This article has two goals. The first is to assess, in the face of accruing reports on the ingenuity of great ape tool use, whether and in what sense human tool use still evidences unique, higher cognitive ability. To that effect, I offer a systematic comparison between humans and nonhuman primates with respect to nine cognitive capacities deemed crucial to tool use: enhanced hand-eye coordination, body schema plasticity, causal reasoning, function representation, executive control, social learning, teaching, social intelligence, and language. Since striking differences between humans and great apes stand firm in eight out of nine of these domains, I conclude that human tool use still marks a major cognitive discontinuity between us and our closest relatives. As a second goal of the paper, I address the evolution of human technologies. In particular, I show how the cognitive traits reviewed help to explain why technological accumulation evolved so markedly in humans, and so modestly in apes.

We examine tool use in relation to the capacity of animals for construction, contrasting tools and nests; place human tool use in a more general problem-solving context, revisiting the body schema in the process; and relate the evolution of language and of tool use.

We discuss the discovery of technologies involving knotted netting, such as textiles, basketry, and cordage, in the Upper Paleolithic. This evidence, in our view, suggests a new way of connecting toolmaking and syntactic structure in human evolution, because these technologies already exhibit an “infinite use of finite means,” which we take to constitute the key transition to human cognition.

Recent data show that human children (up to 8 years old) perform poorly when required to innovate tools. Our tool-rich culture may be more reliant on social learning and more limited by domain-general constraints such as ill-structured problem solving than otherwise thought.

Vaesen disregards a plausible alternative to his position, and so fails to offer a compelling argument for unique cognitive mechanisms. We suggest an ecological alternative, according to which divergent relationships between organism and environment, not exotic neuroanatomy, are responsible for unique cognitive capacities. This approach is pertinent to claims about primate cognition; and on this basis, we argue that Vaesen's inference from unique skills to unique mechanisms is unwarranted.

Human tool behavior is species-specific. It remains a diagnostic feature of humans, even when comparisons are made with closely related non-human primates. The archaeological record demonstrates both the deep antiquity of human tool behavior and its fundamental role in distinguishing human behavior from that of non-human primates.

Vaesen's description of uniquely human tool-related cognitive abilities rings true but would be enhanced by an account of how those abilities would have evolved. I suggest that a process of technological selection operated on the cognitive architecture of ancestral hominids because they, unlike other tool-using species, depended on tools for their survival.

Vaesen suggests that motor control is not among the primary origins of the uniqueness of human tool use. However, recent findings show that cognitive processes involved in control of human limb movements may be much more sophisticated than it was believed previously. The sophistication of movement control may substantially contribute to the uniqueness of humans in tool use.

The cortical representation of concepts varies according to the information critical for their development. Living categories, being mainly based upon visual information, are bilaterally represented in the rostral parts of the ventral stream of visual processing; whereas tools, being mainly based upon action data, are unilaterally represented in a left-sided fronto-parietal network. The unilateral representation of tools results from involvement in actions of the right side of the body.

Chimpanzee/human technological differences are vast, reflect multiple interacting behavioral processes, and may result from the increased information-processing and hierarchical mental constructional capacities of the human brain. Therefore, advanced social, technical, and communicative capacities probably evolved together in concert with increasing brain size. Interpretations of these evolutionary and species differences as continuities or discontinuities reflect differing scientific perspectives.

Design features for language and stone toolmaking (not tool use) involve similar if not homologous cognitive processes. Both are arbitrary transformations of internal “intrinsic” symbolization, whereas non-human tool using is mostly an iconic transformation. The major discontinuity between humans and non-humans (chimpanzees) is language. The presence of stone tools made to standardized patterns suggests communicative and social control skills that involved language.

We propose that Vaesen's target article (a) underestimates the role of language in humans' cognitive toolkit and thereby (b) overestimates the proposed cognitive discontinuity between chimps and humans. We provide examples of labeling, numerical computation, executive control, and the relation between language and body, concluding that language plays a crucial role in “supersizing humans' cognitive toolkit.”

The author describes “higher” and “uniquely human” sociocognitive skills that he argues as being necessary for tool use. We propose that those skills could be based on simpler detection systems humans could share with other animal tool users. More specifically, we discuss the impact of object affordances on the understanding and the social learning of tool use.

The investigative strategy that Vaesen uses presumes that cognitive skills are to some extent hardwired; developmentally plastic traits would not provide the relevant comparative information. But recent views of cognition that stress external resources, and evolutionary accounts such as cultural niche construction, urge us to think carefully about the role of technology in shaping cognition.

Plasticity of body representation fundamentally underpins human tool use. Recent studies have demonstrated remarkably complex plasticity of body representation in humans, showing that such plasticity (1) occurs flexibly across multiple time scales and (2) involves multiple body representations responding differently to tool use. Such findings reveal remarkable sophistication of body plasticity in humans, suggesting that Vaesen may overestimate the similarity of such mechanisms in humans and non-human primates.

I agree with Vaesen that it is a mistake to discard tool use as a hallmark of human cognition. I contend, nonetheless, that tools are not simply external markers of a distinctive human mental architecture. Rather, they actively and meaningfully participate in the process by which hominin brains and bodies make up their sapient minds.

The distinctions drawn by Vaesen are plausible when we are comparing chimpanzees and human beings somewhere between the middle Paleolithic and the Neolithic. But since then new kinds of organization have vastly outstripped these neurological differences to account for the enormous advancement of human technology – from cuneiform to the iPhone – leaving our remarkable evolutionary cousins far behind.

Human life history incorporates childhood, a lengthy post-weaning period of dependency. This species-specific period provides an opportunity for extensive learning and for sophisticated cultural behaviors to develop, including crucial tool use skills. Although I agree that no individual cognitive trait singularly differentiates humans from other animals, I suggest here that without childhood, the traits that are key to human tool use would not emerge.

In his attempt to find cognitive traits that set humans apart from nonhuman primates with respect to tool use, Vaesen overlooks the primacy of the environment toward the use of which behavior evolves. The occurrence of a particular behavior is a result of how that behavior has evolved in a complex and changing environment selected by a unique population.

A comparative fMRI study by Peeters et al. (2009) provided evidence that a specific sector of left inferior parietal lobule is devoted to tool use in humans, but not in monkeys. We propose that this area represents the neural substrate of the human capacity to understand tool use by using causal reasoning.