Replicators: atomi > molekulas > replicēties spējīgas milzu molekulas > pirmās šūnas ar aizsarg-šūnapvalku > etc.

They did not die out, for they are past masters of the survival arts. But do not look for them floating loose in the sea [primeval soup]; they gave up that cavalier freedom long ago. Now they swarm in huge colonies, safe inside gigantic lumbering robots, sealed off from outside world, communicating with it by tortuous indirect routes, manipulating it by remote control. They are in you and in me; they created us, body and mind; and their preservation is the ultimate rationale for our existance. They have come a long way, those replicators. Now they go by the name of genes, and we are their survival machines

/R.Dawkins "The Selfish Gene"