Fossil remains witness the relationship between the appearance of the middle ear and the expansion of the brain in early mammals. Nevertheless, the lack of detachment of ear ossicles in the mammaliaform Morganucodon, despite brain enlargement, points to other factors that triggered brain expansion in early mammals. Moreover, brain expansion in some early mammalian groups seems to have favored brain regions other than the cortex.

The discovery of fossil melanosomes has resulted in a wealth of research over the last 7 years, notably the reconstruction of colour in dinosaurs and fossil mammals. In spite of these discoveries some authors persist in arguing that the observed microbodies could represent preserved bacteria. They contend that bacteria fossilise easily and everywhere, which means that one can never be certain that a microbody is a melanosome without an extraordinary burden of evidence. However, this critique mischaracterises the morphological (...) and structural evidence for interpreting microbodies as fossil melanosomes, and hence the basis for using them in reconstructing prehistoric colours. The claims for bacterial omnipresence in the fossil record are themselves not supported, thus tipping the scales strongly towards melanosomes in the bacteria‐versus‐melanosome controversy. (shrink)

The earliest discoveries of extinct primates and humans profoundly affected the course of evolutionary theory as a scientific model for explaining life and its diversity through time. The absence of such fossils in the early nineteenth century provided important negative evidence to the competing French intellectual schools of Lamarckian evolutionism and Cuvierian catastrophism. Indeed, the first recognition of extinct primates fell serendipitously between the death of Cuvier in 1832 and the revolutionary writings of Darwin in 1859. Largely unknown to history, (...) however, is that four different European scholars, working on three continents, independently discovered and recognized extinct primates within a few months of each other in 1836. The first of these to be formally named, Protopithecus, is ironically the least well known despite being the largest monkey ever discovered in the western hemisphere. The reasons for this forgotten first discovery reflect a general unawareness of South American mammals, and propagation of misinterpretation at a critical time in the history of primatology. (shrink)

Recent controversy about the use of the vertebrate fossil record for external calibration of molecular clocks centers on two issues, the number of dates used for calibration and the reliability of the fossil calibration date. Viewing matters from a palaeontological perspective, we propose three qualitative, phylogenetic criteria that can be used within a comparative framework for the selection of well-constrained calibration dates from the vertebrate fossil record. On the basis of these criteria, we identify three highly suitable (...) new fossil calibration dates for molecular clock estimates: the lungfish–tetrapod split (between 419 and 408 Ma), the bird–crocodile split (between 251 and 243 Ma), and the alligator–caiman split (between 71 and 66 Ma). Together with our previously suggested bird–lizard split (between 252 and 257 Ma), these four fossil dates span a range of very different ages. They are, in our opinion, more suitable for molecular clock calibration than the traditionally used mammal–bird split, which is less well constrained. We plea for closer interactions between paleontologists and molecular biologists in studying the timescale of vertebrate evolution. BioEssays 27:1069–1075, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

Are they needed? To be sure. The Darwinian industry, industrious though it is, has failed to provide texts of more than a handful of Darwin's books. If you want to know what Darwin said about barnacles (still an essential reference to cirripedists, apart from any historical importance) you are forced to search shelves, or wait while someone does it for you; some have been in print for a century; various reprints have appeared and since vanished." -Eric Korn,Times Literary Supplement Charles (...) Robert Darwin (1880-1882) has been widely recognized since his own time as one of the most influential writers in the history of Western thought. His books were widely read by specialists and the general public, and his influence had been extended by almost continuous public debate over the last 130 years. New York University Press' edition makes it possible for the first time to review Darwin's public literary output as a whole, plus his scientific journal articles, his private notebooks, and his correspondence. This is the first complete edition containing all of Darwin's published books, featuring definitive texts recording original paginations with Darwin's indexes retained. All illustrations and plates are presented, inclucing 82 color plates of birds and mammals and several folding maps and plates. The set also features a general introduction and index, and textural introductions in each volume. (shrink)

We suggest that mammalian endothermy was established amongst Middle Jurassic crown mammals, through reviewing state‐of‐the‐art fossil and living mammal studies. This is considerably later than the prevailing paradigm, and has important ramifications for the causes, pattern, and pace of physiological evolution amongst synapsids. Most hypotheses argue that selection for either enhanced aerobic activity, or thermoregulation was the primary driver for synapsid physiological evolution, based on a range of fossil characters that have been linked to endothermy. We argue that, (...) rather than either alternative being the primary selective force for the entirety of endothermic evolution, these characters evolved quite independently through time, and across the mammal family tree, principally as a response to shifting environmental pressures and ecological opportunities. Our interpretations can be tested using closely linked proxies for both factors, derived from study of fossils of a range of Jurassic and Cretaceous mammaliaforms and early mammals. (shrink)

The growing interest and major advances of the last decades in evolutionary developmental biology (EvoDevo) have led to the recognition of the incompleteness of the Modern Synthesis of evolutionary theory. Here we discuss how paleontology makes significant contributions to integrate evolution and development. First, extinct organisms often inform us about developmental processes by showing a combination of features unrecorded in living species. We illustrate this point using the vertebrate fossil record and studies relating bone ossification to life history traits. (...) Second, we discuss exceptionally preserved fossils that document rare ontogenetic sequences and illustrate this case with the patterns of heterochrony observed in Cambrian crustacean larvae preserved three-dimensionally. Third, most fossils potentially document the evolutionary patterns of allometry and modularity, as well as some of the (paleo)ecological factors that had influenced them. The temporal persistence of adaptive patterns in rodent evolution serves to address the importance of ecological constraints in evolution. Fourth, we discuss how the macroevolutionary patterns observed in the tetrapod limb, in the mammal molar proportions, and in the molluscan shell provide independent tests of the validity of morphogenetic models proposed on living species. Reciprocally, these macroevolutionary patterns often act as a source of inspiration to investigate the underlying rules of development, because, at the end, they are the patterns that the neo-Darwinian theory was unable to account for. (shrink)

Most documented extinctions of vertebrates in the last 400 years have been island endemics. In this paper, we focus on the need to develop a historical framework to establish conservation priorities for insular faunas and, in particular, to test the validity of nominal endemics. We use the example of the islands of the North Pacific Coast of North America, a region that includes approximately one-half of all mammals endemic to North American islands north of Mexico. Few of these endemics have (...) been re-evaluated since their original descriptions, although many of these islands have been heavily impacted by habitat conversion, species introductions, over-exploitation, and secondary ripple effects. Evidence from molecular genetics and paleontology suggests that many taxa arrived in the region since the last glacial advance. Some of these nominal endemics show minimal differentiation, while others comprise multiple evolutionary lineages. The NPC may also have played an important role in the in situ diversification of some taxa during the Pleistocene. Evidence, such as new fossil discoveries and numerous described endemics, lends support for refugia hypotheses. However, these ideas cannot be tested until a better understanding of geographic variation and the evolutionary relationships of the fauna and flora of the North Pacific Coast is developed. This framework would provide significant insight into the dynamic biogeographic history of the region and help prioritize conservation efforts. (shrink)

Homo sapiens is a mammal of the order Primates. What most distinguishes primates from other mammals is their ability to cerebrate. Cerebration developed fastest among the Anthropoidea primates , and subsequently the hominids . The increase in brain mass only by Homo sapiens—and only over the past 10,000 years—possess superior Darwinian fitness: for the preceding 30 million years primates had played a rather marginal role in the world’s biological system.Homo sapiens’ success as the creator of developed civilization was possible only (...) thanks to his special adaptation capabilities, shaped by natural selection at the dawn of his existence.Primates first appeared in the Oligocene about 30 million years ago, and the first two-legged anthropoid, Australopithecus, about 6.5–5.7 million years ago. The transition from Australopithecus to the species we call Homo was in many ways an evolutionary milestone. Australopithecus was exclusively herbivorous and formed neither organized communities nor settlements. His successor, Homo erectus, on the other hand, possessed heretofore unknown skills like hunting and gathering, which considerably influenced both his lifestyle and his diet—he increasingly ate meat from cadavers or animals he had killed himself. Fossil remains of Homo erectus dating back two million years have been unearthed throughout Africa, China, Indonesia, Pakistan, the Middle East, and Europe.Homo sapiens derives from the rather small Homo erectus population in East Africa and has been the earth’s only hominid for a relatively short time about 10,000 years ago before he still shared his world with Neanderthal man and the diminutive Homo floresiensis.Despite racial differences there is surprisingly little variation in the human genome. We are all 99 percent genetically alike, moreover genome variations do not correlate to skin color.Homo sapiens’ hunter-gatherer lifestyle led him to seek solutions which today find application only in human communities. In time his biological capabilities were enriched by the skill of speech, this in turn helping to develop creativity, self-awareness, a sense of dignity, and group, ethnic and national loyalty, eventually leading to the emergence of religion as a path to life’s fundamental truths and an antidote to the everpresent fear of death.The Neolithic Revolution began about 10,000 years ago. Several thousand years later the evolution of farming and breeding led to the emergence of the first civilizations. The transition from hunting and gathering to agriculture changed radically not only economic and social structures but, as speech developed, helped form civilizations and cultures.Over the past 2000 years humanity has changed the global environment but has itself remained unchanged in heritability. The awareness that despite all racial, ethnic, cultural, or linguistic differences we belong to an exceptionally homogeneous species, can be an inspiration for humanity to strive towards a universal civilization in which all these differences could be contained. (shrink)

How consciousness appeared much earlier in evolutionary history than is commonly assumed, and why all vertebrates and perhaps even some invertebrates are conscious. How is consciousness created? When did it first appear on Earth, and how did it evolve? What constitutes consciousness, and which animals can be said to be sentient? In this book, Todd Feinberg and Jon Mallatt draw on recent scientific findings to answer these questions—and to tackle the most fundamental question about the nature of consciousness: how does (...) the material brain create subjective experience? After assembling a list of the biological and neurobiological features that seem responsible for consciousness, and considering the fossil record of evolution, Feinberg and Mallatt argue that consciousness appeared much earlier in evolutionary history than is commonly assumed. About 520 to 560 million years ago, they explain, the great “Cambrian explosion” of animal diversity produced the first complex brains, which were accompanied by the first appearance of consciousness; simple reflexive behaviors evolved into a unified inner world of subjective experiences. From this they deduce that all vertebrates are and have always been conscious—not just humans and other mammals, but also every fish, reptile, amphibian, and bird. Considering invertebrates, they find that arthropods (including insects and probably crustaceans) and cephalopods (including the octopus) meet many of the criteria for consciousness. The obvious and conventional wisdom–shattering implication is that consciousness evolved simultaneously but independently in the first vertebrates and possibly arthropods more than half a billion years ago. Combining evolutionary, neurobiological, and philosophical approaches allows Feinberg and Mallatt to offer an original solution to the “hard problem” of consciousness. (shrink)

y interest in paleontology began in a childhood fascination with dinosaurs. I spent a substantial part of my youth reading the modest literature then available for children on the history of life. I well remember the invariant scheme used to divide the fossil record into a series of "ages" representing the progress that supposedly marked the march of evolution: the "Age of Invertebrates," followed by the Age of Fishes, Reptiles, Mammals and, finally, with all the parochiality of the engendered (...) language then current, the "Age of Man.". (shrink)

It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility (...) to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language. (shrink)

Palaeontology developed as a field dependent upon comparison. Not only did reconstructing the fragmentary records of fossil organisms and placing them within taxonomic systems and evolutionary lineages require detailed anatomical comparisons with living and fossil animals, but the field also required thinking in terms of behavioural, biological and ecological analogies with modern organisms to understand how prehistoric animals lived and behaved. Yet palaeontological material often worked against making easy linkages, bringing a sense of mystery and doubt. This paper (...) will look at an animal whose study exemplified these problems: the Chalicothere. Increasingly recognized as a specific type from finds across North America and Eurasia from the early nineteenth century onwards, these prehistoric mammals showed short back legs terminating in pawed feet, long front limbs ending in sharp claws, a long flexible neck, and herbivorous grinding teeth. The Chalicothere became a significant organism within palaeontological studies, as the unexpected mix of characters made it a textbook example against the Cuvierian notion of “correlation of parts,” while explaining how the animal moved, fed and behaved became puzzling. However, rather than prevent comparisons, these actually led to comparative analogies becoming flexible and varied, with different forms of comparison being made with varying methods and degrees of confidence, and with the anatomy, movement and behaviour of giraffes, bears, horses, anteaters, primates and other organisms all serving at various points as potential models for different aspects of the animal. This paper will examine some of the attempts to reconstruct and define the Chalicotheres across a long timescale, using this to show how multiple comparisons and analogies could be deployed in a reconstructive and evolutionary science like palaeontology, and illustrate some of the limits and tensions in comparative methods, as they were used to reconstruct organisms which were thought to be incomparable to any modern animal. (shrink)

Over the first decades of the twentieth century, the fragmentary remains of a huge prehistoric ungulate were unearthed in scientific expeditions in India, Turkestan and Mongolia. Following channels of formal and informal empire, these were transported to collections in Britain, Russia and the United States. While striking and of immense size, the bones proved extremely difficult to interpret. Alternately naming the creature Paraceratherium, Baluchitherium and Indricotherium, paleontologists Clive Forster-Cooper, Alexei Borissiak and Henry Fairfield Osborn struggled over the reconstruction of this (...) gigantic fossil mammal. However, despite these problems, shared work on the creature served as a focus for collaboration and exchange rather than rivalry between these three scientific communities. Not only did the initial interpretation and analysis depend on pre-existing connections between British and American paleontological institutions, but the need for comparative material, recognition and contacts brought British and American scholars into communication and exchange with their counterparts in the Soviet Union. This article examines these processes. It first uses these excavations as a comparative case-study of different manifestations of colonial science in this period, examining how scholars in the Britain, the Russian Empire and the United States used formal and informal colonial links to Asia to pursue new research. It then moves to examine how the common problem of reconstructing this giant animal drew metropolitan scientific communities together, at least for a time. The construction of the Baluchitherium and Indricotherium illustrates the drives to expand research both imperially and internationally in the early-twentieth century, but also the continual problems in resources, institutionalization, transport and communication that could run up against scientific work. (shrink)

Whereas historiography of the debates on “early man in America” isolates Florentino Ameghino's ideas on human evolution from his paleontological and geological work, this paper presents Ameghino's ideas on human ancestors in regard to the controversies over the origin and dispersion of mammals. Therefore, this paper analyzes the constitution of paleontology in Argentina at the end of nineteenth century by describing, firstly, the Ameghino brothers' organization of research. By tackling this aspect I want also to discuss the place of science (...) in late nineteenth-century Argentina. Secondly, I will sketch “Ameghino's ideas” about Patagonia as a center of distribution of mammals, the age of Patagonian strata, and the South American origin of humankind. The Ameghino brothers' logistics of fieldwork created not only the means for finding a remarkable fossil fauna but also a trap that undermined their scientific credibility. Therefore, I will focus on the problem of fieldwork in “distant” places and of scientific wandering in Patagonia. In the polemics presented here, language, transportation systems, visual representations, and technical devices were crucial elements for the creation of paleontological objects. -/- . (shrink)

Ce travail pose la question des critères de la „progression biologique“ , d'après les documents fossiles, dans le monde des organismes, c'est-à-dire de ce perfectionnement qui ne s'arrête pas à l'intérieur du cadre d'un phylum donné, comme le „perfectionnement de l'adaptation“, mais qui conduit, au-de-là de phylums de rang différent, à des types supérieurs, par exemple, des Poissons pas les Amphibies et les Reptiles jusqu'aux Mammifères ou aux Oiseaux. Deux groupes de critères y sont recensés en détail, leur contenu est (...) exposé, et on les examine pour voir s'ils caractérisent sans ambiguïté la „progression biologique“. Le premier groupe comprend les critères de „différenciation croissante“ et „d'intégration harmonique”. Ils sont fondés sur la différenciation morphophysiologique ou plus exactement sur la „totalité” des organismes, c'est-à-dire leur multiplicité dans l'unité. Le second groupe de critères, à savoir „indépendance croissante du milieu” et „autonomie individuelle croissante”, part des relations de l'organisme au milieu et aux autres formes vivantes et souligne la „subsistence” des individus, c'est-à-dire leur plus ou moins grande indépendence ou leur stabilité interne. Comme „totalité” et „subsistence” sont les éléments décisifs d'une définition biologique de l'individu, on peut dire que la „progression biologique“ d'un organisme est d'autant plus élevée que sa totalité et subsistence et par là son être individuel sont plus accusés.Tous les critères mentionnés ne sont pas uniformes. Les motifs de leur imprécision sont divers. Tout d'abord, il n'y a pas encore de définition unique et complète de l'individu biologique, de sorte qu'on ne peut circonscrire d'une manière univoque ce qui confère à un organisme une individualité plus forte ou moins forte. Ensuite les lignées au-delà desquelles s'accomplissent des perfectionnements, et dont l'une reste intérieur au phylum , tandis que l'autre le transcende , sont entrelacées si intimement et d'une façon si particulière qu'elles ne se laissent pas séparer franchement et décrire rigoureusement selon leurs signes distinctifs. Tout représentant d'un phylum, peu importe son palier, est en effet nécessairement inséré dans un milieu et en quelque façon spécialisé. Il n'existe pas des types à caractères phylétiques purs, qui ne montrent dans aucune direction un „perfectionnement de l'adaptation”, mais seulement des marques caractéristiques de la „progression biologique”. Enfin nous ne connaissons pas les restes fossiles que le développement ou la formation des grands phylums du règne animal, à savoir du rameau des Vertébrés et des divers groupes des Invertébrés, mais non pas le plus intéressant et le plus important, leur „progression biologique” jusqu'au degré d'organisation qu'ils présentent déjà à l'époque du Silurien ou plutôt du Cambrien. C'est cela seulement qui permettrait une vue plus profonde sur la nature de la „progression biologique”.Die Arbeit stellt die Frage nach den Kriterien des fossil belegten Biologischen Aufstiegs” der Organismenwelt, d.h. derjenigen Vervollkommnung, die sich nicht innerhalb des Rahmens eines gegebenen Bauplans hält, wie die „Anpassungsvervollkommnung”, sondern über verschiedenrangige Baupläne hinweg zu höheren Typen führt, z.B. von den Fischen über die Amphibien und Reptilien zu den Säugern bzw. Vögeln. Ausführlich werden zwei Gruppen von Kriterien besprochen, ihr Inhalt dargelegt und ihre Eindeutigkeit zur Charakterisierung des „Biologischen Aufstiegs” untersucht. Die erste Gruppe umfasst die Kriterien der „zunehmenden Differenzierung” und „harmonischeren Integration”. Diese legen die morphologisch-physiologische Differenzierung oder genauer die „Ganzheit” der Organismen zugrunde, d.h. ihre Vielheit in der Einheit. Die zweite Kriteriengruppe, nämlich „zunehmende Umweltunabhängigkeit” und „zunehmende individuelle Autonomie”, geht von den Beziehungen des Organismus zur Umwelt und zu andern Lebensformen aus und betont die „Subsistenz” der Individuen, d.h. ihr grösseres oder geringeres Losgelöstsein oder ihre Selbständigkeit. Da nun „Ganzheit” und „Subsistenz” die entscheidenden Elemente einer biologischen Definition des Individuums sind, lässt sich sagen, dass der „Biologische Aufstieg” eines Organismus um so höher ist, je stärker seine Ganzheit und Subsistenz und damit sein Individuumsein ist.Eindeutigkeit kommt allen genannten Kriterien nicht zu. Die Gründe für ihre Unschärfe sind verschiedener Art. Zunächst gibt es noch keine eindeutige und vollständige Definition des biologischen Individuums, so dass sich nicht eindeutig umreissen lässt, was einem Organismus eine stärkere oder weniger starke Individualität verleiht. Dann sind die Linien, über die sich Vervollkommnungen vollziehen und von denen die eine innerhalb des Bauplans bleibt , die andere aber über ihn hinausführt so innig und in so eigenartiger Weise miteinander verflochten, dass sie sich nicht sauber scheiden und in ihren charakteristischen Merkmalen genau beschreiben lassen. Jeder Vertreter eines Bauplans, ganz gleich von welcher Ranghöhe, ist nämlich notwendig in eine Umwelt eingepasst und irgendwie spezialisiert. Es gibt keine Typen mit reinen Bauplanmerkmalen, die nach keiner Richtung hin eine „Anpassungsvervollkommnung”, sondern nur Merkmale des „Biologischen Aufstiegs” aufweisen. Schliesslich kennen wir fossil nur die Entfaltung oder Ausgestaltung der Grossbaupläne des Tierreichs, nämlich des Wirbeltierstammes und der verschiedenen Gruppen der Wirbellosen, nicht aber das Interessanteste und Wichtigste, nämlich ihren „Biologischen Aufstieg” zu der organisatorischen Höhe, mit der sie sich im Silur bzw. im Kabrium bereits vorstellen. Das erst würde einen tieferen Einblick in das Wesen des „Biologischen Aufstiegs” vermitteln.This article deals with the question of the criteria for the “biological ascent” of the organic world, resting on fossil evidence. That is, of that improvement which is not only restricted to the framework of a given “general structure” as is the “improvement of adaptation”, but which also leads beyond general structures of differentiated levels to a higher type,e.g. from the fishes through the amphibians and reptiles to the mammals or birds. Two groups of criteria are discussed at length, their content exposed and their univocity for the characterisation of this “biological ascent” is examined. The first group includes the criteria of “increasing differentiation” and “more harmonious integration”. The basis for these is the morphological-physiological differentiation, or more exactly, the “totality” of the organisms,i.e., their variety-in-unity. The second group of criteria, “increasing independence of environment” and “increasing individual autonomy”, is derived from the relationships of the organism to its environment and to other living forms, and stresses the “subsistence” of individuals,i.e., their greater or lesser degree of independence or self-sufficiency. Now since “totality” and “subsistence” are the decisive elements in a biological definition of the individual, it may be said that the “biological ascent” of an organism is higher, the more perfect its totality and subsistence and therefore its individuality is.The criteria mentioned are not univocal. The reasons for this lack of clarity are varied. First of all, there is no univocal and complete definition of the biological individual, so that it cannot be exactly stated just what gives an organism a more or less perfect individuality. Then the lines, along which improvements are made, and according to which the one remains within the general structure and the other goes beyond the general structure , are so intimately and singularly bound together, that they cannot be cleanly distinguished, and their characteristic notes exactly described. For each representative of a general structure, regardless of its level, is necessarily fitted into an environment and somehow or other specialised. There are no types with only notes of the general structure which show in no direction an “improvment of adaption”, but only the signs of “biological ascent”. Finally, we only have fossil evidence for the development or deployment of the “great general structures” of the animal world, namely that of the vertebrates and of the different groups of invertebrates, not for the most interesting and most important, that is, their “biological ascent” to the level of organisation with which they are found in the Silurian or Cambrian periods. Only that would give us a deeper insight into the essence of “biological ascent”. (shrink)

The darwinistic doctrine of a continuous transformation of the animal world cannot be certified by Paleontology. On the contrary the building-plans of the animals present themselves ready made in the history of the earth. That may be shown before all at the oldest vertebrates which appear in the Silur and Devon in types fundamentally differentiated. Also the higher fishes, the amphibia, reptiles, birds and mammals present themselves ready made and are not to be derived one from another. Beyond the reach (...) of families descendance is unknown; it can, if anyhow, be maintained in the sense of a modification within typologically determined boundaries.Beurlen's Neomorphosis must be refused. The will for might, i.e. the will for dominating the world around, does not exist as a formgiving element, and can, before all, not be responsible there where the new type is separated from the old one by not adaptive, and therefore building constructive qualities.Remonstrances showing that the tradition having gaps in paleontology should not admit the above made conclusions are refused. The things found are, on the contrary, fully sufficient, asHeribert-Nilsson also showed for the fossil floras. The typological manner of contemplating has deciding importance in paleontology, whereas that of the theory of descendance only has a secondary one.La doctrine darwinienne d'une transformation continue du monde animal ne peut pas être confirmée par la paléontologie. Les plans constructifs des animaux apparaissent plutôt achevés dans l'histoire de la terre. Cela se montre avant tout aux plus anciens vertébrés qui font leur apparition dans le silure et le devon par des types variés et différenciés fondamentalement. Aussi les poissons de genres plus élevés, les amphibiens, les reptiles, les oiseaux et les mammifères se présentent achevés et ne sont pas dérivés les uns des autres. En dehors du domaine de la famille la descendance est inconnue, et elle ne pourrait être maintenue que dans le sens de modification au dedans de limites prescrites typologiquement. Il faut rejeter la néomorphose deBeurlen. La volonté du pouvoir, c'est-à-dire la volonté de dominer le milieu n'existe pas comme un facteur créateur de formes et ne peut pas avant tout être responsable là où le nouveau type est séparé de l'ancien par des qualités non adaptives, donc des qualités constructives.Les objections qui veulent prouver qu'une tradition paléontologique, pleine de lacunes, n'admet pas les conclusions faites ci-dessus, sont complètement réfutées. Les découvertes suffisent plutôt complètement, commeHeribert-Nilsson l'a démontré, pour les flores fossiles. La manière typologique de contempler a une signification décisive dans la paléontologie, celle de la théorie de la descendance a seulement une signification secondaire. (shrink)

n 1902, 70 million years after it tripped lightly through the Mesozoic forests in search of meat, the skeleton of a 20-foothightyrannosaurus was dynamited out of a sandstone bluff near Hell Creek, Mont. Wrapped in burlap and plaster and shipped back to New York, the bones were painstakingly reassembled by fossil curator Barnum Brown of the American Museum of Natural History. It was there, one day in 1947, that they happened to scare the bejesus out of 5-year-old Stephen Jay (...) Gould. With a mouthful of teeth as big as bananas, the great reptile gaped down at the little mammal who had usurped its place at the head of the food chain and set him scurrying for the safety of his daddy's pant leg. It was a sublime epiphany. Long after Gould could stare with equanimity at the skull of tyrannosaurus, he was left with the essential mystery that still motivates him as perhaps America's foremost writer and thinker on evolution: why should dinosaurs have ended up in human museums instead of—as one among an infinite number of evolutionary possibilities—the other way around? (shrink)

Transitional forms of the recent classes of vertebrates are only known in paleontology. The well described examples are:Eusthenopteron foordi,Ichthyostega andAcanthostega between Osteichthyes and Amphibia,Seymouria baylorensis between Amphibia and Reptilia,Archaeopteryx lithographica between Reptilia and Aves, and the mammal-like reptiles Pelycosauria, Therapsida and Cynodontia between Reptilia and Mammalia. The description of their phylogenetical heterochronies in terms of peramorphosis and paedomorphosis shows the progressive role of the motorial, especially the locomotorial organ systems and their functions in comparison with the retarded evolution of the (...) axial system, especially the skull and central nervous system. The evolution of the Hominidae shows the same rule. — The evaluation of these transitional forms in their fossil context reveals them as inhabitants of biotopes situated in the border areas of coastal and shore landscapes of marine, brackish or fresh water. These biotopes have obviously favoured the innovations on the high taxonomic level of macro-evolutionary characteristics. (shrink)

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

ABSTRACT While a great deal of scholarly attention has been given to the publication of serialized novels in early Victorian Britain, there has been hardly any consideration of the no less widespread practice of issuing scientific works in parts and numbers. What scholarship there has been has insisted that scientific part-works operated on entirely different principles from the strategies for maintaining readerly interest that were being developed by serial novelists like Charles Dickens. Deploying the methods of book history, this essay (...) examines the reporting of Richard Owen's celebrated paleontological reconstructions from the 1830s and 1840s in the serialized formats of the Proceedings of the Zoological Society, his own History of British Fossil Mammals, and, in particular, the Penny Cyclopaedia. It argues that Owen, along with his close friend William John Broderip, clearly recognized the affective possibilities of the serial format and that they exploited the Penny Cyclopaedia's sequential mode of publication to evoke suspense and expectation in their anonymous but collaboratively authored accounts of Owen's paleontological researches. (shrink)

Many traditional attempts to show that nonhuman animals are deserving of moral consideration have taken the form of an argument by analogy. However, arguments of this kind have had notable weaknesses and, in particular, have not been able to convince two kinds of skeptics. One of the most important weaknesses of these arguments is that they fail to provide theoretical justifications for why particular physiological similarities should be considered relevant. This paper examines recent empirical research on pain and, in particular, (...) explores the implications of the dissociation between the sensory and the affective pain pathways. It is argued that these results show that the belief that nonhuman animals experience pain in a morally relevant way is reasonable, though not certain. It is further argued that the proposal to explore the relationship between consciousness and various forms of learning challenges the aforementioned skeptics to provide more physiological details for their claims that nonhuman mammals are probably not conscious. (shrink)

The standard behavioral index for human consciousness is the ability to report events with accuracy. While this method is routinely used for scientific and medical applications in humans, it is not easy to generalize to other species. Brain evidence may lend itself more easily to comparative testing. Human consciousness involves widespread, relatively fast low-amplitude interactions in the thalamocortical core of the brain, driven by current tasks and conditions. These features have also been found in other mammals, which suggests that consciousness (...) is a major biological adaptation in mammals. We suggest more than a dozen additional properties of human consciousness that may be used to test comparative predictions. Such homologies are necessarily more remote in non-mammals, which do not share the thalamocortical complex. However, as we learn more we may be able to make “deeper” predictions that apply to some birds, reptiles, large-brained invertebrates, and perhaps other species. (shrink)

The present study combines dehumanization research with the concept of organizational trust to examine how employees perceive various types of maltreatment embedded within the organizational practices that form the ethical climate of an organization. With the help of grounded theory methodology, we analyzed 188 employment exit interview transcripts from an ICT subcontracting company. By examining perceived trustworthiness and perceived humanness, we found that dehumanizing employees can deteriorate trust within organizations. The violations found in the empirical material were divided into animalistic (...) and mechanistic forms of dehumanization and linked to perceived integrity and benevolence, respectively. Based on the results, a model describing the link between dehumanization and trust is presented and discussed in relation to the ways in which perceptions of humanness become rooted in practices and affect the basic assumptions underlying ethical organizational behavior. (shrink)

The Consequence Argument is the classic argument for the incompatibility of determinism and our ability to do otherwise. Daniel C. Dennett objects that the Consequence Argument suffers from the same error as a clearly unconvincing argument that there are no mammals. In this paper, I argue that these arguments do not suffer from the same error. The argument that there are no mammals is unconvincing as it takes the form of a sorites, whereas the Consequence Argument does not. Accordingly, Dennett's (...) objection misses its mark. (shrink)

Admixture, the genetic exchange between differentiated populations appears to be common in the history of species, but has not yet been comparatively studied across mammals. This limits the understanding of its mechanisms and potential role in mammalian evolution. The authors want to summarize the current knowledge on admixture in non‐human primates, and suggest that it is important to establish a comparative framework for this phenomenon in humans. Genetic observations in domesticated mammals and their wild counterparts are discussed, and a brief (...) global overview on other clades is presented. Based on this, some of the consequences of gene flow, including incompatibilities and their genomic footprint, as well as adaptive introgression are discussed, and suggestions for a functional genomics approach are made. It is proposed that the field is moving beyond descriptive observations in single species, to a comprehensive analysis of admixture and its impact. Admixture is becoming an integral part of mammalian evolution. (shrink)

Admixture, the genetic exchange between differentiated populations appears to be common in the history of species, but has not yet been comparatively studied across mammals. This limits the understanding of its mechanisms and potential role in mammalian evolution. The authors want to summarize the current knowledge on admixture in non‐human primates, and suggest that it is important to establish a comparative framework for this phenomenon in humans. Genetic observations in domesticated mammals and their wild counterparts are discussed, and a brief (...) global overview on other clades is presented. Based on this, some of the consequences of gene flow, including incompatibilities and their genomic footprint, as well as adaptive introgression are discussed, and suggestions for a functional genomics approach are made. It is proposed that the field is moving beyond descriptive observations in single species, to a comprehensive analysis of admixture and its impact. Admixture is becoming an integral part of mammalian evolution. (shrink)

If a meteorite had not fallen on the earth sixty-five million years ago, we would not be where we are now; or more exactly we would not be here at all. If icebergs had not covered a third of the globe's surface three hundred million years ago, this collision some two hundred and thirty-five million years later would have been of no benefit to us. If drought had not swept over the Eurasian continent some ten million years ago, we would (...) still be in the trees, and nothing would encourage us to come down from them. (shrink)

The use of anecdotes is not a viable research strategy to study animal culture. Social learning processes can often be documented with careful quantitative analyses of observational data. Unfortunately, suggestions that killer whales engage in teaching are entirely based on subjective interpretations of qualitative observations. Thus, of teaching in killer whales cannot be used to argue for the occurrence of culture in marine mammals.

The view that female mammals are more docile appears to arise in part from imposing human values on animal studies. Many reports of sexual dimorphism in physical aggression favouring the male in laboratory rodents appear to select circumstances where that expectation is supported. Other situations that favour the expression of conflict in females have been (until recently) relatively little studied. Although female rodents generally do not show the “ritualised” forms of conflict that characterise male sexual competition, they can use notably (...) damaging strategies (especially if they are of short duration). Such considerations might weigh in the selection of strategies by our own species. (shrink)

Mammals have a very complex, tightly controlled, and developmentally regulated process of dosage compensation. One form of the process equalizes expression of the X‐linked genes, present as a single copy in males (XY) and as two copies in females (XX), by inactivation of one of the two X‐chromosomes in females. The second form of the process leads to balanced expression between the X‐linked and autosomal genes by transcriptional upregulation of the active X in males and females. However, not all X‐linked (...) genes are absolutely balanced. This review is focused on the recent advances in studying the dosage compensation phenomenon in mammals. (shrink)

Endogenous retrovirsuses (ERVs) have long been known to influence gene expression in plants in important ways, but what of their roles in mammals? Our relatively sparse knowledge in that area was recently increased with the finding that ERVs can influence the expression of mammalian resident genes by disrupting transcriptional termination. For many mammalian biologists, retrotransposition is considered unimportant except when it disrupts the reading frame of a gene, but this view continues to be challenged. It has been known for some (...) time that integration into an intron can create novel transcripts and integration upstream of a gene can alter the expression of the transcript, in many cases producing phenotypic consequences and disease. The new findings on transcriptional termination extend the opportunities for retrotransposons to play a role in human disease. (shrink)

The present article discusses different basic semiotic-scientific postulates regarding mammals’ sign activity. On the one hand, there are arguments denying animals sign activity, according to which mammals are not capable of semantic generalization on the basis of conventional linguistic values. According to another approach, mammals’ sign activity can be considered as means of ecological adaptation, that is, the features of animal behaviour based on the information, received by them through their habitat characteristics without direct visual contacts with their kind. Movement (...) elements, behavioural reactions of similar motivation and parameters of the sign field, which represents an animal’s sign-information environment, may have some numerical expression and can becalculated depending on the research tasks. Formalization of the animal activity implies simultaneous consideration of the following parameters: magnitude,intensity, anisotropy and the value of a given sign object. (shrink)

Can mammalian mothers adaptively control the sex of their offspring? The influential Trivers-Willard hypothesis proposes that when maternal condition increases the fitness of sons more than that of daughters, the proportion of sons produced should increase with maternal condition. Studies of mammals, however, often fail to support this hypothesis. This article highlights recent advances, including studies on the assumptions of the TWH and physiological mechanisms for sex-ratio manipulation. Particular emphasis is placed on how factors such as paternal quality, maternal reproductive (...) costs and environmental conditions experienced by mothers early in life can mask/alter the expected relationship between maternal condition and offspring sex ratio or lead to apparent support for the TWH. While there is growing evidence that sex ratio around conception may be maternally and paternally manipulated, a challenge for future studies on sex allocation is to integrate how multiple and potentially opposite selective pressures affect offspring sex ratio. The relationship between offspring sex and maternal condition lies at the heart of one of the most controversial hypotheses in evolutionary biology. This review highlights recent findings on the Trivers-Willard hypothesis with particular emphasis on factors which may mask the relationship of interest or falsely demonstrate it. (shrink)

Important marine mammal areas (IMMAs)—‘discrete habitat areas, important for one or more marine mammal species, that have the potential to be delineated and managed for conservation’ (IUCN Marine Mammal Protected Areas Task Force 2018, p. 3)—were introduced in 2014 by the IUCN Marine Mammal Protected Areas Task Force to support marine mammal and wider ocean conservation. IMMAs provide decision-makers with a user-friendly, actionable tool to inform them of the whereabouts of habitat important for marine mammal survival. However, in view of (...) their non-prescriptive, evidence-based and biocentric nature, the conservation effectiveness of IMMAs is strictly dependent on politicians’ willingness to make use of them. It has been the customary task of advocacy non-governmental organisations to lobby decision-makers to stimulate respect for environmental law, but the scientific community is increasingly joining this effort. Scientists can effectively strengthen a healthy relationship between scientific objectivity and political advocacy without damaging the credibility of conservation science. Thus, those undertaking the identification of IMMAs can be among those responsible for strongly advocating the implementation of IMMAs and other conservation initiatives. (shrink)

Important marine mammal areas (IMMAs)—‘discrete habitat areas, important for one or more marine mammal species, that have the potential to be delineated and managed for conservation’ (IUCN Marine Mammal Protected Areas Task Force 2018, p. 3)—were introduced in 2014 by the IUCN Marine Mammal Protected Areas Task Force to support marine mammal and wider ocean conservation. IMMAs provide decision-makers with a user-friendly, actionable tool to inform them of the whereabouts of habitat important for marine mammal survival. However, in view of (...) their non-prescriptive, evidence-based and biocentric nature, the conservation effectiveness of IMMAs is strictly dependent on politicians’ willingness to make use of them. It has been the customary task of advocacy non-governmental organisations to lobby decision-makers to stimulate respect for environmental law, but the scientific community is increasingly joining this effort. Scientists can effectively strengthen a healthy relationship between scientific objectivity and political advocacy without damaging the credibility of conservation science. Thus, those undertaking the identification of IMMAs can be among those responsible for strongly advocating the implementation of IMMAs and other conservation initiatives. (shrink)

Regenerative medicine promises to greatly impact on human health by improving repair outcomes in a range of tissues and injury contexts. Successful therapies will rely on identifying both intrinsic and extrinsic biological circuits that control wound healing, proliferation, cell survival, and developmental cell fate. Animals such as the zebrafish and the salamander display powerful examples of near‐perfect regeneration and scar‐free healing in a range of injury contexts not attained in mammals. By studying regeneration in a range of highly regenerative species (...) that maintain regenerative potential throughout life, many instructive and permissive factors have been identified that could assist in the development of regenerative therapies. This review highlights some of the recent observations in immune regulation, epigenetic regulation, stem cell mobilization, and regenerative signatures that have improved our understanding of the regenerative process. Potential opportunities in harnessing this knowledge for future translation into the clinic are discussed. (shrink)

Comparative mapping and sequencing show that turnover of sex determining genes and chromosomes, and sex chromosome rearrangements, accompany speciation in many vertebrates. Here I review the evidence and propose that the evolution of therian mammals was precipitated by evolution of the male‐determining SRY gene, defining a novel XY sex chromosome pair, and interposing a reproductive barrier with the ancestral population of synapsid reptiles 190 million years ago (MYA). Divergence was reinforced by multiple translocations in monotreme sex chromosomes, the first of (...) which supplied a novel sex determining gene. A sex chromosome‐autosome fusion may have separated eutherians (placental mammals) from marsupials 160 MYA. Another burst of sex chromosome change and speciation is occurring in rodents, precipitated by the degradation of the Y. And although primates have a more stable Y chromosome, it may be just a matter of time before the same fate overtakes our own lineage. (shrink)

Macphail’s comparative approach to intelligence focused on associative processes, an orientation inconsistent with more multifaceted lay and scientific understandings of the term. His ultimate emphasis on associative processes indicated few differences in intelligence among vertebrates. We explore options more attuned to common definitions by considering intelligence in terms of richness of representations of the world, the interconnectivity of those representations, the ability to flexibly change those connections, knowledge, and individual differences. We focus on marine mammals, represented by the amphibious pinnipeds (...) and the aquatic cetaceans and sirenians, as animals that transitioned from a terrestrial existence to an aquatic one, experiencing major changes in ecological pressures. They adapted with morphological transformations related to streamlining the body, physiological changes in respiration and thermoregulation, and sensory/perceptual changes, including echolocation capabilities and diminished olfaction in many cetaceans, both in-air and underwater visual focus, and enhanced senses of touch in pinnipeds and sirenians. Having a terrestrial foundation on which aquatic capacities were overlaid likely affected their cognitive abilities. Vocal and behavioral observational learning capabilities in the wild and in laboratory experiments suggest versatility in group coordination. Empirical reports on aspects of intelligent behavior like problem-solving, spatial learning, and concept learning by various species of cetaceans and pinnipeds, suggest rich cognitive abilities. The high energy demands of the brain suggest brain-intelligence relationships might be fruitful areas for the study when specific hypotheses are considered, e.g., brain mapping indicates hypertrophy of specific sensory areas in marine mammals. Modern neuroimaging techniques provide ways to study neural connectivity, and the patterns of connections between sensory, motor, and other cortical regions provide a biological framework for exploring how animals represent and flexibly use information in navigating and learning about their environment. At this stage of marine mammal research, it would still be prudent to follow Macphail’s caution that it is premature to make strong comparative statements without more empirical evidence, but an approach that includes learning more about how animals flexibly link information across multiple representations could be a productive way of comparing species by allowing them to use their specific strengths within comparative tasks. (shrink)

Burrowing mammals are ubiquitous on farms in South Africa and can hinder agricultural practices. This study explored farmer perspectives of these species, and specifically the factors that influence these perspectives. Forty-four farmers responded to a questionnaire that assessed their ecological knowledge of, tolerance towards and lethal management of burrowing mammals that occur on their farms. The results from generalised linear models showed that neither farmer age, nor level of education are accurate predictors of ecological knowledge, overall tolerance towards burrowers, or (...) their lethal management. Knowledge of burrowing mammals showed a significant relationship with tolerance, with more knowledgeable individuals displaying higher levels of tolerance. However, a farmer’s overall tolerance towards burrowing species did not affect the number of species managed. Our results also suggest that different values are attached to different species when it comes to lethal management. Thus, farmers commonly controlled the numbers of the problem rodent species, Highveld gerbil (Gerbilliscus brantsii) and Cape ground squirrel (Xerus inauris), but were less likely to manage black-backed jackal (Canis mesomelas) and warthog (Phacochoerus africanus), even when experiencing these as problematic. We suggest that the larger, more charismatic species possibly evoke more sympathy from farmers. Agro-ecosystems are likely to become increasingly important for conservation in the future, and we encourage continued studies on the environmental attitudes and approaches of agricultural practitioners as a means to understanding the current status and future trends in ecologically sustainable agriculture. (shrink)

At fertilization in mammals the sperm activates the egg by triggering a series of oscillations in the intracellular free Ca2+ concentration. The precise sequence of events that occur between sperm‐egg contact and the increases in intracellular Ca2+ remains unknown. Here, we discuss recent evidence supporting the hypothesis that a cytosolic sperm protein enters the egg after gamete membrane fusion and triggers Ca2+ oscillations from within the egg cytoplasm. Biochemical studies suggest that there exists a novel sperm protein, named oscillin, that (...) specifically comigrates with Ca2+ oscillation‐inducing activity. Oscillin has been immunolocalised to the region of the sperm that first fuses with the egg. The concept of a specific protein that triggers Ca2+ oscillations may have wider physiological significance since sperm oscillin can induce Ca2+ oscillations in somatic cells, such as neurons and hepatocytes. Unravelling the novel signalling system involved in mammalian fertilization may help reveal some fundamental molecular mechanisms responsible for triggering cytoplasmic Ca2+ oscillations. (shrink)

Transmissible cancers are elusive and understudied parasitic life forms caused by malignant clonal cells (nine lineages are known so far). They emerge by completing sequential steps that include breaking cell cooperation, evade anti‐cancer defences and shedding cells to infect new hosts. Transmissible cancers impair host fitness, and their importance as selective force is likely largely underestimated. It is, therefore, crucial to determine how common they might be in the wild. Here, we draw a parallel between the steps required for a (...) transmissible cancer to emerge and the steps required for an intelligent civilisation to emerge in the Milky Way using a modified Drake equation. Using numerical analyses, we estimate the potential number of extant marine and bivalve species in which transmissible cancers might exist. Our results suggest that transmissible cancers are more common than expected, and that new lineages can be found by screening a large number of species. (shrink)

The main objective of this essay is to validate some of the principal, currently competing, mammalian consciousness-brain theories by comparing these theories with data on both cognitive abilities and brain organization in birds. Our argument is that, given that multiple complex cognitive functions are correlated with presumed consciousness in mammals, this correlation holds for birds as well. Thus, the neuroanatomical features of the forebrain common to both birds and mammals may be those that are crucial to the generation of both (...) complex cognition and consciousness. The general conclusion is that most of the consciousness-brain theories appear to be valid for the avian brain. Even though some specific homologies are unresolved, most of the critical structures presumed necessary for consciousness in mammalian brains have clear homologues in avian brains. Furthermore, considering the fact that the reptile-bird brain transition shows more structural continuity than the stem amniote-mammalian transition, the line drawn at the origin of mammals for consciousness by several of the theorists seems questionable. An equally important point is that consciousness cannot be ruled out in the absence of complex cognition; it may in fact be the case that consciousness is a necessary prerequisite for complex cognition. (shrink)

Self-medication behaviour is the use of natural materials or chemical substances to manipulate behaviour or alter the body’s response to parasites or pathogens. Self-medication can be preventive, performed before an individual becomes infected or diseased, and/or therapeutic, performed after an individual becomes infected or diseased. We summarized all available reports of self-medication in mammals and reconstructed its evolution. We found that reports of self-medication were restricted to eutherian mammals and evolved at least four times independently. Self-medication was most commonly reported (...) in primates. Detailed analyses of primates suggest that self-medication is a life-history trait associated with body size, absolute brain size and longevity, but we found no support for the hypothesis that self-medication evolved to reduce the costs of social living. Large, longer-lived species might thus benefit uniquely from self-medication. (shrink)

Australia is thought of as the home of marsupials, but South America has 60 or so species of these interesting mammals. The genome of one of these, the South American grey short-tailed opossum, Monodelphis domestica, has just been sequenced and published in June.1 The high quality 6× coverage is the first marsupial genome completed, pipping the 2× coverage of the Australian tammar wallaby at the post by half a year. The opossum genome has an unusual structure with fewer chromosomes than (...) the human genome (9 pairs versus 23 pairs) but a longer total length (3.4 billion versus 3 billion bases). The opossum autosomes, like those of all marsupials, are extremely large but, in contrast, the X chromosome is only 76 Mb long. The opossum genome has turned up several surprises and provided critical new information on the evolution of mammalian genomes2-6. BioEssays 29:1073–1076, 2007. © 2007 Wiley Periodicals, Inc. (shrink)