Lead author Kevin Lala answers questions about the new book.
A new scientific view of evolution is emerging—one that challenges and expands our understanding of how evolution works. In this book, a group of leading biologists draw on the latest findings in evolutionary genetics and evo-devo, as well as novel insights from studies of epigenetics, symbiosis, and inheritance, to examine the central role that developmental processes play in evolution.
What would you say was your book’s main message?
KL: That development matters! How organisms develop – including their behaviour, and their plasticity – and what organisms do – for instance, the changes they bring about in their environments – influence the rate, pattern, and direction of evolution. Exciting new scientific discoveries are expanding evolutionary biology beyond the classical view of gene transmission guided by natural selection. It has become clear that consideration of developmental phenomena is needed for evolutionary biologists to generate better explanations for adaptation and biodiversity.
KL: Evolutionary theory is currently undergoing something of a revamp, as biologists come to terms with a rush of striking findings that challenge the orthodox narrative. A new consensus is beginning to crystallize, in which novel forms of adaptability and dynamical feedbacks play central roles. For instance, historically, biologists tended to assume the inheritance of traits from one generation to the next largely reduced to the transmission of genes from parent to offspring, but it has turned out to be far more complicated. Countless resources other than genes are now known to be passed down the generations, including hormones, symbionts, epigenetic changes, antibodies, and learned knowledge.
Animal culture provides example. Biologists have long been aware of cultural inheritance in humans, but regarded it as a special case. In Evolution Evolving we describe how in the last fifty years, vast evidence for culture in animals has emerged. Familiar examples include chimpanzees fishing for ants and termites with sticks, and birds drinking from milk bottles. Humpback whales in the Gulf of Maine, for instance, have devised an innovative method of feeding on fish shoals known as lobtail feeding, which has spread through populations through cultural transmission. It involves the whale slapping the water surface with its tail fluke, which shocks the fish into tightening their shoal, then the whale swims around the shoal releasing air from its blowhole, which traps the fish in a net of bubbles, before lunging up from beneath to feast on the corralled prey. Interestingly, other humpbacks in the northeast Pacific have a slightly different culture in which they collaborate in teams to coordinate their bubble net feeding. In these cases, the adaptations needed to hunt locally abundant prey did not arise through genetic mutation and genetic inheritance, but through behavioural innovation and cultural inheritance. Such studies show animal culture does more than contribute to inheritance: it allows groups of animals to adjust their behaviour to match their environment. To adapt.
KL: Yes, the scientific understanding of evolution is evolving too, with new ways of explaining evolutionary change. Until recently, biologists would have regarded lobtail feeding in whales as intriguing natural history, but irrelevant to evolution. However, times are changing. There is now extensive evidence, both from the experimental laboratory and from natural populations, for adaptation occurring through the selection of epigenetic, symbiotic, cultural, and other forms of heritable variation. Biologists are coming to the realization that such phenomena are not analogous to biological evolution, they are biological evolution – evolution where inheritance occurs through something other than genes. New ideas, such as extra-genetic inheritance, plasticity-led evolution, niche construction and evolvability are becoming part of the explanatory tool kit of evolutionary biology.
KL: The title captures the core idea that the evolutionary process itself has evolved over time, and continues to evolve. Part of the beauty and simplicity of Darwinism is that all organisms can be understood as evolving through natural selection. And yet recent studies show that organisms differ in how good they are at evolving. If all organisms evolve through the same mechanism, why should that be? The answer is that natural selection is not something that just happens to organisms: their activities and behaviors contribute to whether and how it happens. The form that natural selection takes depends critically on the mechanistic details of how each organism operates – its development, physiology and behavior. Without undermining the central importance of natural selection and other Darwinian foundations, new developmental insights indicate that all organisms possess their own characteristic sets of evolutionary mechanisms.
Organisms have also evolved different abilities to generate and modify fitness differences, and thereby shape the direction of natural selection. For illustration, consider how desert termites evade desiccation by constructing a mound and ‘mining’ water from deep below the surface, which they transport to the nest as dollops of wet soil. In doing so, the termites change the direction of natural selection: selective advantage that might have accrued to evolving thick cuticles that limit desiccation, as seen in other termites, now accrues to the ability to build mounds and dig deep into the soil. Likewise, butterflies are known to respond flexibly to low food availability as caterpillars by developing stronger thoracic muscles, which enables them to fly to better habitats; in doing so, they switch natural selection away from coping with low food availability to favour traits enhancing dispersal. In this way, how organisms develop and what organisms do makes a difference to their evolution. Different capabilities to modify environments (a.k.a. ‘niche construction’) and to develop flexibly (a.k.a. ‘phenotypic plasticity’) further underpin variation among species in evolvability.
KL: Absolutely! Humans do not evolve like mice, fruit flies, or yeast. We interpret natural selection differently because we develop differently, interact with the world differently, and inherit selectable variation differently. Once scientists accept that the evolutionary process evolves then rich explanations for human evolution to be based on scientifically validated and widely observed natural processes, including for some of humanity’s most striking and unique features. For instance, that human technology is off the scale is not unexpected once the manner in which dynamical feedbacks between hands, brains, and social groups create physical and developmental environments is appreciated.
A key take-home message of Evolution Evolving is that humans do not simply react to change, they are active agents who frequently construct the conditions to which they adapt. We are champion niche constructors. Our ancestors didn’t just evolve to be suited to the world; they shaped the world. We describe how the remarkable success of our species, our enhanced capacity to adapt, our astonishing diversity, the bewildering amounts of information that we have generated, and our large-scale cooperation, all follow directly from our heavy reliance on social learning. Human minds were not just built for culture, they were built by culture.
KL: I’ve been privileged to work on this project with a stellar group of scientists. Tobias Uller is Professor of Evolutionary Biology at Lund University, Sweden. He is the coeditor of Evolutionary Causation: Biological and Philosophical Reflections and Philosophy of Science for Biologists. Nathalie Feiner is a Lise Meitner group leader at the Max Planck Institute for Evolutionary Biology at Plön, Germany, and affiliated with Lund University. Marcus W. Feldman is the Burnet C. and Mildred Finley Wohlford Professor of Biological Sciences at Stanford University, USA. He is a co-author, along with John Odling-Smee and me, of Niche Construction. The Neglected Process in Evolution (Princeton) and with Luca Cavalli-Sforza of Cultural Transmission and Evolution (Princeton). Scott F. Gilbert is the Howard A. Schneiderman Professor of Biology at Swarthmore College (emeritus). Scott is the author of two widely used textbooks Developmental Biology (Oxford) and Ecological Developmental Biology (Sinauer).
The main challenge associated with writing this book was to integrate the evolutionary findings of several academic fields into a coherent and novel perspective on evolution. That has been possible only because the authors possess complementary expertise. I have a background in evolutionary and behavioural biology, cultural evolution, and niche construction, Tobias in evolutionary ecology, Nathalie in evo-devo and molecular evolution, Marc in evolutionary genetics and cultural evolution, and Scott in developmental biology and eco-evo-devo. We also all share an interest in the philosophy and history of biology, which is important because we wrestle with some truly fundamental conceptual issues in the book (Where does biological information come from? What controls development? Are organisms active agents? What are the causes of evolutionary change? etc).
Anyone and everyone. Evolution is a fascinating subject, and the field of evolutionary biology is at such an intriguing juncture just now, where biologists are being forced to rethink how evolution works. New scientific discoveries are pouring out almost daily, many of which appear to challenge the orthodox understanding. Phenomena that scientists used to think are impossible – such as the inheritance of acquired characteristics – have now been shown to happen. We’ve tried to communicate some of the excitement that these new findings are generating, and to write in a non-technical accessible style that anyone can comprehend. What is more, Evolution Evolving is brought to life with some fascinating examples of natural history, and beautifully illustrated with lovely line drawings. I hope this book will thrill and inspire readers with an emerging new vision of adaptive evolution.
Kevin N. Lala is Professor of Behavioural and Evolutionary Biology at the University of St Andrews, UK. He is the author of Darwin’s Unfinished Symphony: How Culture Made the Human Mind (Princeton) and other books.
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