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Development consists of a highly ordered suite of steps and transitions, like choreography. Although these sequences are often evolutionarily conserved, they can display species variations in duration and speed, thereby modifying final organ size or function. Despite their evolutionary significance, the mechanisms underlying species-specific scaling of developmental tempo have remained unclear. Here, we will review recent findings that implicate global cellular mechanisms, particularly intermediary and protein metabolism, as species-specific modifiers of developmental tempo. In various systems, from somitic cell oscillations to neuronal development, metabolic pathways display species differences. These have been linked to mitochondrial metabolism, which can influence the species-specific speed of developmental transitions. Thus, intermediary metabolic pathways regulate developmental tempo together with other global processes, including proteostasis and chromatin remodeling. By linking metabolism and the evolution of developmental trajectories, these findings provide opportunities to decipher how species-specific cellular timing can influence organism fitness. Developmental trajectories are often evolutionarily conserved, yet they can display substantial temporal differences across species. In this review, Iwata and Vanderhaeghen discuss how global mechanisms, including mitochondrial metabolism and proteostasis, may contribute to interspecies differences in developmental timescales in various systems. [ABSTRACT FROM AUTHOR]

Human-specific genes are potential drivers of brain evolution. Among them, SRGAP2C has contributed to the emergence of features characterizing human cortical synapses, including their extended period of maturation. SRGAP2C inhibits its ancestral copy, the postsynaptic protein SRGAP2A, but the synaptic molecular pathways differentially regulated in humans by SRGAP2 proteins remain largely unknown. Here, we identify CTNND2, a protein implicated in severe intellectual disability (ID) in Cri-du-Chat syndrome, as a major partner of SRGAP2. We demonstrate that CTNND2 slows synaptic maturation and promotes neuronal integrity. During postnatal development, CTNND2 moderates neuronal excitation and excitability. In adults, it supports synapse maintenance. While CTNND2 deficiency is deleterious and results in synaptic loss of SYNGAP1, another major ID-associated protein, the human-specific protein SRGAP2C, enhances CTNND2 synaptic accumulation in human neurons. Our findings suggest that CTNND2 regulation by SRGAP2C contributes to synaptic neoteny in humans and link human-specific and ID genes at the synapse. [Display omitted] • CTNND2 regulates the pace of synaptic maturation and intrinsic excitability • CTNND2 is necessary for the synaptic accumulation of the ID/ASD protein SYNGAP1 • SRGAP2A inhibition by human-specific SRGAP2C enhances CTNND2 level at synapses • CTNND2 regulation by SRGAP2 proteins likely contributes to human synaptic neoteny Assendorp et al. report that CTNND2, an ID-associated protein, moderates synaptic excitation and excitability and regulates the pace of synaptic maturation across species. They demonstrate that CTNND2 is specifically regulated in humans, which likely contributes to the extended period of synaptic maturation characteristic of human cortical pyramidal neurons. [ABSTRACT FROM AUTHOR]

Abstract In the present paper, the authors use Tinbergen's (1963) seminal four question framework regarding ontogeny, causation, function, and phylogeny to understand individual differences in human shyness. We argue that there are at least two shyness subtypes, an early appearing fearful shyness, and a later emerging self-conscious shyness (Buss, 1986) that develop into avoidant and conflicted shyness, respectively, in early childhood and remain relatively stable into adulthood. We proffer that each shyness subtype is presumed to have a different cause and function: fearful/avoidant shyness results from social novelty, its function is to motivate vigilance, action and avoidance of impending threat and harm from conspecifics, and is subserved by evolutionarily old brain circuits; self-conscious/conflicted shyness results from the experience of competing emotions of interest and fear of negative evaluation in social situations, its function is to allow more time for additional learning to take place about conspecifics' intentions and motives before responding, and is linked to relatively newer brain circuits. We argue for a highly speculative idea that self-conscious/conflicted shyness bifurcated from fearful/avoidant shyness later in human evolution as the neocortex grew bigger, self-awareness emerged, and the nature of social interactions became more complex. We further speculate that conflicted shyness may be reflective of neoteny (i.e., delaying maturity and retaining child-like features into adulthood). We also provide some ways in which this shyness-neoteny hypothesis can be empirically tested. We conclude by suggesting that considering the adaptive value of some temperamental phenotypes has implications for how we view normal and abnormal behavior. [ABSTRACT FROM AUTHOR]

Abstract Insect metamorphosis produces reproductive adults and is commonly accompanied with the direct or indirect development of wings. In some winged insects, the imago is altered by life history changes. For instance, in scale insects and mealybugs, reproductive females retain juvenile features and are wingless. The transcription factor E93 triggers metamorphosis and plays in concert with the juvenile hormone pathway to guarantee the successful transition from juvenile to adult. We previously provided evidence of an atypical down-regulation of the juvenile hormone pathway during female development in the Japanese mealybug. Here, we further investigate how E93 is involved in the production of neotenic wingless females, by identifying its isoforms, assessing their expression patterns and evaluating the effect of exogenous juvenile hormone mimic treatment on E93. This study identifies three E93 isoforms on the 5' end, based on Japanese mealybug cDNA and shows that female development occurs with the near absence of E93 transcripts, as opposed to male metamorphosis. Additionally, while male development is typically affected by exogenous juvenile hormone mimic treatments, females seem to remain insensitive to the treatment, and up-regulation of the juvenile hormone signaling is not observed. Furthermore, juvenile hormone mimic treatment on female nymphs did not have an obvious effect on E93 transcription, while treatment on male prepupae resulted in depleted E93 transcripts. In this study, we emphasize the importance in examining atypical cases of metamorphosis as complementary systems to provide a better understanding on the molecular mechanisms underlying insect metamorphosis. For instance, the factors regulating the expression of E93 are largely unclear. Investigating the regulatory mechanism of E93 transcription could provide clues towards identifying the factors that induce or suppress E93 transcription, in turn triggering male adult development or female neoteny. Graphical abstract Image 1 Highlights • Neotenic female development of Planococcus kraunhiae (Japanese mealybug) correlates with low E93 expression. • E93 expression profile during mealybug male development resembles that in other insects. • JH mimic treatment suppresses E93 expression in male prepupae but not in female nymphs. • Female mealybugs have low sensitivity to JH mimics compared to males and other insects. [ABSTRACT FROM AUTHOR]

Abstract Tardigrades form a monophyletic group of microscopic ecdysozoans best known for surviving extreme environmental conditions. Due to their key phylogenetic position as a subgroup of the Panarthropoda, understanding tardigrade biology is important for comparative studies with related groups like Arthropoda. Panarthropods — and Ecdysozoa as a whole — likely evolved from macroscopic ancestors, with several taxa becoming secondarily miniaturized. Morphological and genomic evidence likewise points to a miniaturized tardigrade ancestor. The five-segmented tardigrade body typically measures less than 1 mm in length and consists of only about 1000 cells. Most organs comprise a relatively small number of cells, with the highest proportion belonging to the central nervous system, while muscles are reduced to a single cell each. Similarly, fully sequenced genomes of three tardigrade species — together with Hox gene expression data — point to extensive modifications, rearrangements, and major losses of genes and even a large body region. Parallels are evident with related ecdysozoans that may have also undergone genomic reductions, such as the nematode Caenorhabditis elegans. We interpret these data together as evidence of miniaturization in the tardigrade lineage, while cautioning that the effects of miniaturization may manifest in different ways depending on the organ or organ system under examination. Highlights • All major organ systems of tardigrades show reductions in number and size of cells. • Respiratory and circulatory systems have probably been lost. • Genome has been reduced and Hox and NK gene clusters have been disintegrated. • Five-segmented body might have resulted from the loss of a large middle region. • Miniaturization may have originated due to the ancestral interstitial lifestyle. [ABSTRACT FROM AUTHOR]

Family groups with helpers occur in several species of fish, birds and mammals. In such cooperatively breeding species all group members help with raising the offspring, i.e. parents and offspring from previous litters. While the ecological reasons and ultimate consequences of allo-parental care have been studied in detail, we know little about its physiological regulation. We propose three alternative hypotheses for the endocrine regulation of allo-parental care. 1. The neoteny-helper hypothesis predicts that helpers that did not undergo adolescence yet show helping behavior without any endocrine mechanisms activating it, as helping is the default response towards infant stimuli. The endocrine changes during adolescence would then deactivate helping behavior. 2. The parent-helper hypothesis predicts that helpers undergo the same endocrine changes as parents (increased prolactin and corticosterone levels; decreased testosterone in males but increased estrogen in females). We predict that this hypothesis is especially important in post-adolescent helpers. 3. The helper-specific hypothesis predicts that there are specific endocrine mechanisms that only exist in helpers but not in breeders. We review evidence for these three hypotheses in 23 species of fish, birds, and mammals. We found no evidence for the helper-specific hypothesis but for both other hypotheses. As predicted, this depended on whether helpers were pre- or post-adolescent, but information on whether or not helpers underwent adolescence was often missing. Thus, future studies should investigate whether or not helpers have reached sexual maturity, differentiate between pre- and post-adolescent helpers, and study behavioral changes in helping behavior during adolescence. We conclude that the neurobiological circuits in the brain necessary for allo-parental care might often be the default stage in helpers from cooperative breeding species, which might be deactivated by specific endocrine mechanisms during adolescence, and then would need reactivation for allo-parental and parental care. [ABSTRACT FROM AUTHOR]

Abstract The neotenic elaterid genus Drilus Olivier, 1790 (Elateridae: Agrypninae: Drilini) contains more than 40 species distributed primarily in the Mediterranean region. The precise number of species remains ambiguous due to the insufficient taxonomic investigation in several areas. Herein, we study Drilus diversity in Cyprus and we recognize the following species: D. humeralis Pic, 1931, D. rectus Schaufuss, 1867, and D. rufipes ( Baudi di Selve, 1871 ). Drilus testaceipes Pic, 1933 syn. nov. is synonymized under D. rectus , and D. truquii ( Baudi di Selve, 1871 ) syn. nov. is synonymized under D. rufipes. As consequence of these taxonomic changes, Drilus humeralis remains the only species endemic to Cyprus. Females of D. rectus and D. rufipes are described and figured for the first time, as well as the larvae of D. rufipes. A key to the males of Drilus species in Cyprus is given. Drilus rectus is recorded in Syria for the first time and D. rufipes is recorded in Rhodes. To examine the phylogenetic relationships of Drilus in Cyprus, we produced the cox1- 3ʹ, cox1- 5′ and rrnL mtDNA sequences for available specimens of D. rectus and D. rufipes and merged them with data from GenBank. Results of the maximum likelihood analysis and Bayesian inference suggest a close relationship between D. rectus and Drilus cf. mertliki from Turkey, and a sister position of D. rufipes to a clade formed by the species from the Ionian Islands, Peloponnese, and Crete. Using the multigene barcoding approach including the above mentioned mitochondrial markers and the nuclear arginine kinase, we have been able to associate the different larval stages from Cyprus with the adult males of D. rufipes , and confirm the intraspecific variability in male body size and antennal coloration. Moreover, the low genetic difference in the cox1- 3′ fragments indicates the close relationship between D. rectus populations from Cyprus and southern Turkey. [ABSTRACT FROM AUTHOR]

Although shyness is a ubiquitous phenomenon and long viewed as a maladaptive characteristic, we know relatively little about the possible brain mechanism(s) underlying and maintaining shyness. Using a prospective longitudinal study, we examined frontal brain maturation in shy children. We collected measures of resting regional EEG spectral power approximately every six months for two years in young school-age children and characterized frontal brain maturation using a growth curve analysis of proportion of spectral power in relative faster-to-slower EEG frequencies. We found that children classified as low in shyness exhibited a significant linear growth in the proportion of overall frontal alpha power relative to delta power across assessments relative to children classified as high in shyness. High shy children displayed no growth in the proportion of overall frontal alpha power relative to delta power across assessments. These preliminary results indicate that high shy children exhibited delayed frontal brain maturation compared to low shy children. We interpret these findings within the context of a proximate explanation, suggesting links between delayed frontal maturation and emotion dysregulatory processes related to an approach-avoidance conflict. We also speculate on an ultimate explanation in which delayed frontal brain maturation may reflect neoteny (i.e., the prolongation and extension of childhood), which may have supported an adaptive function of shyness across human evolution. [ABSTRACT FROM AUTHOR]

The function of life history (LH) strategies acquired in response to ambient conditions during childhood is to maximize reproductive success. Mate preferences that facilitate reproductive goals should thus vary with LH strategies. In two studies, male participants completed measures of LH and mate preferences regarding fertility and good genes, fidelity and good mothers, and modernity and good provisioning (Study 1) or a face identification task designed to assess perceptual sensitivity toward neoteny representing fertility (Study 2). Results showed that men identified as of fast LH preferred physically attractive women and prioritized fertility and good genes over fidelity and good mothers in their mate selections. Moreover, they were sensitive to female fertility features, as evidenced by them spending less time identifying odd faces that differed from other faces in terms of neoteny. These findings suggest that men of faster LH are more likely to invest in mating than parenting and preferred mates of high reproductive potential over those representing high parental investment. [ABSTRACT FROM AUTHOR]

Axolotl ( Ambystoma Mexicanum ) has been emerging as a promising model in stem cell and regeneration researches due to its exceptional regenerative capacity. Although it represents lifelong lasting neoteny, induction to metamorphosis with thyroid hormones (THs) treatment advances the utilization of Axolotl in various studies. It has been reported that amphibians undergo anatomical and histological remodeling during metamorphosis and this transformation is crucial for adaptation to terrestrial conditions. However, there is no comprehensive histological investigation regarding the morphological alterations of Axolotl organs and tissues throughout the metamorphosis. Here, we reveal the histological differences or resemblances between the neotenic and metamorphic axolotl tissues. In order to examine structural features and cellular organization of Axolotl organs, we performed Hematoxylin & Eosin , Luxol-Fast blue , Masson’s trichrome , Alcian blue , Orcein and Weigart’s staining. Stained samples from brain, gallbladder, heart, intestine, liver, lung, muscle, skin, spleen, stomach, tail, tongue and vessel were analyzed under the light microscope. Our findings contribute to the validation of the link between newly acquired functions and structural changes of tissues and organs as observed in tail, skin, gallbladder and spleen. We believe that this descriptive work provides new insights for a better histological understanding of both neotenic and metamorphic Axolotl tissues. [ABSTRACT FROM AUTHOR]

Among the Carnivora, play behaviour is usually made up of motor patterns characteristic of predatory, agonistic and courtship behaviour. Domestic dogs are unusual in that play is routinely performed by adults, both socially, with conspecifics and with humans, and also asocially, with objects. This enhanced playfulness is commonly thought to be a side effect of paedomorphosis, the perpetuation of juvenile traits into adulthood, but here we suggest that the functions of the different types of play are sufficiently distinct that they are unlikely to have arisen through a single evolutionary mechanism. Solitary play with objects appears to be derived from predatory behaviour: preferred toys are those that can be dismembered, and a complex habituation-like feedback system inhibits play with objects that are resistant to alteration. Intraspecific social play is structurally different from interspecific play and may therefore be motivationally distinct and serve different goals; for example, dogs often compete over objects when playing with other dogs, but are usually more cooperative when the play partner is human. The majority of dogs do not seem to regard competitive games played with a human partner as “dominance” contests: rather, winning possession of objects during games appears to be simply rewarding. Play may be an important factor in sociality, since dogs are capable of extracting social information not only from games in which they participate, but also from games that they observe between third parties. We suggest that the domestic dog's characteristic playfulness in social contexts is an adaptive trait, selected during domestication to facilitate both training for specific purposes, and the formation of emotionally-based bonds between dog and owner. Play frequency and form may therefore be an indicator of the quality of dog-owner relationships. [ABSTRACT FROM AUTHOR]

Distinct life stages may experience different selection pressures influencing phenotypic evolution. Morphological evolution is also constrained by early phenotypes, since early development forms the phenotypic basis of later development. This work investigates evolutionary-developmental modification in three life stages and both sexes of 24 Rhipicephalus species using phylogenetic comparative methods for geometric morphometrics of basis capituli (basal mouthpart structure used for host attachment), and scutum or conscutum areas (proxy for overall body size). Findings indicate species using large hosts at early life stages have distinct basis capituli shapes, correlated with host size, enabling attachment to the tough skins of large hosts. Host-truncate species (one- and two-host) generally retain these adaptive features into later life stages, suggesting neoteny is linked to the evolution of host truncation. In contrast, species using small hosts at early life stages have lost these features. Developmental trajectories differ significantly between host-use strategies (niches), and correlate with distinct clades. In two-host and three-host species using large hosts at early life stages, developmental change is heterotopically accelerated (greater cell mass development) before the first off-host period where selection probably favours large individuals able to better resist dehydration when questing (waiting) for less abundant, less active hosts. In other species, development is heterotopically reduced (neotenic), possibly because dehydration risk is bypassed by prolonged host attachment (one-host species – heterotopic neoteny), or is allometrically repatterned possibly by using highly abundant and active hosts (three-host species using small hosts at early life stages – allometric repatterning). These findings highlight complex trade-offs between on- and off-host factors of free-living ectoparasite ecology, which mediate responses to diverse selection pressures varied by life stage and host-use strategy. It is proposed that these trade-offs shape evolutionary-developmental morphology and diversity of Rhipicephalus ticks. [Display omitted] • Species using large hosts at early life stages have distinct basis capituli to facilitate attachment to large hosts. • Evolutionary modulation of developmental trajectories respond to on- and off-host conditions between host-use strategies. • Neoteny occurs in host-truncate species, likely as adaptive responses to selection for using large hosts at early life stages. [ABSTRACT FROM AUTHOR]

Abstract: Parental care is widespread in the animal kingdom and enhances offspring survival. Amphibians exhibit an extraordinary diversity of care strategies, including guarding, transport and even feeding of young. Among amphibians, females are usually the carers, but here we present a case of male parental care in the aquatic salamander Siren intermedia, accompanied by records of external fertilisation. Sirenids are a phylogenetically distinct group within basal salamanders, of which the precise systematic position has long been debated. Our observations of external fertilisation and paternal care of S. intermedia lead us to conclude that apparently both internal fertilisation and maternal care evolved after the split between the more basal groups (Cryptobranchoidea and Sirenoidea) and all other salamanders (suborder Salamandroidea). [Copyright &y& Elsevier]

Abstract: The gonangulum is a sclerite in the female genitalic region of insects. Its presence or full development has long been considered an apomorphy supporting Zygentoma + Pterygota. Recent studies of female genitalia in several insect orders (K.-D. Klass and co-workers) revealed many new data on the gonangulum and homologous sclerotisations (laterocoxa LC9). Herein the gonangulum area is described (including articulations, muscle attachments, sulci) and compared among Archaeognatha, Zygentoma, Odonata, Dermaptera, Dictyoptera, and Notoptera. A wider perspective is provided to the topic by addressing some novel issues: identification of LC9 sclerotisations in non-insect taxa and in insects that secondarily lack an ovipositor; occurrence of homonomous sclerotisations in other abdominal segments of both sexes; morphological interpretation of LC9; and the role of paedomorphosis in LC9 evolution. As a result, there is currently no support for any insect lineage from this character system. For gonangulum-related characters both a significant intra-ordinal variation and frequent homoplasy are demonstrated using various Odonata, Dermaptera, and Dictyoptera as examples. Divergent fates of LC9 in simplified genitalia are shown using a dermapteran and an odonatan. We view all this as a showcase of how a renewed and more detailed examination of a character system can dramatically change the phylogenetic evidence drawn from it. [Copyright &y& Elsevier]

Abstract: Facial attractiveness has been studied extensively, but little research has examined the stability of facial attractiveness of individuals across different stages of development. We conducted a study examining the relationship between facial attractiveness in infants (age 24 months and under) and the same individuals as young adults (age 16–18 years) using infant and adult photographs from high school yearbooks. Contrary to expectations, independent raters’ assessments of infant facial attractiveness did not correlate with adult facial attractiveness. These results are discussed in terms of the adaptive function of heightened attractiveness in infancy, which likely evolved to elicit and maintain parental care. [Copyright &y& Elsevier]

Abstract: A detailed study of the exoskeleton and musculature of the phallic organ of Oxyartes lamellatus (Kirby, 1904) (Phasmatodea: Necrosciinae) is here presented – the first study of this kind for Phasmatodea. The asymmetrical phallic organ shows a highly complicated morphology, with several sclerites and many formative structural elements, of which a sclerotised bulb in the ejaculatory duct wall and a long flagellum arising from near it are among the most conspicuous. Four extrinsic and 20 intrinsic phallic muscles were found; many of these are quite compact bundles or sheets, while a few others are diffuse groups of fibres. Phallic morphology in Oxyartes is compared with the literature data on male genitalia in other Phasmatodea, but this is limited by the superficial treatment of phallic organs in the few relevant previous contributions. Yet, phallic organs appear as a useful new character system for phylogenetic reconstruction and species distinction in Phasmatodea. Comparison with phallic organs in other ‘orthopteroid’ insects shows that these organs are too different among orders as to allow for sound homologisation of phallic substructures. Consideration of development of phallic organs does not help in this aspect. There is no evidence of phasmatodean phallic organs being pedomorphic. [Copyright &y& Elsevier]

Abstract: We describe two geographically differentiated venom phenotypes across the wide distribution range of Bothrops atrox, from the Colombian Magdalena Medio Valley through Puerto Ayacucho and El Paují, in the Venezuelan States of Amazonas and Orinoquia, respectively, and São Bento in the Brazilian State of Maranhão. Colombian and Venezuelan venoms show an ontogenetic toxin profile phenotype whereas Brazilian venoms exhibit paedomorphic phenotypes. Venoms from each of the 16 localities sampled contain both population-specific toxins and proteins shared by neighboring B. atrox populations. Mapping the molecular similarity between conspecific populations onto a physical map of B. atrox range provides clues for tracing dispersal routes that account for the current biogeographic distribution of the species. The proteomic pattern is consistent with a model of southeast and southwest dispersal and allopatric fragmentation northern of the Amazon Basin, and trans-Amazonian expansion through the Andean Corridor and across the Amazon river between Monte Alegre and Santarém. An antivenomic approach applied to assess the efficacy towards B. atrox venoms of two antivenoms raised in Costa Rica and Brazil using Bothrops venoms different than B. atrox in the immunization mixtures showed that both antivenoms immunodepleted very efficiently the major toxins (PIII-SVMPs, serine proteinases, CRISP, LAO) of paedomorphic venoms from Puerto Ayacucho (Venezuelan Amazonia) through São Bento, but had impaired reactivity towards PLA2 and P-I SVMP molecules abundantly present in ontogenetic venoms. The degree of immunodepletion achieved suggests that each of these antivenoms may be effective against envenomations by paedomorphic, and some ontogenetic, B. atrox venoms. [Copyright &y& Elsevier]

Paedomorphosis is an evolutionary change in morphology through an alteration in the rate or timing of a developmental pathway, resulting in more derived species appearing juvenilised in comparison to their ancestors. This concept has long been the subject of extensive, often intimidating, discussion in the animal literature, but is less frequently considered by only a few plant developmentalists. We define the main types of paedomorphosis and explain how they can be applied to plants, considering the differences between plant and animal lifecycles. We provide examples of plant paedomorphoses and point out their likely significance in the evolution of floral diversity. [Copyright &y& Elsevier]

Summary: In previous editorials I have written about the absent-minded and socially-inept ‘nutty professor’ stereotype in science, and the phenomenon of ‘psychological neoteny’ whereby intelligent modern people (including scientists) decline to grow-up and instead remain in a state of perpetual novelty-seeking adolescence. These can be seen as specific examples of the general phenomenon of ‘clever sillies’ whereby intelligent people with high levels of technical ability are seen (by the majority of the rest of the population) as having foolish ideas and behaviours outside the realm of their professional expertise. In short, it has often been observed that high IQ types are lacking in ‘common sense’ – and especially when it comes to dealing with other human beings. General intelligence is not just a cognitive ability; it is also a cognitive disposition. So, the greater cognitive abilities of higher IQ tend also to be accompanied by a distinctive high IQ personality type including the trait of ‘Openness to experience’, ‘enlightened’ or progressive left-wing political values, and atheism. Drawing on the ideas of Kanazawa, my suggested explanation for this association between intelligence and personality is that an increasing relative level of IQ brings with it a tendency differentially to over-use general intelligence in problem-solving, and to over-ride those instinctive and spontaneous forms of evolved behaviour which could be termed common sense. Preferential use of abstract analysis is often useful when dealing with the many evolutionary novelties to be found in modernizing societies; but is not usually useful for dealing with social and psychological problems for which humans have evolved ‘domain-specific’ adaptive behaviours. And since evolved common sense usually produces the right answers in the social domain; this implies that, when it comes to solving social problems, the most intelligent people are more likely than those of average intelligence to have novel but silly ideas, and therefore to believe and behave maladaptively. I further suggest that this random silliness of the most intelligent people may be amplified to generate systematic wrongness when intellectuals are in addition ‘advertising’ their own high intelligence in the evolutionarily novel context of a modern IQ meritocracy. The cognitively-stratified context of communicating almost-exclusively with others of similar intelligence, generates opinions and behaviours among the highest IQ people which are not just lacking in common sense but perversely wrong. Hence the phenomenon of ‘political correctness’ (PC); whereby false and foolish ideas have come to dominate, and moralistically be enforced upon, the ruling elites of whole nations. [Copyright &y& Elsevier]

Life span development and the life course perspective deal with disparate explonanda (outcomes), but share common explanantia (explanatory strategies). Both approaches originated by introducing into the subject matter of age an innovative and sometimes courageous emphasis on context, inspired by discoveries of cohort differences and historical variations in patterns of aging. Despite these promising beginnings four decades ago, key aspects of the relation between lifespan/life course and context remain largely undeveloped, because of an undue reliance on traditional paradigmatic assumptions in both traditions, which we here call the positivist-functionalist (in the following called PF) model. What remains yet underdeveloped and in need of extended interrogation are the fundamental bases of human development and human social relations. These bases include two dialectically interrelated dynamics that are elements of a social-constitutive (SC) model, which recognizes that (1) individual development and agency are not just influenced, but constituted by lived experience in a specific social context, and (2) social systems are constituted only through agentic human action. This paper identifies theoretical resources that can he used to further this inquiry, and illustrates the value of such resources by showing how they can be used to illuminate the problems of agency, linked lives, and questions of the relationship between lifespan/life course and evolutionary thought. [ABSTRACT FROM AUTHOR]

Abstract: The fish ectoparasites Branchiura (Crustacea) display two different ways of attachment to the fish surface as adults: the first maxillae are either hooks (Dolops) or suction discs (Argulus, Chonopeltis, and Dipteropeltis). In larval Argulus foliaceus the first maxillae are hooks. With the first molecular phylogeny of the Branchiura as a background, the present paper discusses the evolutionary scenarios leading to hooks versus suction discs. Specific homologies exist between larval Argulus foliaceus hooks and adult Dolops ranarum hooks. These include the presence of a comparable number of segments/portions and a distal segment terminating in a double structure: a distal two-part hook (in Argulus) or one hook and an associate spine-like structure (in Dolops). In the phylogenetic reconstruction based on three molecular markers (mitochondrial 16S rRNA, nuclear 18S and 28S rRNA), Dolops ranarum is found to be in a sister group position to all other Branchiura, which in this analysis include six Argulus and one Chonopeltis sequences. Based on the molecular phylogeny a likely evolutionary scenario is that the ancestral branchiuran used hooks (on the first maxilla) for attachment, as seen in Dolops, of which the proximal part was subsequently modified into suction discs in Argulus and Chonopeltis (and Dipteropeltis). The sister group relationship of the Branchiura and Pentastomida is confirmed based on the most comprehensive taxon sampling until now. No evidence was found for a branchiuran in-group position of the Pentastomida. [Copyright &y& Elsevier]

Abstract: This research investigated the partner characteristics that are attributed to male facial masculinity, and how these characteristics compare to those attributed to increased age or health in faces. We found that masculinity is perceived as reflecting heightened dominance, but reduced suitability as a long term partner. This is concordant with previous studies and supports the proposal that a masculinity preference could reflect attraction to dominance rather than immunocompetence. Increased health in faces was perceived as increasing dominance, wealth and pro-social traits (faithfulness, commitment, parenting, etc.), which weakens the widely held supposition that health is closely related to masculinity in facial attraction. Results regarding facial maturity were mixed across studies. Furthermore, Study 2 found that the perceived attributes of faces clustered into two dimensions; the first dimension being a ‘halo’ of all seven desirable traits (which varies with healthiness), and the second dimension being a perception of dominance and unsuitability as a partner (which varies with masculinity). [Copyright &y& Elsevier]

Summary: In a recent Medical Hypotheses editorial, I suggested the name psychological neoteny (PN) to refer to the widely-observed phenomenon that adults in modernizing liberal democracies increasingly retain many of the attitudes and behaviors traditionally associated with youth. I further suggested that PN is a useful trait for both individuals and the culture in modernizing societies; because people need to be somewhat child-like in their psychology order to keep learning, developing and adapting to the rapid and accelerating pace of change. Thirdly, I put forward the hypothesis that the major cause of PN in modernizing societies is the prolonged duration of formal education. Here I present a preliminary empirical investigation of this hypothesis of psychological neoteny. Marriage and parenthood are indicative of making a choice to ‘settle down’ and thereby move on from the more flexible lifestyle of youth; and furthermore these are usually commitments which themselves induce a settling down and maturation of attitudes and behaviors. A sevenfold expansion of participation in UK higher education up to 2001 was reflected in delay in marriage and parenthood. Increasing number of years of education is quantitatively the most important predictor of increasing age of the mother at the time of her first birth: among women college graduates about half are aged 30 or older at the time of their first birth – a rise of 400% in 25 years. Parenthood is associated with a broad range of psychologically ‘maturing’ and socially-integrating effects in both men and women. However, the economic effect is different in men and women: after parenthood men are more likely to have a job and work more hours while women change in the opposite direction. The conclusion is that psychological neoteny is indeed increasing, and mainly as a consequence of the increasing percentage of school leavers going into higher education. But at present it is unclear whether this trend is overall beneficial or harmful; and the answer may be different for men and women. [Copyright &y& Elsevier]

Abstract: Plants of 19 annual taxa from the hygro-nitrophilous vegetation of Central European river banks and dried ponds were exposed as seedlings for 42 days to either natural long days (LD=ca. 15.5h) or artificial short days (SD=11h). Phenological and morphological growth parameters such as first flowering, main stem length, leaf size and plant dry weight were measured and compared. Based on their day-length responses, the plants were classified as 11 short-day plants (SDP), 6 long-day plants (LDP) and 2±day neutral plants (DNP). Differences of morphological plant responses under SD (compared with those under LD) reached from none to almost negligible ones in Ranunculus sceleratus, Bidens cernua, Chenopodium ficifolium and Rumex palustris to an extreme reduction in all parameters, as in Chenopodium glaucum×rubrum, Ch. rubrum, Ch. glaucum, Ch. polyspermum, Bidens radiata, Persicaria lapathifolia subsp. brittingeri and subsp. lapathifolia. Growth inhibition was usually combined with neotenic flowering in SDP. Some LDP exhibited clear dormancy responses, like the formation of smaller (winter) rosettes. Erosulate therophytes were mostly SDP while (hemi)rosulate to caespitose winter annuals or short-lived hemicryptophytes were LDP. Plants of seven species that were exposed to natural SD in spring (increasing day length) showed rather different responses. While Bidens radiata flowered in late spring soon after floral induction, other species showed increasing degrees of flowering delay (Chenopodium polyspermum→Xanthium saccharatum→Chenopodium rubrum). Only Atriplex prostrata did not exhibit any sign of floral induction until (decreasing) SD in late summer arrived. In the case of Chenopodium rubrum details of the divergent morphogenesis under SD and LD were studied. In this species SD lead to strong reduction of stem length, leaf number and leaf size, simplification of leaf outline and margins as well as an enhanced ramification in the axils of primary leaves (and cotyledons) instead of metaphylls. The study reveals that for the phytosociological vegetation group Chenopodion rubri, whose populations are mainly confined to river banks with moist but well-aerated sediments, erosulate, therophytic and often neotenic SDP are typical. For the species of the Bidention – that thrive preferentially at the margins of stagnant water on rather wet soils – (hemi)rosulate or caespitose winter annuals are frequent. They are often LDP and survive the cold season in a vegetative state, even under a shallow level of water. The SD response of therophytic pioneers together with an often strong neotenic plasticity is interpreted here as a reassurance for the plants to flower and set seed in riparian habitats that are available for colonization only for a short and insecure period of the year, which due to the asymmetric position of annual low water levels in larger rivers is often not before mid-summer. [Copyright &y& Elsevier]

Abstract: Variation in women''s preferences for male facial masculinity may reflect variation in attraction to immunocompetence or to maturity. This paper reports two studies on (a) the interrelationships between women''s preferences for masculinity, apparent health, and age in male faces and (b) the extent to which manipulating each of these characteristics affects women''s attributions of the remaining characteristics. Both studies were carried out with a large sample of the general public (Studies 1a and 2a) and independently in a laboratory environment with smaller undergraduate samples (Studies 1b and 2b). In both samples, masculinity and age preferences were positively related, and masculinity preferences were not associated with preferences for apparent health. There was also a positive relationship between perceived age and perceived masculinity in both samples, but evidence for a link between perceptions of masculinity and health was equivocal. Collectively, these findings suggest that variation in women''s preferences for masculine proportions in male faces reflect variation in attraction to male age and do not support a strict immunocompetence explanation of preferences for facial masculinity. [Copyright &y& Elsevier]

Abstract: Two new asellote isopod species, Stylomesus hexapodus n. sp. and Haplomesus corniculatus n. sp., are described from samples obtained with an epibenthic sledge in the Southern Ocean deep sea. Both species show the retention of juvenile characters in the adult stages, by the lack of the seventh pair of pereopods, a phenomenon described for the first time for Ischnomesidae. [Copyright &y& Elsevier]

It has been a traditionally held view that winged insects stop molting after they reach adulthood. We observed a fascinating phenomenon of a post-imago molt occurring in the neotenic females of a firefly species in Taiwan over the last two years. By rearing Lamprigera minor larvae to adults, four out of the five unmated females studied were found undergoing an extra molt 8–18 days after adult eclosion. They were reproductively mature when the post-imago molt occurred, as evidenced by the eggs inside their bodies. The four females died without oviposition whereas the only normal female laid eggs. A comparison of exuviae of different stages confirmed the existence of post-imago ecdysis. The adult skin differed from the pupal one mainly in the mouthparts and leg structures. No mix of pupal and adult traits was seen in the adult skin. The females retained the same morphology after the extra molt. A close examination of the post-imago molting females revealed that their oviduct openings were all blocked by larval or pupal skin and thus unable to lay eggs. The reproductive stress may invoke an endocrine disorder and lead to an extra molt. We propose that L. minor females retain their prothoracic glands even as adults, allowing them to molt as adults under certain environmental or physiological conditions. Thus, neoteny of L. minor is reflected in both the external morphology as well as the internal physiology. The possible developmental changes associated with the evolution of neoteny are discussed. • The highly neotenic adult females of Lamprigera minor underwent an extra molt. • No morphological changes were observed after the post-imago molt. • Adults died without oviposition although their bodies were full of eggs. • The comparison of exuviae provided solid evidence of post-imago ecdysis. • The endocrine mechanisms for the development of neotenic females are inferred. [ABSTRACT FROM AUTHOR]

In two separate recent studies, researchers have reported an association between increases in children's shyness (i.e., social avoidance and inhibition) and decreases on frontal baseline electroencephalogram (EEG) alpha-to-delta ratio (ADR) scores (i.e., Schmidt & Poole, 2018, 2020). Here we attempted to extend these findings by examining whether different types of children's shyness were distinguishable on this same frontal ADR score, which is thought to be one electrocortical proxy of brain maturation. We coded expressions of positive shyness (i.e., co-occurrence of smiling and avoidance behaviors) versus non-positive shyness (i.e., avoidance behaviors) from direct observations during a social presentation speech in children (N = 63; M age = 10.41 years) and examined these expressions of shyness in relation to the children's frontal baseline EEG ADR scores. We found preliminary evidence that children expressing positive shyness exhibited the lowest frontal baseline EEG ADR score (i.e., ostensibly less brain maturation) relative to children expressing non-positive shyness and low levels of shyness. We speculate that relatively less frontal brain maturation may be linked to some adaptive features of shyness. [ABSTRACT FROM AUTHOR]

Our declining sleep duration over early human infant development is largely through REM sleep (REM), loss, not of nonREM. It coincides with the infant's increasing locomotion providing for multisensory inputs ('exploratory wakefulness' - EW), together facilitating neural restructuring and behavioural adaptations ('neuroplasticity'). EW also involves curiosity, novelty, navigation, spatial memory, associated emotions, and feeding; all having brain processes particularly active in REM. It is proposed that: 1) REM is a proxy for EW in facilitating neuroplasticity; 2) necessitating REM having a locomotor output, actively inhibited (the atonia); 3) human adults retain many (neotenous) infant characteristics including large amounts of REM towards the end of usual sleep, where REM's qualitative changes indicate reduced sleep pressure, 4) as in infancy, some of our adult REM remains replaceable by EW (without REM rebounds), mostly in this final REM episode whenever EW need prevails. Accordingly, our adult sleep duration is adaptable to habitual shortening via this REM episode substituted by purposeful EW, which could provide extra (day) light exposure for circadian synchrony. Such processes may underlie seasonally shorter (6 h) sleep, eg in hunter-gather people. This flexibility of REM questions the extent of our western 'chronic sleep debt'. Evidence is provided to counter claims that this absent REM would cause obesity and related disorders. 200w. [ABSTRACT FROM AUTHOR]

Summary: The mid-20th century saw the rise of the boy-genius, probably because a personality type characterized by prolonged youthfulness is advantageous both in science and modern life generally. This is the evolution of ‘psychological neoteny’, in which ever-more people retain for ever-longer the characteristic behaviours and attitudes of earlier developmental stages. Whereas traditional societies are characterized by initiation ceremonies marking the advent of adulthood, these have now dwindled and disappeared. In a psychological sense, some contemporary individuals never actually become adults. A child-like flexibility of attitudes, behaviours and knowledge is probably adaptive in modern society because people need repeatedly to change jobs, learn new skills, move to new places and make new friends. It seems that this adaptation is achieved by the expedient of postponing cognitive maturation – a process that could be termed psychological neoteny. (‘Neoteny’ refers to the biological phenomenon whereby development is delayed such that juvenile characteristics are retained into maturity.) Psychological neoteny is probably caused by the prolonged average duration of formal education, since students’ minds are in a significant sense ‘unfinished’. Since modern cultures favour cognitive flexibility, ‘immature’ people tend to thrive and succeed, and have set the tone of contemporary life: the greatest praise of an elderly person is to state that they retain the characteristics of youth. But the faults of youth are retained with well as its virtues: short attention span, sensation- and novelty-seeking, short cycles of arbitrary fashion and a sense of cultural shallowness. Nonetheless, as health gets better and cosmetic technologies improve, future humans may become somewhat like an axolotl – the cave-dwelling salamander which retains its larval form until death. [Copyright &y& Elsevier]

• A new unusual abyssal genus of paramunnid isopods is described from the NW Pacific. • It is distinguished by paedomorphic features (reduced pereonite 7 that lacks legs) • Paedomorphosis seems to be an important adaptation for deep-sea life. • This phenomenon is a common evolutionary strategy for deep-sea Asellota. Reductogonium iroquois gen. nov. sp. nov., a new genus and species of paramunnid isopods from the Northwest Pacific open abyssal plain to the east of the Kuril-Kamchatka Trench, is described based on materials from the KuramBio expedition (2012). The new genus is distinguished from other paramunnid genera by its reduced pereonite 7 that lacks appendages in adult individuals (one seta is presented instead of the pereopod VII on its position). It is also distinguished by its head, which has a medial crest bearing a tuft of setae on its posterior part, and by the extremely long articles of antennae and pereopods. The unusual paedomorphic features of the new genus might be adaptations to deep-sea conditions. Paedomorphosis was recorded for different taxa of deep-sea animals. The reduction of the last pair of pereopods, which corresponds to the state of manca stages, was observed independently in different families and orders of Isopoda. Finding a new species and a new genus of the Paramunnidae with paedomorphic features confirmed that this phenomenon is a common evolutionary strategy for deep-sea Asellota. [ABSTRACT FROM AUTHOR]

Summary The normal aging human brain experiences global decreases in metabolism, but whether this affects the topography of brain metabolism is unknown. Here we describe PET-based measurements of brain glucose uptake, oxygen utilization, and blood flow in cognitively normal adults from 20 to 82 years of age. Age-related decreases in brain glucose uptake exceed that of oxygen use, resulting in loss of brain aerobic glycolysis (AG). Whereas the topographies of total brain glucose uptake, oxygen utilization, and blood flow remain largely stable with age, brain AG topography changes significantly. Brain regions with high AG in young adults show the greatest change, as do regions with prolonged developmental transcriptional features (i.e., neoteny). The normal aging human brain thus undergoes characteristic metabolic changes, largely driven by global loss and topographic changes in brain AG. [ABSTRACT FROM AUTHOR]