进化就是递归:同一个循环的四个名字

细菌每二十分钟分裂一次,并且在某些谱系中已经这样做了三十亿年。这种稳定性足以让地质学感到谦卑。与此同时,以这种细菌开始的谱系产生了眼睛、神经系统、飞行、语言,以及其自身不完整性的正式证明。这种复杂性足以让任何搜索算法都黯然失色。

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不应该起作用的事情#

细菌每二十分钟分裂一次,并且在某些谱系中已经这样做了三十亿年。这种稳定性足以让地质学感到谦卑。与此同时,以这种细菌开始的谱系产生了眼睛、神经系统、飞行、语言,以及其自身不完整性的正式证明。这种复杂性足以让任何搜索算法都黯然失色。

难题不在于稳定性和复杂性同时存在。令人困惑的是,同一个机制应该同时解释两者。自然选择找到最优——从结构上来说,这是一个爬山的过程。登山者到达顶峰并停下来。然而,自然选择一直在攀爬的有机体并没有停止。记录显示,没有终点,没有单一解决方案的收敛,也没有达到最终适应峰值之类的稳定性。1稳定性和无限的新颖性并不是同一过程的预期输出。其中一个应该打破另一个。

下面还有别的东西在跑。经验的标志是生态位构建,即生物体改变影响其后代的选择性环境的系统方式。2当生物体不仅改变其局部栖息地,还改变其后代和竞争者被选择的条件时,适应度景观就不再是固定的地形。它成为步行者在行走时生成的表面。不是爬山。具有不同形式结构的东西。

什么样的过程产生了这种组合——来自同一个引擎的根本稳定性和无限新颖性?不仅仅是选择。选择在景观上找到峰值,无界部分否认景观是固定的。下面还有别的东西在跑。本文认为,其他事物有一个名称——事实上,其中四个名称是由四个研究传统独立指定的,而这些研究传统并不知道它们在命名同一事物。

生物学家被迫承认的事情#

海狸就是教科书上的例子。在一个群体进入退化的农业溪流 12 年后,每块地块的平均植物物种丰富度增加了约 46%,记录的累计物种数量增加了 148%。3 海狸工程师设计的池塘可储存约 100 吨水每 1.8 公顷积水范围内含有 16 吨沉积物和 16 吨碳。4 海狸不仅仅生活在其环境中。它构成了选择性环境的很大一部分,作用于河狸的后代,作用于昆虫、鱼类和鸟类,它们的谱系也将通过池塘生态系统,而且最重要的是作用于河狸自己的后代,他们将继承的不是原始的溪流,而是殖民地创造的工程湿地。

不是巧合或极端情况。这就是生态位构建在生态时间尺度上所采取的形式。

Laland 及其同事 2015 年《扩展进化综合》论文中的正式定义是:生态位构建是“生物体的新陈代谢、活动和选择改变或稳定环境状态的过程,从而影响对自身和其他物种的选择。”2关键条款是“从而影响对自身起作用的选择”——构建生态位的生物体也是在其中选择的生物体。选择压力不是有机体的外部压力;它部分是由有机体自身先前的活动构成的。正式的进化模型证实,这种相互因果关系会产生标准模型无法预测的后果:生态位构建可以驱动原本有害的等位基因固定,支持原本不会出现的稳定多态性,并消除否则会持续存在的多态性。5

大氧化事件在地质尺度上是相同的过程。根据 ASM 微生物学评论的描述,蓝藻在大约 27 亿年前进化,并通过含氧光合作用改变了地球大气层,在大约 2.4-21 亿年前产生了 GOE,这一转变属于地球历史上最重要的生物引起的地球化学转变之一。6 推动这一事件的生物体未能在它们创造的富含氧气的世界中生存下来。但从那时起,每一种需氧生物都生活在一个选择性环境中,其化学反应是由先前的生物活动产生的。建造者的后代——他们所有人——居住在他们祖先建造的世界中。

格局很一般。从海狸水坝到氧气光合作用,生物体不仅仅栖息在它们的环境中——它们构成了它们自己选择的条件。标准进化框架将此视为对模型的修正。不仅如此。递归并不是图中的一个皱纹。它是过程本身的结构特征。

自我情境化,而不是反馈#

反馈循环有固定的规则。恒温器不会重新设计它正在跟踪的温度目标——设定点是从回路外部设置的。输出(测量的温度)作为输入进行回收,但回收规则(什么构成“过冷”,什么触发熔炉)位于循环外部,不受循环影响。输出修改输入。规则保持不变。

自我情境化系统则有所不同。它的输出不仅修改输入,还修改处理后续输入的规则。约束、边界条件、选择压力——这些都来自操作本身,而不是来自操作未触及的外部配置。捕获这一点的正式类是定点结构:一个根据自身描述进行操作的系统,产生一个结果,然后该结果成为下一个操作的上下文。

在形式逻辑中,这种结构的引擎是哥德尔的对角引理。对于任何足够强的形式系统 F 和任何具有一个自由变量的公式 A(x),存在一个句子 D,使得 F ⊢ D ↔ A(⌜D⌝) — D 可证明等价于应用于 D 自己的哥德尔数的公式 A。7 该句子包含对其自身的描述(编码为数字),并断言有关该描述的某些内容。当 A 是“在 F 中不可证明”时,得到的 D 会说“我在 F 中不可证明”——哥德尔句子,这使得不完备性结果落地。该机制是将公式自身的索引替换为自身。系统根据其自身操作的描述进行操作,其结果约束后续步骤。

在计算中,克莱恩第二递归定理指出:对于任何部分递归函数 Q(x,y),都存在一个索引 p,使得 φₚ ≃ λy.Q(p,y) — 一个程序的行为就像将 Q 以其自己的索引作为第一个参数应用一样。8 更通俗地说:程序可以携带自身的描述并根据这些描述进行操作。 lambda 演算中的 Y 组合器将其实现为固定点:它接受函数 F 并返回值 x,使得 F(x) = x,从而实现非递归规范的递归行为。自上下文化的计算实例:通过找到自己的固定点来生成自己的操作上下文的函数。

这些是关于抽象系统的正式结果——关于可计算的动力系统和形式语言。在该正式模型中,Hernández-Orozco 等人。 2018 定理是结束论证的结果:表现出强大的开放式演化(算法复杂性随时间稳定增长)在形式上等同于可计算动态系统中的不可判定性。1可判定系统面临稳定复杂性的绝对限制成长。一个复杂性无限增长的系统必定是不可判定的。这个结果的范围是所述的形式模型,而不是直接的生物进化。在卡德纳斯论证中,它对生物学的影响取决于下面搭建的一座桥梁。

同一事物有四个名称#

四种研究传统,以不同的词汇、不同的年代、不同的问题进行研究,已经对前一节所尖锐的内容进行了命名。没有人引用其他人占据相同的概念基础。每个人都观察同一种动物并描述其解剖结构的不同部分。

罗森——有效因果关系的终结(关系生物学,1985-1991)

罗伯特·罗森 (Robert Rosen) 在《生命本身》 (1991) 中的中心论点是对生命的正式定义:“当且仅当物质系统接近有效因果关系时,它才是一个有机体。”9 在亚里士多德的术语中,有效原因是指带来变革——催化剂、酶、维持组织的流程。罗森的主张:在一个生命系统中,这些动力因本身是在系统内产生的。催化一个反应的酶是由第一个反应所维持的另一个反应产生的。正式结构是(M,R)系统:M表示代谢子系统,R表示再生M的修复子系统。该系统是自蕴含的——所有有效原因都落在一个预测循环内。没有外部输入分配催化剂。他们从自行车运动本身中脱颖而出。

这就是关系生物学中的自我语境化结构。操作条件——催化剂、酶、有效原因——是由它们所促成的操作产生的。罗森提出了另一项有争议的主张:任何图灵机都无法模拟该结构。这种说法与上面得出的正式结果产生了矛盾——卡德纳斯的论证在下面解决了这种矛盾。

Von Foerster — 特征形式和操作闭包(二阶控制论,1970 年代)

海因茨·冯·福斯特从感知而非生物化学角度解决了这个问题。他在二阶控制论领域工作——从 1974 年开始,他将其描述为“观测系统的控制论”,系统包括自己的观察者——他问道:什么是稳定的物体?他的回答是:“对象是特征行为的标记。”感知中的稳定物体是递归观察过程的定点吸引子。特征函数是值 e,使得 F(e) = e — 迭代应用的递归运算符的不变量。10Louis Kauffman 在 2003 年的一篇论文中以数学方式形式化了这一点,证明了如果 F 是运算“封闭在一个盒子里”,在任何初始配置上迭代 F 在极限情况下都会产生满足 X = F(X) 的形式——操作生成的自引用稳定形式,然后操作保持不变。

与上面开发的正式词汇的结构联系是直接的。 F(e) = e 与哥德尔对角引理和 Kleene Y 组合子是相同的定点结构。冯·福斯特(Von Foerster)在控制论领域将其命名至少早于罗森的“生命本身”出现十年。特征形式传统是四种命名中最早的。

Maturana 和 Varela — 自创生 (1980)

马图拉纳和瓦雷拉从牢房里过来。他们对自创生的正式定义来自“自创生和认知”(1980),将生命系统描述为“组件的生产(转化和破坏)过程网络,其中:(i)通过它们的相互作用和转换不断地再生和实现产生它们的过程(关系)网络;(ii)通过将其实现的拓扑域指定为这样的拓扑域,将其(机器)构成为它们(组件)存在的空间中的具体统一体。网络。"11

边界——膜——本身是由它所包围的代谢网络产生的。网络产生边界,边界定义了“内部”与“外部”,即什么算作网络的一部分。操作条件(边界、拓扑、网络标识)由操作本身构成。系统不占用预先给定的域;它在运行时生成域。这是细胞尺度上的自我语境化结构——四种命名中最具体的一种。

Mossio 和 Moreno — 约束闭合 (2010)

莫西奥和莫雷诺最后到达,也是最敏锐的。他们 2010 年的论文在“生物自主性”(2015 年)中进行了扩展,提供了四个命名中最正式精确的一个。他们写道,一个系统是“组织上封闭的”,“如果它由一组充当约束的结构 C₁…Cₙ 构成,这样,对于每个约束 Cᵢ,其维护所需的(至少部分)边界条件由另一个约束 Cⱼ 的直接操作决定,而另一个约束 Cⱼ 的维护又依赖于 Cᵢ 作为直接约束。”12 每个约束都依赖于并维护网络中的至少一个其他约束。典型的例子是:酶封闭的细胞代谢,其中酶催化产生其他酶的反应。运行条件为约束网络;约束网络由它所管辖的操作来维护。

这比单独的自创生更严格。马图拉纳-瓦雷拉表示,该系统生产其组件; Mossio-Moreno 指定系统产生“其组件运行的约束”——管理操作的规则,而不仅仅是实例化它们的部分。这是四个命名中最接近上面开发的正式词汇的一个。

收敛

四个名字。四个词汇。四个学科。四个十年。关闭有效因果关系。特征形。自创生。约束闭包。每个独立地捕获相同的结构属性:系统产生其运行的条件。没有人引用其他人占据相同的概念领域。这并不是牛顿和莱布尼茨独立发现微积分的平行发现——它更加引人注目。牛顿和莱布尼茨正在竞相解决同样的问题。这四个传统不是。他们各自解决不同的问题,并且不自觉地达到相同的正式结构。

这种趋同证明了结构是真实的——而不是投射到不同现象上的哲学便利。四种严肃的传统,每一种都有正式的机构,都得出了相同的答案。他们都在用四种不同的语言描述同一种动物,而且他们都不知道其他人在房间里。

卡德纳斯桥#

罗森的框架提出了一个强硬的主张:任何图灵机都无法模拟封闭于有效因果关系的生命系统。如果他是对的,那么 Hernández-Orozco OEE 不可判定性结果(这是一个关于“可计算”动力系统的定理)与罗森定义的生物学无关。可计算系统结果描述了一类系统;罗森将生活置于课堂之外。如果不对这种紧张局势采取立场,本文就无法同时援引形式主干和生物学主张。

这种张力存在于文学中。 Cárdenas、Letelier、Gutierrez、Cornish-Bowden 和 Soto-Andrade 在《理论生物学杂志》2010 年的一篇论文中发表了对罗森结论的明确挑战。他们的论文认为,罗森的不可计算性结论并非来自他的 (M,R) 系统形式主义本身,并且“对于罗森用于实现此封闭的逻辑存在混淆和误解。”13 他们的关键主张:有效因果关系的封闭,如 (M,R) 系统结构中形式化的那样,可以用 lambda 演算来表达。 Lambda 演算的可表达性是图灵等价的——Church 在 1936 年建立的结果——因此任何可以写成 lambda 项的 (M,R) 系统都位于 Hernández-Orozco 定理所涵盖的形式模型中。如果这是正确的,那么有效因果关系的生物闭合是可计算性兼容的,并且不可判定性结果适用于形式模型的水平——而不仅仅是通过类比。

本文采取相容论立场。卡德纳斯的言论是同行评审文献中发表的反驳,它以保留文章正式策略的方式解决了紧张局势。

桥梁就位后,可以明确提出三个级别的索赔:

第 1 级 — 正式身份(在可计算系统内)。 Hernández-Orozco 等人。 2018 年的结果是一个正式定理:在可计算动力系统中表现出强大的开放式演化的系统必须是不可判定的。1 Rosen 的 (M,R)-系统,关于 Cárdenas 相容主义阅读,可以用 lambda 演算来表达,并且落在这个结果的范围内。在这个层面上,主张是形式上的同一性——相同的数学结构,而不是类比。

**第二级——结构类比(生物进化)。**实际的生物进化是否严格可图灵计算仍然是一个悬而未决的问题——罗森-卡德纳斯的争论尚未解决。在这个层面上,文章主张结构类比:生态位构建下的生物进化具有在正式系统中产生不可判定性的属性。生物体产生自己选择的条件。生态位构建文献(Laland et al. 2015,Laland et al. 1999)证明这种结构特性在生物学中是真实存在的。

第 3 级 — 家族相似性(更广泛的类别)。 Von Foerster 的本征型、Hofstadter 的奇怪循环、哥德尔对角线和 Kleene Y 组合子共享作为家族相似性的自我语境化属性 - 每个实例都展示它,但没有正式的定理同时涵盖所有它们。这是哲学上的回报,而不是形式上的核心。

三层,叠放。故障模式让他们感到困惑。对 2 级声明要求 1 级严格性是过分的。当利基构建文献正在做严肃的实证提升时,将 2 级主张仅仅视为 3 级家族相似性是错误的谦虚。该学科保持了清晰的分层。

霍夫施塔特选择了错误的例子#

霍夫施塔特奇怪的循环有一种不对称性,两次正式的批评已经浮出水面——这种不对称性一旦被发现,就会走向错误的方向。

霍夫施塔特的奇怪循环范例是哥德尔的自指句:形式算术中的一个陈述,其本身就是“我在这个系统中无法证明”。这个循环跨越了各个层面——从算术的对象语言到关于可证明性的元级声明,然后返回——产生了一种真正的自引用稳定形式。14这就是霍夫施塔特通过类比扩展到意识的内容:大脑的自我模型本身是在大脑的神经基质中实现的,创造了一个水平交叉的回报。奇怪的循环解释了自我的体验。

Andrew Westra 2010 年的批评指出了薄弱环节。霍夫施塔特本人写道,哥德尔“精心炮制”了自我指涉的陈述。15韦斯特拉的论点:形式系统的表征能力——它使用哥德尔编号对有关自身的语句进行编码的能力——是奇怪循环的“必要”条件,但不是一个“充分”条件。充分条件是哥德尔自己有意识的建构行为。正式系统不会自动产生奇怪的循环。哥德尔设计了它。韦斯特拉的担忧如下:如果正式系统不会自动产生奇怪的循环——如果一个非常细心的人必须产生一个——那么霍夫施塔特从“正式系统自动产生奇怪的循环”到“大脑自动产生意识”的推论可能建立在错误的前提上。

Nenu 在 2022 年的批评又增加了一层:霍夫施塔特的框架“留下了太多未填充的重要细节”,并且由于类比的行为对霍夫施塔特没有解决的元数学选择很敏感,因此它在结构上不稳定,从而损害了解释性的回报。15

这些批评损害了霍夫施塔特的具体举措。它们不会损害结构性能本身。

这是反转。如果正式系统中的奇怪循环需要外部有意的构造(哥德尔,精心炮制),那么一个在没有任何外部设计者的情况下表现出相同结构属性的系统正在做一些更纯粹的事情。生物进化不是凭空捏造的。没有人坐下来设计一种自我引用的复制机制。复制是递归调用——它是生物复制的本质,而不是它的“相似之处”。该生物体的后代不仅继承了该生物体的基因,还继承了该生物体帮助构建的生态位,然后生态位选择了这些后代。递归调用自动运行三十亿年,不需要外部构造函数。

霍夫施塔特选择哥德尔是因为哥德尔漂亮、精确,并且在1979年就可以使用。他面前没有经验案例。利基构建正是他想要的情况:三十亿年的自语境化组织,不需要有意的构造函数,从未读过证明的单元每二十分钟进行一次递归调用。

生物学是更纯粹的例子。霍夫施塔特的奇怪循环是同一个家族的一个不那么纯粹的成员——它需要一个天才来人为地构建进化自动完成的事情。这种倒置并不是对霍夫施塔特的解雇。他从形式上确定了结构类。但这一类别中最干净的经验成员并不是他所指的那个。

三种反驳,三种回应#

三种反对路线值得直接参与,而不是脚注。

重新描述反对意见(Scott-Phillips 等人,2014 年)

作为理论进步,对利基构建理论最强烈的反对意见是重新描述反对意见,斯科特-菲利普斯、拉兰、舒克、狄金斯和韦斯特在 2014 年的《进化论》对抗性合作中精确地阐述了这一点。怀疑论者的立场:“怀疑论者没有理由认为,无论 NCT 导致什么预测和见解,相同的预测都不能从标准进化理论中得出。”16 同样:利基构建理论在解释上是多余的。从逻辑上讲,没有必要使用NCT来研究或预测进化生物学中的任何东西;传统框架总是足够的。 NCT 增加了词汇量和组织重点,但没有新颖的预测内容。

这篇文章并没有对这一反对意见的核心提出异议。递归框架主要是概念统一的贡献。它在单一结构表征下收集了四个先前的命名,并以生物进化为例——这是一种哲学举措,而重新描述的反对意见是正确的,即哲学举措并不是自动预测的举措。

然而,该框架确实产生了标准二元论框架无法做出或只能通过重新框架才能实现的两项承诺。第一:主要的进化转变是递归函数中类型签名的变化——选择作用的单位的质上不连续的重组,而不仅仅是逐渐积累。 Maynard Smith 和 Szathmáry 通过生物信息存储和传输方式的变化以及新水平选择单位的形成来识别转变。17 West 和同事确认了两步模式:合作群体形成,然后通过分工和相互依赖转变为一个综合实体。17 Bourrat 和同事 (2022) 将破坏权衡事件视为这些转变的标志 — 不是原因,而是转变的标志不连续性。17 递归框架使这种不连续性作为类型签名更改变得清晰可见:健身跟踪单元的变化不是通过逐渐积累,而是通过递归调用的定性重组。

其次:Banzhaf 及其同事将开放式演化系统中的新颖性分为三种类型:变异(模型内的新颖性)、创新(改变模型的新颖性)和涌现(改变元模型的新颖性)。17分类意味着系统在参数空间中的位置决定了哪种类型的新颖性占主导地位。稳定的机制会产生变化型的新颖性;复杂性机制会产生创新或涌现型新颖性。这是本文从 Banzhaf 框架中得出的推论,而不是 Banzhaf 声明的结论,但这是递归框架在标准框架不可见的情况下使可见的逻辑含义。

诚实的立场:该框架主要是概念统一的,并且在这些方面是站得住脚的。上述两个承诺是真实的,也是二元论框架所不做出的承诺。

威廉姆斯不对称性(Fromhage 和休斯顿 2022)

对有机体-环境不对称性的当代技术辩护贯穿于 Fromhage 和 Houston 在《进化论》 2022 年发表的论文中,该论文形式化了 Lewontin-Williams (a)对称性。他们声称:“适应总是不对称的;生物体适应环境,而不是相反。”即使承认双向因果影响(承认生物体改变环境),选择驱动的适应性变化的方向性也是不对称的。18标准进化模型对此进行编码:dO/dt = f(O,E)(生物体因响应而变化到环境),而 dE/dt = g(E)(环境变化独立于生物体的定向适应)。即使因果影响双向流动,这些方程也不是对称的。

文章的回应遵循大冢的因果图框架:标准微分方程中的不对称性是一种建模假设,而不是经验发现。18当性状归因于类型(基因型)时,基因环境独立性是内置于数学结构中的,而不是在自然界中发现的。标准进化论中的有机体-环境二元论反映了模型的范围条件,而不是生物学的形而上学结构。那么,生态位构建批评——生物体改变作用于其后代的选择压力——并不是对标准模型的反驳,而是模型范围条件约束的证据。递归框架并没有以它自己的方式对抗威廉姆斯的不对称性;它正在确定不对称主张成立的范围条件,并询问在这些条件之外还剩下什么。

经验谨慎的怀疑论(Charlesworth、Barton & Charlesworth 2017)

Charlesworth、Barton 和 Charlesworth 在《皇家学会学报 B》中发表的 2017 年《达尔文评论》代表了经验主义谨慎的主流进化生物学立场。他们的判断是:“不需要彻底修改我们对适应性进化机制的理解。”19 仔细的遗传学研究一再表明,跨生物体的明显令人费解的结果与新达尔文主义是一致的。范式转变的生态位构建驱动进化的经验证据——​​生态位构建经常产生标准框架无法解释的主要进化模式的证据——比 EES 倡导者声称的要弱。

本文不是 EES 宣传文章,这里的致谢是真诚的。递归框架的贡献是结构性的——关于生物进化属于哪一类——而不是关于任何给定群体中生态位构建效应的大小。 Laland 和 Charlesworth 之间关于 NC 是否在经验上驱动主要进化模式的争论与生物体产生自身选择条件的结构点正交。即使 NC 在大多数谱系中被证明是一种适度的进化力量,这种结构性的主张也可能是正确的。

该文章承认重新描述反对的力量,遵循不对称性辩论的模型选择框架,并给予实证谨慎。幸存下来的是一个结构性主张——生物进化属于一个指定的类别——这三个反对意见都没有针对这个类别。

相框买什么#

三件事。

首先是错误二分法的瓦解。 Lewontin 在《三重螺旋》中写道,“就像没有环境就没有有机体一样,没有有机体也不可能有环境。”20 这不是神秘主义。这是递归调用内部的实际结果。主体——有机体——和客体——环境——是同一操作中的位置角色,而不是单独的本体论类别。从循环外部来看,有一个过程:生物体改变环境,改变选择压力,改变生物体。从循环内部(进化生物学实际发挥作用的地方)来看,生物体和环境之间的区别仍然有助于建模的便利。崩溃是操作性的,而不是本体论的。二元论并没有被破坏;它已搬迁。

这种重新定位对于阅读进化记录具有实际意义。范瓦伦的红皇后定律 (1973) 指出,任何生物群体的有效环境都会以随机恒定速率恶化 - 因为竞争物种的进化进步会系统地改变彼此的选择格局。21 共同进化动态是非终止:没有达到稳定的最终状态,因为任何谱系的每次适应都会改变所有其他谱系的选择压力。亚麻锈系统在经验尺度上说明了这一点。 Antonovics、Thrall、Burdon 和 Laine 对来自 6 个自然种群的 120 个宿主品系和 60 个病原体品系进行了交叉接种研究,没有发现任何证据表明部分抵抗会减慢共同进化动力学;军备竞赛仍在继续,而不是趋同。22不终止反映了 OEE 不停止的结果:共同进化系统,以交互和递归的方式构建自己的选择环境,无法停止。

第二次和第三次购买是框架的两个预测,表述为预测而不是证明:

其次,随着递归函数中类型签名的变化,主要的进化转变是清晰可见的。健康追踪单元不连续地重组——从基因到基因组,从细胞到多细胞生物,从个体到社会群体。每一次转变都标志着自然选择可以作用的实体类型发生了质的变化。这不是逐渐积累,而是逐渐积累。这是函数签名的改变。

第三,稳定性与复杂性是参数机制效应。稳定体制中的系统会在其现有组织内产生新颖性——主题的变化。复杂性体系中的系统会产生新颖性,从而重组组织本身——这是一个不同的主题。系统在参数空间中的位置决定了它产生哪种新颖性。两者都是自我情境化过程的形式;它们的不同之处在于更新递归结构的哪一层。

主体和客体不是世界赋予我们的范畴。它们是循环分配的位置。跳出循环,就有一个进程。走进去,区别又回来了,再次有用。二元论并没有被破坏。它已搬迁。

参考文献#

Hernández-Orozco, S.、Hernández-Quiroz, F. 和 Zenil, H. (2018)。 开放式进化和出现的不可判定性和不可约性条件。 人工生命,24(1), 56–70。 DOI:10.1162/artl_a_00254。 ↩︎ ↩︎ ↩︎

Laland, K.N., Uller, T., Feldman, M.W., Sterelny, K., Müller, G.B., Moczek, A., Jablonka, E., & Odling-Smee, J. (2015). The extended evolutionary synthesis: its structure, assumptions and predictions. Proceedings of the Royal Society B: Biological Sciences, 282(1813), 20151019. DOI: 10.1098/rspb.2015.1019. ↩︎ ↩︎

Law, A., Gaywood, M.J., Jones, K.C., Ramsay, P., & Willby, N.J. (2017). Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands. Science of the Total Environment, 605–606, 1021–1030. ↩︎

Brazier, R.E., Puttock, A., Graham, H.A., Auster, R.E., Davies, K.H., & Brown, C.M.L. (2020). Beaver: Nature's ecosystem engineers. WIREs Water, 8(1), e1494. DOI: 10.1002/wat2.1494. ↩︎

Laland, K.N., Odling-Smee, F.J., & Feldman, M.W. (1999). Evolutionary consequences of niche construction and their implications for ecology. Proceedings of the National Academy of Sciences, 96(18), 10242–10247. DOI: 10.1073/pnas.96.18.10242. ↩︎

ASM 微生物学。 (2022)。伟大的氧化事件:蓝藻如何改变生活。 ASM.org。 https://asm.org/articles/2022/february/the-great-oxidation-event-how-cyanobacteria-change ↩︎

Raatikainen, P. (2025). Gödel's Incompleteness Theorems — Supplement: The Diagonalization Lemma. Stanford Encyclopedia of Philosophy. https://plato.stanford.edu/entries/goedel-incompleteness/sup2.html ↩︎

Kleene, S.C. (1952). Introduction to Metamathematics. North-Holland Publishing. (Theorems first proved 1938.) See also: Kleene's recursion theorem. Wikipedia. https://en.wikipedia.org/wiki/Kleene%27s_recursion_theorem ↩︎

Rosen, R. (1991). Life Itself: A Comprehensive Inquiry into the Nature, Origin, and Fabrication of Life. Columbia University Press. ↩︎

Kauffman, L.H. (2003). Eigenforms — Objects as Tokens for Eigenbehaviors. Cybernetics and Human Knowing, 10(3–4), 73–90. http://homepages.math.uic.edu/~kauffman/Eigen.pdf. See also: von Foerster, H. (1976). Objects: Tokens for (Eigen-)Behaviors. ASC Cybernetics Forum, 8(3–4), 91–96. Reprinted in von Foerster, H. (2003). Understanding Understanding: Essays on Cybernetics and Cognition, Springer, pp. 261–271. ↩︎

Maturana, H.R. & Varela, F.J. (1980). Autopoiesis and Cognition: The Realization of the Living. D. Reidel Publishing Company, Dordrecht. [library-only; formal definition confirmed via multiple secondary sources including Springer catalog and independent academic reviews] ↩︎

Mossio, M. & Moreno, A. (2010). Organisational closure in biological organisms. History and Philosophy of the Life Sciences, 32(2–3), 269–288. PMID: 21162371. The quoted definition appears in §3 of the paper; see also Moreno, A. & Mossio, M. (2015). Biological Autonomy: A Philosophical and Theoretical Enquiry. Springer. ↩︎

Cárdenas, M.L.、Letelier, J.C.、Gutierrez, C.、Cornish-Bowden, A. 和 Soto-Andrade, J. (2010)。关闭高效因果关系、可计算性和人工生命。 理论生物学杂志,263(1), 79–92。 DOI:10.1016/j.jtbi.2009.11.010。 PubMed:19962389。 ↩︎

Hofstadter, D.R. (1979). Gödel, Escher, Bach: An Eternal Golden Braid. Basic Books. Hofstadter, D.R. (2007). I Am a Strange Loop. Basic Books. ↩︎

Westra, A. (2010). Gödel, Hofstadter, & the Self: A Critical Review of Douglas Hofstadter's I Am a Strange Loop. Numéro Cinq, July 1, 2010. https://numerocinqmagazine.com/2010/07/01/godel-hofstadter-the-self-an-essay-by-adam-westra/. Nenu, T. (2022). Douglas Hofstadter's Gödelian Philosophy of Mind. Journal of Artificial Intelligence and Consciousness, 9(2), 241–266. DOI: 10.1142/S2705078522500011. ↩︎ ↩︎

Scott-Phillips, T.C., Laland, K.N., Shuker, D.M., Dickins, T.E., & West, S.A. (2014). The niche construction perspective: a critical appraisal. Evolution, 68(5), 1231–1243. PMC: 4261998. ↩︎

梅纳德·史密斯 (Maynard Smith),J. 和萨斯玛丽 (Szathmáry),E. (1995)。 进化的主要转变。牛津大学出版社 / W.H.弗里曼。 West, S.A.、Fisher, R.M.、Gardner, A. 和 Kiers, E.T. (2015)。个性的重大进化转变。 美国国家科学院院刊,112(33),10112–10119。 PMC:4547252。Bourrat, P.、Doulcier, G.、Rose, C.J.、Rainey, P.B. 和 Hammerschmidt, K. (2022)。权衡打破作为个体进化转变的模型和适应度解耦隐喻的局限性。 电子生活,11,e73715。 DOI:10.7554/eLife.73715。 Banzhaf,W.,等人。 (2016)。定义和模拟开放式新颖性:要求、指南和挑战。 生物科学理论,135(3), 131–161。 PubMed:27194550。 ↩︎ ↩︎ ↩︎ ↩︎

Fromhage, L. & Houston, A.I. (2022). Biological adaptation in light of the Lewontin-Williams (a)symmetry. Evolution, 76(7), 1619–1624. PMC: 9544502. DOI: 10.1111/evo.14502. Otsuka, J. (2019). The Role of Mathematics in Evolutionary Theory. Cambridge University Press. ↩︎ ↩︎

Charlesworth, D., Barton, N.H., & Charlesworth, B. (2017). The sources of adaptive variation. Proceedings of the Royal Society B, 284, 20162864. PubMed: 28566483. DOI: 10.1098/rspb.2016.2864. ↩︎

Lewontin, R.C. (2000). The Triple Helix: Gene, Organism, and Environment. Harvard University Press. [library-only; near-quote confirmed via PMC1083785 review article and multiple independent secondary sources] ↩︎

范瓦伦,L.(1973)。新的进化法则。 进化论,1(1),1-30。 ↩︎

Antonovics, J., Thrall, P.H., Burdon, J.J., & Laine, A.L. (2011). Partial resistance in the Linum–Melampsora host-pathogen system: does partial resistance make the Red Queen run slower? Evolution, 65(2), 512–522. PMID: 21029078. ↩︎

延伸阅读#

  • 罗森,R. (1991)。 生命本身:对生命本质、起源和制造的全面探究。哥伦比亚大学出版社。 — 关闭有效因果关系和(M,R)系统的主要来源;文章涉及的完整正式论点。大多数读者都没有遇到过罗森;这是建议的第一次后续行动。
  • Maturana, H.R. 和 Varela, F.J. (1980)。 自创生与认知:生命的实现。 D.雷德尔。— 基础的自创生文本。本文引用的正式定义源自此来源;这本书将论证扩展到细胞生物学之外的自生产系统的一般理论。
  • 莫雷诺,A. 和莫西奥,M. (2015)。 生物自主性:哲学和理论探究。施普林格。 ——约束闭合的书本长度的发展;先前四个命名中最正式和最新的一个。十年来的专业文献已经吸收了它;跨学科的观众却没有。
  • Cárdenas, M.L.、Letelier, J.C.、Gutierrez, C.、Cornish-Bowden, A. 和 Soto-Andrade, J. (2010)。关闭高效因果关系、可计算性和人工生命。 理论生物学杂志,263(1), 79–92。 ——桥梁论文。罗森可计算性辩论中已发表的相容论立场;可在 hal.science/hal-00564468v1 上进行开放获取。 1 级正式策略的必读内容。
  • 霍夫施塔特,D.R. (1979)。 哥德尔、埃舍尔、巴赫:永恒的金辫子。基础书籍。 — GEB形阅读器的起点;这篇文章超出了本文的内容,但对于普通读者来说,它仍然是对奇怪循环的最丰富的探索。 -道金斯,R.(1982)。 扩展表型:基因的长距离。牛津大学出版社。威廉姆斯,G.C. (1966)。 适应和自然选择。普林斯顿大学出版社。 — 以基因为中心的观点和有机体-环境不对称性的历史规范陈述。这篇文章直接涉及当代技术防御(Fromhage & Houston 2022),但这些文本是目标受众可能读过的文化试金石版本。

Evolution Is Recursion — Four Names for the Same Loop

Cover

The thing that should not work#

A bacterium divides every twenty minutes and has been doing so, in some lineage, for three and a half billion years. That is stability at a scale that humbles geology. At the same time, the line that began with that bacterium produced eyes, nervous systems, flight, language, and a formal proof of its own incompleteness. That is complexity at a scale that humbles any search algorithm.

The puzzle is not that stability and complexity each exist. The puzzle is that the same mechanism is supposed to explain both simultaneously. Natural selection finds optima — it is, structurally, a hill-climbing procedure. Hill-climbers reach peaks and stop. Yet the organisms that natural selection has been climbing on have not stopped. The record shows no terminus, no convergence on a single solution, no stabilization at anything like a final fitness peak.1 Stability and unbounded novelty are not the expected outputs of the same process. One of them should break the other.

Something else is running underneath. The empirical sign is niche construction — the systematic way organisms modify the selective environments that act on their own descendants.2 When an organism alters not just its local habitat but the conditions under which its offspring and competitors are selected, the fitness landscape is no longer a fixed terrain. It becomes a surface the walkers are generating as they walk it. Not hill-climbing. Something with a different formal structure.

What kind of process generates that combination — radical stability and unbounded novelty from the same engine? Not selection alone. Selection finds peaks on landscapes, and the unbounded part denies the landscape is fixed. Something else is running underneath. This article argues that the something else has a name — four of them, in fact, assigned independently by four research traditions that did not know they were naming the same thing.

What biologists were forced to admit#

Beavers are the textbook case. Twelve years after a colony moves into a degraded agricultural stream, mean plant species richness rises by roughly 46% per plot, and the cumulative number of species recorded increases by 148%.3 The pond the beavers engineer stores approximately 100 tonnes of sediment and 16 tonnes of carbon per 1.8 hectares of ponded extent.4 The beaver does not merely live in its environment. It constitutes a substantial fraction of the selective environment acting on subsequent generations of beavers, on the insects and fish and birds whose lineages will also pass through the pond ecosystem, and — crucially — on the beavers' own descendants, who will inherit not the original stream but the engineered wetland the colony created.

Not coincidence or edge case. This is the form that niche construction takes at the ecological time scale.

The formal definition, from Laland and colleagues' 2015 Extended Evolutionary Synthesis paper, runs: niche construction is "the process whereby the metabolism, activities and choices of organisms modify or stabilize environmental states, and thereby affect selection acting on themselves and other species."2 The critical clause is "thereby affect selection acting on themselves" — the organisms that construct the niche are also the organisms selected within it. The selection pressure is not external to the organism; it is partly constituted by the organism's own prior activity. Formal evolutionary models confirm that this reciprocal causation has consequences the standard model does not predict: niche construction can drive otherwise deleterious alleles to fixation, support stable polymorphisms where none would be expected, and eliminate polymorphisms that would otherwise persist.5

The Great Oxidation Event is the same process at geological scale. According to the ASM Microbiology review's characterization, cyanobacteria evolved approximately 2.7 billion years ago and proceeded to transform Earth's atmosphere through oxygenic photosynthesis, producing the GOE around 2.4–2.1 billion years ago — a shift that ranks among the most consequential biologically-induced geochemical transformations in Earth's history.6 The organisms that drove the event did not survive into the oxygen-rich world they made. But every aerobic organism since then has lived inside a selective environment whose chemistry was produced by prior biological activity. The constructors' descendants — all of them — inhabit a world their ancestors built.

The pattern is general. From beaver dams to oxygenic photosynthesis, organisms do not merely inhabit their environments — they constitute the conditions of their own selection. The standard evolutionary frame treats this as a correction to the model. It is more than that. The recursion is not a wrinkle in the picture. It is a structural feature of the process itself.

Self-contextualizing, not feedback#

Feedback loops have fixed rules. A thermostat does not redesign the temperature target it is tracking — the setpoint is set from outside the loop. The output (measured temperature) recycles as input, but the rules of recycling — what constitutes "too cold," what triggers the furnace — are external to the loop and unaffected by it. Outputs modify inputs. Rules stay fixed.

A self-contextualizing system is something different. Its outputs modify not just the inputs but the rules under which subsequent inputs are processed. The constraints, the boundary conditions, the selection pressures — these emerge from the operation itself, not from an external configuration that the operation leaves untouched. The formal class that captures this is the fixed-point structure: a system that operates on a description of itself, producing a result that then becomes the context for the next operation.

In formal logic, the engine of this structure is Gödel's diagonal lemma. For any sufficiently strong formal system F and any formula A(x) with one free variable, there exists a sentence D such that F ⊢ D ↔ A(⌜D⌝) — D is provably equivalent to the formula A applied to D's own Gödel number.7 The sentence contains a description of itself (encoded as a number), and asserts something about that description. When A is "is not provable in F," the resulting D says "I am not provable in F" — the Gödel sentence, which makes the incompleteness result land. The mechanism is substitution of a formula's own index into itself. The system operates on a description of its own operation, and the result constrains subsequent steps.

In computation, Kleene's second recursion theorem states: for any partial recursive function Q(x,y), there exists an index p such that φₚ ≃ λy.Q(p,y) — a program that behaves as if applying Q with its own index as the first argument.8 More informally: programs can carry descriptions of themselves and act on those descriptions. The Y combinator in lambda calculus implements this as a fixed point: it takes a functional F and returns a value x such that F(x) = x, enabling recursive behavior from a non-recursive specification. The computational instance of self-contextualizing: a function that generates its own operating context by finding its own fixed point.

These are formal results about abstract systems — about computable dynamical systems and formal languages. Within that formal model, the Hernández-Orozco et al. 2018 theorem is the result that closes the argument: exhibiting strong open-ended evolution — stable growth of algorithmic complexity over time — is formally equivalent to undecidability in computable dynamical systems.1 Decidable systems face absolute limits on stable complexity growth. A system whose complexity grows without bound must be undecidable. The scope of this result is the stated formal model, not biological evolution directly. How it bears on biology depends on a bridge built below, in the Cárdenas argument.

Four names for the same thing#

Four research traditions, working in different vocabularies, in different decades, on different problems, have already named what the previous section sharpened. None cited the others as occupying the same conceptual ground. Each looked at the same animal and described a different part of its anatomy.

Rosen — closure to efficient causation (relational biology, 1985–1991)

Robert Rosen's central thesis in Life Itself (1991) is a formal definition of the living: "a material system is an organism if and only if it is closed to efficient causation."9 In Aristotelian terms, efficient causes are the agents that bring about change — the catalysts, the enzymes, the processes that maintain organization. Rosen's claim: in a living system, those efficient causes are themselves produced within the system. The enzyme that catalyzes a reaction is produced by another reaction that the first reaction maintains. The formal structure is the (M,R)-system: M designates metabolic subsystems, R designates repair subsystems that regenerate M. The system is self-entailing — all efficient causes fall within an impredicative cycle. No external input assigns the catalysts. They emerge from the cycling itself.

This is the self-contextualizing structure in relational biology. The operating conditions — the catalysts, the enzymes, the efficient causes — are produced by the operation they enable. Rosen made one additional contested claim: this structure cannot be simulated by any Turing machine. That claim sets up a tension with the formal results developed above — a tension the Cárdenas argument resolves below.

Von Foerster — eigenforms and operational closure (second-order cybernetics, 1970s)

Heinz von Foerster approached the problem from perception, not biochemistry. Working in second-order cybernetics — what he described, from 1974, as the "cybernetics of observing systems," systems that include their own observers — he asked: what is a stable object? His answer: "objects are tokens for eigenbehaviors." Stable objects in perception are the fixed-point attractors of recursive processes of observation. An eigenform is the value e such that F(e) = e — the invariant of a recursive operator applied iteratively.10 Louis Kauffman formalized this mathematically in a 2003 paper, demonstrating that if F is the operation "enclose in a box," iterating F on any initial configuration produces, in the limit, a form that satisfies X = F(X) — a self-referential stable form that the operation produces and that the operation then leaves unchanged.

The structural connection to the formal vocabulary developed above is direct. F(e) = e is the same fixed-point structure as the Gödel diagonal lemma and the Kleene Y combinator. Von Foerster named it in the cybernetics domain at least a decade before Rosen's Life Itself appeared. The eigenform tradition is the earliest of the four namings.

Maturana and Varela — autopoiesis (1980)

Maturana and Varela came at it from the cell. Their formal definition of autopoiesis, from Autopoiesis and Cognition (1980), describes a living system as "a network of processes of production (transformation and destruction) of components which: (i) through their interactions and transformations continuously regenerate and realize the network of processes (relations) that produced them; and (ii) constitute it (the machine) as a concrete unity in the space in which they (the components) exist by specifying the topological domain of its realization as such a network."11

The boundary — the membrane — is itself produced by the metabolic network it encloses. The network produces the boundary, and the boundary is what defines "inside" vs. "outside," i.e., what counts as part of the network. The operating conditions (the boundary, the topology, the network identity) are constituted by the operation itself. The system does not occupy a pre-given domain; it produces the domain as it operates. This is the self-contextualizing structure at the cellular scale — the most concrete of the four namings.

Mossio and Moreno — constraint closure (2010)

Mossio and Moreno arrived last — and sharpest. Their 2010 paper, extended in Biological Autonomy (2015), offers the most formally precise of the four namings. A system, they write, is organisationally closed "if it [is] constituted by a set of structures C₁…Cₙ acting as constraints such that, for each constraint Cᵢ, (at least some of) the boundary conditions required for its maintenance are determined by the immediate action of another constraint Cⱼ, whose maintenance depends in turn on Cᵢ as an immediate constraint."12 Each constraint depends on, and maintains, at least one other constraint in the network. The canonical instance: enzymatically-closed cellular metabolism, where enzymes catalyze the reactions that produce other enzymes. The operating conditions are the constraint network; the constraint network is maintained by the operation it governs.

This is stricter than autopoiesis alone. Maturana-Varela say the system produces its components; Mossio-Moreno specify that the system produces the constraints under which its components operate — the rules governing the operation, not just the parts that instantiate them. This is the closest of the four namings to the formal vocabulary developed above.

The convergence

Four names. Four vocabularies. Four disciplines. Four decades. Closure to efficient causation. Eigenforms. Autopoiesis. Constraint closure. Each independently captures the same structural property: the system produces the conditions under which it operates. None cited the others as occupying the same conceptual territory. This is not parallel discovery in the way that Newton and Leibniz independently discovered calculus — it is more striking. Newton and Leibniz were racing to solve the same problem. These four traditions were not. They were each solving different problems and arriving, unbidden, at the same formal structure.

That convergence is the evidence that the structure is real — not a philosophical convenience projected onto disparate phenomena. Four serious traditions, each with formal apparatus, landed on the same answer. They were all describing the same animal, in four different languages, and none of them knew the others were in the room.

The Cárdenas bridge#

Rosen's framework comes with a hard claim: living systems closed to efficient causation cannot be simulated by any Turing machine. If he is right, then the Hernández-Orozco OEE undecidability result — which is a theorem about computable dynamical systems — is irrelevant to biology as Rosen defined it. The computable-systems result describes a class of systems; Rosen puts life outside that class. The article cannot invoke both the formal backbone and the biological claim without taking a position on this tension.

The tension is live in the literature. Cárdenas, Letelier, Gutierrez, Cornish-Bowden, and Soto-Andrade published the explicit challenge to Rosen's conclusion in a 2010 paper in the Journal of Theoretical Biology. Their paper argues that Rosen's non-computability conclusion does not follow from his (M,R)-system formalism itself, and that "there has been confusion and misunderstanding about the logic Rosen used to achieve this closure."13 Their key claim: closure to efficient causation, as formalized in the (M,R)-system structure, is expressible in lambda-calculus. Lambda-calculus expressibility is Turing-equivalence — a result Church established in 1936 — so any (M,R)-system that can be written as a lambda-term sits inside the formal model the Hernández-Orozco theorem covers. If that is correct, biological closure to efficient causation is computability-compatible, and the undecidability result applies at the level of the formal model — not merely by analogy.

This article takes the compatibilist position. The Cárdenas line is the published rebuttal in the peer-reviewed literature, and it resolves the tension in a way that preserves the article's formal strategy.

With the bridge in place, three levels of claim can be stated explicitly:

Level 1 — Formal identity (within computable systems). The Hernández-Orozco et al. 2018 result is a formal theorem: systems exhibiting strong open-ended evolution in computable dynamical systems must be undecidable.1 Rosen's (M,R)-systems, on the Cárdenas compatibilist reading, are expressible in lambda-calculus and fall within the scope of this result. At this level, the claim is formal identity — the same mathematical structure, not analogy.

Level 2 — Structural analogy (biological evolution). Whether actual biological evolution is strictly Turing-computable remains an open question — the Rosen-Cárdenas debate is not settled. At this level, the article claims structural analogy: biological evolution under niche construction shares the property that generates undecidability in formal systems. Organisms produce the conditions of their own selection. The niche construction literature (Laland et al. 2015, Laland et al. 1999) is the evidence that this structural property is empirically real in biology.

Level 3 — Family resemblance (the broader class). Von Foerster's eigenforms, Hofstadter's strange loops, the Gödel diagonal, and the Kleene Y combinator share the self-contextualizing property as a family resemblance — each instance exhibits it, but no formal theorem spans all of them simultaneously. This is the philosophical payoff, not the formal core.

Three levels, stacked. The failure mode is confusing them. Claiming Level 1 rigor for Level 2 claims is overreach. Treating Level 2 claims as merely Level 3 family resemblance is false modesty when the niche construction literature is doing serious empirical lifting. The discipline is holding the stratification clear.

Hofstadter chose the wrong example#

Hofstadter's strange loop has an asymmetry that two formal critiques have surfaced — and the asymmetry, once seen, runs the wrong way.

Hofstadter's paradigm instance of a strange loop is Gödel's self-referential sentence: a statement in formal arithmetic that says, of itself, "I am not provable in this system." The loop crosses levels — from the object-language of arithmetic down to the meta-level claim about provability, and back — producing a genuine self-referential stable form.14 This is what Hofstadter extends, by analogy, to consciousness: the brain's self-model is itself implemented in the brain's neural substrate, creating a level-crossing return. Strange loops explain the experience of selfhood.

Andrew Westra's 2010 critique identifies the weak joint. Hofstadter himself writes that Gödel "carefully concocted" the self-referential statement.15 Westra's argument: the representational power of the formal system — its ability to encode statements about itself using Gödel numbering — is a necessary condition for the strange loop but not a sufficient one. The sufficient condition was Gödel's own intentional act of construction. The formal system did not automatically produce the strange loop. Gödel designed it. Westra's worry follows: if formal systems don't produce strange loops automatically — if a very careful person had to produce one — then Hofstadter's inference from "formal systems automatically produce strange loops" to "brains automatically produce consciousness" may rest on a false premise.

Nenu's 2022 critique adds a further layer: Hofstadter's framework "leaves too many weighty details left unfilled" and, because the analogy's behavior is sensitive to meta-mathematical choices Hofstadter does not address, it is structurally unstable in ways that impair the explanatory payoff.15

These critiques impair Hofstadter's specific move. They do not impair the structural property itself.

Here is the inversion. If strange loops in formal systems require external intentional construction — a Gödel, carefully concocting — then a system that exhibits the same structural property without any external designer is doing something purer. Biological evolution is not concocted. No one sat down and designed the replication mechanism to be self-referential. Replication is the recursive call — it is what biological reproduction is, not what it resembles. The organism's descendants inherit not just the organism's genes but the niche the organism helped construct, which then selects those descendants. The recursive call runs automatically, for three and a half billion years, with no external constructor required.

Hofstadter chose Gödel because Gödel was beautiful and precise and available in 1979. He did not have the empirical case in front of him. Niche construction is the case he would have wanted: three and a half billion years of self-contextualizing organization, no intentional constructor required, the recursive call made every twenty minutes by cells that have never read a proof.

Biology is the purer instance. Hofstadter's strange loop is a less pure member of the same family — one that needed a genius to construct artificially what evolution does automatically. The inversion is not a dismissal of Hofstadter. He identified the structural class from the formal side. But the cleanest empirical member of that class was not the one he pointed to.

Three counterarguments, three responses#

Three lines of opposition deserve direct engagement, not footnotes.

The redescription objection (Scott-Phillips et al. 2014)

The strongest objection to niche construction theory as a theoretical advance is the redescription objection, stated with precision by Scott-Phillips, Laland, Shuker, Dickins, and West in their 2014 adversarial collaboration in Evolution. The skeptics' position: "the skeptics see no reason to think that whatever predictions and insights NCT leads to, the same predictions could not be derived from standard evolutionary theory."16 Equivalently: niche construction theory is explanatorily redundant. It is not logically necessary to use NCT to study or predict anything in evolutionary biology; the conventional framework was always sufficient. NCT adds vocabulary and organizational emphasis, but no novel predictive content.

The article does not dispute the core of this objection. The recursion frame is primarily a conceptual-unificatory contribution. It gathers four prior namings under a single structural characterization and shows biological evolution as an instance — that is a philosophical move, and the redescription objection is right that philosophical moves are not automatically predictive moves.

The frame does, however, generate two commitments that the standard dualist frame either does not make or reaches only by reframing. First: major evolutionary transitions are type-signature changes in the recursive function — qualitatively discontinuous reorganizations of the unit on which selection acts, not merely gradual accumulation. Maynard Smith and Szathmáry identify transitions by a change in the way biological information is stored and transmitted and the formation of new levels of units of selection.17 West and colleagues confirm the two-step pattern: cooperative group formation followed by transformation into an integrated entity through division of labor and mutual dependence.17 Bourrat and colleagues (2022) identify tradeoff-breaking events as a marker of these transitions — not the cause, but the signature of the discontinuity.17 The recursion frame makes this discontinuity legible as a type-signature change: the fitness-tracking unit shifts not by gradual accumulation but by a qualitative reorganization of the recursive call.

Second: Banzhaf and colleagues classify novelty in open-ended evolving systems into three types — variation (novelty within a model), innovation (novelty that changes the model), and emergence (novelty that changes the meta-model).17 This taxonomy implies that the position of a system in parameter space determines which type of novelty dominates. A stability regime generates variation-type novelty; a complexity regime generates innovation or emergence-type novelty. This is the article's inference from the Banzhaf framework, not Banzhaf's stated conclusion — but it is a logical implication the recursion frame makes visible where the standard frame does not.

The honest position: the frame is mostly conceptual-unificatory, and defensible on those terms. The two commitments above are genuine, and they are commitments the dualist frame does not make.

The Williams asymmetry (Fromhage & Houston 2022)

The contemporary technical defense of the organism-environment asymmetry runs through Fromhage and Houston's 2022 paper in Evolution, which formalizes the Lewontin-Williams (a)symmetry. Their claim: "adaptation is always asymmetrical; organisms adapt to their environment, never vice versa." Even granting bidirectional causal influence — granting that organisms modify environments — the directionality of selection-driven adaptive change is asymmetric.18 The standard evolutionary model encodes this: dO/dt = f(O,E) (organisms change in response to environments), while dE/dt = g(E) (environments change independently of organisms' directed adaptation). The equations are not symmetric, even when causal influence flows both ways.

The article's response follows Otsuka's causal-graph framework: the asymmetry in the standard differential equations is a modeling assumption, not an empirical finding.18 When traits are ascribed to types (genotypes), the gene-environment independence is built into the mathematical structure, not discovered in nature. The organism-environment dualism in standard evolutionary theory reflects the model's scope conditions, not the metaphysical structure of biology. The niche construction critique — that organisms modify the selection pressures acting on their own descendants — is then not a refutation of the standard model but evidence of where the model's scope conditions bind. The recursion frame is not fighting Williams' asymmetry on its own terms; it is identifying the scope conditions within which the asymmetry claim holds and asking what is left outside them.

The empirically-cautious skepticism (Charlesworth, Barton & Charlesworth 2017)

Charlesworth, Barton, and Charlesworth's 2017 Darwin Review in the Proceedings of the Royal Society B represents the empirically-cautious mainstream evolutionary biology position. Their judgment: "no radical revision of our understanding of the mechanism of adaptive evolution is needed."19 Careful genetic studies have repeatedly shown that apparently puzzling results across organisms are consistent with neo-Darwinism. The empirical evidence for paradigm-shifting niche-construction-driven evolution — the evidence that niche construction regularly produces major evolutionary patterns not explainable by the standard framework — is weaker than EES advocates claim.

This article is not an EES advocacy piece, and the acknowledgment here is genuine. The recursion frame's contribution is structural — about which class biological evolution belongs to — and not about the magnitude of niche construction effects in any given population. The debate between Laland and Charlesworth about whether NC drives major evolutionary patterns empirically is orthogonal to the structural point that organisms produce the conditions of their own selection. The structural claim can be true even if NC turns out to be a modest evolutionary force in most lineages.

The article concedes the redescription objection's force, defers to the modeling-choice framing for the asymmetry debate, and grants the empirical caution. What survives is a structural claim — that biological evolution belongs to a named class — which none of the three objections targets.

What the frame buys#

Three things.

The first is the collapse of a false dichotomy. Lewontin wrote in The Triple Helix that "just as there can be no organism without an environment, so there can be no environment without an organism."20 This is not mysticism. It is the practical consequence of standing inside the recursive call. Subject — organism — and object — environment — are positional roles within the same operation, not separate ontological categories. From outside the loop there is one process: organisms modifying environments modifying selection pressures modifying organisms. From inside the loop — which is where evolutionary biology actually works — the distinction between organism and environment remains useful as a modeling convenience. The collapse is operational, not ontological. The dualism is not destroyed; it is relocated.

This relocation has a practical consequence for reading the evolutionary record. Van Valen's Red Queen law (1973) states that the effective environment of any group of organisms deteriorates at a stochastic constant rate — because the evolutionary advances of competing species systematically shift each other's selection landscape.21 Coevolutionary dynamics are non-terminating: no stable end state is reached, because each adaptation by any lineage shifts the selection pressures for all others. The flax-rust system illustrates this at the empirical scale. Antonovics, Thrall, Burdon, and Laine's cross-inoculation study of 120 host lines and 60 pathogen lines from six natural populations found no evidence that partial resistance slows coevolutionary dynamics; the arms race continues rather than converging.22 The non-termination mirrors the OEE non-halting result: the coevolutionary system, constituting its own selection environment reciprocally and recursively, cannot halt.

The second and third purchases are the frame's two predictions, stated as predictions rather than proofs:

Second, major evolutionary transitions are legible as type-signature changes in the recursive function. The fitness-tracking unit reorganizes discontinuously — from gene to genome, from cell to multicellular organism, from individual to eusocial colony. Each transition marks a qualitative change in the kind of entity natural selection can act upon. This is not gradual accumulation; it is the function signature changing.

Third, stability versus complexity is a parameter-regime effect. A system in the stability regime generates novelty within its existing organization — variations on a theme. A system in the complexity regime generates novelty that reorganizes the organization itself — a different theme. Where in parameter space a system sits determines which kind of novelty it produces. Both are forms of self-contextualizing process; they differ in which tier of the recursive structure is being updated.

Subject and object are not categories the world hands us. They are positions the loop assigns. Step outside the loop and there is one process. Step inside and the distinction returns, useful again. The dualism is not destroyed. It is relocated.

References#

  1. Hernández-Orozco, S., Hernández-Quiroz, F., & Zenil, H. (2018). Undecidability and Irreducibility Conditions for Open-Ended Evolution and Emergence. Artificial Life, 24(1), 56–70. DOI: 10.1162/artl_a_00254. ↩︎ ↩︎ ↩︎

  2. Laland, K.N., Uller, T., Feldman, M.W., Sterelny, K., Müller, G.B., Moczek, A., Jablonka, E., & Odling-Smee, J. (2015). The extended evolutionary synthesis: its structure, assumptions and predictions. Proceedings of the Royal Society B: Biological Sciences, 282(1813), 20151019. DOI: 10.1098/rspb.2015.1019. ↩︎ ↩︎

  3. Law, A., Gaywood, M.J., Jones, K.C., Ramsay, P., & Willby, N.J. (2017). Using ecosystem engineers as tools in habitat restoration and rewilding: beaver and wetlands. Science of the Total Environment, 605–606, 1021–1030. ↩︎

  4. Brazier, R.E., Puttock, A., Graham, H.A., Auster, R.E., Davies, K.H., & Brown, C.M.L. (2020). Beaver: Nature's ecosystem engineers. WIREs Water, 8(1), e1494. DOI: 10.1002/wat2.1494. ↩︎

  5. Laland, K.N., Odling-Smee, F.J., & Feldman, M.W. (1999). Evolutionary consequences of niche construction and their implications for ecology. Proceedings of the National Academy of Sciences, 96(18), 10242–10247. DOI: 10.1073/pnas.96.18.10242. ↩︎

  6. ASM Microbiology. (2022). The Great Oxidation Event: How Cyanobacteria Changed Life. ASM.org. https://asm.org/articles/2022/february/the-great-oxidation-event-how-cyanobacteria-change ↩︎

  7. Raatikainen, P. (2025). Gödel's Incompleteness Theorems — Supplement: The Diagonalization Lemma. Stanford Encyclopedia of Philosophy. https://plato.stanford.edu/entries/goedel-incompleteness/sup2.html ↩︎

  8. Kleene, S.C. (1952). Introduction to Metamathematics. North-Holland Publishing. (Theorems first proved 1938.) See also: Kleene's recursion theorem. Wikipedia. https://en.wikipedia.org/wiki/Kleene%27s_recursion_theorem ↩︎

  9. Rosen, R. (1991). Life Itself: A Comprehensive Inquiry into the Nature, Origin, and Fabrication of Life. Columbia University Press. ↩︎

  10. Kauffman, L.H. (2003). Eigenforms — Objects as Tokens for Eigenbehaviors. Cybernetics and Human Knowing, 10(3–4), 73–90. http://homepages.math.uic.edu/~kauffman/Eigen.pdf. See also: von Foerster, H. (1976). Objects: Tokens for (Eigen-)Behaviors. ASC Cybernetics Forum, 8(3–4), 91–96. Reprinted in von Foerster, H. (2003). Understanding Understanding: Essays on Cybernetics and Cognition, Springer, pp. 261–271. ↩︎

  11. Maturana, H.R. & Varela, F.J. (1980). Autopoiesis and Cognition: The Realization of the Living. D. Reidel Publishing Company, Dordrecht. [library-only; formal definition confirmed via multiple secondary sources including Springer catalog and independent academic reviews] ↩︎

  12. Mossio, M. & Moreno, A. (2010). Organisational closure in biological organisms. History and Philosophy of the Life Sciences, 32(2–3), 269–288. PMID: 21162371. The quoted definition appears in §3 of the paper; see also Moreno, A. & Mossio, M. (2015). Biological Autonomy: A Philosophical and Theoretical Enquiry. Springer. ↩︎

  13. Cárdenas, M.L., Letelier, J.C., Gutierrez, C., Cornish-Bowden, A., & Soto-Andrade, J. (2010). Closure to efficient causation, computability and artificial life. Journal of Theoretical Biology, 263(1), 79–92. DOI: 10.1016/j.jtbi.2009.11.010. PubMed: 19962389. ↩︎

  14. Hofstadter, D.R. (1979). Gödel, Escher, Bach: An Eternal Golden Braid. Basic Books. Hofstadter, D.R. (2007). I Am a Strange Loop. Basic Books. ↩︎

  15. Westra, A. (2010). Gödel, Hofstadter, & the Self: A Critical Review of Douglas Hofstadter's I Am a Strange Loop. Numéro Cinq, July 1, 2010. https://numerocinqmagazine.com/2010/07/01/godel-hofstadter-the-self-an-essay-by-adam-westra/. Nenu, T. (2022). Douglas Hofstadter's Gödelian Philosophy of Mind. Journal of Artificial Intelligence and Consciousness, 9(2), 241–266. DOI: 10.1142/S2705078522500011. ↩︎ ↩︎

  16. Scott-Phillips, T.C., Laland, K.N., Shuker, D.M., Dickins, T.E., & West, S.A. (2014). The niche construction perspective: a critical appraisal. Evolution, 68(5), 1231–1243. PMC: 4261998. ↩︎

  17. Maynard Smith, J. & Szathmáry, E. (1995). The Major Transitions in Evolution. Oxford University Press / W.H. Freeman. West, S.A., Fisher, R.M., Gardner, A., & Kiers, E.T. (2015). Major evolutionary transitions in individuality. PNAS, 112(33), 10112–10119. PMC: 4547252. Bourrat, P., Doulcier, G., Rose, C.J., Rainey, P.B., & Hammerschmidt, K. (2022). Tradeoff breaking as a model of evolutionary transitions in individuality and limits of the fitness-decoupling metaphor. eLife, 11, e73715. DOI: 10.7554/eLife.73715. Banzhaf, W., et al. (2016). Defining and simulating open-ended novelty: requirements, guidelines, and challenges. Theory in Biosciences, 135(3), 131–161. PubMed: 27194550. ↩︎ ↩︎ ↩︎ ↩︎

  18. Fromhage, L. & Houston, A.I. (2022). Biological adaptation in light of the Lewontin-Williams (a)symmetry. Evolution, 76(7), 1619–1624. PMC: 9544502. DOI: 10.1111/evo.14502. Otsuka, J. (2019). The Role of Mathematics in Evolutionary Theory. Cambridge University Press. ↩︎ ↩︎

  19. Charlesworth, D., Barton, N.H., & Charlesworth, B. (2017). The sources of adaptive variation. Proceedings of the Royal Society B, 284, 20162864. PubMed: 28566483. DOI: 10.1098/rspb.2016.2864. ↩︎

  20. Lewontin, R.C. (2000). The Triple Helix: Gene, Organism, and Environment. Harvard University Press. [library-only; near-quote confirmed via PMC1083785 review article and multiple independent secondary sources] ↩︎

  21. Van Valen, L. (1973). A new evolutionary law. Evolutionary Theory, 1(1), 1–30. ↩︎

  22. Antonovics, J., Thrall, P.H., Burdon, J.J., & Laine, A.L. (2011). Partial resistance in the Linum–Melampsora host-pathogen system: does partial resistance make the Red Queen run slower? Evolution, 65(2), 512–522. PMID: 21029078. ↩︎

Further Reading#

  • Rosen, R. (1991). Life Itself: A Comprehensive Inquiry into the Nature, Origin, and Fabrication of Life. Columbia University Press. — The primary source for closure to efficient causation and (M,R)-systems; the full formal argument the article engages with. Most readers will not have encountered Rosen; this is the recommended first follow-up.
  • Maturana, H.R. & Varela, F.J. (1980). Autopoiesis and Cognition: The Realization of the Living. D. Reidel. — The foundational autopoiesis text. The formal definition the article quotes derives from this source; the book extends the argument to a general theory of self-producing systems beyond cell biology.
  • Moreno, A. & Mossio, M. (2015). Biological Autonomy: A Philosophical and Theoretical Enquiry. Springer. — The book-length development of constraint closure; the most formal and most recent of the four prior namings. A decade of specialist literature has absorbed it; a cross-disciplinary audience has not.
  • Cárdenas, M.L., Letelier, J.C., Gutierrez, C., Cornish-Bowden, A., & Soto-Andrade, J. (2010). Closure to efficient causation, computability and artificial life. Journal of Theoretical Biology, 263(1), 79–92. — The bridge paper. The published compatibilist position in the Rosen computability debate; available open access at hal.science/hal-00564468v1. Required reading for the formal strategy at Level 1.
  • Hofstadter, D.R. (1979). Gödel, Escher, Bach: An Eternal Golden Braid. Basic Books. — The starting point for the GEB-shaped reader; the article moves beyond this text, but it remains the richest exploration of strange loops for a general audience.
  • Dawkins, R. (1982). The Extended Phenotype: The Long Reach of the Gene. Oxford University Press. Williams, G.C. (1966). Adaptation and Natural Selection. Princeton University Press. — The historical canonical statement of the gene-centered view and organism-environment asymmetry. The article engages the contemporary technical defense (Fromhage & Houston 2022) directly, but these texts are the cultural-touchstone versions the target audience is likely to have read.