The sound was like nothing Tom Hinton had heard before: a chorus of baleful wolf howls, long and loud and coming from seemingly every direction in the darkness. The predators yipped and chirped and crooned to one another for what seemed like forever, sending a shiver of awe and intuitive fear down Hinton's spine.
"It was a primordial experience," he said, something most of humanity hasn't felt for tens of thousands of years. "That dates back to when humans were prey."
It was only possible because of where Hinton was standing, a remote area along the Belarus-Ukraine border that's been uninhabited by humans for decades.
They all left in the wake of a very different sound nearly 30 years earlier: the explosion of the Chernobyl Nuclear Power Plant in 1986, which left dozens dead and drove more than 100,000 people from their homes across a 1,600-square-mile swath of Ukraine and Belarus. These days, abandoned apartment complexes are nothing more than crumbled concrete wrecks. Vines crawl up the decaying walls of old farmhouses and break unintended skylights into their roofs. No one lives in the postapocalyptic setting.
No one human, that is. Wildlife populations there - shaggy-haired wild boar, long-legged elk, the howling choruses of wolves that so captivated Hinton last August - are flourishing.
That's according to a study published last week in the journal Current Biology, which found that mammal numbers in the exclusion zone are as high, if not higher, than in even the most protected parks in Belarus.
"That wildlife started increasing when humans abandoned the area in 1986 is not earth-shattering news," Hinton, a radioecology expert and coauthor on the paper, told the Washington Post. "What's surprising here was the life was able to increase even in an area that is among the most radioactively contaminated in the world."
In other words, whatever the fallout from the disaster may have been, it turned out that the absence of humans was more than enough to compensate.
"It shows I think how much damage we do," said fellow coauthor Jim Smith, an environmental-science professor at the University of Portsmouth.
"Not that radiation isn't bad," he added, "but what people do when they're there is so much worse."
The study is the first real census of wild animals in the exclusion zone. It relies on a decades' worth of helicopter observations in the years right after the disaster, and three winters of scientists' carefully counting animal tracks on foot between 2008 and 2010 in the Belarusian section of the zone.
Though animal numbers were low when scientists first started counting them in 1987 (because no data were taken before the disaster, they can't tell to what degree the populations were hurt by the explosion), they rapidly rose once humans left. Brown bears and rare European lynx - predatory cats the size of a Great Dane - quickly appeared in the forests, even though they hadn't been seen for decades before the accident. Wild boar took up residence in abandoned buildings. Forests replaced humans in the villages' empty streets.
Within 10 years, every animal population in the exclusion zone had at least doubled.
By 2010, the last year of the on-foot census, the populations for most species were as large as in any of Belarus' four national parks. For one species, the wolves, the population was seven times bigger.
This indicates to researchers that chronic exposure to radiation from the explosion has had no impact on overall mammal populations. Whatever fallout may have come from the initial explosion was completely offset by the benefits of life without humans.
This doesn't mean that the zone isn't dangerous, Hinton stressed. He and his colleagues didn't study the individual- and molecular-level damage caused by lingering contamination. While whole populations aren't dying out, individual animals might be getting sick.
But, "the environment is very resilient," Hinton said.
The presence of wolves is particularly telling. As apex predators, they are a sign of the health of the entire ecosystem - if they're flourishing, that means that every other level of species, from elk and deer on down to insects, must also be healthy.
Walking around the exclusion zone is like being in "a national park without the people," Hinton said. The forests are nearly pristine, the animals abundant. What relics of human presence do remain have been almost entirely reclaimed by nature.
Even the Soviet city of Pripyat in Ukraine, which once housed tens of thousands of workers at the Chernobyl plant, has been subsumed by trees.
For Hinton, who is studying the effects of the 2011 Fukushima nuclear disaster in Japan, the impact is both astounding and sobering.
"It's an amazing experience from a wildlife perspective, but it's also a sad experience because you see homes that have been abandoned and you imagine the people's lives that have been disturbed," he said. "It's sad to see the houses and the cars and the baseball bats and you envision the life that people had to drop and leave."