Literally, that which will follow humans. The term is used
in speculation about the future of technology and society
of the futurist, transhuman, or science fiction flavors to denote creatures that have so
altered their fundamental physical or mental forms that they are no
longer really classifiable as human. It encompasses beings with
gross genetic changes to their body structure such as the addition of
wings, gills, or tails, robotic intelligences, electronic intelligence,
and formerly biological humans equipped with advanced prosthetics that
supervise or replace most body functions (think borg). These creatures are
almost always assumed to have far greater intelligence and far longer lifespans than
do human beings.
Treatments of posthumanity sometimes have a markedly utopian feel to them. From the
super-sleepless with their intense communicatory bonds to eachother in Nancy
Kress' Beggar's Ride to the far-future creatures that make an appearance at the
end of Stephen Speilberg's AI, the posthuman are portrayed as being more intimately
connected to themselves and to their worlds than we are. They have a wisdom and
a depth to them that we can't even aspire to. This is an understandable reaction
to the notion of something far more intelligent than we; if it understands more,
and better, than we it will see the necessity of compassion and benevelence even
more clearly than we. In these works posthumanity is something to celebrate.
Another literary tradition exists, of course. This one sees posthumanity as something
to be feared, a threat to be responded to, a fight waiting to happen. From this tradition
sprang both The Terminator's grim robotic future and H.G. Wells' The Time Machine
with two different visions of posthumanity, the Morlocks and the Eloi. This is
posthumanity with an emphasis on the post. Humanity has been destroyed,
either by descendents that hate us or by the unremitting press of time.
A third view of posthumanity also exists. In this view the underlying hardware and software
of the beings may alter dramatically, but the core of what makes something "human" remains
unchanged. They may be faster, smarter, and able to endure the hard vacuum of space without
a suit, but they will still care for their offspring, anger when crossed, rationalize
their actions and in general act very humanish. Posthumanity has been well treated in
this fashion by Vernor Vinge's A Fire Upon the Deep and Linda Nagata's excellent novel,
Vast.
In literature that is closer to being non-fiction than what is cited above Damien Broderick
and Ray Kurzweil illustrate the first view while Bill Joy presents the second. The third
view is the closest thing to "conventional wisdom" on the subject and is typically what others
use as a baseline for any comparisons they try to draw between humans and posthumans.
Recommended reading:
Thanks to fuzzy and blue for reminding me about the Uplift novels.