Social cognition and human aesthetic niche—the evolving human cognition as a participant of human niche construction

The phenomena of organism niche construction and its evolutionary consequence

2.1

The worries for the Modern Synthesis have stimulated the development of alternative theories in the field of evolutionary biology. As evidence grows, the niche construction theory has been gaining traction recently (Laland, 2008, 2013; Laland et al., 2014, 2015, 2016). ‘Niche construction’, refers to the phenomena where organisms actively modify their own and others’ niches (Day, Laland, Odling-Smee, 2003; Odling-Smee, Laland and Feldman, 2003; Scott-Phillips et al., 2014; Laland, Matthews, Feldman, 2016). Moreover, since such modifications usually have the potential to influence selective pressures in the environments, novel episodes of evolution could incur due to significant changes in selective pressures, i.e., niche construction induced evolution. In this sense, the idea of niche construction, by taking the fact (that is, through their environment-shaping activities, organisms can actively affect the evolutionary trajectories of their own) into consideration, brings to the foreground this more inclusive nature of evolution. As a result, for many who advocate a fundamental role of niche construction for organism evolution, this perspective takes up the name ‘niche construction theory’ or ‘NCT’ (Laland and Sterelny, 2006; Kendal et al., 2011; Laland and O’Brien, 2011; Odling-Smee et al., 2013; Laland et al., 2014, 2015; Laland, Matthews, Feldman, 2016; Laland, Odling-Smee, and Endler, 2017).

Other than the different senses in which the term ‘niche’ is previously used (Grinnell, 1917; Elton, 1927; Hutchinson, 1944, 1957; Holt, 2009), when used in NCT, the notion ‘niche’ is defined as, ‘the sum of all the natural selection pressures to which the population is exposed.’⁶ This is a broad and inclusive definition, which also captures the evolving nature of a niche. It allows for the sum total of the conditions where a species in question, through constant interactions with the natural context, maintains the development and persistence of its own⁷. By taking this perspective of regarding species as subjects engaging in different niche constructing processes, the following points become important:

The human cultural niche

2.2

Examples of niche construction in the organismal world are numerous. For current purpose, I will leave some of those much-discussed cases—e.g., of yeast, earth worms, hermit crabs, and beavers (Laland et al., 2016; Bateson, 2017)—aside and focus on the human niche, especially, the cultural niche construction⁸ in human populations.

As a matter of fact, primates do seem to have employed various culturally derived ways of niche construction. For instance, in wild chimpanzee groups, the behaviour of making a primitive form of ‘sponge’ from leaves is regularly found. This behaviour buffers the need of water consumption and is believed to be socially learned (Whiten et al., 1999; Hobaiter et al., 2014; Lamon et al., 2018). Meanwhile, the presence of Japanese macaques’ food-washing activity is suggested to be another example of a behavioural pattern which get transmitted cross-generationally through a cultural manner (Kawamura, 1959; Kawai, 1965; Scheurer and Thierry, 1985). Nevertheless, human populations, still, exhibit an unparalleled level of dependence and exploitation on the wealth of cultural resources in respect of their niche constructing activities.

Whenever we think of ourselves (modern humans), it occurs intuitively and obviously that modern humans are probably the only species that not only modifies its environments in a notably comprehensive scale, but also relies so tightly and heavily on cultural practices in achieving those modifications. With the help of technology, modern humans have been carrying out planet-level cultural niche construction. The earth’s landscape has been profoundly transformed into cities, farmlands, or industrial lands. Natural resources are being transported and re-distributed worldwide through oil tankers, airliners, passenger trains etc. The development in telecommunication (e.g., internet, smartphones, personal computers, etc.) largely enables to a much more efficient exchange of human knowledge across continents, regions, and nations. Furthermore, by sending satellites and research stations, the human culture is accelerating its pace into the outer space.

Apart from the above overview of the magnitude of human cultural niche construction is and how it could have permeated nearly every aspect of human life, there is well-tested evidence showing human-led cultural influences on human genetics. Some famous examples include the spread of phenotypic traits of lactose tolerance, malaria resistance, and starch digestion in human populations (Perry et al., 2007; Rendell et al., 2011; Laland and O’Brien, 2011; Laland, Matthews, and Feldman, 2016). These cases have pointed to a possible fact: human culturally acquired behaviours can lead to non-random evolutionary consequences through a two-way mechanism that acts bilaterally and simultaneously—the buffering of specific selective pressures on one hand (e.g., the pressures for stable food sources that buffered by regular intake of dairy products or starchy crops), the emerging of novel pressures brought about on the other hand (e.g., selection for increased lactose tolerance or amylolytic capacity).

Cultural selection and cultural evolution

2.3

What has been said above has focused on just one type of the outcomes of cultural niche construction: that is, for a cultural practice, the process of cultural niche construction can lead to its refinement and stabilization over time. But when a cultural practice is put into a network of cultural practices like in the real-world condition, another type of outcome that bears equal evolutionary potency is the impact this niche constructing practice may have upon other related practices.

Behavioural patterns that are culturally acquired and transmitted usually cause changes in evolutionary fitness of other cultural traits (by indirectly mediating the course of transmission and the expression of relevant genes). On the analogy of the dam-building beavers⁹, human behavioural traits, when they are organised and expressed through habitual ‘practices’ or ‘traditions’, often exert selective effects on other phenotypic traits that are not so immediately related to the practice itself. Socially learned patterns like, for instance, local norms related to mate choice, religious or superstitious activities, specific technological practices, or even preferences in food choice, could produce far-reaching (but consequential) influence on many other behavioural patterns that coexisting in the same community. Particularly, when these culturally led traits are learned rapidly among industrialized human societies (with the support of technologies and education systems), and when paired with mechanisms such as sexual selection, or assortative mating, they produce strong culture-grounded selections in human population. From this aspect, we can see two notions are relevant: cultural selection and cultural evolution.

Cultural selection emerges when: 1. Some adaptive phenotypic trait is socially learned and spread among individuals of a population; 2. Major sources of selective pressures to which this population exposed stay stable; 3. This trait can be traditionalised, and the cumulative cultural inheritance could then lead to scaffolded learning; 4. Cultural selection for this trait appears.

Cultural evolution, accordingly, is the process in which diverse kinds of phenotypic traits, that are subject to persistent cultural selections, are manifested through behaviours, practices, and traditions of cultural niche construction of a population. What is so important here is that, considering evidence of niche construction we have so far (e.g., the spread of human alleles due to human farming, the dam-building regulated beaver physiology and morphology), it is reasonable to expect that, in the long term, cultural evolution could exert selective pressures on a wider spectrum of genes. If a cultural practice somehow is expressed (or inhibited) in a stable manner, certain genes (partially underlying that practice) can incur either an enhanced or a suppressed expression: think of the differential expressions of amylase genes that contribute to human starch digestion that depend on different levels of the cultural practice of starchy crops farming. At the same time, regardless of whether it is an over-expression or a suppression, the same practice can still affect the expression and the adaptive value of other genes. As a matter of fact, the current human life is inevitably filled with numerous products of the Digital Age. Through a systematic integration with individual’s life, this process of digitalisation and the novel selective pressures it induces might have left its mark in our species biologically. Indeed, there are recent studies which have suggested a correlation between increased risk for suffering an intervened early-stage brain development, ADHD, or depression and habits that contribute to prolonged screen time on digital devices (Madhav, et al., 2017; Hutton et al., 2020). However, to determine whether this correlation is a causal one or whether such culturally acquired traits have produced inheritable cognitive changes, further research is needed.

Human aesthetic niche and the Baldwin effect

3.1

The notion ‘human aesthetic niche’ (used in a general sense, including that of our Homo ancestors) is not to be thought as a subset of the human cultural niche. In line with our discussion of the notion ‘niche’ and ‘niche construction’, the notions of ‘aesthetic niche’ and ‘aesthetic niche construction’ can be defined accordingly as: the total of the selective pressures to which a human population is exposed during the process of aesthetic niche construction, and the specific way of niche construction that relies on human aesthetic resources. Although it is usually the case for modern humans that an example of aesthetic niche construction constitutes an example of cultural niche construction¹⁰. However, we should only see the human aesthetic niche as in effect a sub set of the total ecological niche of human, which overlaps (though largely) with the human cultural niche.

This is supported by the studies of those who advocate an evolutionary psychological theory for human aesthetic mind. In other words, the fact that humans inherit a repertoire of aesthetic sensibilities and preferences for characteristics of the natural world and of the human body. Related topics that are well-tested include: e.g., preference for savanna-like landscapes, above-average body height, a ~0.8 waist to hip ratio, or the averageness of faces, etc. (there is a large body of research on such issues, see e.g., Miller, 2001; Fink and Penton-Voak, 2002; Rhodes, 2006; Buss, 2008, 2016; Dutton, 2009, 2010; Miller and Maner, 2010; Rusch and Voland, 2013). In this regard, we see that aesthetic niche construction could happen outside (i.e., with no reference to cultural resources) the overlapping area with the cultural niche. Besides, as implied by the general dynamics of niche construction, we should not exclude the possibility for fluidity/flexibility since there is no hard line between them.

Roughly, the Baldwin effect is often used to denote the process during which behavioural traits that were initially derived gradually become internalised among individuals of a population (Sterelny, 2004; Papineau, 2005a; Crispo, 2007). An episode of Baldwinisation could happen, theoretically, on following conditions: 1. Some change in selective pressures is caused, making a specific behavioural pattern (let us call it X) adaptive. 2. Such change takes place through a non-radical way, and it persists long enough so that a small portion of the population could acquire X through individual trial and error. 3. Recognition of those ‘fitter’ individuals thus promote social learning of X, which stabilise X as a species-specific mode of behaviour. 4. A stabilised state of performing trait X induces positive selection for elements (at both the phenotypic level and the genotypic level) that facilitate the acquisition of X, thus, gradually makes X innate. As Sterelny describes, this effect is ‘a transition from development contingent on rich and specific environmental signals to development which is insensitive to environmental variation.’¹¹ Indeed, there can be an evolutionary trade-off happening between the cost of learning and the benefits of making the object of learning encoded. When benefits outweigh the cost, this transition could ensue. In spite of this, the Baldwin effect is more like a possible outcome of niche construction. Niche construction provides the major source of adaptive traits, meanwhile the process of Baldwinisation relies on stable external inputs—i.e., persistent selective pressures—to allow the internalisation of the target traits. For sure, niche construction results in modified pressures which usually contribute to the retention of some derived behavioural pattern, but it does not necessarily make it encoded.

Acheulean handaxe making and social cognition within an aesthetic tradition

3.2

The Acheulean industry is a Palaeolithic technological tradition that can be characterised by its continued reliance on the production of a distinctive type of stone tool, the ‘handaxe’. With the development of this tradition, especially from the middle to the late Acheulean, sophisticated handaxes were produced in large quantities. Among them, characteristics of obvious aesthetic concern—e.g., high level of symmetry, well-arranged scars, finely processed edge line, even design features such as hollowing—are found.

Based on the relation between the two classes of niche (aesthetic and cultural) we have just mentioned. The reason why this handaxe making tradition is so important is that: through what we have restored about the development of this material culture, the generations of making and refining (presumably from ~1.78 million years ago to ~500,000 to 300,000 years ago) of this practice had led to an emergence of a profound social learning system, which then gave birth to a culturally grounded aesthetic cognition—a mode of cognition, I suggest, that might be the ancestor of the kind we have when we appreciate arts.

For sake of a more focused and concise argument here, I will leave aside specifics such as technological issues in specimen evaluation and provide key milestones that would sustain this proposed scenario of cognitive evolution.

At its very beginning, there must be a transition from the previously dominant form of stone tool—the Oldowan choppers and flakes—to Acheulean handaxes. That is, there must be selective pressures that were buffered by the use of handaxes which enabled the handaxe to outperform Oldowan tools in the first place. According to studies on handaxe practicality (Galán and Domínguez-Rodrigo, 2014; Key and Lycett, 2017b), handaxes are considerably more efficient when dealing with heavy-duty tasks such as butchering (in which a handaxe could be used as a multi-purpose tool for de-fleshing, cutting, or smashing). Meanwhile, analyses based on animal fossils (Layton et al., 2012) and the identification of the earliest known case of porotic hyperostosis¹², a likely marker of habitual meat intake (Domínguez-Rodrigo et al., 2012) both point to the possibility that systematic group hunting could have existed in early Acheulean, thus heavy-duty work might reasonably constitute a significant part of the daily routine of Acheulean individuals.

Secondly, as the handaxe became prevalent, a result of this widely employed mode of niche constructing practice would be a set of strong selective pressures on factors which facilitate the practice of handaxe making. Considering those facts about the costly nature (at both individual and group levels) of maintaining a handaxe making tradition:

Therefore, factors that buffering these costs (i.e., selective pressures) would be under selection.

It is at this stage, I suggest, that the Acheulean handaxe tradition had promoted the social learning in Palaeolithic populations. For the societies that integrated so tightly with this stone technology of handaxe production, it would be crucial for individuals to become a good handaxe maker, and for the group to preserve and share the valuable knowledge required in handaxe making. Considering the costly nature and the complexity involved in this technology, during the middle to the late Acheulean, a developed social learning system might be in place. Within this system, a behavioural pattern that bonds experienced individuals with other less experienced ones could take place. That is, through a possible teaching-learning relationship, the cost of high-fidelity transmissions of valuable skills and knowledge between individuals and over generations would be decreased. In this manner, a concept/idea of someone being a good teacher/maker could emerge and be recognised in an Acheulean society. The preference for a good ‘teacher’ and the acknowledgement of expertise, would probably lead to a competitive social context: only those who have successfully shown their skills would be treated as the one others could learn from. Eventually, this seemed to have laid the ground for the aesthetic culture we see in those well-made handaxes. In this sense, the exaggerations (e.g., being large in size, having high degree of symmetry) in handaxe morphological traits are to be understood as honest signals.

Furthermore, it is possibly due to the perceptual fluency¹³ and perceptual bias at the beginning (Hodgson, 2011, 2015, 2019; Flavell et al., 2020) and a level of Baldwinisation (as an outcome of Acheulean aesthetic niche construction) at later time that symmetry became a type-feature (in the vein, an effective honest signal too) of handaxe. According to the studies of this core feature of handaxe—e.g., in general, a chronological increase in handaxe symmetry can be seen based on specimens from sites around the world; handaxe symmetry plays little or no role in terms of handaxe practicality; high level of symmetry in handaxe is more like a deliberate design rather than a by-product of the making process (Saragusti et al., 1998; Machin, Hosfield and Mithen, 2007; Beyene et al., 2013; Hodgson and Verpooten, 2014; Iovita et al., 2017; Key and Lycett, 2017a; Shipton, Clarkson, and Cobden 2018; White and Foulds, 2018)—we can reasonably regard handaxe symmetry as an aesthetic feature.

With evidence at hand, I claim that it could be the case that because of the persistent practice of handaxe making, at least by the middle to late Acheulean, hominins’ societies had become in essence aesthetically and culturally intertwined. It is in those societies, an aesthetic culture and correspondingly, a culturally grounded aesthetic cognition emerged.