Controversies in the evolutionary social sciences: a guide for the perplexed

It is 25 years since modern evolutionary ideas were first applied extensively to human behavior, jump-starting a field of study once known as 'sociobiology'. Over the years, distinct styles of evolutionary analysis have emerged within the social sciences. Although there is considerable complementarity between approaches that emphasize the study of psychological mechanisms and those that focus on adaptive fit to environments, there are also substantial theoretical and methodological differences. These differences have generated a recurrent debate that is now exacerbated by growing popular media attention to evolutionary human behavioral studies. Here, we provide a guide to current controversies surrounding evolutionary studies of human social behavior, emphasizing theoretical and methodological issues. We conclude that a greater use of formal models, measures of current fitness costs and benefits, and attention to adaptive tradeoffs, will enhance the power and reliability of evolutionary analyses of human social behavior.     

Neither metaphysical dichotomy nor pure identity:: Clarifying the emergentist creed

Emergentism is often misleadingly described as a monolithic “third way” between radical monism and pluralism. In the particular case of biology, for example, emergentism is perceived as a middle course between mechanicism and vitalism. In the present paper I propose to show that the conceptual landscape between monism and pluralism is more complex than this classical picture suggests. On the basis of two successive analyses—distinguishing three forms of tension between monism and pluralism and a distinction between derivational and functional reduction—I define three different versions of emergentism that can be considered as consistent middle courses between monism and pluralism (respectively theoretical, explanatory and causal emergence). I then emphasise the advantage of this taxonomy of the concepts of emergence by applying the results of my analysis to the historical controversy that pertains to the relationship between life and matter.     

Neither apposition nor superposition: the compound eyes of the Chestnut Leafminer Cameraria ohridella

The two lemon-shaped compound eyes of the moth Cameraria ohridella measure in dorsal–ventral direction 263.0 μm in male and 238.9 μm in female individuals. In anterior–posterior direction no significant differences were found between the sexes, eye length being about 194.6 μm. The eyes of males consist of ca. 417 hexagonal facets, while those of females contain 367. In both sexes facet diameters are approximately 11.5 μm. Despite the size differences of the eyes in the two sexes, ultrastructurally they are identical and both possess ommatidia of 80 μm mean length. The ultrastructure of the eye is described and compared with that of other compound eyes of Lepidoptera. Anatomically the eyes represent a type intermediate between apposition and refractive superposition kind. A distal rhabdom is present in the space that in the eyes of larger moths with superposition optics is occupied by the so-called clear zone. A tracheal tapetum and longitudinal screening pigment migrations, typical of superposition but not apposition eyes are present despite the lack of a clear zone. Thus, our results support an earlier calculated minimal theoretical limit for superposition eyes.     

Racial classification in the evolutionary sciences: a comparative analysis

Human racial classification has long been a problem for the discipline of anthropology, but much of the criticism of the race concept has focused on its social and political connotations. The central argument of this paper is that race is not a specifically human problem, but one that exists in evolutionary thought in general. This paper looks at various disciplinary approaches to racial or subspecies classification, extending its focus beyond the anthropological race concept by providing a comparative analysis of the use of racial classification in evolutionary biology, genetics, and anthropology.     

Neither the SCN nor the adrenals are required for circadian time-place learning in mice

During Time-Place Learning (TPL), animals link biological significant events (e.g. encountering predators, food, mates) with the location and time of occurrence in the environment. This allows animals to anticipate which locations to visit or avoid based on previous experience and knowledge of the current time of day. The TPL task applied in this study consists of three daily sessions in a three-arm maze, with a food reward at the end of each arm. During each session, mice should avoid one specific arm to avoid a foot-shock. We previously demonstrated that, rather than using external cue-based strategies, mice use an internal clock (circadian strategy) for TPL, referred to as circadian TPL (cTPL). It is unknown in which brain region(s) or peripheral organ(s) the consulted clock underlying cTPL resides. Three candidates were examined in this study: (a) the suprachiasmatic nucleus (SCN), a light entrainable oscillator (LEO) and considered the master circadian clock in the brain, (b) the food entrainable oscillator (FEO), entrained by restricted food availability, and (c) the adrenal glands, harboring an important peripheral oscillator. cTPL performance should be affected if the underlying oscillator system is abruptly phase-shifted. Therefore, we first investigated cTPL sensitivity to abrupt light and food shifts. Next we investigated cTPL in SCN-lesioned- and adrenalectomized mice. Abrupt FEO phase-shifts (induced by advancing and delaying feeding time) affected TPL performance in specific test sessions while a LEO phase-shift (induced by a light pulse) more severely affected TPL performance in all three daily test sessions. SCN-lesioned mice showed no TPL deficiencies compared to SHAM-lesioned mice. Moreover, both SHAM- and SCN-lesioned mice showed unaffected cTPL performance when re-tested after bilateral adrenalectomy. We conclude that, although cTPL is sensitive to timing manipulations with light as well as food, neither the SCN nor the adrenals are required for cTPL in mice.     

Neither host-specific nor random: vascular epiphytes on three tree species in a Panamanian lowland forest

BACKGROUND AND AIMS: A possible role of host tree identity in the structuring of vascular epiphyte communities has attracted scientific attention for decades. Specifically, it has been suggested that each host tree species has a specific subset of the local species pool according to its own set of properties, e.g. physicochemical characteristics of the bark, tree architecture, or leaf phenology patterns. METHODS: A novel, quantitative approach to this question is presented, taking advantage of a complete census of the vascular epiphyte community in 0.4 ha of undisturbed lowland forest in Panama. For three locally common host-tree species (Socratea exorrhiza, Marila laxiflora, Perebea xanthochyma) null models were created of the expected epiphyte assemblages assuming that epiphyte colonization reflected random distribution of epiphytes in the forest. KEY RESULTS: In all three tree species, abundances of the majority of epiphyte species (69-81 %) were indistinguishable from random, while the remaining species were about equally over- or under-represented compared with their occurrence in the entire forest plot. Permutations based on the number of colonized trees (reflecting observed spatial patchiness) yielded similar results. Finally, a third analysis (canonical correspondence analysis) also confirmed host-specific differences in epiphyte assemblages. In spite of pronounced preferences of some epiphytes for particular host trees, no epiphyte species was restricted to a single host. CONCLUSIONS: The epiphytes on a given tree species are not simply a random sample of the local species pool, but there are no indications of host specificity either.     

Neither common nor garden: The garden as a refuge for threatened plant species

An increasing number of plant species are being lost to the world primarily as a result of massive levels of degradation to wild habitats, and in a smaller number of cases through inappropriate trading. A handful of these extinctions have been prevented, or perhaps delayed, through cultivation in gardens and nurseries (Melville, 1970). In a well-stocked garden-centre the amateur horticulturist can purchase a number of species now extinct in the wild. These species survive as genetic fragments of the diversity originally present in the lost wild population. This paper, through a series of case studies, discusses the ambivalent relationship between the horticulturist and species conservation.     

Neither compatible nor self-incompatible pollinations of Brassica napus involve reorganization of the papillar cytoskeleton

Compatible pollination of Brassica napus necessitates pollen hydration, pollen germination and growth of the pollen tube through the loosened walls of stigmatic papillar cells, whereas self-incompatible (SI) pollinations fail at one of these stages. Analyses of the early stages of pollination show that at high (but not low) relative humidities, both compatible and SI pollen hydrates, but SI germination is reduced and the rare pollen tubes generally fail to penetrate the papillar walls, although there is some wall loosening. Inside the papillae, both compatible and SI interactions may induce the formation of callose, but there is no evidence for a major accumulation of cytoplasm or secretory vesicles in the vicinity of the pollen tubes and neither microtubule nor F-actin patterns re-arrange in this zone. These observations indicate that the source of the wall-loosening enzymes is probably the pollen tube or pollen coat, and that the common cellular responses of plants to attempted invasions have become suppressed in the papilla–pollen tube interaction.     

Visual Acuity Testing: Feedback Affects Neither Outcome nor Reproducibility,but Leaves Participants Happier

Assessment of visual acuity is a well standardized procedure at least for expert opinions and clinical trials. It is often recommended not giving patients feedback on the correctness of their responses. As this viewpoint has not been quantitatively examined so far, we quantitatively assessed possible effects of feedback on visual acuity testing. In 40 normal participants we presented Landolt Cs in 8 orientations using the automated Freiburg Acuity Test (FrACT, <michaelbach.de/fract. Over a run comprising 24 trials, the acuity threshold was measured with an adaptive staircase procedure. In an ABCDDCBA scheme, trial-by-trial feedback was provided in 2 x 4 conditions: (A) no feedback, (B) acoustic signals indicating correctness, (C)visual indication of correct orientation, and (D) a combination of (B) and (C). After each run the participants judged comfort. Main outcome measures were absolute visual acuity (logMAR), its test-retest agreement (limits of agreement) and participants’ comfort estimates on a 5-step symmetric Likert scale. Feedback influenced acuity outcome significantly (p = 0.02), but with a tiny effect size: 0.02 logMAR poorer acuity for (D) compared to (A), even weaker effects for (B) and (C). Test-retest agreement was high (limits of agreement: ± 1.0 lines) and did not depend on feedback (p>0.5). The comfort ranking clearly differed, by 2 steps on the Likert scale: the condition (A)–no feedback–was on average “slightly uncomfortable”, the other three conditions were “slightly comfortable” (p<0.0001). Feedback affected neither reproducibility nor the acuity outcome to any relevant extent. The participants, however, reported markedly greater comfort with any kind of feedback. We conclude that systematic feedback (as implemented in FrACT) offers nothing but advantages for routine use.     

Chronically Administered Lithium Alters Neither myo-Inositol Monophosphatase Activity nor Phosphoinositide Levels in Rat Brain

Rats were exposed to either 29 consecutive days of LiCl injections or 27 and 39 days of dietary Li2CO3, followed by injected LiCl at the end of the diet to insure a constant level of exposure to the drug. At the end of the period of chronic exposure to lithium, the rats were sacrificed and brain myo-inositol-1-phosphate phosphohydrolase (myo-inositol monophosphatase) activity was measured. In none of the experiments was there any difference in the lithium-sensitive activity toward myo-inositol monophosphatase when comparing the control and chronic groups. These brains and those from another group of rats that had been given Li2CO3 in their diet for 41 days, followed by 7 additional days of LiCl injections, were also examined for changes in the levels of the phosphoinositides. No reproducible differences in the absolute tissue levels of those lipids were found when control and chronic lithium groups were compared. These results are contrary to published reports which suggest that myo-inositol monophosphatase activity increases and that the phosphatidylinositol level decreases in rat brain as a result of chronic administration of lithium.