Vaesen should be congratulated for proposing a multifaceted account of a human uniqueness. Too often, hypotheses of human uniqueness posit a single breakthrough, with a subsequent cascade of other traits. Vaesen, to his credit, offers a package of cognitive skills that he believes underlies a single unique trait: cumulative cultural evolution. However, the comparative method that Vaesen uses to get to this package of cognitive skills is problematic. By engaging in straight comparison of chimp and human cognitive skills, Vaesen omits the possibility for the co-evolution of cognition, technology, and culture that potentially underpins human uniqueness. The comparison also presumes that these traits are not developmentally plastic.
The co-evolutionary picture is important given recent models of cognition that emphasise the importance of the external world in cognitive processes and the acquisition of cognitive skills (Clark Reference Clark2008; Clark & Chalmers Reference Clark and Chalmers1998; Menary Reference Menary2010; Sterelny Reference Sterelny2010a) and neural plasticity (Quartz & Sejnowski Reference Quartz and Sejnowski1997). In particular, the hypothesis of cultural niche construction of Kim Sterelny argues that these human interactions with the world are important for human cognitive evolution. The developmental and cultural environment of hominins helps shape cognitive processes (Sterelny Reference Sterelny2003; Reference Sterelny2010b; Reference Sterelny2012). Tools, and the behaviours of other tool users and makers, can act as scaffolds to cognition.
Moreover, Vaesen never mentions how his list of cognitive skills gets “in the head” of humans; but the assumption that drives the comparative method is that the skills are evolved and hardwired traits. Co-evolutionary models such as niche construction offer an alternative developmental route for these skills.
We can see the potential impact of these alternative models of cognition in relation to the Acheulean tool culture that Vaesen briefly discusses in the second part of his article. Vaesen suggests that there is not much variability in Acheulean tool form, and that it lacks evidence of cumulative development. Consequently, Vaesen infers that the associated cognitive skills he thinks are necessary to possess a cumulative culture are therefore absent.
However, many archaeologists point out that there is in fact a great deal of variation in tool manufacturing methods, materials, and raw material resource strategies (Lycett & Cramon-Taubadel Reference Lycett and Cramon-Taubadel2008; Lycett & Gowlett Reference Lycett and Gowlett2008; McNabb et al. Reference McNabb, Binyon and Hazelwood2004; Sharon Reference Sharon2009). So whilst tool form, and possibly even tool use, is fairly constant, tool manufacturing methods do in fact show some signs of cumulative culture. So, the evidence for Vaesen's package of cognitive skills is potentially present in manufacturing methods, even if it is absent from the final tool form. Lycett and Gowlett (Reference Lycett and Gowlett2008) suggest that this is the result of transmission between generations that allows for the accumulation of variation in manufacturing skills but fails to transmit and accumulate variations in tool form. Using ideas about the co-evolution of culture and cognition, and acknowledging the role that external resources play in cognitive processes, we can make sense of this contradiction.
As a social animal, hominins may take the presence of tools and other toolmakers as physical and behavioural templates for their further tool production. Hominins or modern sapiens making a tool can use as a template other tools possessed by individuals in their community. Consequently, the “idea” of a tool need not be “in the head” of an individual, as tools possessed by other members of the group can play this role. There are any number of external resources that can assist individuals to stay “on track” in their manufacturing task.
This social world is crucial in learning to make tools. Other toolmakers are accessible behavioural templates of toolmaking activities. Tools, and other tool users, create an environment that can support the development of cognitive skills associated with tool manufacture. Tools are made in a world where there are other people making tools, and where there is close contact between toolmakers and their behavioural outputs. For a young hominin learning to make a tool, this environment provides a situation where the cost of learning a tool is relatively low. There are lots of behavioural templates around, some of whom may even have a genetic interest in ensuring the young hominin acquires the appropriate skills (Sterelny Reference Sterelny2010b; Reference Sterelny2012).
In his section on executive control (sect. 12.2), Vaesen notes that individuals with certain brain lesions can achieve complex sequences of tasks where there is clear “next steps” available in the form of environmental cues (the lunch box packing case; sect. 6) but cannot achieve tasks where purely mental planning is necessary (Tower of London tasks; sect. 6). For a social organism, tool manufacturing quite likely resembles the first task, with abundant physical props and a community of users and makers. Tools may scaffold executive control (Jeffares Reference Jeffares2010b).
Therefore, we can resolve the apparent paradox of the Acheulean by understanding the environment that the tools are made in. Acheulean tools are made in a social context; and being members of a toolmaking community buffers the transmission of skills, reduces learning costs, and allows variation to develop. Nevertheless, the hominins that made these tools appear to not have the capacity to accumulate technological improvements in tool form. This suggests that suitable buffering effects were not present during deployment activities, or that different processes encouraged standardisation of tool form (Jeffares Reference Jeffares2010a).
Regardless of the details of this case, what should be clear is that we have to acknowledge that cognitive skills do not straightforwardly facilitate technological accumulation. There is a cognitive ecology of co-evolutionary processes, external resources, scaffolds, and developmental influences that shape human cognition, both now and in the past. This matters to understanding human uniqueness and how it evolved.
Humans make tools because they live in a unique cultural environment that helps them learn, and fine-tune, the cognitive skills necessary for toolmaking. To understand cumulative culture, we must understand how culture scaffolds the learning of cognitive skills, and not presume the skills that underlie it. By not considering the historical environment and the external environment as part of that matrix of forces that shapes cognition, Vaesen potentially ignores the possibility that some of his package of cognitive skills are learnt.
Vaesen should be congratulated for proposing a multifaceted account of a human uniqueness. Too often, hypotheses of human uniqueness posit a single breakthrough, with a subsequent cascade of other traits. Vaesen, to his credit, offers a package of cognitive skills that he believes underlies a single unique trait: cumulative cultural evolution. However, the comparative method that Vaesen uses to get to this package of cognitive skills is problematic. By engaging in straight comparison of chimp and human cognitive skills, Vaesen omits the possibility for the co-evolution of cognition, technology, and culture that potentially underpins human uniqueness. The comparison also presumes that these traits are not developmentally plastic.
The co-evolutionary picture is important given recent models of cognition that emphasise the importance of the external world in cognitive processes and the acquisition of cognitive skills (Clark Reference Clark2008; Clark & Chalmers Reference Clark and Chalmers1998; Menary Reference Menary2010; Sterelny Reference Sterelny2010a) and neural plasticity (Quartz & Sejnowski Reference Quartz and Sejnowski1997). In particular, the hypothesis of cultural niche construction of Kim Sterelny argues that these human interactions with the world are important for human cognitive evolution. The developmental and cultural environment of hominins helps shape cognitive processes (Sterelny Reference Sterelny2003; Reference Sterelny2010b; Reference Sterelny2012). Tools, and the behaviours of other tool users and makers, can act as scaffolds to cognition.
Moreover, Vaesen never mentions how his list of cognitive skills gets “in the head” of humans; but the assumption that drives the comparative method is that the skills are evolved and hardwired traits. Co-evolutionary models such as niche construction offer an alternative developmental route for these skills.
We can see the potential impact of these alternative models of cognition in relation to the Acheulean tool culture that Vaesen briefly discusses in the second part of his article. Vaesen suggests that there is not much variability in Acheulean tool form, and that it lacks evidence of cumulative development. Consequently, Vaesen infers that the associated cognitive skills he thinks are necessary to possess a cumulative culture are therefore absent.
However, many archaeologists point out that there is in fact a great deal of variation in tool manufacturing methods, materials, and raw material resource strategies (Lycett & Cramon-Taubadel Reference Lycett and Cramon-Taubadel2008; Lycett & Gowlett Reference Lycett and Gowlett2008; McNabb et al. Reference McNabb, Binyon and Hazelwood2004; Sharon Reference Sharon2009). So whilst tool form, and possibly even tool use, is fairly constant, tool manufacturing methods do in fact show some signs of cumulative culture. So, the evidence for Vaesen's package of cognitive skills is potentially present in manufacturing methods, even if it is absent from the final tool form. Lycett and Gowlett (Reference Lycett and Gowlett2008) suggest that this is the result of transmission between generations that allows for the accumulation of variation in manufacturing skills but fails to transmit and accumulate variations in tool form. Using ideas about the co-evolution of culture and cognition, and acknowledging the role that external resources play in cognitive processes, we can make sense of this contradiction.
As a social animal, hominins may take the presence of tools and other toolmakers as physical and behavioural templates for their further tool production. Hominins or modern sapiens making a tool can use as a template other tools possessed by individuals in their community. Consequently, the “idea” of a tool need not be “in the head” of an individual, as tools possessed by other members of the group can play this role. There are any number of external resources that can assist individuals to stay “on track” in their manufacturing task.
This social world is crucial in learning to make tools. Other toolmakers are accessible behavioural templates of toolmaking activities. Tools, and other tool users, create an environment that can support the development of cognitive skills associated with tool manufacture. Tools are made in a world where there are other people making tools, and where there is close contact between toolmakers and their behavioural outputs. For a young hominin learning to make a tool, this environment provides a situation where the cost of learning a tool is relatively low. There are lots of behavioural templates around, some of whom may even have a genetic interest in ensuring the young hominin acquires the appropriate skills (Sterelny Reference Sterelny2010b; Reference Sterelny2012).
In his section on executive control (sect. 12.2), Vaesen notes that individuals with certain brain lesions can achieve complex sequences of tasks where there is clear “next steps” available in the form of environmental cues (the lunch box packing case; sect. 6) but cannot achieve tasks where purely mental planning is necessary (Tower of London tasks; sect. 6). For a social organism, tool manufacturing quite likely resembles the first task, with abundant physical props and a community of users and makers. Tools may scaffold executive control (Jeffares Reference Jeffares2010b).
Therefore, we can resolve the apparent paradox of the Acheulean by understanding the environment that the tools are made in. Acheulean tools are made in a social context; and being members of a toolmaking community buffers the transmission of skills, reduces learning costs, and allows variation to develop. Nevertheless, the hominins that made these tools appear to not have the capacity to accumulate technological improvements in tool form. This suggests that suitable buffering effects were not present during deployment activities, or that different processes encouraged standardisation of tool form (Jeffares Reference Jeffares2010a).
Regardless of the details of this case, what should be clear is that we have to acknowledge that cognitive skills do not straightforwardly facilitate technological accumulation. There is a cognitive ecology of co-evolutionary processes, external resources, scaffolds, and developmental influences that shape human cognition, both now and in the past. This matters to understanding human uniqueness and how it evolved.
Humans make tools because they live in a unique cultural environment that helps them learn, and fine-tune, the cognitive skills necessary for toolmaking. To understand cumulative culture, we must understand how culture scaffolds the learning of cognitive skills, and not presume the skills that underlie it. By not considering the historical environment and the external environment as part of that matrix of forces that shapes cognition, Vaesen potentially ignores the possibility that some of his package of cognitive skills are learnt.