"Are emotions algorithms for survival?"
The trouble humanity has always had while contemplating her own nature, lies in complexity providing more than one solution to similar problems. Individually, our cognitive strategies diverge for greater collective coverage. Genetic efficiencies, experiential refinement, and deliberate manipulation vary results.
By the insights I have gained by life long introspection, I offer that emotional system provides "smoothing", and "weighting".
The weighting may be considered a form of survival algorithm insofar as it primitively associates with the mind's facility for inductive reasoning (defaulting to attachments at birth, growing more complex through reinforcement throughout the lifetime.
As smoothing, the inherently abstract nature of information is grainy. Consider what may make one piece of information more important than another. Meaning derives from long complex (and branching) chains from root implications to perceived values. The emotional subsystem provides a smoothing between independently compartmentalized neural processes.
"By default" emotions may work one way, with the reinforcement of training they may work a different way, with some special kinds of development they may be either overridden or enhanced to spectacularly un-intuitive results.