Tomorrow, in a Year is the studio version of the music commissioned by the Danish performance group Hotel Pro Forma for its opera based on Charles Darwin's On the Origin of Species. It is a collaboration between The Knife, Mt. Sims and Planningtorock. It was released digitally on 1 February 2010 through The Knife's own label Rabid Records prior to the physical release.

The lyrics contain excerpts of Darwin's writings, particularly On the Origin of Species. These are often without context, though the meaning of some songs is clear, for example 'Seeds' refers to Darwin's experiments to determine why certain plants are found on the coasts of many continents, despite their separation, in which he demonstrated that seeds of some plants remain viable after weeks in cold seawater, and 'Annie's Box' refers to the pivotal moment when Darwin's daughter Annie died of tuberculosis, which damaged his Christian faith, helping him to overcome his fears about the church's reaction to On the Origin of Species.

The music appears to have been composed to reflect the long arc of evolution, with the first songs having a hard, noisy and simple quality, subsequent tracks building in beauty and complexity, and incorporating progressively more lyrics and musical sounds based on animal vocalisations. Choreography was also inspired by animal behaviour including the courtship dances of birds. The opera was completed in 2009 to mark the 150th anniversary of the publication of On the Origin of Species and toured Europe in 2010.

The album was recorded, mixed and produced in Berlin, Stockholm and Copenhagen between 2008 and 2009. Recording for the live percussion took place at Sounds Studio in Iceland, while outdoor sounds were recorded at the Mamori Artlab Workshop on the Amazon River, Brazil. Tomorrow, In a Year features guest appearances by mezzo-soprano Kristina Wahlin, Danish actress Lærke Winther Andersen and Swedish pop artist Jonathan Johansson.