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We have been publishing new compilations of energy levels for single elements in all stages of ionization as each is completed. Those now in print in the Journal of Physical and Chemical Reference Data are helium (1973), sodium (1981), magnesium (1980), aluminum (1979), silicon (1983), potassium (1979), calcium (1979), scandium (1980), titanium (1979), vanadium (1978), chromium (1977), manganese (1977), iron (1982), cobalt (1981) and nickel (1981). A volume containing atomic energy levels of all rare earth elements was issued in 1978. We have now updated our compilations for the iron period (K through Ni, 235 spectra), which will be published in a single volume.
Tables of wavelengths, line classifications, and transition probabilities have been critically compiled for ionized spectra of neon (Ne V-VIII), magnesium (Mg V-X), silicon (Si VI-XII), and sulfur (S VIII-XIV) in the 20 Å-170 Å region. The tables provide basic atomic data for about 3300 transitions in support of astronomical studies from the Chandra X-ray Observatory.
Parasites are detrimental to host fitness and therefore should strongly select for host defence mechanisms. Yet, hosts vary considerably in their observed parasite loads. One notable source of inter-individual variation in parasitism is host sex. Such variation could be caused by the immunomodulatory effects of gonadal steroids. Here we assess the influence of gonadal steroids on the ability of guppies (Poecilia reticulata) to defend themselves against a common and deleterious parasite (Gyrodactylus turnbulli). Adult male guppies underwent 31 days of artificial demasculinization with the androgen receptor-antagonist flutamide, or feminization with a combination of flutamide and the synthetic oestrogen 17 β-estradiol, and their parasite loads were compared over time to untreated males and females. Both demasculinized and feminized male guppies had lower G. turnbulli loads than the untreated males and females, but this effect appeared to be mainly the result of demasculinization, with feminization having no additional measurable effect. Furthermore, demasculinized males, feminized males and untreated females all suffered lower Gyrodactylus-induced mortality than untreated males. Together, these results suggest that androgens reduce the ability of guppies to control parasite loads, and modulate resistance to and survival from infection. We discuss the relevance of these findings for understanding constraints on the evolution of resistance in guppies and other vertebrates.
Classification schemes are useful when they elucidate common underlying mechanisms, bring together diverse examples, or illustrate gaps in knowledge for empirical investigation. Kline's scheme merges different approaches, but is orthogonal to existing schemes and overemphasizes evolved specializations, potentially at the detriment of clarifying teaching processes. Focus on underlying mechanisms, what is learned, and consequences for information transfer may provide additional utility.
Investigations of biases and experiential effects on social learning, social information use, and mirror systems can usefully inform one another. Unconstrained learning is predicted to shape mirror systems when the optimal response to an observed act varies, but constraints may emerge when immediate error-free responses are required and evolutionary or developmental history reliably predicts the optimal response. Given the power of associative learning, such constraints may be rare.
Outcome transparency and the weight given to social information both play important roles in decision making, but we argue that an overarching influence is the degree to which individuals can and do gather information. Evolution, experience, and development may shape individual specializations in social decision making that carry over across contexts, and these individual differences may influence collective behavior and cultural evolution.
If we use the 1992 publication date of The Adapted Mind as the birth date of evolutionary psychology then, at the time of writing, it is now 21 years old, traditionally the age at which children become adults and are expected to make their way in the big, wide world. It therefore seems to be an appropriate time to ask whether evolutionary psychology has, as it were, become a respectable member of the scientific community, or whether it is still metaphorically tied to the apron strings of its progenitors at the University of California, Santa Barbara: loved by its parents but ignored or even despised by its peers?
Part of an answer to this question can be seen in some subtle changes to this book compared to previous editions. When we wrote the first edition way back in the late 1990s and early 2000s the Santa Barbara version of evolution psychology was pre-eminent. The manifesto that was enshrined in The Adapted Mind proposed domain specific mental modules that evolved in some mythical time and place referred to as the Environment of Evolutionary Adaptedness, or the EEA. We were enthralled by tales of hunter-gatherers in the Upper Pleistocene, of images of minds festooned with tools like Swiss Army knives, and of the principle that minds adapted for ancestral tasks might be less than successful in the twentieth (as it then was) century. This precocious child gained many vocal supporters in the scientific community, philosopher Daniel Dennett and psycholinguist Steven Pinker to name just two prominent members. But there were many critics and many points of criticism. Developmentalist Annette Karmiloff-Smith, for example, questioned the notion of innate mental modules, evolutionary anthropologists such as Eric Alden Smith pointed at problems with the concept of the EEA and David Buller, well, David Buller seemed to dislike all of it. Not to be outdone by his erstwhile colleague, philosopher Jerry Fodor – who started the whole modularity movement in the first place – wrote a book with Massimo Piattelli-Palmarini which attempted to show that the whole concept of evolution by natural selection was philosophically untenable (an argument that was dismantled by two other philosophers, Ned Block and Philip Kitcher, who managed to keep their faces admirably straight throughout).
personality • niche fitting • heritability • frequency dependent selection • intelligence • general intelligence (g) • multiple intelligences
A great deal of research in psychology has focused on differences among individuals. Psychologists have been particularly interested in individual differences in personality and intelligence, investigating the underlying causes of these differences and how they might affect other aspects of life such as career development, success in relationships and susceptibility to mental illness. Evolutionary psychology with its focus on ultimate questions asks a different question. What is the function, if any, of individual differences? Why, for example, are some people sensation-seeking extraverts while others are timid stay-at-home introverts? Why are some people smart and others less so? One answer could be that these characteristics reflect differences in upbringing; that they are the result of environmental rather than genetic differences. Intelligent individuals were given more educational opportunities than less intelligent individuals; extraverts were encouraged to be bold and so on. But this cannot be the whole story. Research has shown that many of these traits are heritable, suggesting that at least some of the variation in the aforementioned characteristics is down to the effects of genes. But this poses another problem. We know that natural selection promotes certain genes over others by virtue of their superior phenotypic effects, thereby reducing genetic variability in a species, so why haven’t all of these genetic differences been removed from the gene pool? Is there some hidden benefit in having variability in personality and intelligence within our species? This chapter focuses on these (and other) questions, and in doing so it draws on material covered in previous chapters and points the way to the future of evolutionary psychology; an evolutionary psychology that views genes as dynamic, shaping the phenotype using decision rules that act upon environmental information.
learnability argument • ostensive communication • Universal Grammar (UG) • parameter setting • inflectional morphology • derivational morphology • FOXP2 gene • specific language impairment social grooming hypothesis • social contract hypothesis
Without language, social interaction would be impoverished beyond recognition. It enables us to reveal our innermost thoughts to others, or, if the mood takes us, to disguise them with misinformation and lies. With language, action can be coordinated so that a group of people can act as one – even if chimpanzees could conceive of a pyramid they still couldn’t build one because they lack the ability to coordinate action through language. Language also, as we shall see in chapter 14, enables hard-won knowledge to be passed on to others – including our children – enabling culture to proliferate in ways that would not have been possible in our languageless ancestors. When language evolved it was evolutionary dynamite. Not only did it vastly extend the range of things that ancestral humans were capable of, enabling them, perhaps, to outcompete other hominins around at the time, but it is also likely to have had an impact on the evolution of the brain itself. It is unlikely that our languageless ancestors had brains identical to ours but lacking the appropriate language circuitry; it is more likely that the gradual increase in communicative sophistication led to huge leaps in the way that the mind worked. So great are the advantages of language to our species that surely it must have been the product of natural (or sexual) selection. This chapter begins by outlining the modular account of language, currently popular within evolutionary psychology. We then go on to discuss when in our evolutionary history language might have emerged and finally we present some accounts as to why language evolved.
life history theory • attachment styles • r–K continuum • C–F continuum • principle of allocation • shared environment • non-shared environment • behavioural genetics • group socialisation theory • moral development
Some early developmentalists were influenced by Darwinian thinking. John Bowlby, for instance, proposed that the child is born with certain biological needs and that normal development is dependent upon these needs being met. Failure to do so could result in a wide range of problems in later life including criminality, intellectual under-achievement, promiscuity and psychological disturbances. More recently an evolutionary approach known as life history theory has been used to understand human development. This perspective suggests that some individual differences might be the result of children deploying different evolutionary strategies based on their childhood environment. Behavioural genetics research has also been crucial in unravelling the effects of nature and nurture on the developing child. This has led to a controversial theory which states that socialisation is carried out in peer groups. Finally we also discuss evolutionary approaches to moral development presenting research that suggests that the function of the moral sense is to enable us to exist in groups with non-kin.
What is development for?
Childhood presents us with something of a paradox. Evolutionary theory teaches us that the only valid strategy in the game of life is to pass on more copies of your genes than your competitors, in which case it might seem strange that humans (and many other organisms) spend such a large amount of time being unable to reproduce. Furthermore, rearing offspring produces a considerable drain on parents’ resources, reducing the survival chances of both parties (young orphans are unlikely to survive in many species). Given these basic facts it would seemingly make evolutionary sense for childhood (defined as that part of the life cycle where the individual is sexually immature) to be as short as possible in order to maximise reproductive opportunities and minimise the burden of parenting. So why is it that human beings (and other primates) have such a long childhood? Assuming that evolutionary theory is correct, how can we explain such a long period of sexual immaturity? Put another way, what is childhood for?
inclusive fitness • direct and indirect fitness • coefficient of relatedness • kin altruism • parental investment • parent–offspring conflict • K- and r-selection • parental manipulation
To many people human behaviour is social behaviour. Linguistic communication is meaningless unless used between at least two people; sex by definition involves more than one person (usually, although not invariably, two); child rearing and sibling relationships are clearly social and most working practices occur in groups. Humans do engage in some solitary activities – reading a book or taking a bath, for example, are not normally social events. But even by primate standards, we are an extremely socially integrated species. So it’s not surprising that some evolutionary theorists have suggested that evolutionary psychology may have the greatest impact on social psychology (Neuberg et al., 2010; Wilson, 2012). Social behaviour can broadly be divided into pro- and antisocial patterns of response. Both can be found frequently in interactions that involve kin. Social scientists have long sought to explain why such love–hate relationships exist in families. Evolutionary psychologists think they have the answer – to them it’s all about evolved psychological mechanisms that would have aided inclusive fitness during the EEA.
Social psychology and evolutionary theory
Social psychology is a well-developed area of psychological enquiry. During the twentieth century, social psychologists developed theories to account for, among other things, group conformity, in- and out-group stereotyping, intergroup aggression, social concept and attitude formation (Hewstone et al., 2012). Moreover, it has been very successful in testing these theories in both the lab and field. So what can the evolutionary approach bring to improve our understanding of human social behaviour?
superorganic • cultural transmission • evoked culture • transmitted culture • dual inheritance theory • gene-culture co-evolution • culturegens • memes and memetics • imitation
The study of culture is usually the preserve of social anthropologists, sociologists and cultural theorists who have developed sophisticated theories to describe and explain cultural phenomena. Recently, there has been much interest in an evolutionary approach to culture. In contrast to many earlier theories these evolutionary theories attempt to provide ultimate rather than proximate explanations of culture. One of the biggest ultimate questions about culture is why do we have culture at all? From this perspective, the phenomenon of culture is not something that ‘just happened’; there is good evidence that human culture needs a particular sort of brain in order to sustain it. Therefore, there is a distinct possibility that the emergence of culture conferred some advantage to our ancestors in terms of their inclusive fitness (see chapters 2 and 7). In addition to ultimate questions, evolutionists have also asked proximate questions. What, for example, are the cognitive processes that are necessary to enable the transmission of culture, what psychological factors can lead to changes in cultural practices and what is the relationship between culture and genes? The following chapter addresses these and other questions in exploring the relationship between evolution and culture.
The importance of culture
Human beings have come a long way in a remarkably short time. In a mere 10,000 years or so – the blink of an eye by evolutionary standards – we have gone from living in small hunter-gatherer communities with primitive artefacts to vast liberal democracies with intensive agriculture, writing, mass education and Twitter. Ten thousand years is generally regarded as too short a time for our brains to have changed significantly, so the difference between us and our ancestors is unlikely to be a result of changes in our mental hardware (the brain). Rather it seems that these differences are due to continual changes in software – the knowledge that we have acquired and the practices that this knowledge informs. These repeated software upgrades come courtesy of other people through the process of cultural transmission.
nativism • empiricism • constructivism • epigenetic landscape • imprinting • critical period • sensitive period • Machiavellian intelligence • theory of mind • autism • Williams syndrome • neuroconstructivism • biological preparedness • cortical plasticity
Evolutionary psychology often makes strong claims about innateness, that the child is born with innate (inborn) mental modules that enable it to develop competencies in areas that have strong fitness implications. For this reason, early cognitive development has become one of the battlegrounds for evolutionary psychologists and their critics. In this chapter we evaluate the modularity hypothesis, introduced in chapter 1, and look at developmental evidence for and against this particular claim of evolutionary psychology. As a result of some evidence that apparently contradicts the notion of innate modules some have concluded that evolutionary psychology itself is untenable. Others, however, propose that modularity is not an essential component of evolutionary psychology and that evolutionary psychology can progress without a commitment to modularity.
Nature, nurture and evolutionary psychology
One of the central debates of developmental psychology is the so-called ‘nature versus nurture’ debate. This asks to what extent human behaviour is the result of environmental factors (nurture) and to what extent it is the result of innate biological factors (nature). This question has a long history, starting at least as early as the Ancient Greek philosophers, and has been revisited by a variety of thinkers ever since. Throughout history the pendulum of opinion has swung in favour of one or other of these forces as new theories are developed and evidence accumulated. Recently the evolutionary approach has led to a renaissance in nativism as a means of explaining human behaviour and, in particular, that human development is constrained by the existence of innate mental modules.