A scientist of the future

Richard Dawkins begins The Genetic Book of the Dead with an arresting claim: that “your body and your genome can be read as a comprehensive dossier on a succession of colourful worlds long vanished, worlds that surrounded your ancestors”. The analogy is not quite accurate, because we can’t read that dossier directly. There is no current technology that will allow us to scrape away the millions, or billions, of generations between us and our ancestors swimming in Cambrian seas or crawling through Hadean slime. Too many mutations and adaptations have overwritten those “colourful worlds”. To overcome this limitation Dawkins’s survey adopts the point of view of a “scientist of the future” (SOF), who, rather better equipped, will be able to examine fossil remains to reveal the detailed features of our world and its deep history.

The author illustrates this approach with a photograph of a lizard clinging to the trunk of a tree. The lizard is so well camouflaged that it takes the reader a few seconds to spot its body against the similarly coloured and textured tree bark. If presented with the fossilized skin of such a lizard, he argues, the SOF would have no problem identifying its arboreal habitat. And were she to study the red-grey mottled skin of the horned lizard of the Mojave, she would instantly surmise that it lived in a sandy, stony desert.

This is indeed where the horned lizard lives, but Dawkins is making a subtler point. With advanced technologies, the SOF will be able to discern even invisible habitat features that natural selection has stamped into the genomes and bodies of today’s animals and plants (and that such detailed environmental information about the past is encoded in the fossil record as it stands). For example, the SOF will be able to read features of today’s Cornish coast, its ambient air pressure, temperature and wind speed, from an examination of the aerodynamic properties of the tail feathers of a gull that once swooped over its cliffs.

Of course, Dawkins cannot yet know what insights the SOF’s perspective will provide, so ultimately he has to settle for his own perspective on evolution. He is his own best SOF, and perhaps that is really the point of the conceit – to make his own opinions about animal evolution seem self-evident. For instance, nearly all fish propel themselves through the water, either with fins or with the sinuous motion characteristic of eels, sharks or the extinct ichthyosaur. In contrast, dolphins and whales swim up and down. Why? According to Dawkins, it seems likely that whale and dolphin locomotion is a relic of the galloping gait of their common bear-like ancestor. He goes on to examine the convoluted evolutionary history of turtles and tortoises, noting that the tortoises familiar to us are known as land turtles in America. You might think this is just a cultural difference in nomenclature, but in fact fossil evidence insists that our grass-grazing tortoises used to swim in the sea, and that these ancestral aquatic turtles had land-dwelling forebears of their own. So, “what we British call tortoises are just sea turtles who … returned to the land”. (In Alice in Wonderland the Mock Turtle’s teacher is an old sea turtle called Tortoise.)

Similarly complex developmental and evolutionary paths seem to have been taken by various body parts, including the paired pharyngeal nerves that enervated the larynx and associated tissue in the neck of the giant dinosaur brachiosaurus. Dawkins describes how, early in its development, these nerves grew close to tissues that would become head, neck, heart and thorax; then, as the neck lengthened, the heart and its vessels descended into the chest, taking the developing pharyngeal nerve on a twenty-metre detour to reach the larynx, which remained in the neck. He argues that these examples of bad design can be explained only by the blind forces of Darwinian natural selection, which makes no distinction between its “mistakes” and the parallel, seemingly logical evolution of organs such as long tongues for rooting out insects from their burrows, or the paddled feet of burrowing animals such as the mole and mole cricket.

Birdsong is also championed as a product of natural selection, honed by what might be called the aesthetic sense of female birds in preferring the songs of certain mates to others, and the ability of the most successful male songs to manipulate female physiology to favour mating. Dawkins also argues that the human imagination may have evolved as a kind of “vicarious internal simulation” machine, used to assess “within the safe confines of the skull” the possible consequences of actions. And while camouflage is a familiar topic in evolutionary biology, he comes to it with many new insights and observations. He notes that the otherwise excellent camouflage of a grey owl against the grey-brown bark of a tree is spoilt by its vertebrate bilateral symmetry (the bark has no such symmetrical regularity), and that this flaw is probably the result of “some deep embryological constraint”, meaning a feature of embryological development that cannot be rewired without, for example, messing up essential symmetries involved in organ development or function. He also differentiates cleverly between animals that always look like themselves – he calls them two-dimensional “paintings” – and others that are “statues”, where the 3D body is capable of resembling something else (a caterpillar that looks like a twig, say, or a fish that resembles floating seaweed) in order to deceive predators or prey.

The author’s most famous book, The Selfish Gene (1976), used a “gene’s eye perspective” to shift the focus of natural selection from the individual or species to the gene and claimed that our bodies are mere “gigantic lumbering robots” operated by our genes. This view of things scored early successes, particularly in accounting for the “altruism” of worker bees or ants that sacrifice their reproductive capacity to care for the queen’s offspring, in apparent contradiction of the tenets of Darwinian natural selection, which should favour the individual’s fitness to reproduce. From the “gene’s eye view” the worker’s “altruism gene” is favoured by natural selection because the peculiar inheritance pattern in ants. Workers share 75 per cent of their genes with their sisters (the queen’s offspring), but would share only 50 per cent with their own offspring if they reproduced sexually. Therefore, the altruism gene has a higher chance of being passed to the next generation through the queen’s offspring than through the worker’s offspring. It selfishly promotes apparently selfless behaviour to ensure its own survival.

The success of Dawkins’s first book propelled the “selfish gene” perspective from the field or laboratory into public consciousness. It was even claimed to have been an inspiration for the individualism of the financial boom years in the 1980s and 1990s. But several advocates – most famously the entomologist and ecologist E. O. Wilson – later abandoned the “gene’s eye view” to accept that natural selection also acts at an individual or group level. Dawkins devotes a whole chapter of The Genetic Book of the Dead to arguing against this perspective, insisting that “essentially all serious biologists studying animal behaviour in the wild have adopted … the gene’s eye view”. This is biology viewed through his proprietary lens, a perspective some might consider unbalanced considering the number of excellent papers on multi-scale selection written in recent years.

Dawkins moves onto less adversarial ground when he revisits the theme of his 1982 bookThe Extended Phenotype to explore the observable characteristics of a wide variety of species, among them the nests of caddisfly larvae, potter wasps and bowerbirds, as well as the burrows of moles, mole crickets and their “megaphones”. He also undertakes a fascinating exploration of the role of deception in nature, including the “deplorable” cuckoo, a brood parasite that tricks nesting birds into rearing its young. What is both remarkable and puzzling is that the common cuckoo lays her eggs in the nests of many bird species, yet manages to mimic the colour and patterning of the clutch normally produced by each host. The remaining chapters explore Dawkins’s view of the evolution of seals and fish, concluding with an insightful exploration of the grim strategies that pathogens and parasites have evolved to maximize their genes’ success at the expense of their hosts.

The Genetic Book of the Dead is avowedly a far-ranging “reverie”. Unlike Richard Dawkins’s earlier books, it lacks a unifying theme or big idea (besides the notion that natural selection is the most creative force in the known universe). But the looser format gives him time and room to showcase his extensive knowledge of the natural world. The result is a book that will inform, intrigue and fascinate its readers.

Johnjoe McFadden is Professor of Molecular Genetics at the University of Surrey. His most recent book is Razor Sharp: The role of Occam’s razor in science, 2021

The post A scientist of the future appeared first on TLS.