Book Review: Crossings: How Road Ecology Is Shaping the Future of Our Planet

***** An eye-opening and thought-provoking reportage

Crossings book covering showing yellow text on top of an image of a winding road snaking through an evergreen forest.The road to hell might be paved with good intentions, but the roads to pretty much everywhere else are paved with the corpses of animals. In Crossings, environmental journalist Ben Goldfarb explores the outsized yet underappreciated impacts of the ~65 million kilometres of roads that hold the planet in a paved stranglehold. These extend beyond roadkill to numerous other insidious biological effects. The relatively young discipline of road ecology tries to gauge and mitigate them and sees biologists join forces with engineers and roadbuilders. This is a wide-ranging and eye-opening survey of the situation in the USA and various other countries.

As Goldfarb points out, roadkill is as old as the road but the phenomenon went into overdrive with the invention of the combustion engine and a new-found need for speed that menaced humans and animals alike. With the morbid curiosity typical of biologists, Dayton and Lilian Stoner published the first tally of motorcar casualties in 1925, in the process diagnosing “a malady with no name” (p. 16), as the word roadkill would not be coined for another two decades. The word road ecology was only coined in 1993 by Richard Forman, though it was translated from the German Straßenökologie that was coined in 1981 by Heinz Ellenberg.

As a discipline, road ecology both studies the impact of roads and formulates solutions. Particularly common, and featured extensively in this book, are wildlife crossings. Underpasses serve many animals but others have different needs such as overpasses or canopy rope bridges. Amphibians and reptiles are given a helping hand with toad tunnels and bucket brigades. Fish migration is being restored by retrofitting culverts that are better navigable.

An empty long, winding road running through trees going down a hill.
The long and winding road by Mussi Katz, via flickr.

To us, roads are the unnoticed connective tissue that links places of extraction with industry and commerce, and shuttles commuters between home and work. For other animals, they are barriers: despite the good intentions, wildlife crossings cannot serve all animals equally and cannot be constructed everywhere. Millions of animals still die in collisions every day. Goldfarb addresses the very real concerns of extirpation, habitat fragmentation, interrupted migrations, and noise pollution. With roads come humans who bring deforestation, hunting, real estate development, urban sprawl, tourism, etc.

Amidst this litany of harms, Goldfarb features several topics that will be eye-opening even to ecologists. There is the little-known history of how the US Forest Service constructed one of the world’s largest road networks of now mostly abandoned forest tracks. Roads also feed a diverse community of scavengers that includes humans; a necrobiome that “airbrushes our roadsides, camouflaging a crisis by devouring it” (p. 181). In Syracuse, Goldfarb faces the racist legacy of interstate highways that were bulldozed straight through Black and Latino neighbourhoods. Plans are now afoot to reverse this wrong, move the highway, and create a community where people can again walk to their destinations. In a brilliant flourish, Goldfarb connects this back to the book’s main topic: “Road ecologists and urban advocates are engaged in the same epic project: creating a world that’s amenable to feet” (p. 287).

Badbury Rings Avenue in Dorset showing a long downhill slope with large oak trees either side.
Badbury Rings Avenue – No HDR by JackPeasePhotography, via flickr.

So far, so good. Goldfarb’s writing shines and certain turns of phrase are memorable. I was initially concerned how US-centric this book would be. Though weighted towards US examples, Goldfarb also visits Wales, Costa Rica, Tasmania, and Brazil, and discusses several European initiatives.

Despite the gloomy picture, there are some encouraging signs. The US Forest Service has started decommissioning parts of its road network. Brazil, meanwhile, shows what government regulation can achieve. Here, highway operators are held legally responsible for dealing with the harm and costs resulting from collisions. Contrast this with the USA, Goldfarb observes sharply, where individual drivers are blamed for collisions. This “deflects culpability from the car companies building ever more massive SUVs and the engineers designing unsafe streets” (p. 295). As with addressing climate change, individual action only gets us so far; making roads safer demands systemic change, “a public works project, one of history’s most colossal” (p. 296).

And yet, something nagged at me. The focus on mitigation smacks of a palliative solution and Goldfarb concedes the limitations of road ecology. Crossings and fences will not stop the many other impacts of roads and risk becoming “a form of greenwashing […] a fig leaf that conceals and rationalizes destruction” (p. 265). As with other environmental problems, should we not first focus on abandoning or reducing certain behaviours, instead of turning to techno-fixes? Can we imagine something more radical? Can Goldfarb?


Tarmac country road running between two oil seed rape fields.
Country road and yellow field by Susanne Nilsson, via flickr.

To his credit, he admits wrestling with this problem. “The most straightforward solution to the road’s ills would be a collective rejection of automobility […] In the course of writing this book, I’ve felt, at times, like a defeatist—as though, by extolling wildlife passages, I foreclose the possibility of a more radical, carless future” (p. 295). I would have loved to see him explore this further in a dedicated chapter. Instead, Goldfarb comes down on the side of pragmatism. Bicycles and public transport are great for making urban areas more liveable, but most roadkill happens elsewhere. Furthermore, personal mobility is only part of the story, with logistics making up a huge chunk of traffic. The eye-opening chapter on Brazil, and the outsized influence of China’s Belt and Road Initiative that sees it invest in infrastructure globally, is a forceful reminder that the developmental juggernaut is nigh impossible to slow down. One road ecologist points out that you cannot seriously enter the discussion around roads if you oppose social and economic development, while another chimes in that, whether we like it or not, more roads will be built. Although I do not think resistance is futile, Goldfarb leaves me sympathetic to the road ecologists who are desperately trying to nudge construction projects in directions “that, if not quite “right,” are at least less wrong” (p. 270).

Goldfarb acknowledges the input of some 250 people and even then stresses his book is far from the final word on the subject. He encourages readers to take it as a starting point and read deeper, providing 43 pages of notes to the many sources of information he has used. I would additionally recommend A Clouded Leopard in the Middle of the Road by Australian road ecologist Darryl Jones which was published last year but seems to have flown under the radar compared to Goldfarb’s book. Overall, Crossings is a wide-ranging, eye-opening, and thought-provoking reportage that deserves top marks.

Book Review: The Last Days of the Dinosaurs

*****A unique on the story of dinosaur extinction and its aftermath

The day an asteroid slammed into the Yucatán Peninsula some 66 million years ago is a strong contender for “the worst day in history”. The K–Pg extinction ended the long evolutionary success story of the dinosaurs and a host of other creatures, and has lodged itself firmly in our collective imagination. But what happened next? The fact that a primate is tapping away at a keyboard writing this review gives you part of the answer. The rise of mammals was not a given, though, and the details have been hard to get by. Here, science writer Riley Black examines and imagines the aftermath of the extinction at various times post-impact. The Last Days of the Dinosaurs ends up being a fine piece of narrative non-fiction with thoughtful observations on the role of evolution in ecosystem recovery.

Before delving in, a brief word on what is not in the book. Black does not discuss the history of the research that discovered evidence of an asteroid impact, such as the iridium spike and the crater. Nor does she go into the ongoing debate on the relative contributions of the asteroid and Deccan Trap volcanism. Instead, Black’s approach is to imagine a day in the life of the survivors at various time points post-impact: after an hour, a day, a month, a year, a century, all the way up to one million years. She focuses on the Hell Creek formation in western North America as it offers one of the clearest windows into the mass extinction and its aftermath. Most chapters have a short coda that looks at how life was faring elsewhere on the planet. Black’s style of choice is narrative non-fiction: she is resurrecting individual animals and imagining their lives. As she explains in her preface, to allow full immersion, she is not interrupting the flow of her story with notes and references, which are found at the back of the book. An extensive, 58-page(!) chapter-by-chapter appendix reveals her process and discusses what we know, what is hypothetical, and where she has speculated to smooth over the gaps in our knowledge.

Barringer Crater in Arizona.
Barringer Crater by Simon Morris, via flickr.

Now, when this book was announced, just the prospect of dipping into the story of the disaster and the ensuing recovery already had me excited. However, The Last Days of the Dinosaurs surpassed even these expectations for two main reasons.

First, there are plenty of exciting new ideas and scientific findings here. Black’s interpretation of the impact will no doubt ruffle some feathers as it is particularly catastrophic. Forget the often-depicted idea of an asteroid seen streaking across the sky, Black writes, this thing came in fast at some 45,000 miles per hour (~20 km/s). Forget, too, the often-depicted drawn-out hunger winter for the surviving dinosaurs. I had not come across this idea before, but Black writes how a global heat pulse that lasted several hours fried anyone that could not crawl underground or stay submerged underwater. This is based on estimates of the amount of material ejected by the impact that, upon re-entry, heated the atmosphere to several hundreds of degrees centigrade. It would have ignited global wildfires. Finally, the impact injected vast amounts of sulfate aerosols into the atmosphere as the impact site was rich in calcium sulfate. The ensuing acid rain “might have effectively erased some of the slowly forming fossil record” (p. 256), explaining why fossils are hard to find in the layers around the K–Pg boundary.

Fossil of dinosaur jaw full of sharp teeth.
Fossil of dinosaur jaw full of sharp teeth by Ivan Radic, via flickr.

Regarding the survivors, Black has plenty of interesting ideas too. As seen at other times and other places, there was a fern spike. A rapid initial proliferation of ferns is frequently seen in devastated ecosystems where plants have died. And why did birds survive? One novel idea is that the survival of beaked, but not toothed birds is part of the answer. “Maintaining a mouth of sharp teeth comes with a reliance on animal food. […] A consumer that feeds on other consumers has very little to survive on now. But beaked birds do not face the same constraints” (p. 117). With the extinction of toothed birds and pterosaurs, the beaked birds were poised for an evolutionary radiation. Something similar happened with the mammals. Black prominently mentions the idea that Elsa Panciroli promoted in Beasts Before Us, that “it was competition between mammals that limited the number of different forms and niches Mesozoic mammals evolved into” (p. 158). With the extinction of more archaic mammaliaformes, the placental and marsupial mammals would flourish.

The second reason the book surpassed my expectations is Black’s reflections on the process of evolution and its role in ecological recovery. This is where her prose sings in places. One thousand years post-impact “[…] there is no script for what’s about to unfold, no cast of characters that inevitably must be filled” (p. 142). One million years post-impact a reptilian resurgence seems unlikely, but “the rise of the mammals is anything but assured […] When a global disaster ends one evolutionary dance, shifting the tempo, another begins, with no certainty as to who will lead” (p. 182). She poignantly notes how the fossil record “is not in any way a complete record of life on Earth. It is a record of fortuitous burials” (p. 254). And on the process of evolution, she writes how variation and happenstance provide “the raw material for natural selection and other evolutionary forces to shunt down different pathways. Not that there is any intent to this. It’s a passive state, a constantly running routine that is merely part of existence itself” (p. 196). This is music to my ears and Black’s writing is one of the highlights of this book.

Fossil of a dinosaur hand in a museum in sand.
Fossil of a dinosaur hand in a museum by Ivan Radic, via flickr.

Writing about such an iconic event carries the risk of intense scrutiny. No doubt, some experts and other palaeo-nerds will disagree with some of the details presented here. I think her appendix is sufficiently explicit about where she speculates and where she has chosen not to hedge her bets on different explanations. I was willing to read the book in this spirit, as one possible interpretation of how things might have unfolded, though one that Black carefully backs up with scientific evidence. My quibbles are rather minor instead. One is that the book has no index, the other is that there are no notes to the appendix. Relegating the discussion of the underlying science to the appendix is a defensible choice. But not properly referencing the studies mentioned here is, to me, a minor blemish on an otherwise excellent book.

If you have any interest whatsoever in dinosaurs and their extinction, this book comes highly recommended. Her take on the topic, dipping into the extinction and recovery at various moments post-impact, is novel. I am not familiar with other books attempting this. As a bonus, I expect that many readers will come away with a better understanding of the process of evolution.

Last days of the Dinosaurs book cover showing a T-Rex skeleton.

The Last Days of the Dinosaurs is available from our online bookstore.

Book Review: Dinosaur Behaviour

**** Handsomely illustrated and accessible

Front cover of dinosaur behaviour showing a group of large dinosaurs.

 Reconstructing how dinosaurs behaved from just their fossilised bones might seem like science fiction but is very much science fact. In Dinosaur Behavior: An Illustrated Guide, veteran palaeontology professor Michael J. Benton joins forces with palaeoartist Bob Nicholls to do what it says on the tin: write a richly illustrated introductory book on dinosaur behaviour that is well-suited for novices.

In Dinosaur Behaviour, Benton takes the reader through five main topics: physiology (which sets the pace for everything else), locomotion, senses and intelligence, feeding, and social behaviour (which includes courtship, reproduction, parental care, and communication). One or several ‘forensics’ boxes in each chapter introduce the basic gist of certain methods.

Reading through this book, it becomes abundantly clear that our understanding of dinosaur behaviour relies on two approaches. Though Benton does not mention it as explicitly as in his previous book The Dinosaurs Rediscovered, the first of these is new high-tech toys and tools. Examples include computed tomography (CT) scanners, normally used in hospitals, to make detailed X-ray scans of fossilised brains (so-called endocasts) and so determine brain anatomy. Or finite element analysis normally used in engineering to model forces and stresses on jaws and teeth and so determine e.g. bite force. The second approach is ‘old-fashioned’ comparative anatomy and ethology: it pays to have a good knowledge of natural history when you are a palaeontologist. One example is the histological study of fossil dinosaur bones. Cutting thin bone sections and examining these under a microscope shows that some dinosaurs closely resemble mammals and birds, supporting the idea that smaller species were endotherms (‘warm-blooded’, i.e. generating their own body heat). Or take the microscopic study of melanosomes (pigment-containing organelles) in fossil feathers to determine colour in life. A final example is the comparison of footprints made by modern running birds with fossil tracks to determine things such as gait and running speed. 

If you are well-versed in (popular) palaeontology, much of what is presented here will be familiar. Even so, I picked up interesting titbits. One example is a recent study of Psittacosaurus that describes a cloaca, the multipurpose orifice also seen in birds where the digestive, urinary, and reproductive tracts all open to the outside world. This suggests that dinosaur sex, for at least some species, was a matter of the appropriately named cloacal kiss rather than the brandishing of reptilian genitals. Other insights fell into the embarrassing ‘I should have known this’ category. We tend to think of walking on two legs as something advanced because our mammalian ancestors walked on all fours, but for dinosaurs, it was the reverse; they started out bipedal and quadrupedality only evolved later in e.g. the large sauropods. Particularly interesting is the study by Kat Schroeder and colleagues who looked at fossil communities of theropods and noticed a so-called carnivore gap: there is a lack of medium-sized ones in the fossil record, even though there are medium-sized herbivores. One explanation could be that dinosaur eggs had an upper size limit, meaning that young carnivores hatched small and had an awful lot of growing to do. As they did, ‘they passed through a whole range of feeding modes, each step along the way acting like a different species’ (p. 137), effectively plugging the ecological niche of medium-sized carnivores.

Despite the broad range of topics, there are some curious omissions. The chapter on feeding e.g. discusses jaws, teeth, and the use of isotopes to determine diet, but not microwear analysis of teeth. What I found most surprising is that Benton does not introduce the concept of trace fossils or ichnology, their study. Yet, examples such as trackways (some possibly showing long-distance migrations), coprolites (fossil poop), and nests are all discussed here. Another surprising omission is that the two-page bibliography does not include most studies mentioned in the text, even though it references other technical articles.

Dinosaur Behavior is mostly very suitable for readers with little to no background in palaeontology. Benton explains even basic terminology (physiology, cannibalism) as he goes, though there is the occasional curveball. One example is the morphospace diagram showing a principal component analysis on page 131, which, I hope those with a background in statistics will agree, is a rather abstract way of visualizing data that requires a bit more explanation than is given here. Though the book is published by Princeton University Press, it has been produced by UniPress Books who can be considered the spiritual successor to popular science publisher Ivy Press. What this means is that information is accessibly presented in bite-sized sections on one or several page spreads, with long sections further divided using subheadings. The downside is that this restricts how thoroughly topics can be explored. Leafing through e.g. Naish & Barrett’s Dinosaurs: How They Lived and Evolved shows more nuance in its chapter on behaviour.

Finally, I have to mention the excellent colour and black-and-white artwork by Bob Nicholls that livens up the text. I loved the drawing of courtship in Confusiusornis on pages 168–169. Despite the overlap in topic, this is all-new artwork compared to Locked in Time. Other diagrams have all been carefully designed or redrawn, using colours where appropriate. The only design element that did not work for me was the choice of sans-serif font which made e.g. the letters a and o hard to tell apart. 

Serious palaeontology buffs might find the contents here somewhat superficial, but overall, this is a handsomely illustrated book that offers an accessible introduction suitable for novices and possibly even curious high-school pupils. It would also make for a great gift. 

Front cover of dinosaur behaviour showing a group of large dinosaurs.

Dinosaur Behaviour: An Illustrated Guide is available from our online bookstore.

Book Review: Blue Machine

***** An engrossing odyssey into oceanography

In a break from many other books about the deep sea that talk about animals, Blue Machine focuses on the ocean itself, revealing a fascinating planetary engine. Equal parts physical oceanography, marine biology, and science history, topped off with human-interest stories, Czerski has written a captivating book that oozes lyricism in places.

Czerski is an accidental oceanographer, stumbling into the discipline from a background in physics. She boasts a long list of science communication credentials as a TV presenter, podcast host, columnist, public speaker, and author. This is a big book with chunky chapters but Czerski keeps the flow going by alternating between scientific explanations, fascinating experiments, and remarkable historical episodes. I find the deep sea endlessly fascinating and have been drawn ever further into oceanography through my reviews, yet something was always missing. This book has finally scratched the oceanographic itch I have long been trying to satisfy. How so, you might ask?

Stormy sea and waves crashing against a stony beach.
Stormy Waters IMG_6958 by Ronnie Robertson, via flickr.

Start with that introduction. If you zoom right out, what sets a planet’s temperature, and with it the potential for life, is the balance between energy input from the sun and energy loss to the universe in the form of heat. From this grand, cosmic perspective, what the ocean with its circulating currents does is intercept some of that incoming energy and prevent it from immediately escaping again, instead “diverting it on to a much slower path through the mechanisms of the Earth: ocean, atmosphere, ice, life and rocks” (p. 5). From an energy point of view, “the Earth is just a cascade of diversions, unable to stop the flood but tapping into it as it trickles past; and the ocean is an engine for converting sunlight into movement and life and complexity, before the universe reclaims the loan” (p. 6). To me, this was such an awe-inspiring, attention-grabbing perspective on life on Earth, expressed so eloquently, that I wondered: is Czerski the new Ed Yong of oceanography? Tell me more, please!

What helps to understand the above perspective is the fact that the ocean is a vast three-dimensional environment that is constantly in motion, creating and maintaining differences at different scales. Heat and salinity create different layers of water that do not readily mix, meaning the ocean is stratified. This results in gigantic underwater conveyor belts and waterfalls. What makes these processes interesting is the shape of the container holding all this water: i.e. the continents and underwater topography. The local gravitational pull of the underlying rocks deforms the water surface, creating domes and holes over very large surface areas, a shape known as the geoid. Many more fundamental features and principles are described though she admits that she cannot squeeze the full complexity of the ocean into one book, treating other topics only briefly or not at all.

Bright blue, large wave tubing with splashes all around it.
The tube by Misty, via flickr.

Admirably, Czerski is equally at home in the marine biology department and she features some wonderful critters here. True, these abound in all good popular science books about the deep sea, but her physics background allows her to show how the physical and biological worlds intertwine. A beautiful example of this is the mesoscale eddies that are spun off by oceanic gyres: large islands of rotating water that become temporary havens for all the plankton and fish that find themselves inside. The formation of these wandering buffets is such a regular phenomenon that large ocean predators such as tuna can make a living by roaming the seas in search of them.

Another captivating element is the many ingenious experiments, both historical and current, that she describes here. We almost developed a method to collect a long-term dataset on the global ocean’s temperature by bouncing sound waves through the seas, but the idea stalled after a successful pilot experiment in 1991. More successful is the Continuous Plankton Recorder Survey which has been running for the last 90 years, deploying mechanical recorders towed behind ships that use elegant internal clockwork to capture plankton on long strips of mesh and have gathered valuable long-term records.

The physical world also entwines with human history. One example is the narrow northern half of the Indian Ocean where gyres do not form but seasonal currents flow eastwards and westwards. The 14th-century Chinese Ming Dynasty used these to send expeditions of large ships laden with valuables up and down the coast of Asia and Arabia, trading goods for political influence and prestige. I was similarly captivated by the poorly known story of the 18th-century Scottish herring lassies: bands of female contractors who travelled south along the English coast each summer, following the southwards moving herring fleet. While the men worked the boats out at sea, the women were ready in ports and at beaches to gut, salt, and pack each day’s landing before the freshly-caught fish could spoil. Hard-working, skilled, and independent, they were decades ahead of most other women in Victorian England.

Wave Breaking on rocks at Asilomer State Beach.
Wave Breaking Asilomer State Beach by Charlie Day, via flickr.

All of this is backed up by an attitude that, coming from a scientist, is refreshingly clued in to social issues. This becomes explicit in the final chapter where she addresses the environmental issues she has so far avoided. Though a popular mantra in politics is that we need to follow the science, she opposes this “for the simple reason that science does not lead. Where leadership comes from is a clear statement of values” (p. 381). Science can inform these, yes, but we have to decide what we care about for ourselves and our communities. Going down this path involves hard questions without simple answers, and nuance rather than binary “I am right, you are wrong” categories. It also means breaking with our perception of “the ocean as the end of a one-way pipe” (p. 289). There is no “away” on this planet for our trash. And it means breaking with a culture of infinite growth on a finite planet. Her thinking here is influenced by her contact with Polynesian cultures that value cooperation, openness, and teamwork, in contrast to the Western mindset of ownership and power play.

If I need to sound a critical note it is the lack of illustrations. Though the UK version features nice endpapers and a stunning cover, there are only two maps and two illustrations in the rest of the book. Especially some of the physical oceanography principles would have benefited from explanatory diagrams.

Blue Machine is an engrossing odyssey into oceanography. Czerski brings her substantial experience in science communication to bear on this topic and has written a transformative book. She brings to life the watery fabric of the ocean itself in ways I have not encountered before.