  Even when concepts similar to emergence have been used since antiquity, we
lack an agreed definition. However, emergence has been identified as one of the
main features of complex systems. Most would agree on the statement ``life is
complex''. Thus, understanding emergence and complexity should benefit the
study of living systems.
  It can be said that life emerges from the interactions of complex molecules.
But how useful is this to understand living systems? Artificial life (ALife)
has been developed in recent decades to study life using a synthetic approach:
build it to understand it. ALife systems are not so complex, be them soft
(simulations), hard (robots), or wet (protocells). Then, we can aim at first
understanding emergence in ALife, for then using this knowledge in biology.
  I argue that to understand emergence and life, it becomes useful to use
information as a framework. In a general sense, I define emergence as
information that is not present at one scale but is present at another scale.
This perspective avoids problems of studying emergence from a materialist
framework, and can be also useful in the study of self-organization and
complexity.
