Recently, the group of McBride reported a stunning observation regarding peroxisome biogenesis: newly born peroxisomes are hybrids of mitochondrial and ER-derived pre-peroxisomes. What was stunning? Studies performed with the yeast Saccharomyces cerevisiae had convincingly shown that peroxisomes are ER-derived, without indications for mitochondrial involvement. However, the recent finding using fibroblasts dovetails nicely with a mechanism inferred to be driving the eukaryotic invention of peroxisomes: reduction of mitochondrial reactive oxygen species generation associated with fatty acid oxidation. This not only explains (...) the mitochondrial involvement, but also its apparent absence in yeast. The latest results allow a reconstruction of the evolution of the yeast's highly derived metabolism and its limitations as a model organism in this instance. As I review here, peroxisomes are eukaryotic inventions reflecting mutual host endosymbiont adaptations: this is predicted by symbiogenetic theory, which states that the defining eukaryotic characteristics evolved as a result of mutual adaptations of two merging prokaryotes. See also the video abstract here: https://youtu.be/HtyKhQ3DSxg Eukaryotic peroxisomes illustrate effects of symbiogenesis, following the non-phagocytotic merger of an archaeon and a bacterium. Internal ROS formation upon fatty acid oxidation was reduced by the invention of peroxisomes for extra-mitochondrial FA oxidation. Both peroxisomal membranes and their oldest enzymes seem ultimately derived from the pre-mitochondrion. (shrink)

Beta‐oxidation of fatty acids and detoxification of reactive oxygen species are generally accepted as being fundamental functions of peroxisomes. Additionally, these pathways might have been the driving force favoring the selection of this compartment during eukaryotic evolution. Here we performed phylogenetic analyses of enzymes involved in beta‐oxidation of fatty acids in Bacteria, Eukaryota, and Archaea. These imply an alpha‐proteobacterial origin for three out of four enzymes. By integrating the enzymes' history into the contrasting models on the origin of eukaryotic (...) cells, we conclude that peroxisomes most likely evolved non‐symbiotically and subsequent to the acquisition of mitochondria in an archaeal host cell. (shrink)

Under the putative influence of dietary selection pressure, the subcellular distribution of alanine:glyoxylate aminotransferase 1 (AGT) has changed on many occasions during the evolution of mammals. Depending on the particular species, AGT can be found either in peroxisomes or mitochondria, or in both peroxisomes and mitochondria. This variable localization depends on the differential expression of N‐terminal mitochondrial and C‐terminal peroxisomal targeting sequences by the use of alternative transcription and translation initiation sites. AGT is peroxisomal in most humans, but it (...) is mistargeted to the mitochondria in a subset of patients suffering from the rare herediatry disease primary hyperoxaluria type 1. Mistargeting is due to the unlikely combination of a normally occurring polymorphism that generates a functionally weak mitochondrial targeting sequence and a disease‐specific mutation which, in combination with the polymorphism, inhibits AGT dimerization. The mechanisms by which AGT can be targeted differentially to peroxisomes and/or mitochondria highlight the different molecular requirements for protein import into these two organelles. (shrink)

At first glance the three eukaryotic protein translocation machineries – the ER‐associated degradation (ERAD) transport apparatus of the endoplasmic reticulum, the peroxisomal importomer and SELMA, the pre‐protein translocator of complex plastids – appear quite different. However, mechanistic comparisons and phylogenetic analyses presented here suggest that all three translocation machineries share a common ancestral origin, which highlights the recycling of pre‐existing components as an effective evolutionary driving force.Editor's suggested further reading in BioEssays ERAD ubiquitin ligases Abstract.

Aspects of peroxisome evolution, uncoupling, carnitine shuttles, supercomplex formation, and missing neuronal fatty acid oxidation (FAO) are linked to reactive oxygen species (ROS) formation in respiratory chains. Oxidation of substrates with high FADH2/NADH (F/N) ratios (e.g., FAs) initiate ROS formation in Complex I due to insufficient availability of its electron acceptor (Q) and reverse electron transport from QH2, e.g., during FAO or glycerol‐3‐phosphate shuttle use. Here it is proposed that the Q‐cycle of Complex III contributes to enhanced ROS (...) formation going from low F/N ratio substrates (glucose) to high F/N substrates. This contribution is twofold: 1) Complex III uses Q as substrate, thus also competing with Complex I; 2) Complex III itself will produce more ROS under these conditions. I link this scenario to the universally observed Complex III dimerization. The Q‐cycle of Complex III thus again illustrates the tension between efficient ATP generation and endogenous ROS formation. This model can explain recent findings concerning succinate and ROS‐induced uncoupling. (shrink)

As free‐living organisms, alpha‐proteobacteria produce reactive oxygen species (ROS) that diffuse into the surroundings; once constrained inside the archaeal ancestor of eukaryotes, however, ROS production presented evolutionary pressures – especially because the alpha‐proteobacterial symbiont made more ROS, from a variety of substrates. I previously proposed that ratios of electrons coming from FADH2 and NADH (F/N ratios) correlate with ROS production levels during respiration, glucose breakdown having a much lower F/N ratio than longer fatty acid (FA) breakdown. Evidently, higher endogenous ROS (...) formation did not hinder eukaryotic evolution, so how were its disadvantages mitigated? I propose that the resulting selection pressures favoured the evolution of a variety of eukaryotic ‘innovations’: peroxisomes for FA breakdown, carnitine shuttles, the linkage of beta‐oxidation to antioxidant properties, uncoupling proteins (UCPs) and using mitochondrial uncoupling during beta‐oxidation to reduce ROS. Recently observed relationships between peroxisomes and mitochondria further support the model. (shrink)

Of two contending models for eukaryotic evolution the “archezoan“ has an amitochondriate eukaryote take up an endosymbiont, while “symbiogenesis“ states that an Archaeon became a eukaryote as the result of this uptake. If so, organelle formation resulting from new engulfments is simplified by the primordial symbiogenesis, and less informative regarding the bacterium‐to‐mitochondrion conversion. Gradualist archezoan visions still permeate evolutionary thinking, but are much less likely than symbiogenesis. Genuine amitochondriate eukaryotes have never been found and rapid, explosive adaptive periods characteristic (...) of symbiogenetic models explain this. Mitochondrial proteomes, encoded by genes of “eukaryotic origin“ not easily linked to host or endosymbiont, can be understood in light of rapid adjustments to new evolutionary pressures. Symbiogenesis allows “expensive” eukaryotic inventions via efficient ATP generation by nascent mitochondria. However, efficient ATP production equals enhanced toxic internal ROS formation. The synergistic combination of these two driving forces gave rise to the rapid evolution of eukaryotes.Also watch the Video Abstract. (shrink)

This book is a volume in the Penn Press Anniversary Collection. To mark its 125th anniversary in 2015, the University of Pennsylvania Press rereleased more than 1,100 titles from Penn Press's distinguished backlist from 1899-1999 that had fallen out of print. Spanning an entire century, the Anniversary Collection offers peer-reviewed scholarship in a wide range of subject areas.

This discussion recounts the development of several anthropological definitions of human nature. It then examines conclusions of studies in other disciplines that make possible a revised empirical definition of human nature and which have led to re-examination of paleoanthropological data classed as unimportant under the rubrics of preceeding studies. Finally, this discussion appraises certain of these data, as they pertain to the question: "Do empirical evidences suggest that a human nature, as well as a human structure, may be the product (...) of evolutionary processes?". (shrink)

The idea that cultural evolution exhibits variation, competition, and inheritance and therefore can be studied by adjusting the Darwinian theory of evolution by natural selection is an attractive one. It has been argued by a number of authors (e.g., Campbell 1960; Monod 1970; Dawkins 1976; Cavalli-Sforza and Feldman 1981; Boyd and Richerson 1985; Durham 1991; Aunger 2002; Mesoudi et al. 2004) and pursued in a variety of ways, some (Dawkins and memeticists) staying close to the Darwinian model, others (...) (e.g., Boyd, Richerson, and their collaborators) being more innovative. We agree that there are relevant analogies between biological and cultural evolution and, in particular, that cultural items do exhibit variation, competition, and cumulative modification. On the other hand, we believe that a proper understanding of the mechanisms of cultural propagation drawing on the work of cognitive and social scientists (see Sperber and Hirschfeld 1999 for a review) contradicts the idea that culture exhibits inheritance in the strict sense needed for the theory of evolution by natural selection to apply straightforwardly to it. If so, it will take more than adjusting the Darwinian model to be faithful to the Darwinian inspiration. (shrink)

By conceptualizing Sexual Selection, Darwin showed a way to analyze intra-specific individual differences within an evolutionary perspective. Interestingly, Sexual Selection is often used to investigate the origins of sports, arts, humor, religion and other phenomena that, in several languages, are simply called “play.” Despite their manifested differences, these phenomena rely on shared psychological processes, including playfulness. Further, in such behaviors there is usually considerable individual variability, including sex differences, and positive relationship with mating success. However, Sexual Selection is rarely applied (...) in the study of play, with exception to what is concerned as infant training behavior for adult sex roles. We offer an integrated grounding of playful phenomena aligning evolutionary propositions based on sexual selection, which might stimulate further exploration of playfulness within evolutionary perspective. (shrink)

This paper examines the process through which micro-businesses ‘go green’. It builds upon previous studies that have identified the different drivers of this greening process. However, rather than a static focus on specific drivers, the study articulates the evolution of environmental practices over time. The paper uses comparative case studies of six micro-businesses to build a composite sequence analysis that plots the greening process from its roots through to large-scale and ambitious ecological projects. The study identifies three distinct stages (...) that businesses pass through during this greening process. This has important implications for policy-makers and advisors as it was found that the support needed by the businesses changed as they passed through these different stages. In particular, it was found that appropriate support is currently lacking at certain key points of the businesses' greening development. The paper therefore adds to current understanding of small business ecological responsibility by showing how activities and drivers change with the level of engagement. Pointers are provided as to how support can be improved. (shrink)

_Forgetting Machines. Knowledge Management Evolution in Early Modern Europe_ investigates the evolution of scholarly practices and the transformation of cognitive habits in the early modern age, focussing on the development of note-taking systems and data storage devices.

As documented in Part I, monogenism, the descent of all human beings from Adam and Eve, was closely linked to the Catholic doctrine of original sin throughout the first half of the twentieth century. Theological reservations about polygenism, the more scientifically supported account of human origins through a transitional population, was brought to a head by Pius XII’s 1950 encyclical Humani generis. Although the encyclical allowed discussion of human evolution, polygenism was prohibited because “It does not appear how such (...) a view can be reconciled with the doctrine of original sin.” Nevertheless, during and after Vatican II de facto theological acceptance of polygenism became commonplace even though the prohibition was not withdrawn. While some modern conceptions of original sin make a reliance upon monogenism unnecessary, another school of thought emphasizes a spiritual rather than a biological understanding of the concept. It remains to be seen whether polygenism can be unanimously accepted as a scientific phenomenon that is not theologically threatening. Reflection on the Vatican’s long period of ambivalence about the motion of the earth suggests that a similar prospect can be foreseen for polygenism even though it is subject to development in a manner that geostasis was not. (shrink)

Embryos and microscopes share a long, remarkable history and biologists have always been intrigued to watch how embryos develop under the microscope. Here we discuss the advances in microscopy which have greatly influenced our current understanding of embryogenesis. We highlight the evolution of microscopes and the optical technologies that have been instrumental in studying various developmental processes. These imaging modalities provide mechanistic insights into the dynamic cellular and molecular events which drive lineage commitment and morphogenetic changes in the developing (...) embryo. We begin the journey with a brief history of microscopy to study embryos. First, we review the principles and optics of light, fluorescence, confocal, and electron microscopy which have been key techniques for imaging cellular and molecular events during embryonic development. Next, we discuss recent key imaging modalities such as light‐sheet microscopy, which are suitable for whole embryo imaging. Further, we highlight imaging techniques like multiphoton and super resolution microscopy for beyond light diffraction limit, high resolution imaging. Lastly, we review some of the scattering‐based imaging methods and techniques used for imaging human embryos. (shrink)

As part of the ongoing attempt to fully naturalize the concept of human being--and, more specifically, to re-center it around the notion of agency--this essay discusses an approach to defining the content of representations in terms ultimately derived from their central, evolved function of providing guidance for action. This 'guidance theory' of representation is discussed in the context of, and evaluated with respect to, two other biologically inspired theories of representation: Dan Lloyd's dialectical theory of representation and Ruth Millikan's biosemantics.

If there is a common theme through the rich diversity of Max Charlesworth’s academic life and works, it is the quest to understand human action as meaningful, significant and subject to interpretation rather than reducible to the explanatory techniques of positivistic science. This orientation is summed up in the philosophical concept of intentionality. Intentionality is a key notion for continental philosophers whose ideas formed the subject-matter of Max’s legendary course in ‘Contemporary European Philosophy’ at Melbourne University and later, of the (...) foundation philosophy programs at Deakin University. The origins of the concept of intentionality are to be found in mediaeval philosophy – another of Max’s teaching areas, and a commitment to intentionality is deeply implicit in his engagement with the religious and the spiritual as well as with ethics.In this essay I trace the changing conceptions of intentionality in recent philosophy and in doing so, indicate developments within the continental philosophical tradition and its shifting relations with the analytical tradition in Australian philosophy. (shrink)

Bacterial resistance mechanisms to the antibiotics known as β‐lactams, which include the penicillins and cephalosporins, can take several forms but frequently involve the production of β‐lactamases from either plasmid‐ or chromosomally‐encoded loci. Gram negative bacteria express a β‐lactamase from evolutionarily related chromosomal ampC genes. Genetic analysis of both inducible and constitutively expressed AmpC β‐lactamases provide insights into the mechanisms regulating production of the enzyme. Evolutionary relationships between the genes of different species are discussed, as well as the regulatory mechanisms that (...) in both laboratory mutants and clinical isolates lead to overproduction of β‐lactamase. (shrink)

In this honorific volume, his protigi F. LeRon Shults has gathered a chorus of excellent voices in van Huyssteen's main areas of philosophy, science, and ...

In the first section I present a disagreement between a number of scholars concerning the goodness, indifference, evil or even wickedness both of nature and of nonhuman creatures. Section 2 examines and rejects the response to these diverse judgements that values are generated by human valuers employing different perspectives. In Section 3, the thesis that nonhuman animals are commonly either wicked or immoral is considered. The next two sections address the value or disvalue of predation and parasitism, and then of (...) waste, selfishness and suffering. In the Section 6 I conclude that the evolutionary system of nature has vast overall value, and that although there are widespread evils within it, the only significant alternatives are a lifeless world, a world without sentient life, and a world of constant supernatural intervention, all probably worlds without such a positive balance of value as the actual world. (shrink)

The aim of this article is to present an evolutionarily grounded explanation of why we speak in sentences. This question is seldomly addressed, neither in the Chomskian tradition nor in cognitive linguistics. I base my explanation on an analysis of different levels of communication. I identify four levels: praxis, instruction, coordination of common ground and coordination of meaning. The analysis will be focused on the evolutionary benefits of communicating about events as a way of coordinating actions. A cognitively grounded model (...) of events will be outlined. My central thesis is that the communicative role of sentences is to express events. (shrink)

Argues that death is not unchanging, but rather has evolved over time.