Definition
A survival machine is Richard Dawkins's term (synonymous with vehicle) for an organism considered as a temporary, disposable structure built by replicators (genes) to carry themselves through their life cycle and into the next generation. The body is the survival machine; the genes are what survives.
The vocabulary deliberately reverses the conventional framing. Where biology textbooks treat the organism as the primary unit ("the organism reproduces, survives, behaves"), the survival-machine framing treats the organism as the gene's tool. Bodies die; genes are potentially immortal. Selection acts to refine the survival machine for its purpose of replicator-propagation.
Why it matters
How it works
The replicator's problem is to persist across geological time despite the universe's tendency toward entropy. The solution is to build a vehicle: a transient, protein-based structure that defends the replicator, gathers resources, finds copies of itself in mating partners, and produces new copies.
Selection refines the vehicle. Genes that build better-functioning survival machines leave more descendants; their machine-building blueprints are over-represented in the next generation. Across billions of years, this process has built vehicles of staggering complexity — including the one reading this sentence.