The spectre of the Anthropocene haunts an insightful journey into our wild past

A growing number of scientists maintain that our current geological epoch should be classified as the Anthropocene, which speaks bluntly to humanity’s impact on the global environment.

Yeo chose not to frame her book around this concept. But it is the spectre that haunts the landscapes she vividly evokes.

To wit, Yeo peels back the layers of humanity’s imprint on the natural world to reveal its inner cores – and the seeds that hold the promise of at least a partial restoration.

One arresting example of many that she explores is that of the ponds that once dotted much of the English countryside. Yeo tells us that in the 19th century rural England and Wales were sprinkled with 800,000 ponds which provided many essential services such as drinking water for horses that ploughed the fields.

“Though their purpose may have been pragmatic, these watering holes also acted as islands of aquatic biodiversity. Ponds are among our most humble habitats, ignored or even reviled – ‘pond life’ is hardly a compliment – yet together they support two-thirds of freshwater species,” she writes.

But the ubiquitous pond would evaporate over much of the English countryside in the 19th century as agriculture intensified and demanded more land for crops, and by the 1980s just a quarter remained.

“Yet… these ponds left an indelible impression on the landscape. If you have ever noticed mist pooling over a patch of land, or found a puddle that refuses to drain, or observed a strange pattern in the crops, then it is possible that you are in the presence of one of these ‘ghost ponds’,” Yeo says.

There is now a movement to resurrect old ponds which – buried beneath the soil – still brim with the promise of life that was silenced when they were drained and filled.

Scientists “have shown that it is possible to germinate species from seeds and oospores that have been buried in pond mud for at least 150 years”.

“That these ecosystems can rise from the dead, irrespective of the sins heaped upon them, seems nothing short of a miracle,” Yeo observes.

And contrary to public perceptions in an age when anthropogenic climate change is regarded as the burning environmental issue, species are far more adaptable in the face of ecological pressure than is generally assumed.

A case in point highlighted by Yeo is that of the European bison, which have long been considered to be a forest-dwelling species, with the last remnants of the population confined to wooded fragments in Eastern Europe.

The long-held assumption was that they were creatures of the forest. Yet the steppe bison of Europe that went extinct 15,000 years ago was, as its name suggests, a grazer. That is also true of the North American bison. And Cape buffalo are beasts of the savanna.

That led a South African ecologist named Graham Kerley – who visited the Mammal Research Institute at Białowieża Forest in Poland – to ask “why these European people have cows in the forest”.

The upshot of this was a 2012 paper that hypothesised that the ancient forests where the bison roamed were not the last remnant of the species’ original habitat “but rather the last hideaway of a species on the run”.

The bison had retreated into the forest and even when pastures were opened up by European farmers – providing the animals with grazing opportunities – conflict with humans confined the species to the woods.

The scientific term of art here is the “refugee species” hypothesis. Yeo twins this with “changing baseline syndrome” – a concept popularised more than a decade ago by natural history writer George Monbiot in his book Feral, which speaks to our propensity for regarding the current state of much of the natural world as normal.

“Shifting baseline syndrome and the refugee species hypothesis are surely the two most depressing concepts in ecology,” Yeo writes. “And yet, instead of allowing that baseline to inch forward, we can learn to push it back.”

Human overkill

In peeling back the layers of the past – and how this has shaped the present and what it means for the future – Yeo examines the worldwide extinction of mostly large herbivores that occurred during the Pleistocene and the early Holocene epoch which began about 11,700 years ago.

The reasons for this megafauna vanishing act have for decades been highly contested scientific terrain. Theories advanced include a lethal zoonotic disease exchange from early humans to animals and the fallout from a meteorite that crashed into Earth about 13,000 years ago.

But these are sideshows to the main debate, which broadly pits those who regard climate change as the main driver against those who track the archaic spoor of the extinctions to Paleo-hunters – the “Overkill hypothesis”.

Africa is the cradle of humankind and the extinctions coincide with the exodus of our ancestors – and their kin – from the Mother Continent and across the planet. African megafauna were spared this fate because such species co-evolved with Homo sapiens.

There is a growing scientific embrace of the overkill theory and a rich literature to support it. Yeo plants her spear firmly in this camp, as does this reviewer. It is perhaps a sign of the times that Yeo does not dwell much on these debates in her acceptance of overkill.

This removal of so much of the world’s megafauna would in turn have ecological consequences that have shaped the global environment to this day. 

In my own view, this makes this first act of what is now seen as the unfolding “Sixth Extinction” the Anthropocene’s origin story.

This is implicit in Yeo’s often wonderfully crafted narrative. Elephants, for example, are regarded as “physical habitat engineers” and the removal of their extinct kin on a global level triggered a trifecta of major ecological changes: the loss of relatively open landscapes and their replacement with denser formations such as forests, increased fires sparked by this combustible density, and the decline of plant species that co-evolved with megafauna.

She notes that in the 1980s the South African ecologist Norman Owen-Smith, based on his studies of elephants, suggested that the combined impact of the world’s megafauna “‘could have been greater than anything yet documented in Africa’”.

Yeo also draws our attention to a 2021 paper by a group of academics which argued that by 10,000 BCE – before the dawn of agriculture – humans had already occupied and shaped nearly three-quarters of Earth’s land surface.

There were many paths that blazed the trail to that conclusion and the canopy of research on this front continues to unfold.

It is an area of research that has long been of interest to this reviewer and I will just add a few observations on this score. This is not meant as a critique of Yeo’s fine book but rather to point to the arresting spoors of enquiry that can be tracked on this fascinating terrain.

The missing link in the discourse around the human overkill theory is the “why” question. In short, why would Paleo human hunters have devoted so much energy to killing off large, dangerous mammals?

I have previously raised the possibility in this publication that if one accepts the overkill hypothesis then human-wildlife conflict was surely at least a contributing factor. In all of the peer-reviewed scientific papers that I have reviewed on the subject this link is never made and the “why” question is almost never addressed. 

But the fact of the matter is that almost all of the Pleistocene megafauna that went extinct were, from a human perspective, dangerous. This “Paleo hit list” went beyond large herbivores and included a menacing assortment of carnivores.

It’s also clearly the case that these extinctions at the hands of human hunters must have had many subsequent historical consequences, allowing us to view this through the prism of what historians refer to as the longue durée.

This in turn raises questions about what the historian of ancient Africa Christopher Ehret has referred to as the “artificial separation of our human story into something called ‘history’ and something else called ‘prehistory’. Whatever humans have done in the past is history.”

And an emerging field of historical enquiry that looks at the role that non-human animals, and animal agency, have played in history, provide fresh and revealing ways to reframe this issue. 

Human-wildlife conflict suggests agency on both sides. The term “conflict” implies more than one protagonist. And if the Pleistocene extinctions arose in part from such conflict, then it has played a previously unexplored role in our shared human and animal history.

Yeo, without drawing such an explicit conclusion, points in this direction near the end of her book, citing a seminal 1897 paper by the pioneering childhood psychologist Stanley Hall titled A Study of Fears.

Gathering the fears of 1,700 people from surveys, Hall’s study found that the most common one was that of animals. He noted that this would have made sense among primeval children but seemed perplexing in a late 19th-century urban environment.

But such fears are wired into us from our distant past. Through conflict, we eliminated many of the monsters in our midst, in the process of taming our landscapes of fear – another recent field of ecological enquiry.

Yet the fear remains. DM