We applaud Gintis's attempt to provide an evolutionary-based framework for the behavioral sciences, and note a number of similarities with our own recent cultural evolutionary structure for the social sciences. Gintis's proposal would be further strengthened by a greater emphasis on additional methods to evolutionary game theory, clearer empirical predictions, and a broader consideration of cultural transmission.

Cultural group selection seems the only compelling explanation for the evolution of the uniquely human form of cooperation by large teams of unrelated individuals. Inspired by descriptions of sanctioning in mutualistic interactions between members of different species, I propose partner choice by powerful individuals or institutions as an alternative explanation for the evolution of behavior typical for “team players.”

Economics and evolutionary biology share a long history of interaction and parallel development. This pattern persists with regard to how the two fields address the issues of selfishness and cooperation. The recent renewed emphasis on empiricism in both fields provides a solid foundation on which to build a truly scientific unification of the behavioral sciences.

The adaptationist framework is necessary and sufficient for unifying the social and natural sciences. Gintis's “beliefs, preferences, and constraints” (BPC) model compares unfavorably to this framework because it lacks criteria for determining special design, incorrectly assumes that standard evolutionary theory predicts individual rationality maximisation, does not adequately recognize the impact of psychological mechanisms on culture, and is mute on the behavioural implications of intragenomic conflict.

The human information-acquisition process is one of the unifying mechanisms of the behavioral sciences. Three examples (from psychology, neuroscience, and political science) demonstrate that through inspection of this process, better understanding and hence more powerful models of human behavior can be built. The target method for this – process tracing – could serve as a central player in this building process of a unified framework.

The synthesis proposed by Gintis is valuable but insufficient. Greater consideration must be given to epistemological diversity within the behavioral sciences, to incorporating historical contingency and institutional constraints on decision-making, and to vigorously testing deductive models of human behavior in real-world contexts.

The cognitive psychology of judgment and decision making helps to elaborate Gintis's unified view of the behavioral sciences by highlighting the fact that decisions result from multiple systems in the mind. It also adds to the unified view the idea that the potential to self-critique preference structures is a unique feature of human cognition.

For two decades, the integrated causal model of evolutionary psychology (EP) has constituted an interdisciplinary nucleus around which a single unified theoretical and empirical behavioral science has been crystallizing – while progressively resolving problems (such as defective logical and statistical reasoning) that bedevil Gintis's beliefs, preferences, and constraints (BPC) framework. Although both frameworks are similar, EP is empirically better supported, theoretically richer, and offers deeper unification.

An evolutionary model of human behavior should privilege emotions: essential, phylogenetically ancient behaviors that learning and decision making only subserve. Infants and non-mammals lack advanced cognitive powers but still survive. Decision making is only a means to emotional ends, which organize and prioritize behavior. The emotion of pride/shame, or dominance striving, bridges the social and biological sciences via internalization of cultural norms.

The beliefs, preferences, and constraints framework provides a language that economists, and possibly others, may largely share. However, it has got so many levels of indeterminacy that it is otherwise almost meaningless: when no evidence can ever be a problem for scientific construct Z, then there is a problem for Z, for nothing can also be considered supportive of Z.

My response to commentators includes a suggestion that an additional principle be added to the list presented in the target article: the notion of human society as a complex adaptive system with emergent properties. In addition, I clear up several misunderstandings shared by several commentators, and explore some themes concerning future directions in the unification of the behavioral science.

A broad range of evidence regarding the functional organization of the vertebrate brain – spanning from comparative neurology to experimental psychology and neurophysiology to clinical data – is reviewed for its bearing on conceptions of the neural organization of consciousness. A novel principle relating target selection, action selection, and motivation to one another, as a means to optimize integration for action in real time, is introduced. With its help, the principal macrosystems of the vertebrate brain can be seen to form a centralized functional design in which an upper brain stem system organized for conscious function performs a penultimate step in action control. This upper brain stem system retained a key role throughout the evolutionary process by which an expanding forebrain – culminating in the cerebral cortex of mammals – came to serve as a medium for the elaboration of conscious contents. This highly conserved upper brainstem system, which extends from the roof of the midbrain to the basal diencephalon, integrates the massively parallel and distributed information capacity of the cerebral hemispheres into the limited-capacity, sequential mode of operation required for coherent behavior. It maintains special connective relations with cortical territories implicated in attentional and conscious functions, but is not rendered nonfunctional in the absence of cortical input. This helps explain the purposive, goal-directed behavior exhibited by mammals after experimental decortication, as well as the evidence that children born without a cortex are conscious. Taken together these circumstances suggest that brainstem mechanisms are integral to the constitution of the conscious state, and that an adequate account of neural mechanisms of conscious function cannot be confined to the thalamocortical complex alone.

By themselves, mesencephalic subcortical mechanisms provide a preattentive kind of consciousness, related to stimulus-related, short-latency dopamine release triggered by collicular input. Elaborate forms of consciousness, containing identifiable objects (visual, auditory, tactile, or chemical), imply longer-lasting phenomena that depend on the activation of prosencephalic networks. Nevertheless, the maintenance of these higher-level networks strongly depends on long-lasting mesencephalic dopamine release.

Postulating the subcortical organization of human consciousness provides a critical link for the construal of pain in patients with impaired cortical function or cortical immaturity during early development. Practical implications of the centrencephalic proposal include the redefinition of pain, improved pain assessment in nonverbal humans, and benefits of adequate analgesia/anesthesia for these patients, which certainly justify the rigorous scientific efforts required.

Attention research with prefrontal patients supports Merker's argument regarding the crucial role for the midbrain in higher cognition, through largely overlooked and misunderstood prefrontotectal connectivity. However, information theoretic analyses reveal that both exogenous (i.e., collicular) and endogenous (prefrontal) sources of information are responsible for large-scale context-sensitive brain dynamics, with prefrontal cortex being at the top of the hierarchy for cognitive control.

The insight that, in terms of behaviour control, the mesodiencephalic system is superordinate to the cortex should have profound implications for behavioural sciences. Nevertheless, the thalamocortical system could still be deemed an “organ of consciousness” if we came to accept that consciousness is not central to purposeful behaviour, in accordance with instinct theory. Philosophically, Merker's concepts of basic consciousness and ego-centre warrant critical discussion.

In this commentary we discuss the possibility of subcortical consciousness and its implications for fetal anesthesia and analgesia. We review the neural development of structural and functional elements that may participate in conscious representation, with a particular focus on the experience of pain.

Merker suggests that the thalamocortical system is not an essential system for consciousness, but, instead, that the midbrain reticular system is responsible for consciousness. Indeed, the latter is a crucial system for consciousness, when consciousness is regarded as the waking state. However, when consciousness is regarded as phenomenal consciousness, for which experience and perception are essential elements, the thalamocortical system seems to be indispensable.

Merker's core idea, that the experience of being conscious reflects the interactions of actions, targets, and motivations in the upper brainstem, with cortex providing the content of the conscious experience, merits serious consideration. However, we have two areas of concern: first, that his definition of consciousness is so broad that it is difficult to find any organisms with a brain that could be non-conscious; second, that the focus on one cortical–subcortical system neglects other systems (e.g., basal forebrain and brainstem cholinergic systems and their cortical and thalamic target areas) which may be of at least equal significance.

Painful stimuli evoke functional activations in the cortex, but electrical stimulation of these areas does not evoke pain sensation, nor does widespread epileptic discharge. Likewise, cortical lesions do not eliminate pain sensation. Although the cortex may contribute to pain modulation, the planning of escape responses, and learning, the network activity that constitutes the actual experience of pain probably occurs subcortically.