Never say die

Reading Remnants of Ancient Life by Dale Greenwalt for New Scientist, 11 January 2023

What is a fossil made of? Mineralised rocky fossils are what spring to mind at a first mention of the word, but the preserved fauna of the burgess shale are pure carbon, a kind of proto-coal. Then there are those tantalising cretaceous insects preserved in amber.

Whatever they are made of, fossils contain treasures. The first really good microscopic study of (mineralised) dinosaur bone, revealing its internal structure, was written up in 1850 by the British palaeontologist Gideon Mantell.

Still, classifying fossil organisms on the basis of their shape and their location seemed to be virtually the only weapon in the paleobiologist’s arsenal — until 1993. That was the year Michael Crichton’s novel Jurassic Park famously captured the excitement of a field in turmoil, as ancient pigments, proteins, and DNA were being detected (not too reliably at first) in all manner of fossil substrates, including rock.

Jurassic Park’s blood-sucking insects fossilised in amber were a bust. Though seemingly perfectly preserved on the outside, they turned out to be hollow.

Mind you, the author of Remnants (a dull title for this vivid and gripping book) has himself has managed to get traces of ancient haemoglobin out of the bloated stomach of a fossilised mosquito — so never say die.

Greenwalt, who spends eleven months of every year “buried deep in the bowels of the Smithsonian’s National Museum of Natural History in Washington, DC,” has brought to the surface a riveting account of a field achieving insights quite as revolutionary as any conjectured by Crichton. The finds are extraordinary enough: a cholesterol-like molecule in a 380-million-year-old crustacean; chitin from the exoskeleton of a fossil from the 505-million-year-old burgess shale. Even more extraordinary are the inferences we can then draw about the physiology, behaviour, and evolution of these extinct organisms. Even from traces that are smeared, fragmented, degraded, and condensed, even from cyclized and polymerized materials, valuable insights can be drawn. It is even possible to calculate and construct putative “ancestral proteins” and from their study, conclude that Earth’s life had its origins at the mouths of deep ocean vents!

The story of biomolecules in palaeontology has its salutary side. A generation of brilliant innovators have had to calm down, learn the limitations of their new techniques, and return, as often as not, to the insights of comparative anatomy to confirm and calibrate their work. Polymerase-chain-reaction sequencing (PCR) is the engine powering our ever older and ever more complete ancient DNA sequences, but early teething problems included publication of a DNA sequence thought to be from a 120-million-year-old weevil that actually belonged to a fungus. Technologies prove their worth over time.

More problematic are the cul-de-sacs. In 2007 Greenwalt’s colleague, the palaeontologist Mary Schweitzer reported her lab had recovered short sequences of collagen from the femur of a 68-million-year-old Tyrannosaurus rex. As Matthew Collins at the University of Copenhagen complains, “It’s great work. I just can’t replicate it.” Schweitzer’s methodology has survived 15 years’ hard interrogation, it may simply be that animal proteins cannot survive more than about 4 million years. That still makes them much hardier than plant proteins, which only last for about 30,000 years.

Against these fascinating controversies and surprising dead-ends Greenwalt sets many wonders, not least “the seemingly unlimited potential of ancient DNA to shed light on the ancestry of our species, Homo sapiens”. And for short-changed botanists, there’s an extraordinary twist in Greenwalt’s tale whereby it may become possible to classify plants based, not on their morphology or even their DNA, but on the repertoire of small biomolecules they leave behind. “The biomolecular components of plants have been found as biomarkers in rocks that are two and a half billion — with a ‘b’!—years old,” Greenwalt exclaims (p204). The 3.7-billion-year-old cyano-bacteria that produced stromatolites in Greenland are the same age as the rocks at Mars’s Gale Crater: “Are authentic ancient biomolecules on Mars so implausible?” Greenwalt asks.

His day job may keep him for months at a time in the Smithsonian’s basement, but Greenwalt’s gaze is set firmly on the stars.

“The idea that life is absurd bothers him”

Reading Life As Told by a Sapiens to a Neanderthal by Juan José Millás and Juan Luis Arsuaga for the Telegraph, 27 July 2022

In 2013 the oldest known human DNA was discovered, in a complex of caves in the Sierra de Atapuerca in northern Spain. It belongs to an early hominid, Homo heidelbergensis, who lived 400,000 years ago, and to whom we owe the invention of the fireplace.

Arsuaga has built an illustrious career around excavations in Atapuerca, a site humans have occupied continuously for a million years, from the dawn of Homo sapiens to the bronze age. He knows a lot about how humans evolved, and he is an eloquent communicator. “As he talked,” the novelist Juan José Millás recalls, “I realised what a great sense of the theatrical Arsuaga had. He was a master of oral storytelling. He knew when he had his audience, and when he was running the risk of losing them. He endeared himself by combining intellectual precision with a kind of helplessness.”

It’s Aruaga’s eloquence that first persuaded Millás that the two of them should collaborate on a book — a Boswellian confection in which Millás (humble, curious, a klutz, and frequently brow-beaten) follows Arsuaga around with a dictaphone capturing the great man’s observations. “In Spain,” he remarks, early on, “there are two principal periods: the first runs from the Neolithic to 1958, at which point the social planning by the Opus Dei technocrats comes in. Until then, the countryside was a place full of people, full of voices, life here was not a sad thing, there were children running around. It would be like walking down the street. By 1970, the countryside was empty, there was nobody left.”

Millás casts Arsuaga as the representative of Homo sapiens: articulate, eclectic, self-aware and tragical. Millás casts himself as Homo neanderthalis, not quite as quick on the uptake as his more successful cousin. Neanderthals are a species not exactly lost to history (Sapiens and Neanderthals interbred, after all) but no longer active in it, either.

The idea is that Arsuaga the high-brow leads our beetle-browed narrator hither and thither across northern Spain, on foot or in his trusty Nissan Juke, up lost valleys (to understand the evolution of hunting) and through deserted playgrounds (to grasp the mechanics of bipedalism), past market stalls (to grasp the historical significance of diet) and into a sex shop (to discuss the relative size of primate testicles) and building, bit by bit, a dazzling picture of the continuities that exist between our ancient and contemporary selves.

For many, the devil will be in the detail. Take, for example, Millás’s Neanderthals. He is not exactly wrong in what he says about them, but he is writing, in the most general and allusive terms, into a field that is developing frighteningly fast. It‘s hard, then, for us to know how literally to take the author’s showier gestures. Millás says, about that famous interbreeding, that “The Sapiens, being the smart ones, did it out of vice, while the Neanderthals, who were more naïve, did it out of love.” With Neanderthal intelligence and sociality a topic of so much fierce debate, such statements as this may be met with more scepticism than appreciation.

This is as much a buddy story as it is a virtuosic work of popular science. In unpacking our evolutionary past, Millas also brings his human subject to light. Arsuaga holds to the tragic view of life espoused by the fin de siecle Spanish essayist Miguel de Unamuno. Millás, a more common-or-garden depressive, finds Arsuaga’s combination of high spirits and annoyance hard to read. Deposited on the outskirts of Madrid, and half suspecting he’s been actually thrown out of Arsuaga’s Nissan, Millás realises that the palaeontologist “experiences sudden bursts of sadness that he sometimes conceals beneath an ironic demeanour, and sometimes beneath passing bad moods. I think the idea that life is absurd bothers him.”

Aruaga’s tragic sense entends to the species. We are the self-domesticating species: “To the Neanderthal,” he says, “the Sapiens must have seemed like a teddy bear.” We have evolved social complexity by shedding the adult seriousness we observe in less social mammals. (“I’ve been to Rwanda, looking at old gorillas,” says Aruaga, “and I can assure you they don’t play at all, they don’t laugh at anything.”) Over evolutionary time, we have become more playful, more infantile, more docile, and we have done this by executing, imprisoning and marginalising those who exhibit an ever-expending list of what we consider anti-social traits. So inanity will one day conquer all.

I wish Millás was a less precious writer. Very early on the pair arrive at a waterfall. “What had we come here for?” Millás writes: “in principle, to see the waterfall, and perhaps so the waterfall could see us, too.” Such unredeemable LRBisms are, I suppose, a form of protective coloration, necessary for a novelist and poet of some reputation: an earnest of his devotion to propah lirtritchah.

It’s when Millás forgets himself, and erases the distance he meant to maintain between boffins and scribblers, that Life becomes a very special book indeed: a passionate, sympathetic portrait of one life scientist’s world view.

Models of innocence and contentment

Reading Mark Witton and Ellinor Michel’s The Art and Science of the Crystal Palace Dinosaurs, for New Scientist, 1 June 2022

The Great Exhibition of 1851 was a huge success — so huge, in 1852 the huge iron and glass structure that had contained it was reassembled on parkland in Penge in South London to form the centrepiece of a complex of gardens, fountains and unusual attractions.

Dispel any notion that Penge was an afterthought: the permanent exhibition cost nine times as much as the Great Exhibition itself. And the Geological Court — arguably its most beguiling attraction — continues to enchant and inspire.

Cleverly landscaped and planted to evoke lost landscapes, peppered with artificial geological features and sculptures of long-extinct creatures, this naturalistic celebration of geology and palaeontology opened to the public in 1854. Whole teams of experts were involved in the enterprise, led by natural history artist Benjamin Waterhouse Hawkins, geologist David Thomas Ansted, and mining engineer James Campbell. Theirs was the world’s first attempt at depicting prehistoric worlds at scale in sculptural form.

Today elephantine sloths, Jurassic marine reptiles and delicate pterosaurs continue to watch other warily from the banks of artificial islands. Delicate, weathered, and in most cases colourless (the British weather is not kind to Victorian cement) they are also oddly modern-looking. The whole concept of a “dinosaur” was hardly over a decade old when the Court opened, and the field was advancing fast. Visitors were startled to discover that dinosaurs weren’t at all the appalling dragons that artists had imagined just a few years before. “It seems a very model of innocence and contentment,” wrote one journalist of the Iguanodon, “a huge antediluvian illustration of the amiability produced by a strictly vegetarian face.”

Paleoartist Mark P Witton and evolutionary biologist Ellinor Michel have assembled a work of scholarship that’s also a rich visual resource, indispensable for historians and prehistorians alike. Given the sheer vulnerability and fragility of the site, a record this rich and detailed — and so frankly charming — is long overdue.