2. The centrality of reproduction in modern evolutionary theories of aging

The available data suggest that although aging has always been present as a human reality, it was, until recently, a phenomenon restricted to a small percentage of the general population. According to biodemographic records, the average life expectancy of a person born in Western Europe between 1500 and 1900 fluctuated between 35 and 45 years. The most prevalent causes of morbidity and mortality in that period were diseases such as cholera or respiratory infections, also responsible for high rates of perinatal and infant mortality.Footnote ² Changes in general living conditions in industrialized and developing countries combined with biomedical advances and associated health improvements resulted in a significant growth in world population and a simultaneous increase in people reaching the so-called ‘third age’.Footnote ³ Thus, by 2017, life expectancy in those countries had already reached 79 years.Footnote ⁴ These trends have stimulated study and research on human and organic aging, which explains the proliferation of biogerontological theories that came to light during the last century, of which Medvedev, with perhaps excessive zeal, listed more than 300.Footnote ⁵

For expository purposes, here we will use the typology introduced by Weinert and Timiras, who summarized the entire registry of biogerontological models in four categories, according to the level of organization at which the explanatory factor is located, namely: molecular, cellular, systemic, and evolutionary.Footnote ⁶ An example of the first class is the telomere theory, which explains eukaryotic cell aging based on telomere shortening throughout the successive repetitions of the cell cycle; in the second group, prominent is the theory of free radicals, which understands senescence as a phenomenon derived from oxidation; and among the third, the immunogenetic theory can be highlighted, which, in its explanans, appeals to the weakening of the immune system as a cause of the considerable increase in infections, neoplasias, and autoimmune diseases that accompany human old age.Footnote ⁷ It is undeniable that all these models have provided valuable insights regarding the molecular and cellular pathways that participate in the biological dimension of aging. But it is also a fact that none has been able to answer satisfactorily the question of why we age. Despite their diversity, these approaches rest on a shared ontological basis, of a mechanistic type, which leads them to try to explain aging of an organism by appealing to the structural or functional decay of one or more of its parts.Footnote ⁸

The only category mentioned by Weinert and Timiras that seems to escape this logic – and the one that today appears to claim great importance and presence – is the one labeled ‘evolutionary’.Footnote ⁹ These theories are framed in the broader context of neo-Darwinism, an integrative proposal that emerged during the third and fourth decades of the last century as the fruit of the collective efforts of scientists from different specialties.Footnote ¹⁰ According to the resulting model, the interindividual variabilities observed in living beings are the effect of random changes in the hereditary material (whether mutations or chromosomal recombinations).Footnote ¹¹ Following the idea of natural selection developed by Charles Darwin – partly inspired by the earlier work of Robert Malthus – neo-Darwinian theorists postulated that those characteristics that directly or indirectly favor the survival of an organism until the reproductive phase of its life cycle are inherited by subsequent generations with greater frequency.Footnote ¹² By modifying the allelic frequencies of species over time, therefore, natural selection – combined with other phenomena such as genetic drift and gene flow – would act as a driving force of evolution.Footnote ¹³

Given this framework, it is not surprising that reproduction plays a fundamental role as an explanatory factor in evolutionary models of senescence as well. Following in part the pioneering works of Weissman and Fisher,Footnote ¹⁴ two theories of this kind have today been consolidated, namely, accumulation of mutations and pleiotropic antagonism. The former is usually associated with the name of Peter Medawar, whose work An Unsolved Problem in Biology criticizes Weismann’s approach (according to which senescence would respond to the need to discard the elderly population to make room for future generations) because it omits the relevance of what he calls extrinsic senescence.Footnote ¹⁵ To illustrate his point, Medawar proposes a thought experiment where a limited number of test tubes, potentially immortal in that they do not deteriorate or age, are subjected to an elimination of 10% of their population each month, being replaced by an equivalent number of new test tubes to keep the population stable. If this process is maintained for long enough – continues the author – new tubes will end up predominating, due to a simple matter of probabilities.Footnote ¹⁶ The conclusion drawn is that the longer living beings survive, the greater their probability of being eliminated by external or extrinsic factors.

Regarding the genes that regulate aging, Medawar maintains that they result from the fixation of thousands of random mutations in the germ line that, although deleterious for the living being, are only so once reproductive time has passed. These mutations, therefore, will not be eliminated efficiently by natural selection.Footnote ¹⁷ To show this, he uses the example of test tubes again. On this occasion, we have two populations, A and B, that suffer the loss of 10% of their population; A presents a monthly turnover rate of 10%, while B faces a rate of 11%, but at the price of its individuals suffering spontaneous combustion upon reaching 2 years of existence. The result is that, despite the assured destruction that B presents, the 1% turnover advantage it has with respect to A will drastically increase its numbers, justifying the benefit in earlier stages at the cost of a detrimental effect in more advanced stages.Footnote ¹⁸

Complementing Medawar’s work, Williams Hamilton stressed the trade-off between fertility and mortality: the lowest mortality described in a population coincides with the highest point of fertility, this being the basis for the accumulation of mutations. Through a series of mathematical and statistical models, Hamilton reaches the conclusion that natural selection will resist a trait that determines an increase in the incidence of mortality in early stages of life but not in the post-reproductive period, which would allow the damage to accumulate.Footnote ¹⁹ On the other hand, he raises the possibility of an evolution of this post-reproductive period in humans, based on the hypothesis that parental care leads to an improvement in mortality outcomes across the population. Indeed, it is reasonable to think that parents with a longer post-reproductive period can take more and better care of their children and grandchildren, with a positive impact on survival and reproductive value.Footnote ²⁰

In 1957, George C. Williams published the so-called theory of pleiotropic antagonism which, in a certain sense, corrected and complemented some aspects of the theory of mutation accumulation.Footnote ²¹ Williams defines senescence as ‘a group of adaptively unfavorable morphogenetic changes’Footnote ²² but, unlike Medawar and Hamilton, proposes that natural selection is not indifferent but actively opposes it. True to the foundations of neo-Darwinian theory, Williams observes that nature is a highly competitive environment, and that senescence is not an all-or-nothing affair but rather a continuum. Therefore, even early and mild manifestations of senescence can affect an individual’s probability of leaving offspring. In Williams’ words: ‘No matter how low the mortality rate, there is always a greater chance of surviving to age A than to age A + 1’.Footnote ²³ To explain the widespread occurrence of senescence in living beings, then, it is necessary to postulate some other factor or cause, distinct from the mere neglect of natural selection. In Williams’ theory, this factor is precisely the pleiotropic effect of some genes.

To understand Williams’ innovation, it is important to note that in genetics, pleiotropism designates the phenomenon by which a gene can cause distinct and unrelated phenotypic effects.Footnote ²⁴ According to this author, then, there are genes that exhibit a somewhat opposite pleiotropism, insofar as they contribute to improved reproductive fitness Footnote ²⁵ at early ages but nevertheless have harmful consequences for the individual in later stages and ultimately lead to aging.Footnote ²⁶ To explain this pattern, he proposes that the selection of one gene over others depends on the magnitude of its effect and its impact on total reproductive probability.Footnote ²⁷ Thus, any consequence derived from these genes manifesting late in life has less impact on reproductive probability, and thus less value from the perspective of natural selection. There is, in other words, an evolutionary trade-off that privileges early advantages that ensure greater reproduction, despite the harm these traits could cause in later periods of individuals’ life cycles. McDonald exemplifies this phenomenon through the process of calcium fixation in vertebrates. In this subphylum, bone calcification results in a phenotype that significantly increases the probability of an organism reaching the reproductive stage and inheriting its genes; however, this same process, in later stages of ontogeny, can cause calicification of the parenchyma of some internal organs, such as blood vessels and myocardium.Footnote ²⁸ As the first of these effects exerts a greater impact on reproductive probability, the genes that regulate calcification are preserved by natural selection, despite their eventual deleterious effect in late ontogenic phases.

So, given that the maximal probability of an individual generating viable offspring is reached at the same time as sexual maturity, it will only be once that phase is reached that senescence can manifest as a phenomenon. It is worth noting that while it is easy to find empirical support for this theory in organisms with an accelerated growth rate, in humans, it becomes more difficult, which is why alternatives are sought, such as analysis of genetic studies and reviews thereof to determine the significance of pleiotropic antagonism in human senescence.Footnote ²⁹

Beyond their differences, a common conceptual element remains among the theories presented: reproduction. Certainly, this activity plays an essential role in the narratives that biogerontology offers today of phenomena such as the selection of traits, the beginning of deleterious processes, and the reason why traits with variable effects on organisms are privileged. It is not surprising that this is so; the theories referred to are conceptually derived from the neo-Darwinian model, in which both the inheritance of modifications of the genetic material and the selective pressure of the environment directly concern the generative activity of organisms. Although the originality of Charles Darwin and the authors responsible for the neo-Darwinian synthesis on this point cannot be underestimated, a careful examination of the history of philosophical and biological thought will verify that reproduction has claimed a place of importance in approaches other than evolutionary. This is the case, as we see in the following section, of Aristotle in Antiquity and Thomas Aquinas in the Middle Ages.

3. Reproduction in Aristotelian and Thomistic philosophy

On the basis of the lists offered by Aristotle,Footnote ³⁰ later tradition identifies certain vital operations or activities as characteristics of the three degrees of corporeal life, namely, vegetative, sensitive, and human. The characteristic operations of the vegetative life – which is basic, because it constitutes a first elevation of the living above the nonliving; and fundamental, since the two higher levels have to also assume this, in proportion to their respective natures – are those of nutrition, growth, and reproduction or generation.Footnote ³¹ The first aims to maintain the living being in its substance;Footnote ³² the second points to the increase of the living being according to the accident of quantity;Footnote ³³ the third, finally, is that operation by which a living being generates another living being specifically identical to itself.Footnote ³⁴

Perhaps more relevant than the catalog itself is what these activities reveal about the living being in its ontological constitution. A first distinctive note of these operations is what has been called, alternatively, autonomy, autarchy, or spontaneity.Footnote ³⁵ These terms point to a common and highly significant fact: The living being is capable of executing these acts ex se.Footnote ³⁶ This is significant because it shows the living being as an agent of its operations, i.e., an entity that, unlike the inert being, does not suffer but rather actualizes and performs its own acts by and from itself.

The second characteristic note of the vital act is immanence. As we emphasize elsewhere, in relation to this point, the positions of Aristotle and Aquinas do not seem exactly coincident.Footnote ³⁷ For the Stagirite, an act is immanent if the action is identified with its terminus, as occurs in the act of understanding, since thinking – says Aristotle – and having thought are one and the same thing.Footnote ³⁸ Aquinas, on the other hand, admits that the identification of act and terminus that occurs in intellectual operations is of course revealing but constitutes not the very crux of immanence but rather its most excellent realization. What determines an act as immanent, instead, is its effect remaining in its agent, perfecting it, in ontological terms.Footnote ³⁹ In light of this clarification, therefore, it can be affirmed that all vital acts – including vegetative ones – are such not only in view of their autonomy but also their immanence, although of course, both notes are instantiated with analog perfection in the various degrees of living.Footnote ⁴⁰

Although this seems to be a school debate, the truth is that its consequences fully affect the problem dealt with here. Indeed, the autonomy of the reproductive act does not pose problems, at least not for those who fit within the framework of the Aristotelian or Thomistic tradition. But what can be said about the immanence of this activity? Even assuming the deeply rooted Thomistic notion of immanence, it is not entirely clear how a living being that generates another specifically identical one could be perfected in the process. This is especially clear if we focus on a key passage from Book IV of the Summa contra gentiles, in which Aquinas outlines a hierarchy of the living based precisely on the immanence of their actions. He asserts there that the reproductive operation of the tree ends in something – the fruit – different from the tree itself; the same does not happen, for example, in the act of sensing, whose term remains in the animal itself performing it.Footnote ⁴¹ Viewing the problem from this angle, we could conclude that, unlike nutrition and growth, the reproductive act is autonomous but not immanent, a conclusion undoubtedly alien to Thomistic doctrine, since it implies a certain devaluation of an act that Aquinas expressly qualifies as the most perfect of vegetative vital activities.Footnote ⁴²

To respond to this difficulty, it is necessary to place it in its broader context. Within the framework of Thomistic doctrine, every entity is called to similitudo Dei in accordance and proportion to its nature. This universal vocation of creation is concretized in an equally universal tendency of every creature to remain in existence, thus imitating the absolute eternity of the Ipsum esse subsistens.Footnote ⁴³ Due to its corruptibility, the corporeal living beingFootnote ⁴⁴ cannot achieve this survival as an individual but can achieve it, quodammodo, in its species, to whose permanence it contributes by generating new individuals of the same type through reproduction.Footnote ⁴⁵ But it should not be overlooked that this improvement does not exclude the living being that is the agent of the reproductive act; on the contrary, as part of the species that remains in being, and of the universe perfected, the progenitor living being becomes a participant in a cosmic order that includes it, although transcending it.Footnote ⁴⁶ This is how the superiority of this operation at the level of vegetative vital acts must be understood, to which Aquinas alludes, as we saw, on more than one occasion.

4. Reproduction, biological organization, and aging

The discussion about reproduction is not a mere medieval excursus but a key piece of the thesis we shall articulate here. Before that, however, we must address a question that the very idea of aging poses, in the face of the hylomorphic structure under which both Aristotle and Aquinas conceive of natural bodies in general and corporeal living beings in particular: What exactly decays in the living being over time? It cannot be the soul, as this would expressly contradicts the letter of Aristotle and Aquinas, as we will see, and it is not surprisingly so: For these authors, the psyché of a living being is its substantial form, i.e., a first act that, as such, cannot experience bodily changes per se.Footnote ⁴⁷ This is so precisely because this soul is not a body but a co-principle that originates and founds corporality. Even less can it be matter that declines in senescence, since it is not only a co-principle but potentially one lacking any actuality, according to Aquinas.Footnote ⁴⁸ But if it is not then the form nor the matter that properly ages, why does the compound of both, i.e., the living thing, age?

This could be interpreted as a sign of the theoretical insufficiency of hylomorphism, but before adhering to so resounding a conclusion, it is necessary to point out that contemporary evolutionary theories do not offer a satisfactory explanation of senescence either. As noted above, both the mutation accumulation theory and pleiotropic anatagonism afford reproductive drive a central role; in the former, it is the cessation of that activity that marks the parallel cessation of natural selection and explains the organic decay of senescence; the latter postulates that natural selection still plays a part in old age, but it will always privilege the phenotypic traits that allow an organism to reproduce. Note, however, that in both models – as with the neo-Darwinian theory on which they ultimately depend – the reproductive tendency constitutes a factum with no further explanation. If, in the epistemological domain in which these theories are proposed, this omission is acceptable, the same does not occur at the level of philosophy. In short, if we are unable to explain the reproductive tendency of corporeal living beings, we cannot know why they age.

We believe that the hylemorphic theory not only has the resources to address the issues of reproduction and aging of the corporeal living being but furthermore provides an explanatory framework in which the contributions of current biogerontological approaches can be integrated. To move in that direction, we start by highlighting a couple of texts in which Aristotle and Aquinas explicitly refer to old age, in a way highly significant for our purposes. The first states that if an old man could have the eye of a young man, he would see like that;Footnote ⁴⁹ commenting on this point, the second adds that ‘… the weakness of the action is not due to a weakness of the soul, but of the organ’.Footnote ⁵⁰ The crux of these passages, initially somewhat laconic and enigmatic, lies in what they say about the organ, in one case explicitly, in the other, exemplified in the eye. The modern word organ has its etymological root in the term ὄργανον (through the Latin organum), designating, among other things, an instrument or utensil.Footnote ⁵¹ In the sense Aristotle and Aquinas use the term, it is part of the living being, and this is because it is not pure but organized matter. As a well-known representative of the neo-Aristotelian trend in the philosophy of biology, David S. Oderberg asserts that the unity of the organ is strong, from an ontological point of view, but is subordinate to that of the organism.Footnote ⁵² It is in and through this subordination that the organ acquires the characteristic morphological and functional organization that makes it an instrument of vital operations. The root of this organization, of course, is the soul, but it must not be overlooked that organization and actualization are not exactly the same, as Aquinas teaches when he states that the complexion or harmony traceable in living beings is not their soul; rather, complexion and harmony have their cause in the actualization the soul exercises in the corresponding compound.Footnote ⁵³

Aquinas’ clarification cannot be overlooked, but an additional aspect of this relationship between organization and actualization should not be omitted either. Indeed, many everyday situations show that, to remain in being, the living being depends on the adequate maintenance of its biological organization. A disease that severely affects the morphological and/or functional organization of the living being can undoubtedly lead to corruption; the same result can be produced by an agent who abruptly alters that organization, as with wounds caused by weapons; prolonged starvation will also prevent the living being from maintaining its organization, to the point of being incompatible with life. How do we interpret this?

According to our thesis, the relationship between actualization and organization is not unidirectional but bidirectional. In short, the substantial form of a living being can participate in esse and simultaneously communicate it (which is what an actualization consists of) to matter, but this is only possible if there is a minimal entitative disposition that makes such communication possible; this disposition is precisely what we call biological organization.Footnote ⁵⁴ If this organization does not exist or suffers gradual or sudden deterioration, the soul can no longer communicate the act of being to the compound, and corruption takes place. To delve further requires taking into account that, in the Thomistic scheme, a compound substance, precisely because it is determined by quantity, is a continuous whole made up of diffluent parts that maintain a positional order among themselves.Footnote ⁵⁵ If the continuity of these parts is broken, there is no longer, strictly speaking, one substance, but two or more. This also applies to the living composite substance, of course, although in this case, the order of the parts is not only positional but also operational. In other words, biological organization is, above all, a positional order of parts whose purpose or telos is the performing of vital activities, in such a way that the deprivation or disruption of that organization will result in the impossibility of executing such activities. This situation is incompatible with an organic life, not only at the factual level but above all the ontological one, because without these vital activities (and this applies especially to vegetative activities), the organic living being cannot maintain the positional order of its parts and continue to constitute a single compound substance.Footnote ⁵⁶ That is to say, biological organization is a minimal entitative disposition because it ensures the quantitative continuity of the composite substance, thus enabling the actualization of matter by the substantial form.

This now poses a problem, because if for form to actualize matter requires matter already having an organization, and organization, in turn, requires formalization, there would be no organic living beings at all. The solution takes us back to the problem of reproduction and aging. Certainly, corporeal living beings are generated from other specifically identical living beings.Footnote ⁵⁷ In the reproductive act, the parent contributes part of its own organicity (either directly or through specialized cells called gametes, depending on whether it is asexual or sexual reproduction, respectively); this organicity, whose organization causally derives from the substantial form of the progenitor, behaves as a minimal entitative disposition that can make viable the actualization of matter by the new substantial form (that of the descendant) that has been educed.Footnote ⁵⁸ From that first moment of existence, an ontogeny unfolds in which at least three characteristic phases can be distinguished:

1. i. Development: The organization received from the parent(s) is perfected through a growing actualization of matter by form, operationally manifested in the activity of growth; in turn, greater organization allows greater actualization, in a reciprocal deployment. At this stage, reproduction is not carried out, although the growing organization generates and matures the organic structures that will, in a later phase, intervene in that activity (represented with a dashed line in Figure 1a). As in all phases of ontogeny, extrinsic factors exert damage on the organization in a fundamentally random pattern; however – as predicted by evolutionary theories, and in accordance with Thomistic philosophy – the natural tendency of the living being to reach its full form favors growth to such an extent that the balance is strongly tilted toward the development of biological organization (thick causal line in Figure 1a).

2. ii. Maturity: At this stage, the form is already displaying the actualization of which it is capable; its correlate is the acquisition of a full organization according to species. The living being is now in a position to reproduce. From this moment, and as explained by evolutionary theories and Aquinas’s doctrine, the vital dynamism of the living being is intensely focused on reproduction and, in part, also on growth, especially in its regenerative aspect. Random damage continues to occur in the organization, but growth manages to counteract it to maintain a relatively stable organic balance (Figure 1b).

3. iii. Post-reproductive: In most species, there is a late phase in which reproductive activity ceases or at least decreases in effectiveness. In accordance with the postulates of the evolutionary theories of senescence, in this phase, some potentially deleterious traits could be expressed; these are evolutionary side products selected for their advantageous role in previous stages of ontogeny. This phenomenon, added to the random damage of the environment, will affect the organization, and with this, the growth/regeneration activity will experience a decline (represented by a dashed arrow with a bar in Figure 1c). This further inhibits the operation of growth, and, therefore, the organization. The result is the progressive and gradual cycle of disorganization we know as aging, such that the more disorganization, the less growth there will be, which will cause more disorganization, less growth, and so on. Finally, the actualization exercised by form on matter becomes unfeasible, and the death of the living being occurs.

Figure 1.

(a) Developmental phase. The organization enables the performing of growth/regeneration activity, and this, in turn, enhances and favors such organization. This growing organization manages to counteract the random effects of internal and external factors, so there is no detectable aging. Little to no energy is used for reproduction. (b) Maturity phase. The activity of the living being turns strongly toward reproduction; although there is no longer growth stricto sensu, the organization is maintained thanks to regenerative activity, which allows a balancing to the damage caused by internal and external factors. (c) Senescence phase. Once the reproduction phase is completed, the living being has fulfilled its purpose, and its growth/regeneration activity decreases drastically.  The organization, therefore, suffers the gradual effects of damage caused by external and internal factors, resulting in aging.

5. Some considerations about this model and its possible projections

The integration proposed allows us to establish a complementarity between the Thomistic doctrine of the living being and the evolutionary biogerontological theories in force today. Following the reflection of Thomas Aquinas, we can say that reproduction is the culmination of organic life, at least in its vegetative dimension. In other words, organic life aspires and tends to perpetuate itself through reproduction. But this leaves the question in suspense: Why, once the reproductive phase has occurred or is completed, does the living thing decline and age? The two current evolutionary theories (mutation accumulation and pleiotropic antagonism) together provide a plausible explanation: Because the selective pressure of the environment is exerted in view of reproduction (this being harmonious with the Thomistic idea of reproduction as a tendency toward divine resemblance), and what happens next is simply not subject to this selective process, or if it is, to a lesser extent. Note that admitting this does not necessarily imply accepting the completeness of the neo-Darwinian proposal but rather its suitability as an explanatory model at the intraspecific level.Footnote ⁵⁹ On the other hand, and as discussed below, it is important to keep in mind that the organic decline visible in old age does not occur in a vacuum but depends, ultimately, on the nature or essence of the living being in question.

In our hypothesis, the pattern of decline in growth/regeneration activity that occurs in old age does not seem modifiable at the moment, and if it is in the future, everything indicates it will be to a restricted extent. The same does not occur with the prevention of damage that affects biological organization. Here, we have limited ourselves to designating such damage as if a single homogeneous category of events, but the available experimental results suggest that diverse and numerous genetic, cellular, and systemic processes intervene at this level, some of them – but not all – interrelated with each other.Footnote ⁶⁰ Nothing prevents us, at least in principle, from intervening in these sequences of events to preserve biological organization better and for longer. This is not equivalent to a suppression of aging, but it could at least promote a healthier and more functional old age. In this sense, our approach distances itself from the rigid limits proposed by mechanism,Footnote ⁶¹ and also from the unfounded hopes that transhumanism fuels.Footnote ⁶²

Despite its inexorability, and the fact that old age brings with it a functional loss for those who experience it, it should not be overlooked that, in the interpretation we have advanced, senescence is a process subordinate to the life and nature of the living being. A living being is a substantial unit, endowed with its own – vital – activity, and which is positioned, at least in part, as an active subject of its decay. Biogerontology provides indirect testimony of this when it informs us that although there are interindividual variations, old age does not occur chaotically but rather following a characteristic pattern for each species. This regularity also finds its place in our interpretation: form and matter are essential co-principles, making up the essence or nature of the corporeal being. The organization that is the fruit and means of the actualization that form exerts on matter, therefore, cannot but manifest the essence of the living being, and the same happens with the disorganization that affects it.Footnote ⁶³ Each living being ages in accordance with its specific way of being. In a cultural moment in which the distinction between old age and illness seems to become blurred, our hypothesis could serve as a basis for introducing some timely philosophical and ethical clarifications.

But the virtuality of the classical notion of life, in its Aristotelian and Thomistic side, is not limited to what is suggested here. This approach can illuminate certain aspects of contemporary science and, in particular, the attempts carried out in the field of theoretical biology to account for the nature and causes of biological organization. Although the epistemic and methodological limits of this type of approach, and those expressly philosophical, are not always clear, we can mention, among several others, the contributions of Maturana and Varela,Footnote ⁶⁴ Hooker,Footnote ⁶⁵ Collier,Footnote ⁶⁶ Bickhard,Footnote ⁶⁷ Kauffman,Footnote ⁶⁸ Juarrero,Footnote ⁶⁹ and, more recently, Ruiz-Mirazo, Moreno, and Mossio.Footnote ⁷⁰ The last group, in particular, has sought to overcome the criticisms leveled at the theory of autopoiesis – especially its abstract and functionalist character and omission of the relational dimension proper to organic lifeFootnote ⁷¹ – by introducing the idea of autonomy as a distinctive feature of biological systems, with its three distinctive notes of organizational closure of constraints, regulation, and adaptive agency.Footnote ⁷² Especially interesting is the effort undertaken by these authors to distinguish the question about the nature of life from the other question referring to their genealogy and evolution, and also the distance they maintain with respect to some genocentrist reductionisms still latent in the contemporary biology.Footnote ⁷³ Less satisfactory, however, seems to be the ontological foundation that Moreno et al. provide regarding autonomy and, especially, organizational closure as a feature of biological organization.

As Christopher J. Austin has emphasized, Aristotelian philosophy has experienced a reinvigoration in contemporary metaphysical discussions, but interest in hylemorphic doctrine has not been at the center of that renewal.Footnote ⁷⁴ Austin himself, and other authors such as De Haan, Jaworski, Koons, and Oderberg, among several others, have tried to remedy this by showing the relevance and even necessity of a hylemorphic approach (in some of its numerous variants) to corporeal realities, and specifically organic living beings.Footnote ⁷⁵ On our part, we think this philosophical tradition can, in fact, provide a robust ontology to base biological organization, through which many contemporary contributions could certainly be rescued. Work of this kind could impact not only our understanding of the phenomenon of aging but also other relevant issues in biology and biomedicine, such as, for example, the origin and evolution of corporeal life and the pathogenesis of some highly prevalent conditions today, such as cancer or neurodegenerative diseases, in which pathological biological disorganization takes place.