No one, you would think, aspires to be a night-soil man. Yet in the late 1950s, Shi Chuangxiang’s labours in the latrines of Beijing briefly won him national praise. He was proclaimed a socialist hero and met the head of state. Back then, human excreta mattered, so much so that gangs fought for the plummest spots. Why? Because cities, until relatively recently in human history, were a part of healthy ecosystems that operated according to the principles of nutrient exchange: take, use, return, all in neat equilibrium. The spoils of Mr Shi (who was nicknamed ‘Stinky Shit Egg’), collected at a time when synthetic plant food was not widely available in China, became the organic fertiliser that was intended to power the country’s Great Leap Forward in agriculture.

As Urban Jungle makes abundantly clear, this cycle of reciprocity has now been ruptured everywhere. City and countryside have become estranged; moreover, nature has been expelled from urban centres. Rivers have been diverted underground. Wetlands have been filled in. Woods have been unceremoniously cut down. The results are sadly obvious. For the 4.46 billion people who reside in today’s cities, the feel of concrete underfoot and the smell of car fumes in the air are everyday realities. It’s little wonder that depression levels among urbanites are one fifth higher than among their rural peers.

In his new book, Ben Wilson, a London-born historian who – tellingly – now resides in leafy Suffolk, does not set out to depress us further. Instead, with the same upbeat spirit that pervaded his last book, Metropolis (about cities as repositories of innovation), he points in the other direction. Our cities can, to borrow a line from the Thriving Cities Initiative’s vision for creating a circular economy, become places for ‘people, plants, and animals’. The question is ‘how?’

This is not a manual for green-minded urban planners; nor is it an eco-inspired rhapsody. The urban jungle Wilson has in mind is firmly planted in the real world. Rewilding our cities is, he states frankly, ‘impossible’. Wilding them, on the other hand – now that is doable. Across seven main chapters – looking at suburbia, parks, the ‘crack in the concrete’ (think demolition sites, empty lots and so on), trees, water, food and animals – Wilson provides an array of fascinating examples of urban ecology through the ages.

Take the citadel of Tikal built by the Mayans. For over six centuries, these newcomers to the Yucatán peninsula sustained a megalopolis thanks to a sophisticated system of terraced farms, irrigation channels and underground reservoirs. Similarly, in Angkor Wat, in forest-strewn Cambodia, low-density housing was built on mounds amid rice paddies. There, city and countryside were one, Wilson notes: ‘Angkor was like an overgrown, continuous village in a wet landscape.’

More recent examples include Singapore, a pioneer of urban nature retrofitting. The early expansion of Singapore was a natural disaster, as coral reefs and mangrove forests gave way to cityscape. ‘As much as 73 per cent of the island’s native flora and fauna has been driven to extinction,’ Wilson writes. But since attaining independence, it has become a model of urban biodiversity (founding father Lee Kuan Yew dubbed himself ‘the chief gardener’), a ‘City in a Garden’ in which 56 per cent of the surface area is covered in vegetation.

Wilding our cities does not even need a top-down push. Ripping up our lawns and allowing wildflowers back in can do wonders. Back gardens, after all, can count for around one quarter of a city’s total area. ‘Think of all those barren flat roofs, all that idle space between buildings and along roads, and the immense acreage dedicated to the driving and parking of cars,’ Wilson declares. ‘Nature is capable of insinuating itself almost anywhere in the built environment if we only allow its growth.’

In that ‘if’, though, lies the sticking point. Just because we can green our cities doesn’t mean we will. Centuries of urbanisation have led us to be suspicious of the nature on our doorstep. The source of yesterday’s nutritious nettle soup is now a ‘weed’ to be nuked with herbicide. Such sentiments are not new. In a notorious legal case in 1900, a court in St Louis, Missouri, convicted a prominent resident for allowing ‘uncultivated vegetation’ in his front yard. The offending plants in question? Sunflowers.

Thistles, burdocks, nettles: meet the ‘immigrants and opportunists’ of the floral kingdom, the uninvited hobos who lurk where they shouldn’t, spreading disorder and portending chaos. In a sweeping overview that takes us from the Colosseum (an overgrown ruin until the early 19th century) to the abandoned streets of Detroit (an example of ‘post-industrial picturesque’), Wilson reveals the historical roots of today’s city–nature divide.

He also reveals the stories behind many of our man-made green urban spaces – what the author, who is never shy of a well-placed pun, refers to as ‘urbane nature’. New York’s Central Park, for instance, was cooked up in the late 1850s, with topsoil trucked in from New Jersey and plants shipped over from Europe. Its design is an ‘arcadian fantasy’ of aristocratic hunting parks in merry olde England. In 2007, as many as 60 per cent of the plant species in America’s most famous park were non-native.

For all mankind’s meddling, nature is obdurate. It didn’t stop evolving just because humans tried to keep it out. Wilson asks us to imagine our cities from the perspective of certain plants or animals. If you’re a seaside goldenrod or a strip of Danish scurvy grass, then the sodium-enriched verges created by winter salt trucks are a dream habitat. For a peregrine falcon, the difference between a twenty-storey skyscraper and a hundred-foot cliff is minimal: the dive-bombing potential is equally great. Nonetheless, not all natural species can adapt. As Wilson admits, our cities as they currently stand are the ‘site of eco-apocalypse’. Even putting the rights of nature aside, wilding our streets is in our self-interest. Just ask a psychologist or a physician. We’re happier, healthier and safer with nature near at hand.

Written in an authoritative yet accessible style, Urban Jungle contains a range of intriguing insights. Despite its non-hectoring tone, the book offers a clear warning. We continue to live out of kilter with nature at our peril. Look at Tikal and Angkor Wat. They went from being temples to human accomplishment to ruins in the rainforest. Nature will live on. But our cities: who knows? Let’s rip up our lawns first and then try to answer the question.