In Terry Pratchett’s science fiction novel The Dark Side of the Sun a search for the enigmatic galactic forerunner race the Jokers hinges on the meaning of that phrase. In the end (and this isn’t a spoiler – the novel was published 35 years ago) the “dark side of the sun” is revealed to refer to the Jokers’ return to a non-sapient state to await the evolution of other, different, minds with new perspectives.

I was recently reading the science fiction encyclopedia entry on Devolution. It’s one of those words (like deceleration) which a pedant might chide you for using – it implies an inherent direction in evolution.
There’s a strong subset of science fiction concerned with more highly advanced or highly evolved species than our own, or our own transcendence. But there’s also a number of authors who imagine an alternate future where humans devolve (subscend?), losing self-awareness.

The power of the concept of devolution links, in my mind, with a kind of Lovecraftian existential horror, in which the universe is revealed to be pitilessly indifferent to fragile, ephemeral mind.

This genre can be divided into two groups of voluntary and involuntary loss.

The reasons a species might voluntarily turn out the cognitive lights include:

  1. To pass the time: as with Pratchett’s aforementioned Jokers;
  2. To return to a more natural state: Greg Egan’s novel Diaspora mentions a posthuman grouping known as the Dream Apes who switch off their higher brain function to live more harmoniously with nature;
  3. To return to a more innocent state: distinct from the previous in being a moral rather than a philosophical consideration. The multiple species illegally inhabiting the planet Jijo, from David Brin’s Uplift universe, collectively chose to return to a pre-sapient state to atone for the transgression of settling a “fallow” world (“the path of redemption”). The Glavers have progressed furthest along the path.
  4. To evade an enemy: Neal Asher’s Atheter species chose to set aside their sapience in order to survive the sophont-eliminating trap of Jain technology, becoming the comical gabbleducks. I created this as another motive, but the Atheter were also compelled by guilt, as in the previous entry.

On the other side, the external causes of a loss of sapience are also varied:

  1. Sapience leads to existential risk: Bruce Sterling’s Shaper/Mechanist story ‘Swarm’ tells of a Betelgeusian species that evaded the “trap of progress” that drives clever species to extinction (or vanishing from the galactic stage, effectively the same thing. (“… intelligence is not a survival trait.”). The swarm only produces short-lived (1000 years!) sapient caste members in response to specific threats – perhaps this is a voluntarily engineered state after all?
  2. Sapience is a phase: In Karl Schroeder’s Permanence races are seen to evolve out of a sapient stage as they master problems. (“A species that succeeds in really mastering something like physics has no more need to be conscious of it.”) Milan M. Ćirković enthusiastically endorsed Schroeder’s book as a “novel” solution to the Fermi Paradox.
  3. Sapience is evolutionarily costly: Peter Watts, despite apparently disagreeing with Schroeder, reached the same endpoint in his masterful Blindsight in which non-sapient species are able to outcompete sophonts (“Compared to nonconscious processing, self-awareness is slow and expensive”).
  4. Sapience can be lost if unused: perhaps the same as 2 above. The subhuman (though sapient) Eloi in H. G. Wells’ The Time Machine lived in a world of ease for 800,000 years, and presumably were no longer selected for traits like intelligence or curiosity. Over the course of a million years the sole surviving human population in Kurt Vonnegut’s Galápagos evolve into a seal-like species: the ability to swim being a more useful survival trait for the island-dwellers than a large brain. Olaf Stapledon’s Last and First Men deals repeatedly with different kinds of mind and the loss of sapience in future super- and sub-human species

[Just as an end note, please try and use “sapient” to refer to self-aware entities and “sentient” to refer to those capable of sensory experience (coming from the Latin sentire, to feel). Thus an animal can be sentient but not sapient in the way that Homo sapiens (“wise or knowing man”) is. I think there is a need for a clear distinction here.]