Mixed microbial communities, usually composed of various bacterial and fungal species, are fundamental in a plethora of environments, from soil to human gut and skin. Their evolution is a paradigmatic example of intertwined dynamics, where not just the relations among species plays a role, but also the opportunities -- and possible harms -- that each species presents to the others. These opportunities are in fact \textit{affordances}, which can be seized by heritable variation and selection. In this paper, starting from a systemic viewpoint of mixed microbial communities, we focus on the pivotal role of affordances in evolution and we contrast it to the artificial evolution of programs and robots. We maintain that the two realms are neatly separated, in that natural evolution proceeds by extending the space of its possibilities in a completely open way, while the latter is inherently limited by the algorithmic framework it is defined. This discrepancy characterises also an envisioned setting in which robots evolve in the physical world. We present arguments supporting our claim and we propose an experimental setting for assessing our statements. Rather than just discussing the limitations of the artificial evolution of machines, the aim of this contribution is to emphasize the tremendous potential of the evolution of the biosphere, beautifully represented by the evolution of communities of microbes.
翻译:通常由各种细菌和真菌物种组成的混合微生物群落,在从土壤到人类腹部和皮肤的众多环境中是根本的。它们的进化是一个相互交织的动态的典型例子,其中不仅物种之间的关系发挥作用,而且每个物种向其它物种带来的机会 -- -- 和可能的伤害。这些机会实际上是由遗传变异和选择所能够抓住的\ textit{fordance}。本文从混合微生物群落的系统观点开始,着重关注经济能力在进化中的关键作用,我们把它与程序和机器人的人工进化加以对比。我们坚持认为,这两个领域是完全分开的,因为自然进化通过以完全开放的方式扩展其可能性而产生,而后者本身受到它所定义的算法框架的内在限制。这种差异性也是一种设想的机器人在物理世界中演变的环境。我们提出论据,支持我们的主张,并提出一个用来评估我们的声明的实验性环境。我们不仅讨论机器人为进化的局限性,而且这种进化的目的是通过生物进化来强调进化的巨大进化潜力。