Women and men have evolved psychological traits adapted to different types of competition in the EEA (environment of evolutionary adaptedness). While women appear not to be as well adapted as men for violent status struggles, the decline of routine violence in status contests raises interesting questions about gender and status competition in contemporary societies.

Sex differences in aggressive behavior are probably adaptive but the costs and benefits of risky aggression to women and men may be different from those suggested in Campbell's target article. Moreover, sex differences are more likely to reflect differences in the costs of aggression to females and males rather than differences in its benefits.

Four issues relevant to sex differences in human aggression and violence are considered. (1) The motivation for play and serious aggression in children and juvenile animals is different. Consequently, the evolutionary explanations for each may be different. (2) Sex differences in intrasexual aggression may be due to effects of the attacker or the target. There is evidence that both males and females are more physically aggressive against males and less physically aggressive against females. The evolutionary explanation for each component of the sex difference in intrasexual aggression may be different. (3) Aggression and violence are defined. The former is the attack, and the latter is the consequent injury or death. The evolutionary explanation for each may not be the same. (4) Most men and women are neither physically aggressive nor criminally violent. The evolutionary explanations of sex differences in aggression and violence should take this polymorphism into account.

Female competition generally takes nonviolent form, but includes intense verbal and nonverbal harassment that has profound social and physiological consequences. The evolutionary ecological model of competitive reproductive suppression in human females, might profitably be applied to explain a range of contemporary phenomena, including anorexia.

The thesis that women will be more intent on staying alive fails to take into account that current strategies are those of the winners in the evolutionary race. Moreover, because like tends to mate with like, risk taking will be averaged out between the sexes. Finally, Campbell's narrow view of parental investment fails to acknowledge the indirect contributions of males.

Human mating and parenting are more complex than has been implied by many evolutionarily based theories of sex differences. While focusing on sex differences might shed some light on the evolution of mating and parenting, this level of analysis is rather imprecise. More important, it ignores several ecological variables that should have influenced mating/parenting decisions and behaviors in both sexes.

In their competition for higher-status men, women with higher socioeconomic status use indirect forms of aggression (ridicule and gossip) to derogate lower-status female competitors and the men who date them. Women's greater tendency to excuse their aggression is arguably a cultural enhancement of an evolutionarily based sex difference and not solely a cultural construction imposed by patriarchy.

Campbell's target article is a stimulating attempt to extend our understanding of sex differences in risk-taking behaviors. However, Campbell does not succeed in demonstrating that her account adds explanatory power to those (e.g., Daly & Wilson 1994) previously proposed. In particular, little effort was made to explore the causal links between survival (staying alive) and reproduction.

When aggression is conceptualised in terms of a cost-benefit ratio, sex differences are best understood by a consideration of female costs as well as male benefits. Benefits must be extremely high to outweigh the greater costs borne by females, and circumstances where this occurs are discussed. Achievement of dominance is not such a circumstance and evidence bearing upon women's egalitarian relationships is reviewed. Attempts to explain sex differences in terms of sexual dimorphism, sex-of-target effects, social control, and socialisation are found to be inadequate. The suggestion that the stigmatisation of female aggreession arises not from patriarchal imposition but from statistical rarity (resulting from evolutionary pressures) is given serious consideration. Two hypotheses (“internal read-out” versus social/epidemiological representations) are described to explain the relationship between sex differences in behaviour and corresponding lay explanations.

If the cortex is an associative memory, strongly connected cell assemblies will form when neurons in different cortical areas are frequently active at the same time. The cortical distributions of these assemblies must be a consequence of where in the cortex correlated neuronal activity occurred during learning. An assembly can be considered a functional unit exhibiting activity states such as full activation (“ignition”) after appropriate sensory stimulation (possibly related to perception) and continuous reverberation of excitation within the assembly (a putative memory process). This has implications for cortical topographies and activity dynamics of cell assemblies forming during language acquisition, in particular for those representing words. Cortical topographies of assemblies should be related to aspects of the meaning of the words they represent, and physiological signs of cell assembly ignition should be followed by possible indicators of reverberation. The following postulates are discussed in detail: (1) assemblies representing phonological word forms are strongly lateralized and distributed over perisylvian cortices; (2) assemblies representing highly abstract words such as grammatical function words are also strongly lateralized and restricted to these perisylvian regions; (3) assemblies representing concrete content words include additional neurons in both hemispheres; (4) assemblies representing words referring to visual stimuli include neurons in visual cortices; and (5) assemblies representing words referring to actions include neurons in motor cortices. Two main sources of evidence are used to evaluate these proposals: (a) imaging studies focusing on localizing word processing in the brain, based on stimulus-triggered event-related potentials (ERPs), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI), and (b) studies of the temporal dynamics of fast activity changes in the brain, as revealed by high-frequency responses recorded in the electroencephalogram (EEG) and magnetoencephalogram (MEG). These data provide evidence for processing differences between words and matched meaningless pseudowords, and between word classes, such as concrete content and abstract function words, and words evoking visual or motor associations. There is evidence for early word class-specific spreading of neuronal activity and for equally specific high-frequency responses occurring later. These results support a neurobiological model of language in the Hebbian tradition. Competing large-scale neuronal theories of language are discussed in light of the data summarized. Neurobiological perspectives on the problem of serial order of words in syntactic strings are considered in closing.

Pulvermüller assumes that words are represented as associations of two cell assemblies formed according to Hebb's coincidence rule. This seems to correspond to the linguistic notion that words consist of lexemes connected to lemmas. Standard examples from theoretical linguistics, however, show that lemmas and lexemes have properties that go beyond coincidence-based assemblies. In particular, they are inherently disposed toward combinatorial operations; push-down storage, modelled by decreasing reverberation in cell assemblies, cannot capture this. Hence, even if the language capacity has an associationist characterization at some level, it cannot just be co-occurrence-based assembly formation.

Word class-specific differences in brain evoked potentials (EP) are discussed for connotative meaning and for function versus content words. A well-controlled experiment found matching lexical decision times for function and content words, but clear EP differences (component with maximum near 550 msec) among function words, content words, and nonwords that depended on brain site. Another EP component, with a 480 msec maximum, differentiated words (either function or content) from nonwords.

Holistically ignited Hebbian models are fundamentally different from the serially organized connectionist implementations of language. This may be important for the recovery of language after injury, because connectionist models have provided useful insights into recovery of some cognitive functions. I ask whether cell assembly modelling can make an important contribution and whether the apparent incompatibility with successful connectionist modelling is a problem.

To deal with syntactic structure, one needs to go beyond a simple model based on associative structures, and to adopt a dynamical systems perspective, where each phrase and sentence of a language is represented as a trajectory in a syntactic phase space. Neural assemblies could possibly be used to produce dynamics that in principle could handle syntax along these lines.

In his target article, Pulvermüller addresses the issue of word localization in the brain. It is not clear, however, how cell assemblies are localized in the case of sensory deprivation. Pulvermüller's claim is that words learned via other modalities (i.e., sign languages) should be localized differently. It is argued, however, based on experimental and theoretical ground, that they should be found in a similar place.

The Hebbian view of word representation is challenged by findings of task (level of processing)-dependent, event-related potential patterns that do not support the notion of a fixed set of neurons representing a given word. With cross-language phonological reliability encoding more asymmetrical left hemisphere activity is evoked than with word comprehension. This suggests a dynamical view of the brain as a self-organizing, connectivity-adjusting system.

Pulvermüller's discussion needs more explanation of how the proposed assemblies remain assembled after formation and how they can be accessed later among all the possible assemblies, many of which involve many of the same neurons. Alternative Hebbian strengthening mechanisms may provide additional information, and, developmental studies of the assemblies might provide insights into their evolution.

The correlative coactivation of sensory inputs, Hebb's “second rule,” probably plays a critical role in the formation of word representations in the neocortex. It is essential to the acquisition of word meaning. The acquisition of semantic memory is inseparable from that of individual memory, and therefore the two probably share the same neural connective substrate. Thus, “content” words are represented mainly in postrolandic cortex, where individual perceptual memories are also represented, whereas “action” words are represented in frontal cortex, with executive memories. The activation of a memory network may not necessarily entail the high-frequency oscillatory firing of its cells, though reverberation remains a plausible mechanism of short-term memory.

Pulvermüller traces the differences in brain activity associated with function and content words. The model considers words displayed primarily in isolation. Research on letter detection suggests that what distinguishes function from content words are their roles in text. Hence a model that fails to consider context effects on the processing of words provides an insufficient accounting of word representation in the brain.

Pulvermüller's Hebbian model implies that an impairment in the word form system will affect phonological articulation and phonological comprehension, because there is only a single representation. Clinical evidence from patients with word-form deafness demonstrates a dissociation between input and output phonologies. These data suggest that auditory comprehension and articulatory production depend on discrete phonological representations localized in different cortical networks.