate the reading of this work by numerous plans. From time to time, a box " specialist corner" will complete descriptions given in the text of the work, in a more technical way. I indicate also to the end of the work a glossary defining scientific terms, and a bibliography based mainly on reviews of French expression. In science, monthly reviews allow to have quickly informed new discoveries, even though selection undergone by their authors can leave of quoted by important rates but which seem too much dared.

R.Raynal

Dr of the Toulouse university, France, 2001