Our planet’s past lies hidden under the dirt. It wears the scars of its formation and change in its crust, and it, too, is a mortuary, memorializing its inhabitants in stone, fossils acting as grave marker, mask and body. Those worlds, those otherlands, cannot be visited — at least, not in a physical sense. You can never visit the environments through which titanic dinosaurs strode, never walk on their soil nor swim in their water. The only way to experience them is rockwise, to read the imprints in the frozen sand and to imagine a disappeared Earth. This book is an exploration of the Earth as it used to exist, the changes that have occurred during its history, and the ways that life has found to adapt, or not.
In Otherlands, paleobiologist Thomas Halliday skips backwards through time, visiting sixteen distinct eras from Earth’s history and describing the life, climate, and geological forces at work in each. This is cutting edge science — many of the earliest species can only be inferred by the slightest of impressions they left behind; many more will never make themselves known to us — and Halliday’s prose in describing his rebuilt worlds is comprehensive, evocative, and accessible. There’s always something humbling about confronting how unimportant our own species has been in the long history of the Earth, and as we are forced to acknowledge that we are driving the latest Great Extinction Event, I suppose there’s comfort in knowing that after we are gone, the Earth will diversify and other species will fill the Homo sapien niche. A fascinating read that makes the science come alive. (Note: I read an ARC through NetGalley and passages quoted may not be in their final forms.)
To consider the landscapes that once existed is to feel the draw of a temporal wanderlust. My hope is that you will read this in the vein of a naturalist’s travel book, albeit one of lands distant in time rather than space, and begin to see the last 500 million years not as an endless expanse of unfathomable time, but as a series of worlds, simultaneously fabulous yet familiar.
From the salt flats of a drained Mediterranean Sea to the lush forests of a tropical Antarctica, Halliday describes vanished worlds that are at once familiar and not. I highlighted dozens of passages in Otherlands — interesting factoids and nice bits of writing — but with the ease of copy/pasting from a digital ARC, I acknowledge that that would be far too much to put in a review. (The following tidbits were placed behind spoiler tags on goodreads for my own use.)
• The loris has access to glands in its armpit which, when combined with saliva, can produce a venom capable of causing anaphylactic shock in humans. In behaviour, colour and even bite, the primate has come to resemble the snake, a sheep in wolf’s clothing. Today, the ranges of the loris and cobras do not overlap, but climate reconstructions reaching back tens of thousands of years suggest that once they would have been similar. It is possible that the loris is an outdated imitation artist, stuck in an evolutionary rut, compelled by instinct to act out an impression of something neither it nor its audience has ever seen.
• To grow new bones every year requires enormous amounts of calcium. The demand is so intense that modern-day red deer on the Hebrides are known to wait outside shearwater burrows in spring, crunching down on the chicks as they emerge above ground for the first time and obtaining calcium from their bones, while white-tailed deer in North America are notorious nestling predators of a variety of small songbirds. Antlers are expensive.
• Every monkey in the Amazonian rainforest, from spider monkeys to howler monkeys, tamarins to marmosets, owes its existence to a few lucky survivors from their own presumably difficult and traumatic ocean voyage. The distance to cross from Africa to South America at the time was considerably lower, about two thirds of the width of the modern Atlantic, but this is still a huge distance when relying on rain and pooled water in leaves for a supply of drinking water. Even assuming continuous movement in exactly the right direction, the communities of rafting monkeys must have survived at sea for over six weeks.
• The abundance of food at Seymour Island has proven too much of an attraction, and this sawfish has presumably followed the eastern coastal waters of South America to reach its destination. The saw acts as both locator and capturer of food, with thousands of sensitive ampullae along its length detecting changes in electric fields. Because vertebrates control muscle movement using flows of charged calcium ions, if a herring so much as twitches, the sawfish will know, swiping its saw through the water at high speed, hacking at the seabed with the edge, or pinning its prey down with the flat as it manoeuvres the fish towards its mouth.
• At the moment the Chicxulub meteor struck, all primates, flying lemurs, tree shrews, rabbits and rodents had yet to diversify. They were united within one, perhaps two or three species, common ancestors to all. Our ancestors are here, and they contain within their genetic code the essence of what it means to be a primate. The ancestors of some of the largest land mammals that will ever exist, the 17-ton rhinoceros cousin Paraceratherium, are here, and are the same individuals whose descendants will miniaturize and fly as the smallest, the bumblebee bat. The range of anatomical forms will expand rapidly, exploring the different possibilities of being a mammal, before eventually specializing into the groups we know in the present. It seems an almost biblical promise: your descendants will reach all corners of the Earth and beyond it.
• The penchant for visual display, at least, will persist in dinosaurs until the modern day — no group of vertebrates has the variety, the detail and the vibrancy of colour and shape as birds. Indeed, reptiles, from birds to lizards, have colours that humans cannot see, patterns that fluoresce under ultraviolet light. Given that this seems to be an ancestral trait, it is possible that non-avian archosaur display, including pterosaurs and dinosaurs, extends beyond the human visual spectrum.
• Each cell is semi-independent, and a single sponge blurs the line between individual and colony. If you were to put one in a blender, it would re-aggregate — a different shape, but still a working organism, a functioning sponge.
• The largest logjam in historical times lasted for nearly 1,000 years in the lands of the Caddoan Mississippian culture, now in Louisiana. Known as the Great Raft, it at one time covered more than 150 miles of river, an ever-shifting carpet of trunks slowly decaying in the water, and was an important element of local folklore and agriculture, providing fertile floodwater and trapping silt for crops. It would still be here today if it had not been blown up to allow boats through. Once it was gone, the river flooded the land downstream, requiring further dams to be built, and changing the dynamics of water flow in the region.
*****
This is now undoubtedly a human planet. It has not always been, and perhaps will not always be, but, for now, our species has an influence unlike almost any other biological force. The world as it is today is a direct result — not a conclusion or a denouement, but a result — of what has gone before. Much of life in the past happens in a steady state of slow-changing existence, but there are times when everything can become upended. Unavoidable impacts from space, eruptions at a continental scale, global glaciation — the all-pervasive transitions that force life’s structures to remodel themselves. Had any of those events happened in another way, or not happened at all, the then-unwritten future could have emerged very differently. It is by looking at the past that palaeobiologists, ecologists and climate scientists can address the uncertainty about the near- and long-term future of our planet, casting backwards to predict possible futures.
Reading about species that dominated their world for millions of years before some natural cataclysm wiped them out can be pretty demoralising, from the point-of-view of a species that’s only been around for a few hundred thousand years and is just starting to get the hang of how to best use these big brains. On the one hand, even if we pull together and concentrate on regenerating our environment, we’ve already wiped out the vast majority of large animals on the planet, climate change is threatening the rest (including us), and a supervolcano could blow up at literally any second; it’s easy to feel as helpless as a dinosaur in the path of the incoming Chicxulub meteor. But on the other hand, we are the wise ape, a part of nature and not separate from it, and we can use these big brains to learn lessons from the past and approach the future with more self-awareness than any dinosaur ever had. Halliday ends his trip through deep history on a hopeful note: change is inevitable, but our imminent extinction is not. Well worth the read.
