Evolution of Cognition

Finlay et al. address the importance of developmental constraints in brain size evolution. I discuss some aspects of this view such as the relation of brain size with processing capacity. In particular, I argue that in human evolution there must have been specific selection for increased processing capacity, and as a consequence for increased brain size.

A dorsalization mechanism is a good candidate for the evolutionary origin of the isocortex, producing a radial and tangential expansion of the dorsal pallium (and perhaps other structures that acquired a cortical phenotype). Evidence suggests that a large part of the dorsal ventricular ridge (DVR) of reptiles and birds derives from the embryonic ventral pallium, whereas the isocortex possibly derives mostly from the dorsal pallium. In early mammals, the development of olfactory-hippocampal associative networks may have been pivotal in facilitating the (...) selection of a larger and more complex dorsal pallium which received both collothalamic and lemnothalamic sensory information. Finally, although it is not clear exactly when mammalian brain expansion began, fossil evidence indicates that this was a late event in mammaliaform evolution. (shrink)

In early hominins, there possibly was high selective pressure for the development of reciprocal mother and child vocalizations such as proposed by Falk. In this context, temporoparietal-prefrontal networks that participate in tasks such as working memory and imitation may have been strongly selected for. These networks may have become the precursors of the future language areas of the human brain.

Striedter's accessible concept-based book is strong on the macroevolution of brains and the developmental principles that underlie how brains evolve on that scale. In the absence of greater attention to microevolution, natural selection, and sexual selection, however, it is incomplete and not fully modern on the evolution side. Greater biological integration is needed.

Dispassionate cruelty and the euphoria of hunting or battle should be distinguished from the emotional savoring of victims' suffering. Such savoring, best called negative empathy, is what puzzles motivational theory. Hyperbolic discounting theory suggests that sympathy with people who have unwanted but seductive traits creates a threat to self-control. Cruelty to those people may often be the least effortful way of countering this threat.

The target article provides important theoretical contributions to psychology and Bayesian modeling. Despite the article's excellent points, we suggest that it succumbs to a few misconceptions about evolutionary psychology (EP). These include a mischaracterization of evolutionary psychology's approach to optimality; failure to appreciate the centrality of mechanism in EP; and an incorrect depiction of hypothesis testing. An accurate characterization of EP offers more promise for successful integration with Bayesian modeling.

The concept of ontogenetic niche is used here to interpret how species-typical behaviors develop through active, context-dependent processes. Ontogenetic niches typically include social stimuli, such as those arising from parents, siblings, and others that provide 'nurturing' in the form of resources, stimulation, and affordances for development. This approach is a useful alternative to wrestling with artificial dichotomies such as nature-nurture.

Juslin & Vll (J&V) advance our understanding of the proximate mechanisms underlying emotional responses to music, but fail to integrate their findings into a comprehensive evolutionary model that addresses the adaptive functions of these responses. Here we offer such a model by examining the ontogenetic relationship between music, ritual, and symbolic abstraction and their role in facilitating social coordination and cooperation.

Burns proposes an intriguing hypothesis by suggesting that the “schizophrenia genes” might not be regulatory genes themselves, but rather closely associated with regulatory genes directly involved in the proper growth of the social brain. We point out that this account would benefit from incorporating the effects of localized lesions and aberrant hemispheric asymmetry on cortical connectivity underlying the social brain. In addition, we argue that the evolutionary framework is superfluous.

In our target article, we discussed the standards of evidence that could be used to identify adaptations, and argued that building an empirical case that certain features of a trait are best explained by exaptation, spandrel, or constraint requires the consideration, testing, and rejection of adaptationist hypotheses. We are grateful to the 31 commentators for their thoughtful insights. They raised important issues, including the meaning of “exaptation”; whether Gould and Lewontin's critique of adaptationism was primarily epistemological or ontological; the necessity, (...) sufficiency, or utility of design evidence, phylogenetic analyses, homology, and molecular genetics in distinguishing exaptations from adaptations; whether adaptationists accept adaptationist hypotheses too quickly; and the real utility of adaptationism to human behavioral science. We organize our response along the major points of the target article, in some situations defending our original claims and in others modifying them. While debate on these issues will undoubtedly continue, we are cautiously optimistic that the main points of the target article (as modified by our response) will help move the debate in a positive direction. (shrink)

1 Adaptationism is a research strategy that seeks to identify adaptations and the specific selective forces that drove their evolution in past environments. Since the mid-1970s, paleontologist Stephen J. Gould and geneticist Richard Lewontin have been critical of adaptationism, especially as applied toward understanding human behavior and cognition. Perhaps the most prominent criticism they made was that adaptationist explanations were analogous to Rudyard Kipling's Just So Stories. Since storytelling is an inherent part of science, the criticism refers to the acceptance (...) of stories without sufficient empirical evidence. In particular, Gould, Lewontin, and their colleagues argue that adaptationists often use inappropriate evidentiary standards for identifying adaptations and their functions, and that they often fail to consider alternative hypotheses to adaptation. Playing prominently in both of these criticisms are the concepts of constraint, spandrel, and exaptation. In this article we discuss the standards of evidence that could be used to identify adaptations and when and how they may be appropriately used. Moreover, building an empirical case that certain features of a trait are best explained by exaptation, spandrel, or constraint requires demonstrating that the trait's features cannot be better accounted for by adaptationist hypotheses. Thus, we argue that the testing of alternatives requires the consideration, testing, and systematic rejection of adaptationist hypotheses. Where possible, we illustrate our points with examples taken from human behavior and cognition. Key Words: adaptation; ADHD; brain allometry; constraint; epistemology; evolutionary psychology; exaptation; female orgasm ; optimization; special design; waist-hip ratio. Footnotes1 The authors contributed equally to this paper. Order of authorship was determined alphabetically. Correspondence may be addressed to any of the authors. (shrink)

The causes of asymmetries for handedness and cerebral speech are of scientific interest, but is it sensible to try to determine which of these came first? I argue that (1) first causes belong to mythology, not science; (2) much of the cited evidence is weak; and (3) the treatment of individual differences is inadequate in comparison with the right shift theory.

Grouping severe mental disorders into a global category is likely to lead to a “theory of everything” which forcefully explains everything and nothing. Speculation even at the phenotypic level of the single disorder cannot be fruitful, unless specific and testable models are proposed. Inclusive fitness must be incorporated in such models. (Published Online November 9 2006).

Strong adaptationists would explain complex organic designs as specific adaptations to particular ancestral environments. Weak adaptationists don't assume that complex organic functioning represents evolutionary design in the sense of niche-specific adaptation. For some domain-specific competencies (folkbiology) strong adaptationism is useful, not necessary. With group-level belief systems (religion), strong adaptationism can become spurious pseudo-adaptationism. In other cases (language), weak adaptationism proves productive.

We agree with Archer that human sex differences in aggression are well explained by sexual selection, but note that explanations of human behaviors are not logically mutually exclusive from explanations and therefore should not be framed as such. We discuss why this type of framing hinders the development of both social learning and evolutionary theories of human behavior.

While admirable, Guala's discussion of reciprocity suffers from a confusion between proximate causes (psychological mechanisms triggering behaviour) and ultimate causes (evolved function of those psychological mechanisms). Because much work on commits this error, I clarify the difference between proximate and ultimate causes of cooperation and punishment. I also caution against hasty rejections of of experimental evidence.

An evolutionary model of crying requires consideration of nonhuman primate data. Chimpanzees do not have colic. Although they have a peak of fussiness at 6 weeks with a decline by 12 weeks whether raised by biological mothers or in a human nursery, their crying is always consolable. Colic may be a by-product of delayed rates of brain development; that is, neoteny.

In addition to ensuring that appropriate standards of evidence are employed when attempting to identify adaptations, researchers should investigate all nonevolutionary factors that could potentially explain their results. Evolutionary analyses may be undermined by alternative, non-evolutionary explanations either because not all relevant information is included in an evolutionary analysis, or because inappropriate methods incapable of detecting an adaptation are employed.

Archer provides seemingly compelling evidence for his claim that sexual selection explains sex differences in human aggression better than social role theory. I challenge Archer's interpretation of some of this evidence. I argue that the same evidence could be used to support the claim that what has been selected for is the ability to curb aggression and discuss implications for Archer's theory.

Kirkpatrick's contribution is evaluated in the context of historical developments and persistent crisis in the psychology of religion. The field has been characterized by the lack of a unifying theory, as well as by some literature being driven by religious apologetics. Kirkpatrick's approach has been truly theory-driven, always seeking a general psychological framework for analyzing religion and religiosity. His personal odyssey led him to embrace Bowlby's attachment theory, which has had a unique impact of research in academic psychology. But then (...) Kirkpatrick demonstrates his honesty and courage in realizing that the attachment framework was less than adequate for the task of unifying the field. Instead, he invites us to join him in embracing the broader framework of cognitive-evolutionary theory, which should serve as the unifying framework for the field. I concur with his judgment. (shrink)