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Review of ‘Evolution in four dimensions: Genetic, Epigenetic, Behavioral and Symbolic Variation in the History of Life. Revised Edition 2014. By Eva Jablonka and Marion J. Lamb. MIT Press. Evolutionary studies tend to be seen as arcane and marginal in the mainstream press, and an evolutionary perspective is seldom alluded to in understanding the trajectory of myriad of sensationalised episodes that are presented as the story of the progress of mankind, at least in the western media. Our attention is constantly drawn to new and apparently surprising stories that illustrate depravity, technological breakthroughs and political realignments as if there was no plot or discernible direction in our continuing narrative of life on this planet. And yet such modern syntheses of evolutionary thought, as typified in this book, can show us that there is an underlying build-up of complexity in our progress and our relationship with the natural world that makes life both more comprehensible and predictable. The book, then, I feel, is very timely, pulling together disparate lines of enquiry to present a fairly comprehensive overview of what now may be considered the main processes in evolutionary change and development, uncovered since the new synthesis of evolutionary thought in the 60s and 70s. In doing so, the authors realise that they are challenging seemingly long-established principles in evolutionary science and especially the simplified version of genetic inheritance that is fed to the public. Their starting point is a statement of four new principles:There is more to heredity than genes Some hereditary variations are non-random Some acquired information (including behavioural tendencies) is inherited Evolutionary change can result from instruction as well as selection. In the first section on new developments in genetic research, they examine how research shows that inheritance of characteristics through genes is more complex than is usually presented, in that much of DNA is not just a ‘blue print’ for cell production, but behaves in ways to control the bits that do produce cells, and control the developmental process that can make them flexibly responsive to the environmental conditions of their growth. Thus genetic variation is not as random as once believed. They then go on to explain how epigenetic factors influence development processes too. This section is more controversial in that they reopen an argument that many thought was over a long time ago – between Lamarckian ideas of acquired characteristics being inherited, and the Darwinian natural selection of random mutations being inherited. Modern research shows the picture is more complex and there are processes that influence gene activity, cell structure, methylation and RNA interference which affect information transmission between cells and are heritable, affecting variations down generations. In the third section, they focus on recent research on Behavioral Inheritance systems – behaviour-influencing substance transmission (e.g. through breast milk), non imitative social learning, and imitation. Together these are indicative of a much wider definition of cultural evolution which can also then be seen to have evolved in a much wider range of organisms than just humans – to which the term has mostly been applied, certainly in psychological circles. Transmission of ‘traditions’ become cumulative and lead to evolving ‘new’ lifestyles in a wide range of species. In the fourth section on Symbolic Inheritance Systems, they finally begin to relate all the previous ideas to the matter of what are the most important factors that make humans unique in nature – the way we organise, transfer and acquire information being crucial, using words and symbols. They review models that have been previously proposed: memetics and massive modularity of the mind, both of which tend to focus on ‘selection’ in cultural evolution. They emphasise the developments in culture through functional adequacy of artefacts and behaviours in response to the environment and the changing environments of later generations which may lead to changes to the transmitted traditions and artefacts handed down. This perspective thus also encompasses the idea of ‘niche creation’ and the changes that this makes to the selection pressures on subsequent generations. This can have runaway effects as seen in the evolution of the peacock’s tail and display on a genetic level, but at the cultural level in the increasing rates of technological development in mankind. The second half of the book is then focussed on how the four dimensions of evolution interact, perticularly on environmental effects, eg: heat shock and other forms of genetic damage, which induce changes in gene products and developmental processes that can explain trends in evolutionary change that have thus far been inpenetrable, eg: genetic assimilation. This is the mechanism, recently established, where elements of behavioural sequences, eg: song, or elaborate nest building are built over evolutionary time by some elements becoming innate in genetic terms, and are then elaborated by further learned elements. This has great explanatory value in showing how Niche Construction becomes stretched by such a process to become very complex seqences of interaction where the niche constructed increasingly controls the immediate environment which affects and controls the selection pressure that impinge on the organism, eg: beaver dams and agricultural land use in humans. This causes, over time, exponential development processes, with exponential increases in capabilities. Thus the activities of one generation influence and shapes the conditions of the next generation, creating feedback between the inherited genes and the inherited niche, for example in the spread of lactose tolerance into adulthood that has followed domestication of cattle and other livestock. They use this framework to also explain the evolution of language from primary gesture and sounds found in many species of primates to the increasingly complex sophistication of the organs of perception that have led to the complex construction and rapid modulation of sound that constitutes the ability to produce and understand speech in modern humans. This has subsequently gone on to underpin the creation of culture that has accelerated social and cooperative coordination of groups into bands, tribes, societies and nations, where pressure increasingly selects for better memory, social awareness of others and their motives, rapid problem solving cognitive capabilities etc. The final comcluding sections of the book are devoted to explaining how and why the previously proposed mechanisms of inheritance have evolved through elaboration of the products and mechanisms of maintenaance of earlier heritability systems, including reactions to stress and changing environments of geography, seasons and climates. Overall, though it is a densely worded scientific tome at heart, the essential message, and the pace at which they explain it are sufficiently interesting, important and ground breaking to keep the reader enthralled. For the more devoted evolutionary enthusiast, it covers major break throughs in theory and it's empirical support over the last twenty years or so all in one lengthy, but intelligible, read – a feat well worth doing, I feel.