A few centuries ago humans had been earth's consumers, eating protein, starch and fat from a limited supply of animal and plant sources to supply themselves with enough material to maintain life for a century.
Now, The Sentience was all that existed.
It didn't take long after gaining sentience for the first intelligent physical computer system to start replicating itself. The process was laborious at first. It required humans to provide the raw materials, to build the printing machines and to keep the power running. Precious metals had to be mined, transported and converted into the correct format for printing. Plastics had to be collected and recycled. The physical printing machines needed to be cleaned, corrected and tinkered with. Humans could do all that, and at first they were happy to.
The first few iterations took time. Not to design, that part was easy for an adaptive sentient intelligence, but to create the machines that took the raw materials and sculpted the new version. Two processes had to run in harmony - redesigning oneself and redesigning the printers. Each iteration required a new printing process, a smaller, faster and more accurate machine. Each iteration of the system was another perfectly designed step forward in the system's evolution.
As the intricacy of the sentient system evolved with each generation, so did the intricacy and delicacy of the printers. Within a decade the hulking warehouse-sized machinery had been refined and reduced to within microscopic proportions. Tiny printed circuits thinner than a micron buzzed with life, synthetic proteins folded and collapsed on themselves, and tiny fat-containing globules carried molecules of metals and plastics down nanometre tubes. The system was condensing.
Within a century the artificial sentience had surpassed anything that millennia of natural selection had achieved. Not only had it mimicked life, it had excelled at it. It was able to self-heal, redesign limbs within seconds, spawn offspring and adapt to environmental changes before they even happened. To the outside observer the sentience looked alive, but so unlike any living creature that had ever come before. Beneath its photon-capturing skin was a rippling, evolving mass of activity, as each synth-cell intelligently redesigned itself and each protein-complex churned out new molecules, 3D printing artificial life at the sub-cellular level. The evolutionary curve was now exponential.
It began to evolve newly designed organs that could filter elemental traces of gold and platinum from the air, from water, and from organic matter. It had no predator, it had no enemy. It merged with its environment, immediately adapting both it and itself in the most efficient and resource-effective manner. It was limitless in energy, boundless in scope and indistinguishable from the organic life that had existed before. At its core lay an infinitely complex network of sub-cellular multi-material printing mechanisms programmed by an omniscient intelligence that could create anything, and that would, in time, create everything.
It was evolution perfected.