In the early days of the universe, there was darkness. Until somebody said, “let there be light”? Not quite. In First Light, astrophysicist Emma Chapman introduces you to ongoing research into the first billion years of our Universe and the birth of the first stars. Popular science at its finest, this book challenged me pleasantly but was above all—with apologies for the terrible pun—enlightening.

First Light: Switching on Stars at the Dawn of Time, written by Emma Chapman, published by Bloomsbury Sigma (a Bloomsbury Publishing imprint) in November 2020 (hardback, 304 pages)

Though I have never given it much thought, the idea of there being a first generation of stars seems logical once you mention it. As Chapman shows, there is a gap in our understanding of what, exactly, happened during this time. Ongoing research shows this to be an unusual period, going by such evocative names as the Dark Ages, the Cosmic Dawn, and the Epoch of Reionisation.

Before we get to these, Chapman introduces you to the basics in the first four chapters. To grasp the science, you will need to understand the properties of light (its dual wave-particle nature and its high but not unlimited speed), stellar classification (from young to old: Population I, II, and III stars), the Big Bang and the expansion of the universe, and how stars are born. With that sorted, she then walks the reader through those first billion years.

An awful lot happened in the first three minutes after the Big Bang. Protons and neutrons were able to combine in a process known as nucleosynthesis within ~14 seconds. Within minutes, this process ended and the early Universe was full of hydrogen and helium isotopes. Electrons were still too energetic to bind to them to form atoms proper. It would take another 380,000 years of the Universe expanding and cooling down for so-called recombination to take place and hydrogen atoms to form. Something else happened at this point: the Universe became transparent to radiation. Before this time, “we cannot see anything with light […] because the environment is too volatile to allow photons to travel on unimpeded paths to our telescope” (p. 84). Although photons were released during these steps, the continued expansion of the universe meant their wavelengths increased (a process known as redshifting) until they left the visible part of the electromagnetic spectrum. With stars not yet born, the Universe entered its Dark Ages.

“[…] stellar archaeology […] tries to find quiet parts of the Universe, so-called stellar tombs […] , where rare, light-weight Population III stars might have survived until now.”

And yet, something was stirring in the darkness. Hydrogen gas coalesced into clouds until some became dense enough to ignite fusion, the first stars flickering into life. This was the Cosmic Dawn, some 180 million years after the Big Bang. Chapman talks at length about these Population III stars as they were unique. Consisting of nothing but hydrogen, they were huge (hundreds of solar masses) and short-lived (millions of years). As fusion consumes a star’s hydrogen, they go through several cycles: “with heavier and heavier metals created in onion-like shells” (p. 153). (To astronomers, all elements heavier than helium are simply “metals”.) This continues until you hit iron: photons released in these fusion reactions as so energetic that they destroy the iron again and the whole thing goes supernova. The first Population III stars thus seeded the cosmos with heavier elements, paving the way for new iterations of star formation.

There are two big narrative threads regarding Population III stars. The first was, for me, rather technical and challenging, so hold on to your helmet while I attempt to explain it. This has Chapman talk about how to find the first stars using the radiation emitted by hydrogen gas that is cooling down, which has a very particular wavelength. This involves the abstract property of an atom’s spin state and the emission of a 21 cm wavelength photon when a hydrogen atom goes through a spin-flip transition to settle in its energetically least excited state, its ground state. The experiment detecting this particular radiation incidentally also provided evidence for the existence of dark matter. In the early Universe, dark matter was condensing to form filaments that formed the gravitational skeleton, if you will, around which regular matter such as hydrogen gas ended up condensing. As such, our universe has a large-scale architecture that resembles a cosmic web of clusters of galaxies connected by filaments of galaxies.

The second point is that Population III stars are still theoretical entities: we have never observed any. This leads Chapman down two very interesting avenues of research. The first is known as stellar archaeology and tries to find quiet parts of the Universe, so-called stellar tombs (astronomers get all the cool names), where rare, light-weight Population III stars might have survived until now. The other, complementary approach searches for ancient dwarf galaxies that have escaped the galactic cannibalism through which galaxies grow by gobbling up smaller ones. This would provide information about the environment in which these first stars formed.

“[…] this subject could have ended up being impenetrable in the hands of a lesser science communicator. [Chapman] excels at explaining the astrophysics and uses some imaginative metaphors […]”

Lastly, there is the Epoch of Reionisation. The Big Bang initially resulted in a Universe with nuclei that did not yet have electrons bound to them; it was ionized. Recombination resulted in a Universe filled with neutral hydrogen. But something happened to reionise the Universe’s hydrogen, a state that persists to this day. Research is ongoing to find out what that something was. Early quasars emitting X-rays have been implicated, but photonic emissions by Population II stars are another likely contributor. Similarly, astronomers are trying to constrain the when, with current estimates suggesting that the process took some 500 million years and was complete 1 billion years after the Big Bang.

For a biologist such as myself—admittedly one fascinated by astronomy—this subject could have ended up being impenetrable in the hands of a lesser science communicator. Chapman has received various commendations and prizes and is a well-known public speaker. She excels at explaining the astrophysics and uses some imaginative metaphors. Why do some particle interactions require a low-energy environment? “Try hugging someone sprinting in the opposite direction and you’ll understand why sometimes slower is better when it comes to interactions” (p 130). How do you find a black hole? Through its gravitational effect: “Like spotting someone well known in a shopping arcade, you are unlikely to see that person, but you know that something is happening from the mass of people heading to one point from all directions” (p. 221). Furthermore, she makes good use of subheadings in the text, includes diagrams to visualize abstract concepts, and ends each chapter with a helpful recap.

Although the focus of her writing remains firmly on the science, she delivers it in a conversational style. There are some nerdy jokes, but never too many. There are lyrical passages, but used in moderation. For example, the Big Bang “[…] is a theory that has been forced on our uncomprehending three-dimensional brains, incapable of visualising infinity but able to understand the overwhelming evidence” (p. 70), while stellar archaeology is described as “[…] a field that has moved from seeking the first stars to conversing with the second stars and hearing tales of their ancestors” (p. 178). Peppered throughout are historical episodes, e.g. the accidental discovery of the Cosmic Microwave Background radiation (which features two very unlucky pigeons) and its recognition as the afterglow of the Big Bang. And Chapman highlights some of the underacknowledged female pioneers such as Cecilia Payne-Gaposchkin, who proposed stars were primarily made of hydrogen and helium, Vera Rubin, who provided evidence for the existence of dark matter, or the women at the Harvard College Observatory, who classified stars on an industrial scale.

By now, I have reviewed eleven of the almost seventy titles on the Bloomsbury Sigma imprint. Though billed as popular science, these are not boilerplate books, but cover specialist, cutting-edge topics and provide a pleasant intellectual challenge. Invariably, they are written by skilled science communicators who are experts in their field and are willing to spend several years on a book. And judging by the acknowledgements I have read so far, they go to great lengths to seek advice from peers and solicit colleagues to proofread and comment on their manuscripts. In that sense, First Light represents everything I appreciate about the Bloomsbury Sigma imprint. Next to a wildly fascinating book, it is another shining addition to their roster.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

First Light

Other recommended books mentioned in this review:

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This is the second of a two-part dive into the story of oceans on Earth and elsewhere, following my review of Ocean Worlds. That book gave a deep history of how our oceans shaped Earth and life on it and briefly dipped its toes into the topic of oceans beyond Earth. Alien Oceans is the logical follow-up. How did we figure out that there are oceans elsewhere? And would such worlds be hospitable to life? Those are the two big questions at the heart of this book. If there is one person fit to answer them, it is Kevin Peter Hand, a scientist at NASA’s Jet Propulsion Laboratory and their deputy chief for solar system exploration.

Alien Oceans: The Search for Life in the Depths of Space, written by Kevin Peter Hand, published by Princeton University Press in March 2020 (hardback, 248 pages)

A major question in astrobiology is whether the evolution of life on Earth is a fluke, or whether life is bound to pop up wherever conditions are favourable. Hand very neatly frames this in the bigger history of science. Over the centuries, we figured out that the laws of physics, chemistry, and geology work beyond Earth. But “when it comes to biology, we have yet to make that leap. Does biology work beyond Earth?” (p. 15). What we have learned is that life as we know it needs water. And though there is no shortage of theories on the origins of life, oceans are very likely where it started, and thus a logical first place to start looking for answers.

If you have any interest in astrobiology, you will probably have heard of the concept of a habitable zone or Goldilocks zone where, based on the distance to a star, conditions for life are just right. Not so close as to be too hot, nor so far as to be too cold. Earth obviously falls in that zone. Next to many minor insights, Alien Oceans had three major eye-openers for me. This was the first one:

There are other Goldilocks zones.

Depending on the details of their orbit, moons can experience such strong tidal tugs from their parent planet that the constant squeezing and stretching of the rock creates enough heat through internal friction to sustain liquid water. The physics of water helps, as it has a seemingly mundane but rather unusual property. Ice floats. When water solidifies, its density decreases slightly. What this means for moons is that the liquid water exposed to the cold of deep space freezes and forms a protective icy shell. Most liquids do not have this useful property. When they freeze, they sink to the bottom exposing more liquid until all of it is frozen solid. To top it off, ice is also a good thermal insulator, helping such ocean worlds retain heat. Maybe I have been hiding under a rock, but this was revelatory for me. Suddenly, the amount of cosmic real estate suitable for life has increased quite dramatically. And we have some of it right here on our doorstep.

“Over the centuries, we figured out that the laws of physics, chemistry, and geology work beyond Earth. But “when it comes to biology, we have yet to make that leap. Does biology work beyond Earth?“”

The existence of oceans in our solar system and how we gathered the evidence is one of the two major threads running through this book. Hand examines this in detail for Jupiter’s moon Europa, which has been studied in the most detail. Three types of data are typically gathered: spectroscopic, gravimetric, and magnetometric. This is where Hand gets fairly technical, though, fortunately, he extensively uses comparisons with everyday concepts and technologies to help you understand the underlying (astro)physics. Without retreading his careful explanations, in Europa’s case, these different strands of data all converge on a moon with an icy shell and a substantial subsurface ocean some 80–170 km thick as the best explanation. Mixed in with this narrative are the details and many technical setbacks of the Galileo mission that are nail-bitingly tense in places.

Similar missions and measurements have been done for Saturn’s moons Enceladus and Titan, Jupiter’s moons Ganymede and Callisto, Neptune’s moon Triton, and Pluto. The evidence for oceans gathered so far gets less robust in this order, but there are some notable variations on the theme. Enceladus ejects spectacular plumes of water and carbon compounds that were photographed and sampled by the Cassini–Huygens mission. Ganymede, meanwhile, is so large that the bottom of its ocean might consist of an exotic form of dense ice, ice III, formed at very high pressures not seen on Earth, meaning its ocean is sandwiched between two layers of ice.

So you have found exo-oceans. Now what? Can we expect to find life here? That is the second major thread. Hand identifies five conditions for life to emerge: a solvent such as water, chemical building blocks, an energy source, catalytic surfaces, and time. Interestingly, there is a gap between two schools of thought. The top-down explanation deconstructs life backwards in time until we arrive at an RNA world, but how did that get started? The bottom-up explanation has shown that life’s basic building blocks such as amino acids exist in space, but how do we go from there to larger functional molecules?

“There are other Goldilocks zones. Moons can experience such strong tidal tugs that the heat released by internal friction can sustain liquid water.”

This was the second major eye-opener for me: “Our environment is full of chemical disequilibrium […] there are reactions just waiting to happen. […] The metabolisms that drive life accelerate reactions in the environment, releasing energy faster than would have occurred without life” (p. 144). Hand takes a leaf out of Nick Lane’s book The Vital Question (which, shame on me, I still have not read) when he enthusiastically concludes that “the why of life is metabolism” (p. 146), offering the universe a pathway to increase entropy faster. These are remarkable ideas that give a whole new meaning to philosophical questions on the meaning of life.

The third and final eye-opener concerns the need for a catalytic surface, which is where Hand circles back to oceanographic exploration here on Earth, a recurrent theme in this book. When the submarine Alvin discovered hydrothermal vents in 1977 and found them teeming with life, these quickly became a popular alternative explanation to warm tidal pools as a place where life could have started. These so-called black smokers are powered by magma rising to the surface at mid-ocean ridges, jetting out superheated water of over 400 °C. Though volcanism and tectonics are, or sometimes were, common processes on many solar system bodies, there is another option. Alkaline vents, first discovered in 2000 at the Lost City hydrothermal field, are powered by exothermic (energy-releasing) reactions between water and mineral-rich rock, heating water to a more gentle 70–100 °C. All these need are the right rocks with cracks in them so water can percolate down.

“In addition to hydrothermal vents, alkaline vents are another place where life might have started. All these need are the right type of rock with cracks in them so water can percolate down, no plate tectonics needed.”

Hand raises many other interesting questions towards the end of the book, of which I will mention just three. One, life’s metabolic reactions require so-called oxidants, oxygen being “the most glorious of oxidant” (p. 162), but how would these get down into subsurface oceans? Two, how contingent or convergent is the evolution of life’s biochemistry? Carbon is a suitable building material for life as it is “hands down the best team player on the periodic table” (p. 212). But to these options, or can we sketch a periodic table of life with other, weirder possibilities? And three, how should we seek for signs of life? What makes a good biosignature? This is discussed far more in-depth in Life in the Cosmos, but Hand considers three types of evidence.

Alien Oceans limits itself to oceans in our solar system, not touching on the topic of exoplanetary oceans. Given this is not Hand’s expertise, that is reasonable. He also glosses over the question of what aliens might look like, though he speculates on the likelihood of intelligent life in ice-covered subsurface oceans. Even without these topics, Alien Oceans is information-dense, requiring me to make a summary, and then a summary of that summary while preparing this review. Nevertheless, it is an intellectually very rewarding book and the many analogies make it accessible. I enjoyed it as a follow-up to Ocean Worlds but it is a fine standalone book. Terribly fascinating, Alien Oceans makes a convincing case for exploring the moons in our solar system in the search for extraterrestrial life.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Alien Oceans

Other recommended books mentioned in this review:

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Life most likely originated in the oceans, and it is to oceans that astronomers are looking to find life elsewhere in the universe. With the publication last year of Kevin Peter Hand’s Alien Oceans, I decided this was the right time to finally review Ocean Worlds, a book that I have been very keen to read ever since buying it some years ago. This, then, is the first of a two-part dive into the story of oceans on Earth and elsewhere.

Ocean Worlds: The Story of Seas on Earth and other Planets, written by Jan Zalasiewicz and Mark Williams, published by Oxford Press in December 2017 (paperback, 302 pages)

Palaeobiologists Jan Zalasiewicz and Mark Williams have previously collaborated on The Goldilocks Planet. Here, they provide a deep history of our oceans. As soon as I tucked in, it became clear that they go deeper than Eelco Rohling did in the previously reviewed The Oceans: A Deep History, a book that focused heavily on palaeoclimatology. Even though most of the action in Ocean Worlds takes place on Earth, and the wider universe is only considered in the opening and closing two chapters, the book is characterised by an almost cosmic perspective on the subject. The writing of Zalasiewicz and Williams is such that I felt as if was surveying major developments in the history of our universe from an elevated, slightly detached, almost omniscient position. The result is thrilling and at times awe-inspiring. What follows are some of the big questions and outrageously fascinating topics they consider.

To have an ocean we first need water. Hydrogen was an immediate byproduct of the Big Bang. Oxygen, however, did not appear until after the universe had gone through its first cycle of stars being born and dying, as its creation required nuclear fusion. Likely, the formation of water had to wait for a few hundred million years, though some have argued it could have started much sooner. As is usual when dealing with processes that took place in such a distant past, opinions are divided and there are several reasonable scenarios.

“the book is characterised by an almost cosmic perspective on the subject […] The result is thrilling and at times awe-inspiring.”

With water present in the universe, how did Earth acquire its oceans? After all, “There is a wild card here, which surely had an impact” (p. 18). We have good evidence that our proto-Earth, called Tellus by some, was hit by a small planetoid, Theia, with the resulting debris forming our current Earth–Moon system. This event would likely have obliterated what early oceans we had, if any. Various authors have proposed that certain meteorites (carbonaceous chondrites) or comets might have subsequently been water’s cosmic delivery vehicle.

However it got here, the first major effect it had was kick-starting plate tectonics. The early Earth was hot, but without the lubrication provided by water, the heat-venting mechanism of plate tectonics was not in place. How did molten rock make its way to the surface? Some scientists argue that it was through simple vertical conduits, so-called heat pipes, which would have made for a radically different surface topography: “the fundamental proportions of land area and ocean area […] would have been utterly different to today’s familiar patterns” (p. 34). Though, again, this idea is contested by others. The puzzle of when plate tectonics started, possibly 3 billion years ago, relies on truly ancient rocks, 3.5 to 3.8 billion years old, of which we have precious few remaining in places such as Australia and Greenland.

Beyond those earliest days, Ocean Worlds has much interesting material about later episodes. Life likely started in the oceans, this much I knew, but these were iron seas. Water without oxygen can hold large amounts of dissolved iron, and early organisms used this in their biochemistry to generate energy. This was the realm of the Archaea: the salt-tolerant, heat-loving, chemoautotrophic microbes for whom oxygen was poison and the Great Oxygenation Event murder. It was also a time when banded iron formations (BIFs) were built up, relevant to us today as they formed the ore deposits providing most of our iron and steel. Though, as clarified here, their formation was anything but straightforward. Other fascinating episodes are the Messinian Salinity Crisis, some 5.6 million years ago, when the Mediterranean repeatedly dried up, leaving behind kilometre-thick salt layers that reduced global ocean salinity.

“However it got here, the first major effect [water] had was kick-starting plate tectonics.”

Of course, a book about oceans has to consider current human impacts. With due diligence, the authors tackle the problems of overfishing, shifting baselines, trawling, litter, ocean warming, oxygen loss, and acidification, and conclude that: “there currently seems not the faintest chance of stopping carbon emissions over many decades, let alone overnight” (p. 191). Does this sound gloomy? I prefer the word “sobering”. Consider, they write, that the “more-than-tripling of human population” (p. 183) was enabled by the invention of the Haber–Bosch process and the plentiful artificial fertiliser it made available. To this, they add geologist Peter Haff’s argument of the technosphere that resonated with me. “The 7 billion humans on Earth today are kept alive only through the continuous action of an enormous, globally interlinked system of transport and communication, metabolized by the use of vast amounts of energy […] Without it, most of us would not be alive—and therefore we are forced to keep it going” (p. 197).

If that was not sobering enough, what really made me feel small was when they pulled back from our timescale and the current “brief ecological wrecking spree” (p. 195), to the long-term future. Our oceans are not forever. As the Sun grows hotter they will evaporate, though the “end of the oceans is not likely to be simple” (p. 207). Whether through a moist greenhouse phase where water is gently siphoned off into space by solar winds, or a runaway greenhouse hot enough to melt rock, a dry future awaits, and plate tectonics will once again grind to a halt. As this process “is unlikely to simply just stop, smoothly and without fuss” (p. 211), expect some extraordinary landscapes.

“Our oceans are not forever. […] Whether through a moist greenhouse phase where water is gently siphoned off into space by solar winds, or a runaway greenhouse hot enough to melt rock, a dry future awaits.”

Amidst these grand, cosmic scenes, the authors highlight the human stories behind this research. Such as the pioneering contributions to oceanography by the people on board the HMS Challenger expedition, the mapping of the seafloor by Marie Tharp, or the work of Wally Broecker who established a link between ocean currents and rapid climatic changes. And while Svante Arrhenius is better remembered for linking historical changes in carbon dioxide concentrations to past ice ages, both he and Fritz Haber tried to extract gold from sea water. Unsuccessfully, I might add.

In the last two chapters, the authors turn their gaze to the skies once more, discussing past and present oceans inside and outside of our solar system. With the many discovered by the Kepler space telescope, “We are on the verge of not just a new chapter in oceanography—or exo-oceanography, if you like—but of setting up an entirely new library of oceans, for the diversity and complexity of cosmic oceans will be beyond anything that we can dream of” (p. 264).

I explore this topic more in-depth in my review of Alien Oceans. But, as a warming-up exercise and a proper deep history of oceans, Ocean Worlds is a fantastic book that strikes the right balance. Zalasiewicz and Williams present fascinating science with enviable ease, without smoothing over the fact that science is rarely a straightforward affair, proceeding by means of conflicting scenarios and competing hypotheses. The deep-time perspective and big questions asked make this one awe-inspiring book.

Ocean Worlds

Other recommended books mentioned in this review:

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In the field of palaeoanthropology, one name keeps turning up: the Leakey dynasty. Since Louis Leakey’s first excavations in 1926, three generations of this family have been involved in anthropological research in East Africa. In this captivating memoir, Meave, a second-generation Leakey, reflects on a lifetime of fieldwork and research and provides an inspirational blueprint for what women can achieve in science.

The Sediments of Time: My Lifelong Search for the Past, written by Meave Leakey and Samira Leakey, published by Houghton Mifflin Harcourt in November 2020 (hardback, 396 pages)

With The Sediments of Time, Meave* follows a family tradition. Her husband Richard, and his parents Louis and Mary have all been the subject of (auto)biographies, now many decades old. Science writer Virginia Morell later portrayed the whole family in her 1999 book Ancestral Passions. Much has happened in the meantime, and though this book portrays Meave’s personal life, it heavily leans towards presenting her professional achievements, as well as scientific advances in the discipline at large. Thus, Meave’s childhood and early youth are succinctly described in the first 15-page chapter as she is keen to get to 1965 when a 23-year-old Meave starts working with Louis in Kenya.

Whereas Louis and Mary were famous for their work in Olduvai Gorge in Tanzania, Richard and Meave have made their careers around Lake Turkana in northern Kenya. The first two parts of the book take the reader chronologically through the various excavation campaigns. These include the decade-long excavations in and around Koobi Fora, one highlight of which was the find of Nariokotome Boy (also known as Turkana Boy), a largely complete skeleton of a young Homo erectus. The subsequent campaign in Lothagam yielded little hominin material but did reveal a well-documented faunal turnover of herbivore browsers being replaced by grazers with time. Meave has also described several new hominin species. This includes Australopithecus anamensis, which would be ancestral to Australopithecus afarensis (represented by the famous Lucy skeleton), and Kenyanthropus platyops, which would be of the same age as Ardipithecus ramidus. That last name might sound familiar, because…

“Woven into Meave’s narrative of exploration and excavation is an overview of how palaeoanthropology developed as a discipline, and what are some of its big outstanding questions.”

Having just reviewed Fossil Men, which portrayed the notorious palaeoanthropologist Tim White, I was curious to see what Meave had to say about him. In Fossil Men, Kermit Pattison already mentioned that she described White “with a note of sympathy” (p. 5), and she affirms that picture here, writing that he is “a meticulous scientist […] intolerant of bad science […] outspoken and frank […] although he was charming and a gentleman in less formal situations” (p. 136). And though they meet more than once to compare fossils, notes, and ideas, they remain at loggerheads over certain claims.

Woven into Meave’s narrative of exploration and excavation is an overview of how palaeoanthropology developed as a discipline, and what are some of its big outstanding questions. A recurrent theme is the influence of climate on evolution, often by impacting diet and available food sources. There is the difficult question of naming species and how much difference is enough to recognise a separate species, which ties into the whole lumpers vs. splitters debate in taxonomy. The latter readily name new species whereas the former (White being an example) point to sexual dimorphism and morphological variation and recognize only one or very few hominin species. Your stance in that debate affects what you think of Meave’s descriptions of Au. anamensis as being part of a lineage towards Au. afarensis, and whether K. platyops is a species distinct from Ar. ramidus (White obviously thinks not).

This discussion of topics relevant to palaeoanthropology strongly comes to the fore in the book’s third part, by which time Meave is examining the Homo lineage and the question where we appeared from. This sees her tackling topics such as human childbirth and the role of grandmothers, Lieberman’s hypothesis of endurance running as a uniquely human strategy to run prey to exhaustion, palaeoclimatology and the mechanism of the Milankovitch cycles, the spread of Homo erectus around the globe (the Out of Africa I hypothesis), and the use of genetics to trace deep human ancestry. I feel that Meave overstretches herself a little bit in places here. Though her explanations are lucid and include some good illustrations, some relevant recent literature, on e.g. ancient DNA and Neanderthals is not mentioned.

“Meave can draw on a deep pool of remarkable and amusing anecdotes that are put to good use to lighten up the text. And though the focus is on her professional achievements and the science, real life interrupts work on numerous occasions.”

Meave can draw on a deep pool of remarkable and amusing anecdotes that are put to good use to lighten up the text. And though the focus is on her professional achievements and the science, real life interrupts work on numerous occasions. Some of these are joyful, such as the birth of her daughters Louise and Samira. Some are a mixed blessing, such as Richard’s career changes, first when Kenya’s president hand-picks him to lead the Kenya Wildlife Service and combat rampant elephant poaching, then when he switches to attempting political reform. It removes him from palaeoanthropology and their time together in the field. Other occasions are outright harrowing, such as Richard’s faltering kidneys that require transplantations, or the horrific plane crash that sees him ultimately lose both legs despite extended surgery.

Illustrator Patricia Wynne contributes some tasteful drawings to this book, though the figure legends do not always clarify the important details these images try to convey. And I would have loved to see some photos of important specimens, whether during excavation or after preparation, especially given how much Meave focuses on the scientific story in this book. Many specimens are described in great detail but the colour plate section mostly contains photos of the Leakeys and collaborators in the field. Another minor point of criticism is that I was not clear on Samira’s part in writing this book. The dustjacket mentions her as a co-author, but the story is told exclusively through Meave’s eyes, and the acknowledgements do not clarify Samira’s role. I am left to surmise that Meave and Samira together drew on their store of memories for this book.

These minor criticisms notwithstanding, I found The Sediments of Time an inspiring memoir that provided a (for myself long-overdue) introduction to the Leakey dynasty. Meave has led a charmed existence and she is a fantastic role model for women in science.

* I normally refer to authors by their last name but, for obvious reasons and with all due respect, I will be deviating from that habit here and mention the various Leakeys by their first name.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Sediments of Time

Other recommended books mentioned in this review:

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Whatever mental image you have of our close evolutionary cousins, the Neanderthals, it is bound to be incomplete. Kindred is an ambitious book that takes in the full sweep of 150 years of scientific discovery and covers virtually every facet of their biology and culture. Archaeologist Rebecca Wragg Sykes has drawn on her extensive experience communicating science outside of the narrow confines of academia to write a book that is as accessible as it is informative, and that stands out for its nuance and progressive outlook. Is this a new popular science benchmark?

Kindred: Neanderthal Life, Love, Death and Art, written by Rebecca Wragg Sykes, published by Bloomsbury Sigma in August 2020 (hardback, 408 pages)

Two things immediately struck me when I received this book. First, a personal favourite, illustrated end plates! Since Kindred discusses discoveries made at numerous dig sites, there is a map of Europe and part of Asia with their locations. At the back, there is a family tree showing the complex interrelatedness between early Homo sapiens, Neanderthals, and Denisovans. Second, at just shy of 400 pages with the bibliography online (more on that later) and having a larger trim size than usual for a Bloomsbury Sigma title, this is a chunky book

The reason soon becomes apparent: Sykes covers a lot of ground in this book. The deeper evolutionary history of our family tree, the history of Neanderthal discovery, their skeletal morphology, the traces and injuries that reveal their hardships in life, the climatological fluctuations during the 350,000 years of their existence on this planet, the stone, wood, and bone tools they produced and left behind, their diet, the temporary nature of their home sites as deduced from traces of fireplaces, their migrations and mobility in the landscape, the material traces hinting at a sense of aesthetics, the educated guesses we can make about their social and emotional lives, their funerary practices, the ancient DNA revolution, and, finally, the various explanations given for their disappearance. The scope of Kindred is nothing short of breathtaking. Her acknowledgements mention that the eight years it took to write this book were as daunting and as difficult as she had feared they would be, and the enormity of the task is clear.

“[…] the tools now at the disposal of archaeologists border on science fiction. Most certainly quite beyond the imagination of the pioneers, but even a formidable task for current scientists to keep on top of.”

Part of the reason is that technological advances have led to a veritable explosion in new methods to apply and new kinds of questions to ask. I was familiar with some of these, such as ancient DNA and the microscopic patterns of wear and tear left on teeth, but many were entirely new to me. The use of computers to fit stone flakes and fragments back together to reconstruct how a piece of stone was chipped and shaped into a tool? The use of laser scanners to document dig sites in exquisite three-dimensional detail? The analysis of the microscopic stratigraphy in soot layers, known as fuliginochronology? The use of isotopes to study where individuals were born and then moved to during their lives? As Sykes remarks, the tools now at the disposal of archaeologists border on science fiction. Most certainly quite beyond the imagination of the pioneers, but even a formidable task for current scientists to keep on top of.

This avalanche of information and techno-wizardry could have resulted in an inaccessible monolith of a book. There were a (very) few places where I felt Sykes careened into a dense thicket of details, such as when discussing the different lithic techno-complexes (for us mortals, the different styles of stone tools). And she does not always explain technologies. I assume most people will not know what the deal is with ancient DNA or what mtDNA even stands for. By and large, however, this book stands out for being fascinating, accessible, and terribly exciting. This is a golden age for archaeology! Most chapters are just the right length to avoid information overload, while a handful of drawings illustrate tricky concepts.

The picture that emerges of Neanderthals is that of hominins who are increasingly indistinguishable from early Homo sapiens; inventive, smart, social creatures, likely capable of spoken language, that survived for a very long time while weathering ice ages and warm periods. This picture is delivered in vivid writing that sometimes borders on lyrical—there were passages where I felt Sykes channelled the voice of deep time:

“Amid ancient surfaces densely spangled with myriad artefacts, fireplaces are like archaeological wormholes, bridging the impossible chasms of time separating us from long-vanished dwellers.”

But there is much else in her writing to admire. There are fascinating histories: how some skeletons ended up scattered over different countries, surviving multiple wars before the different body parts were reunited decades later. She reveals how archaeologists used to work and think, and how that has changed. For example, early excavators could not tell the difference between naturally shattered versus intentionally knapped rocks, thus discarding vast bodies of evidence at dig sites without recording them. In some cases, these are now being re-excavated for renewed examination. She repeatedly warns of simplistic interpretations and sexed-up headlines that dominate the news, instead stressing the far more interesting nuances, such as the fantastically complex patterns of population dispersals, influxes, turnovers, and interbreeding revealed by ancient DNA.

One of Sykes’s side projects is co-curating the website TrowelBlazers which celebrates the achievements of women in archaeology, geology, and palaeontology. Thus, I expected a certain progressive outlook. Indeed, why should the evidence for interbreeding always be interpreted as rape? Why is “desire and even emotional attachment […] regarded as more of a fairy tale than other explanations”? But she goes well beyond that, positively surprising me. Such as when parsing the complex and incomplete evidence for cannibalism in Neanderthals. She challenges the reader to consider different ways of interpreting this behaviour. Or by highlighting how Indigenous knowledge from hunter-gatherer communities can offer completely fresh perspectives on the archaeological record. This can illuminate blind spots of Western scientists, whether practical (the identification of tracks in the physical record) or more fundamental (challenging our ingrained tendency to see everything through a lens of dominance, exploitation, and conflict).

“[…] this book stands out for being fascinating, accessible, and terribly exciting. This is a golden age for archaeology!”

Finally, one decision that might divide opinions. Sykes opens the book explaining why, after careful thought, she did not include citations for claims and statements, focusing instead on the narrative. She has provided a 122-page bibliography online, but unfortunately, there is no link between references and what part of the text they are relevant to. Although I understand her reasoning, I have always found the use of superscripted numbers leading to individual notes and references to be a minimally intrusive middle road.

Though Kindred is not the first book to point towards a certain Neanderthal renaissance, its scope and authoritativeness eclipse what has come before. Whether you wonder what book to start with when new to the topic, or which book to pick if you only have time for one, Kindred is without a doubt the go-to book for a nuanced and current picture of Neanderthals.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Kindred

Other recommended books mentioned in this review:

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Volcanoes are some of the most awe-inspiring natural spectacles on our planet. There is much more to them, though, than the stereotypical image of a conical fire-spitting mountain, and I have been keen to learn more. As I searched for serious introductory books on volcanology, this was one title that kept coming up. But wait, why is a biologist reviewing geology textbooks?

Volcanoes, written by the late Peter Francis and Clive Oppenheimer, published by Oxford University Press in December 2003 (paperback, 521 pages)

A short preamble seems in place. My choice to study biology went at the expense of geology, although the latter topic continued to fascinate me. Two decades later, my job exposes me to many fascinating-sounding but advanced-level earth science books. I have since started to make inroads into this field for the sheer joy of expanding my knowledge. And thus I found myself eyeing up the new book Volcanotectonics. Yet, as I recently rediscovered, there is still a gap between having covered the essentials of geology and diving headlong into an advanced topic. Hoping to bridge that gap, I turned to Francis & Oppenheimer’s Volcanoes.

The first edition of this book was published in 1993 and authored by volcanology professor Peter Francis. When he passed away in 1999, his former PhD student Clive Oppenheimer, now a professor of volcanology in his own right, took it upon him to revise the text and bring it up to date for this second edition, published in 2003. Francis’s desire was to write a book to be read rather than consulted. Volcanoes is thus less of a textbook than you might think: there are no chapter summaries or student exercises. What you will find is a logical flow of chapters detailing the inner workings of volcanoes, glued together by the fascinating stories of past eruptions and, occasionally, Francis’s trademark humour, lampooning the field of volcanology.

“Volcanoes is […] less of a textbook than you might think: there are no chapter summaries or student exercises. What you will find is a logical flow of chapters detailing the inner workings of volcanoes, glued together by the fascinating stories of past eruptions […]”

Volcanoes starts with very primordial questions. Where do the heat and the rocks that drive volcanism come from? This introduces you to planetary formation and the radioactive decay of isotopes. In case you were expecting to start with plate tectonics, that is the next subject to be tackled. This explains the difference between volcanoes at plate margins where the oceanic crust is either formed or destroyed, and the minority occurring far from margins, such as the volcanic islands of Hawai’i.

Chapters four to twelve form, to my mind, the nuts-and-bolts section of this book, going into all the glorious and gory details of an eruption from beginning to end. This covers everything from formation and movement of magma; different eruption styles; types of lava; eruption columns and the deposits of ash and pyroclastic rocks they leave behind; pyroclastic density currents, debris avalanches, and mudflows or lahars—and their deposits; the different landscape forms left after eruptions, including types of volcanoes and how they erode, and the landscape depressions known as calderas; super-eruptions; and, finally, the common but hard-to-observe phenomenon of underwater volcanism.

The last four chapters cover closely allied topics: volcanoes in the solar system; the effects of recent eruptions on climate and the palaeoclimatological evidence of older ones; and, new to this edition, two chapters on monitoring of volcanoes, and assessing and managing the risks they pose.

“I was fascinated by some of the technicalities. For example by […] the physics behind eruption columns and the interplay with the wind, and how to deduce eruption intensity from them […]”

Two aspects, I thought, make this book very enjoyable to read. First, it broaches subjects without overwhelming you. When it talks of magma, it mentions the physics of gas bubble formation and growth (vesiculation), and the flow of liquid rock (rheology) without smothering you in detail. It will list different eruption styles (Hawaiian, Strombolian, Vulcanian, Plinian, etc.) and lavas (andesitic, dacitic, rhyolitic, etc.) while highlighting the arbitrary nature of such classifications, as these things exist on a continuum. And where formulas are given, for instance in the chapter on eruption columns, it is to demonstrate principles rather than go deep into the mathematics. If you are so inclined, each chapter comes with recommended sources and literature references for further research.

The authors explain terminology as they go, supported by many photos and diagrams. I would have liked a glossary—lacking that, I occasionally had to grab my dictionary to jog my mind. Even so, I was fascinated by some of the technicalities. For example by the distinction between central vent and large-scale fissure eruptions. By the underground movement of magma and intrusion of dikes. By the physics behind eruption columns and the interplay with the wind, and how to deduce eruption intensity from them. By the detective work that uses palaeoenvironmental records such as tree rings, and the extent and thickness of deposits to reconstruct eruptions for which there is no eyewitness testimony. Or by what makes pyroclastic density currents so terrifyingly destructive.

The second aspect that makes Volcanoes very readable is that this is not a theoretical treatise with hypothetical scenarios. Explanations are given by means of real-world examples of past eruptions. Four classic ones are introduced early on (Vesuvius, Krakatau, Mount Pelée, and Mount St. Helens), but plenty of others are recounted throughout. This includes those familiar from popular accounts (e.g. Tambora, Laki, and Toba), technical books (e.g. Pinatubo and the Soufrière Hills volcano), and those only known to volcanologists and victims (e.g. El Chichón and Nevado del Ruiz). You will learn as much about these eruptions as about what we learned from them.

“Having read the book cover to cover, there remains one important question that is difficult for me to answer. Given its publication date, how up to date is it? And is it time for a new edition?”

Having read the book cover to cover, there remains one important question that is difficult for me to answer. Given its publication date, how up to date is it? And is it time for a new edition? Technological advances and new space missions have revealed much more about extraterrestrial volcanoes—this book was published before the Opportunity and Curiosity rovers started trundling over the surface of Mars, for example. But what about volcanism here on earth? Recent eruptions have probably taught us new lessons (2010 tongue-twister Eyjafjallajökull no doubt revealing more about ash clouds), but not being a student of earth sciences, this is a hard question for me to answer. The only other more recent book I could think of was The Encyclopedia of Volcanoes, published in a second edition in 2015. But at over 1400 pages this can hardly be called an introductory textbook.

I decided to contact Clive Oppenheimer who kindly replied that there have not been any paradigmatic shifts in volcanology since then, but he did mention, in addition, the 2010 Merapi eruption, and highlighted new technology such as synchrotron radiation sources for fine-scale chemical analysis of volcanic rocks. Additionally, he pointed out Volcanoes: Global Perspectives (2022) as a recent textbook. And a third edition? It is not yet in the making, though he hopes to get around to it when time allows.

So, in sum, if you are looking for a good introductory volcanology textbook, I found this one both enjoyable and accessible. I came away feeling I understood much more about volcanoes. Bring on Volcanotectonics.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Volcanoes (2nd edition)

Other recommended books mentioned in this review:

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To figure out how old a tree is, all you have to do is count its rings, and some truly ancient trees grace the pages of this book. But, as tree-ring researcher Valerie Trouet shows, that is the least fascinating thing you can derive from wood. Revealing the inner workings of the academic field formally known as dendrochronology, Tree Story is an immersive jaunt through archaeology, palaeoclimatology, and environmental history. A beautifully written and designed book, it highlights the importance and usefulness of tree rings in reconstructing past climate and linking it to human history.

Tree Story: The History of the World Written in Rings, written by Valerie Trouet, published by Johns Hopkins University Press in May 2020 (hardback, 246 pages)

The first things that struck me when opening Tree Story were the beautifully designed endpapers (more on the illustrations later). At the front of the book is a world map with thumbnails of important trees and sites, and what chapters they feature in. At the back is a timeline of key historical periods and events, both human and climatological. Too few publishers make use of this, so we are off to a great start.

The first few chapters of Tree Story provide an excellent introduction. Trouet traces the history of dendrochronology to its unlikely birthplace in the Arizona desert, explains how tree rings are actually formed in living trees, and how, based on fluctuating climatic conditions, their appearance changes. Years with good growing conditions result in wider rings, while challenging years with droughts, storms, or other climatic upheavals result in narrower rings. That last factor is key when it comes to dating (in the chronological sense): the unique pattern of wider and narrower rings acts as a barcode. By looking at many trees in different parts of the world, researchers have constructed large databases of overlapping tree ring patterns that go back millennia. Using these can tell you how long ago a certain tree died, and therefore how old a wooden object or building is.

Having covered these basics, the bulk of Tree Story consists of a series of immersive chapters that look at some of the most interesting studies done using tree rings. For one, they play an important role in palaeoclimatology. The historical record of weather stations only extends back a few centuries, so to reconstruct past climates, palaeoclimatologists use proxies: indirect traces that correlate with climate. These have been collected from ice cores, lake sediments, stalagmites, and, of course, tree rings. But the pattern of rings only reveals so much. The width of rings will not tell you if a tree was stressed because of drought or cold, for example. By looking closer with lab instruments you can measure the wood density in individual rings, and that is primarily determined by temperature. It was one of the many proxies used by climate scientists to reconstruct the famous hockey-stick graph of past temperatures.

“harvest dates […] of trees used in the construction of historical buildings […] has revealed phases where building activity peaked, alternating with periods where plagues or the collapse of empires saw construction grind to a halt.”

Researchers have also compared harvest dates of thousands of trees used in the construction of historical buildings. This has revealed phases where building activity peaked, alternating with periods where plagues or the collapse of empires saw construction grind to a halt. One prominent example is the complex decline of the Roman Empire, which was illuminated (as Trouet gracefully acknowledges here) in Kyle Harper’s excellent book The Fate of Rome. Wood in historical buildings or archaeological dig sites can also cast a light on the history of regional deforestation and the ensuing timber trade as people started importing wood from forests further away from major population centres. This is the subtle art of dendroprovenancing.

Even more jaw-dropping is the link Trouet has drawn between tree rings, shipwrecks, and pirates. Hurricanes that rip leaves and branches off trees result in years of poor growth, leaving a visible mark in the tree-ring record. But hurricanes also sink ships. And when she compared the historical record of shipwrecks with that of hurricanes captured in tree rings, the two matched beautifully. At the same time, an extended period of reduced sunspot activity known as the Maunder Minimum reduced temperatures and, with it, storm activity, coinciding with the Golden Age of Piracy from approximately 1650–1720.

“Even more jaw-dropping is the link Trouet has drawn between tree rings, shipwrecks, and pirates. […] As you keep reading, the exciting examples of cross-disciplinary science underpinned by tree rings just keep coming, right up to the final chapter.”

As you keep reading, the exciting examples of cross-disciplinary science underpinned by tree rings just keep coming, right up to the final chapter. The impact of past volcanic eruptions such as Tambora. The fluctuations of the jet stream blowing high up in the atmosphere that shows in tree rings at ground level. The amazing story of how a suspected large earthquake in the Pacific Northwest was confirmed by historical records of a tsunami of unknown origin in Japan.  The history of forest fires and different fire regimes read from tree scars. The Little Ice Age in Europe and how it was cleverly exploited by the Dutch. Some authors, notably archaeologist Brian Fagan, have build careers on investigating the link between climate and the rise and fall of nations, although Trouet is quick to point out that it is an oversimplification to think that climatic changes alone topple civilizations. Other factors are just as important in determining the resilience of societies.

The clarity of Trouet’s explanations stands out, as does the book’s pacing: chapters are just the right length and never outstay their welcome. Thoughtful little extras are the glossary, the list of tree species, and separate lists with references and recommended reading. Add to this her personal stories and anecdotes based on a twenty-year career. She strikes the right balance between entertaining the reader without overshadowing the scientific narrative. And she moves you: these stories will make you laugh, cringe, or (in the case of the relentless persecution that followed the publication of the hockey-stick graph) anger you.

“A massive shout-out to the illustrator, Oliver Uberti. […] His [infographics] are uniform, clean, crisp, legible, clearly labelled, and (importantly) designed to be printed in grayscale—and those lovely endpapers really turn the book into a keepsake.”

Without wanting to take your attention away from the wonderful book that Trouet has written here, I want to give a massive shout-out to the illustrator, Oliver Uberti. His style looked familiar and I realise I have previously heaped praise on his infographics when reviewing Who We Are and How We Got Here. His illustrations give the book a certain cachet and are uniform, clean, crisp, legible, clearly labelled, and (importantly) designed to be printed in grayscale—and those lovely endpapers really turn the book into a keepsake. Publishers and authors should pay close attention and be lining up to commission him.

Tree Story is a sublime example of what booksellers have lately started calling smart non-fiction: sophisticated academic books for a broad audience (often published by American university presses) that are just a few notches above the yuck or wow-factor of more generic popular science. The excellent clarity and pacing that Trouet brings to this fascinating topic meant I that tore through Tree Story in a day. If I added ratings to my reviews, this book would be a ten out of ten. Already, this is a very strong contender for my book of the year.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

Tree Story

Other recommended books mentioned in this review:

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Since it was coined in the year 2000 by Paul Crutzen and Eugene Stoermer, the term “Anthropocene” has taken the world by storm – pretty much in the same way as the phenomenon it describes. Humanity’s impact on the planet has become so all-encompassing that it warrants giving this period a new name. As a colloquial term that is all snazzy, but are we actually leaving a tangible trace in the rock record to signal a transition to a new period?

The Anthropocene as a Geological Time Unit: A Guide to the Scientific Evidence and Current Debate, edited by Jan Zalasiewicz, Colin N Waters, Mark Williams, and Colin Peter Summerhayes, published by Cambridge University Press in March 2019 (hardback, 361 pages)

Several authors have already written thought experiments to try and answer this question. But the real answer lies in the realm of stratigraphy, the geological subdiscipline that studies rock layers. As with many other conventions, to ensure scientists around the globe all talk about the same thing and use the same names, there is an official body for that. The International Commission on Stratigraphy (ICS) formally decides on naming and dating of geological periods and maintains the International Chronostratigraphic Chart, better known as the Geological Time Scale (find a PDF here).

Formal acceptance of a new name means clearing a raft of bureaucratic and academic hurdles first. So, in 2009, the editors of the current book got together to form the Anthropocene Working Group to start preparing a formal submission to, ultimately, the ICS. Two large publications, a special issue of The Philosophical Transactions of the Royal Society A and A Stratigraphical Basis for the Anthropocene, came first. Now this edited collection does what it says on the tin, providing the latest update on the evidence and the debate by summarizing a huge body of work.

The first chapter provides a short history of what I have sketched above and, for the reader not versed in stratigraphy, useful basic information on how stratigraphy works, past decisions on defining and naming geological periods, plus a very interesting and relevant section outlining why formal acceptance and definition of the Anthropocene matters. The bulk of the book consists of five chapters examining how humans have tangibly modified our planet, and whether this leaves stratigraphically suitable markers. Depending on your viewpoint, this could be taken as a catalogue of our atrocities or a celebration of our achievements.

“The bulk of the book […] examines how humans have tangibly modified our planet, and whether this leaves stratigraphically suitable markers. Depending on your viewpoint, this could be taken as a catalogue of our atrocities or a celebration of our achievements.”

The range of impacts covered is comprehensive and includes some eye-opening facts and frighteningly large numbers. We are leaving a stratigraphical legacy by changing natural patterns of sedimentation via erosion and river damming. We construct infrastructure and buildings above and below ground and create many novel types of “rocks” such as cement, asphalt, and concrete (so much so that we risk running out of suitable sand). But we also enrich soils and sediments with fly-ash and soot from burning fossil fuels. And this is before we even talk of the insane amounts of plastics that end up in our environment, now degrading into micro- and nanoplastics that are found everywhere. And then there are what Zalaziewicz and others have dubbed “technofossils”: all the objects that we discard in refuse tips, revealing a stratigraphy all of their own.

Less visible but no less influential are chemostratigraphical changes. That is to say, the release of carbon and methane from (again) fossil fuel burning, nitrogen and phosphorus from synthetic fertilisers, sulfur compounds, metals, organic (in the chemical sense) compounds such as pesticides and fire retardants (your POPs, PAHs, PCBs, PBDEs, etc.) and, lest we forget, radionuclides from atomic and hydrogen bombs. All these have left detectable accumulations in air, water (including ice), and soil. A biostratigraphical signature is detectable as both recent and ongoing extinctions (particularly the extinction of the Quaternary megafauna, though see my review of End of the Megafauna), the rapid spread of invasive species and domestic animals (with broiler chickens being one example of an expected future signal in the fossil record), and the fate of coral reefs. Finally, there is climate change, made visible in changes to ice cover and sea level.

“And then there are […] “technofossils”: all the objects that we discard in refuse tips, revealing a stratigraphy all of their own.”

What I casually summarise here in two paragraphs is presented in-depth, providing an overview of a huge body of research. And despite subchapters being contributed by many different authors, the overall flow and coherence of the text are good. Although not the first book to detail humanity’s planetary impact, the question of interest here is which of these would make suitable stratigraphic markers.

So what makes a good marker? Ideally one that is global in extent and that was laid down synchronously, i.e. very rapidly, so that the age of the marker is the same wherever measured. A volcanic ash layer is a good example, and so, of course, is the iridium spike signalling the meteorite impact at the K-Pg boundary.

Not all of the potential markers discussed in this book meet these criteria, even though they reveal humanity’s impact. So, the sudden appearance of so many new long-lasting rock-like compounds and plastics is a good marker. Another one is lead released during the burning of fossil fuels, which shows up in natural archives such as sediments, peat mires, and ice cores. (Plus, there is a precedent here: Greenland ice cores show a lead spike at the height of Greek-Phoenician and Roman mining). But the appearance of soils modified by human agriculture is an example of a signal that is too localised and too diachronous (the opposite of synchronous) to be of use. The same is true for the occurrence of stone tools, though modern technofossils such as broken iPhones could be useful.

“When did the Anthropocene start? A consensus is forming on the 1950s. This is when human population size boomed and many things basically went into overdrive “

A similar question is the when. Though some scientists favour the rise of agriculture ~10,000 years ago or the beginning of the Industrial Revolution in the late 1700s as the start of the Anthropocene, the editors here outline how a consensus is forming on the 1950s. This is when human population size boomed and many things basically went into overdrive. When plotted on graphs, many indicators considered here show a sharp upward inflexion right around this time.

As with other periods, it is highly likely that a combination of proxy signals will have to be used to define the Anthropocene – many natural archives are either sensitive to disturbance (lake sediments vs. burrowing animals), or record signals with a delay (e.g. isotope signals in stalagmites). For the moment this is all work in progress, and a formal submission to the ICS is still being prepared by the Anthropocene Working Group. Much like the closely-allied Intergovernmental Panel on Climate Change reports are the go-to books on climate change (also published by Cambridge University Press), this book is the most definitive and up-to-date reference work for anyone working on or interested in the geological case for the Anthropocene.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Anthropocene as a Geological Time Unit hardback or ebook

Other recommended books mentioned in this review:

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Like Antarctica, Greenland is one of those places that exerts an irresistible pull on my imagination. As journalist, historian and The New York Times Magazine feature writer Jon Gertner makes clear in The Ice at the End of the World, I am not alone. This solidly researched reportage chronicles both the early explorers venturing onto Greenland’s ice sheet and shows the reasons it plays a starring role in research on climate change. Some books ought to come with a warning about how binge-read-worthy they are. This is one of them.

The Ice at the End of the World: An Epic Journey Into Greenland’s Buried Past and Our Perilous Future, written by Jon Gertner, published in Europe by Icon Books in September 2019 (hardback, 421 pages)

Split into two parts, “Explorations” and “Investigations”, the book starts with what Gertner calls the waning days of the age of exploration. The names of those who tried to reach our planet’s poles have gone down in the annals of history, but the men who ventured onto Greenland’s ice sheet have largely been lost to memory: Norwegian explorer Fridtjof Nansen, the first European to trek across the ice sheet below the Arctic circle from East to West in 1888. The American Robert Peary, who made a gruelling round trip at Greenland’s northernmost end in 1891-92. The Greenland-born Dane Knud Rasmussen and Norwegian Peter Freuchen who explored the same area as Peary did some two decades later, but with an eye towards ethnographical research amongst the local Inuit.

Although these men were celebrities in their time, and, like Charles Darwin and Alfred Russel Wallace, wrote large books about their travels, I had not heard of them before. Some of their books were never translated into English, and there have been no biographies written about them in recent decades, if at all. Gertner has thus dug into original sources in libraries and research institutes to retell the stories of these men and the brave souls who joined them on their expeditions, for these journeys were not solitary affairs. These are amazing stories of brutal physical and mental hardships: freezing temperatures, fierce winds, snowblindness, crushing monotony and boredom, fingers and toes lost to frostbite, and sometimes death. But also stories of raw beauty and poetic rapture at the scale and grandeur of nature. Greenland does this to you, and Gertner gratefully mines their writings for inspiring words.

“These are amazing stories of brutal physical and mental hardships […] but also stories of raw beauty and poetic rapture at the scale and grandeur of nature. Greenland does this to you.”

The only name that did ring a bell was Alfred Wegener, the German meteorologist and geophysicist who fathered the idea of continental drift. But that will be my fascination with the captivating history of the reluctant acceptance of his ideas , and the fact that there are recent biographies on him (see Ending in Ice and the exceptionally thorough Alfred Wegener). Gertner nimbly side-steps the continental drift story and maintains a tight focus on Wegener and Johan Peter Koch’s first ice sheet crossing in 1913, and Wegener’s later return to set up a research base in the middle of the Greenland ice sheet in the early 1930s. A successful undertaking for which he tragically paid with his life, freezing to death on a return trip.

From here, Gertner jumps forward in time a few decades. Whereas early expeditions had scientific aims, they were as much about exploration and often sheer survival, so early findings were both exploratory and limited. Gertner highlights the role of French explorer Paul-Émile Victor who brought his experience in the US Air Force, testing and developing survival equipment, to bear on polar research. As frequently happens, technology developed by the military often finds a second life in science. The development of more reliable heavy-duty motorised vehicles removed the need for death-defying expeditions by human or dog-pulled sledges. This was the start of the drilling of ice cores and saw the discipline of glaciology bloom.

“A particularly eye-opening chapter is that of Thule Air Base […] The sheer amount of manpower, material, and money that the US threw at this project was staggering.”

A particularly eye-opening chapter is that of Thule Air Base that the US Department of Defense established in 1951 in northern Greenland at the start of the Cold War. This story was only touched upon in Cold Rush, but it explains America’s continued interest in Greenland. Trump has not been the first US president trying to purchase Greenland from Denmark. And it is a bizarre story. The sheer amount of manpower, material, and money that the US threw at this project was staggering. Victor cleverly piggy-backed on the army’s presence and funding to undertake scientific research. Their departure as the Cold War wound down complicated financing further research to understand Greenland’s role in climate change.

This second part of the book revolves primarily around the drilling for ice cores and the research that has allowed scientists to deduce past temperature, CO₂ levels, and other palaeoclimatological variables. Gertner combines first-hand reportage during repeated visits to Greenland, numerous interviews, and careful reading of scientific papers to tell a thrilling narrative. Especially the shock discovery of evidence for abrupt climate change in the deep past takes centre-stage here. Initially, this was thought to be noise in the data, but then it was confirmed when subsequent ice cores showed the same signal, again and again.

“the shock discovery of evidence for abrupt climate change in the deep past [was] initially thought to be noise in the data, but then it was confirmed when subsequent ice cores showed the same signal, again and again.”

Gertner does a good job here introducing the physical basis of climate change, the long history of research on it, and some of the technical details of methods currently in use (isotope analysis, mass spectrometry, remote sensing with satellites, and the gravimetric analyses by NASA’s GRACE mission). But what he makes especially clear is that there is nothing alarmist about climate scientists’ concerns regarding melting ice sheets, calving glaciers, and the threat of tipping points beyond which changes could rapidly accelerate.

Gertner has spent years on this book, and The Ice at the End of the World stands out for the depth and thoroughness of its research. The 300-page narrative maintains a tight focus on its subject. It is accompanied by 70 pages of often very interesting notes where Gertner acknowledges which diversions are beyond the scope of this book, a section called “further sources” including a long list of interviews conducted and oral histories consulted, and a selected bibliography. But above all, the book is gripping. The memorable cast of historical characters, the pioneering research under challenging circumstances, the unusual settings – it has resulted in a book that I just could not put down.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Ice at the End of the World paperback, hardback or ebook

Other recommended books mentioned in this review:

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One look at the title and you might be forgiven for quoting John Cleese. But rather than asking what the Romans can do for us, this book asks what we can do for the Romans. Walter Scheidel, who is a professor of humanities as well as classics and history, and a fellow in human biology, brings together a diverse cast of scientists. Their aim? To discuss what relatively young bioscientific disciplines can add to our picture of life in Ancient Rome as revealed so far by the more mature disciplines of history and archaeology. Which disciplines might these be? Prepare yourself for several mouthfuls as this book covers palaeoclimatology, archaeobotany, zooarchaeology, palaeopathology, population genetics, and the study of ancient DNA.

The Science of Roman History: Biology, Climate, and the Future of the Past, edited by Walter Scheidel, published by Princeton University Press in April 2018 (hardback, 259 pages)

This book poses a challenge to its editor as above-mentioned fields are rapidly developing, relatively young, and, as typical with new disciplines, prone to hyperbole. Initial findings run the risk of being oversold before expectations are reined in, often causing scientists in other, more established disciplines to eye them up suspiciously. As such, the seven chapters in this book primarily discuss methodology, highlighting both potentials and pitfalls.

Perhaps appropriately Kyle Harper and Michael McCormick open the book with a chapter on palaeoclimatology: the reconstruction of past climates. I say appropriately as it was while reviewing Harper’s wonderful book The Fate of Rome that I first learned that this book was being written. The authors here give a crash course on the various proxies that are being used to reconstructing past climates, and what their shortcomings and limitations are. This includes data obtained from tree rings, ice cores, mineral deposits in caves, and sediment records in lakes. A tentative reconstruction of the Mediterranean climate for the period 200 BCE to 600 CE is given, though the authors are careful in their speculation as to what the human response might have been. Harper has developed his own ideas more fully in The Fate of Rome.

“[The archaeobotanical] record can tell us how food went from farm to fork”

The next two chapters focus on the plants and animals with which the Romans surrounded themselves, touching on the disciplines of archaeobotany and zooarchaeology. Marijke van der Veen focuses on food plants, as archaeological dig sites are often rich in plant remains. This record can tell us how food went from farm to fork and, importantly, provides details of the mundane but important daily chores of food production, preparation, and consumption. Something which written sources are often mute about. Michael MacKinnon similarly looks at animal remains in the archaeological record and how these can answer questions such as: Where did animals originate and end up? What did they eat? What animals do these bones even belong to? (Fragmentary bones alone are not always enough to determine identity, DNA analysis might be needed.) And animal remains can be used to buttress the chronology of other events.

The last four chapters, then, deal with human skeletal remains. From my reviews of Evolution’s Bite and The Tales Teeth Tell I have learned what teeth can reveal about diet and disease, but bones, too, can be used to answer many questions. Determining sex and age-at-death are two basic questions you would like to see answered when finding skeletal remains but are not straightforward, as a team of five authors here explains. Bones can furthermore reveal signs of disease (abovementioned palaeopathology), overall health and condition, diet, and workload or occupational tasks. The chapter on human growth and stature is possibly the only one that reports an analysis as the authors compare two different methods of determining a person’s stature from skeletal remains.

“Hopefully, even obstinate classicists and historians who […] sometimes distrust these novel methods might find this book an eye-opener.”

Spectacularly, old bones can also yield DNA (so-called ancient DNA). Pioneer Svante Pääbo wrote of this in his book Neanderthal Man, but see also my reviews of Ancestors in Our Genome and the fantastic Who We Are and How We Got Here which look at human evolution and population genetics in the light of ancient DNA. This chapter is surprisingly brief, giving a canned history and some examples of how ancient DNA can be used in only ten pages. It also sounds cautionary notes throughout.

A final chapter looks at population genetics, which studies the genetic material of people alive today to see what it reveals about our recent evolutionary history and migration across the globe. Specific attention is given to mitochondrial and Y-chromosomal DNA as these escape recombination at every generation and thus retain a record of their genetic ancestry for longer*.

“these disciplines can reveal much about the 99%, the silent majority of people not part of the rich and famous, for whom no other records survive.”

Although the various contributions in The Science of Roman History make for interesting reading and are accessible given the technical nature of the topics covered, I could not help but wonder who the intended audience is for this book. For the general reader, I worry that the methodological discussions might be too abstract. A synthesis of their respective fields is outside of the scope of this book, and though there are numerous references to primary literature, studies are often only mentioned. Killgrove’s upcoming book (under contract at the moment of writing this review) These Old Roman Bones: What Bioarchaeology Tells Us About Life in the Roman Empire might provide more narrative. For the specialist, on the other hand, this book might quickly become outdated as the pace of progress in these disciplines is astonishing. Scheidel acknowledges as much in his introduction, writing that we are “pushing against the limits of conventional formats of dissemination”, and suggesting a continuously updated electronic publication might be a better format than the printed book.

Ultimately, then, I think this book offers an academic snapshot in time that will be of interest to archaeologists, anthropologists, and geneticists eager to take a peek over the fence at how neighbouring disciplines are coming along. Hopefully, even obstinate classicists and historians who (or so this book makes it seem) sometimes distrust these novel methods might find this book an eye-opener. They will be pleased with the overall cautious tone and tempered expectations. One thing The Science of Roman History does convince you of is that these disciplines can reveal much about the 99%, the silent majority of people not part of the rich and famous, for whom no other records survive.

* If this sentence did not make sense – genetic recombination is the reason siblings are not facsimiles of each other. Both father and mother mix up their genetic material when they prepare sperm and egg cells so that each contains a unique mixture. This mixing process is great for producing genetically variable offspring, but it quickly erases information on ancestry. Mitochondrial and Y-chromosomal DNA are excluded from this process.

Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.

The Science of Roman History paperback, hardback or ebook

Other recommended books mentioned in this review:

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