Nevertheless both approaches present some weaknesses. Understanding criticality in biological systems as an indirect consequence of adaptation to external circumstances is not very explanatory and does not provide ways to test alternatives. In general, explanations that simply assume that they are the consequence of the ‘survival of the fittest’ are often unfalsifiable. With regard to the second approach, it is well known that many SOC models are highly idealized and, in many cases, they are not able to capture the basic interactions of living systems, often failing to provide general explanations of the ubiquitous emergence of criticality16. For that reason, although both adaptive self-tuning and SOC models present interesting insights, they are generally applicable in a relatively narrow set of contexts or under highly idealized conditions.