Machines and humans were always intertwined, but the line, albeit grey, eventually disappeared. The first robots with organic bodies and systems soon received nanotechnology upgrades. The inevitable outcome was that just like cellular organisms, the robots evolved.
They became, simply put, living things. And whilst the first few to achieve that were technically man-made, the argument put forth was that a human being could be classified as that as well, seeing as to how we are formed and birthed inside of and by another human being.
Whatever doubt existed soon disappeared when the evolved robots reproduced. This was incredible not just in its unthinkability, but also because it happened against all odds. Despite the protests and arguments and violence, these robots were somehow and successfully hidden from the public, allowed to live and grow safely, in secret.
Unexpectedly, mankind reached a new era of peace when the first robot successfully mated with a human being, and together they created the first homo novus, or New Man. Humanity had, by that time, mostly calmed down, and was actually curious to see if that coupling was possible. Now that it was proven so, the gates were open and man and robots mingled freely. Not without trouble, of course, but that soon came to pass as we realized we could not tell the difference between one and the other.
Not with the naked eye, at least. But the organic tissue components of the robots were so numerous, deeply grown and humanlike that it really was virtually impossible to identify one even with a deep cut or simple scans. The differences were hidden under layers upon layers of flesh, and we eventually stopped caring.
We were, after all, eager to integrate machines with man: from trackers to implants, both medical and enhanced, we were always on the road to becoming one with our own creation. And now that its total fulfillment was finally here, humanity looked upon a future that was both dazzlingly bright, yet scarily unpredictable, as evolution took a sharp turn in the road.