Cultural and dual-inheritance models of evolution present ambiguities not typically present in biological evolution. Criteria and the ability to specify the adaptive value of a trait or cultural practice become less clear. When niche construction is added, additional challenges and ambiguities arise. Its dynamic nature increases the difficulty of identifying adaptations, tracing the causal path between a trait and its function, and identifying the links between environmental demands and the development of adaptations.

Genes controlling the choice of sexual strategy must be sensitive to critical environmental contingencies, including the presence of other strategically relevant genetic traits. To determine which strategy works best for each individual, one must assess both its environment and itself within that environment. Psychosexual development involves an assessment of sociosexual affordances, strategically calibrating optimal utilization of physical and psychosocial assets.

We suggest that innatism and constructivism may differ only in their time scale.

The capacity for flexible niche construction increases suddenly and dramatically when discrete memories and sensorimotor associations become woven into an interconnected worldview. Ontogenetic learning is as vital to culture as social learning because it is the wellspring of cultural novelty. Human altruism may result from pressures exerted at the level of cultural rather than biological replicators.

By assuming that REM sleep either plays a critical role in all memory consolidation or no role in any, Vertes & Eastman have chosen to reject, rather than explain, robust experimental findings of a role for sleep in memory and learning. In contrast, Nielsen has attempted to integrate conflicting findings in the dispute over REM versus NREM mentation. Researchers must trust the data more and the theories less, and build integrative rather than exclusionary models if they hope to resolve these knotty problems effectively.

[Nielsen; Vertes & Eastman]

Proxies of mate value must be evolutionarily salient. Gangestad & Simpson (G&S) have made a good case that fluctuating asymmetry is an important proxy of male mate value that correlates well with genetic and developmental quality. The use of financial variables as proxies for male investment ability by Gangestad, Simpson, and virtually every other investigator of human mating in evolutionary perspective, is, however, more problematic.

It is becoming increasingly clear that acquiring cognitive skills is feasible only with significant developmental constraints. However, recent research provides the strongest evidence to date for constructivist development. Here, we examine how these two apparently conflicting perspectives may be reconciled. Specifically, we suggest that subcortical and cortical structures possess divergent developmental strategies, with many subcortical structures satisfying Fodor's criteria for modularity. These structures constitute an early behavioral system that guides the construction of later emerging cortical structures, for which there is little evidence for modularity. Thus, we focus on how the dynamic time course of development itself implicitly constrains the emergence of cortical representations, reducing the requirement for built-in encodings of knowledge in cortical circuits, as on the traditional nativist conception.

Gangestad & Simpson present an evolutionary functional analysis of mating strategies. This commentary interprets their argument using a central concept from life history theory, return from investment. Incorporating return from investment allows further specification of costs and benefits from short-term mating in women as well as men and in ecological settings of high environmental variation in mortality and resource availability.

Laland et al.'s model of human evolution and cultural change needs to incorporate theory and research in human psychological development. The psychological approach that focuses on sociocultural contributions to growth offers a way of thinking about individual development that would complement and extend this model.

The idea that dreams function as fright-simulations rests on the adaptionist notion that anything that has form has function, and psychological argument relies on the mentalist assumption that dream reports are accurate reports of experienced events. Neither assumption seems adequately supported by the evidence presented.

[Revonsuo]

I distinguish different versions of the “niche construction” idea. Some are primarily scientific, while others are more philosophical. Laland, Odling-Smee & Feldman's is mostly scientific, but given that fact, there are some changes they could make to their account. I also compare the target article to Lewontin's classic 1983 paper.

Critics of evolutionary psychology object that it is not rigorous science compared to other evolutionary science. Advocates reply that it is rigorous science, and that the critics are uninformed. Still, informed people having opposing preconceptions of what counts as rigor may reach opposing evaluative conclusions. I shall clarify the very idea of rigorous evolutionary histories in relation to the basic objection that “evolution without history” is not rigorous.

The pharmacological literature on negative dream experiences is reviewed with respect to Revonsuo's threat rehearsal theory of dreaming. Moderate support for the theory is found, although much more work is needed. Significant questions that remain include the precise role of acetylcholine in the generation of negative dream experiences and dissociations between the pharmacology of waking fear and anxiety and threatening dreams.

[Revonsuo]

Laland et al.'s bidirectional model is a welcome starting point that can be enhanced by a full incorporation of systems thinking into its framework. Systems thinkers note that culture is not transmitted linearly in chunks but is co-constructed within subgroups. Niche construction, particularly among primates, should be studied primarily through the effects that social relationships have on selection pressures.

Dynamical simulations of male and female mating strategies illustrate how traits such as restrictedness constrain, and are constrained by, local ecology. Such traits cannot be defined solely by genotype or by phenotype, but are better considered as decision rules gauged to ecological inputs. Gangestad & Simpson's work draws attention to the need for additional bridges between evolutionary psychology and dynamical systems theory.

Revonsuo argues that the biological function of dreaming is to simulate threatening events and to rehearse threat avoidance behaviors. He views recurrent dreams as an example of this function. We present data and clinical observations suggesting that (1) many types of recurrent dreams do not include threat perceptions; (2) the nature of the threat perceptions that do occur in recurrent dreams are not always realistic; and (3) successful avoidance responses are absent from most recurrent dreams and possibly nightmares.

[Hobson et al.; Revonsuo]

Definitions of dreaming are not required to map formal features of mental activity onto brain measures. While dreaming occurs during all stages of sleep, intense dreaming is largely confined to REM. Forebrain structures and many neurotransmitters can contribute to sleep and dreaming without negating brainstem and aminergic-cholinergic control mechanisms. Reductionism is essential to science and AIM has considerable heuristic value. Recent findings support sleep's role in learning and memory. Emerging technologies may address long-standing issues in sleep and dream research.

Laland et al. suggest that as a specific evolutionary force niche construction has entailed the encephalization of the brain. While not denying rapid co-evolution of brain traits and abilities with niches and cultures, I argue that encephalization reflects a classical genetic buffer system allowing rapid evolutionary adaptation independent of the nature of the selective pressure.

High mating effort and antisocial and delinquent behaviors are closely linked. Some delinquent behaviors may honestly signal genetic quality. Men who exhibit high mating effort and who have high genetic quality would be expected to engage in more sexual coercion than other men because its costs to them are lowered by female preferences for them as sexual partners.

Niche construction theory inherits flaws from previous gene-culture coevolutionary theories. Units of cultural transmission have not yet been defined. Vertical transmission is not necessarily an overwhelmingly important part of culture. The assumption that human genetic interests and human cultural interests are in synch is a form of naive group selection.