In the days since suburban Minnesota dentist Walter Palmer was outed as the hunter who killed Cecil the lion, there has been no shortage of public fury.

Angry animal lovers from around the world flooded Palmer’s Yelp and Facebook page with thousands of negative reviews. Zimbabwean officials said they are investigating Palmer for poaching. An online petition urging the White House to extradite Palmer quickly sped past 100,000 signatures.

Celebrities as different as Ricky Gervais and Newt Gingrich condemned the lion killing. Mia Farrow tweeted out the dentist’s business address — only to delete it — and she faced a backlash after some online mistakenly believed she’d published Palmer’s home address.

But by far and away the most radical reaction belonged to People for the Ethical Treatment of Animals.

PETA called for Palmer to be charged, tried and if found guilty “preferably hanged.”

Here is the official statement from PETA co-founder and President Ingrid Newkirk:

Hunting is a coward’s pastime. If, as has been reported, this dentist and his guides lured Cecil out of the park with food so as to shoot him on private property, because shooting him in the park would have been illegal, he needs to be extradited, charged, and, preferably, hanged. To get a thrill at the cost of a life, this man gunned down a beloved lion, Cecil with a high-powered weapon. All wild animals are beloved by their own mates and infants, but to hunters like this overblown, over-privileged little man, who lack empathy, understanding, and respect for living creatures, they are merely targets to kill, decapitate, and hang up on a wall as a trophy. The photograph of this dentist, smiling over the corpse of another animal, who, like Cecil, wanted only to be left in peace, will disgust every caring soul in the world.

The statement isn’t out of character for the organization, which has earned a reputation as the one of the most radical defenders of animal rights.

Since its founding 35 years ago, PETA has repeatedly exposed instances of animal cruelty. Along the way, the organization has grown in fame and stridency.

Back in 1980, Alex Pacheco was a political science student at George Washington University. Scarred from witnessing the inside of a slaughterhouse, however, his real passion was saving animals.

Shortly after meeting Newkirk and founding PETA, Pacheco decided to go undercover in an animal testing laboratory to see what the conditions were like. He got a job at the Institute for Behavioral Research in Silver Springs, Md., where a doctor by the name of Edward Taub was conducting experiments in which he severed the nerves of macaque monkeys in an attempt to study the rehabilitation of crippled limbs.

Pacheco secretly recorded what he said were horrific conditions.

“Because of a massive and long-standing rodent problem, rat droppings and urine covered everything, and live and dead cockroaches were in the drawers, on the floor and around the filthy scrub sink,” he wrote. “No one bothered to bandage the monkeys’ injuries properly (on the few occasions when bandages were used at all), and antibiotics were administered only once; no lacerations or self-amputation injuries were ever cleaned. Whenever a bandage was applied, it was never changed, no matter how filthy or soiled it became. They were left on until they deteriorated to the point where they fell off the injured limb.”

“The stench of the laboratory permeated everything,” he continued. “When I got home I would have to strip, stand under the shower and scrub to get the smell out of my skin and hair. I could see the evidence of IBR’s filth and decomposition under my nails and in the lines of my skin. If only I could have scrubbed the image of the monkeys out of my mind. It became increasingly difficult to go back to IBR every day, yet I knew that I would have to continue if I was to succeed in helping these monkeys and other animals in similar situations.”

When Pacheco came forward with his evidence, police raided the laboratory, confiscated the monkeys and charged Taub with animal cruelty. Taub was convicted on six counts, but eventually the convictions were overturned on appeal and he was allowed to continue his studies.

PETA would fight for more than a decade to gain custody of the monkeys. In the process, the small organization would grow as it made powerful friends, equally powerful enemies and took center stage in the emerging debate over animal rights.

As The Post’s Peter Carlson wrote in 1991, the case of the Silver Springs monkeys would transform PETA into a worldwide force for animal rights, an organization both beloved and bitterly reviled:

It was the first time in American history that police raided a scientific research laboratory because of alleged cruelty to animals, and both sides — the animals rights activists and the animal research industry — immediately identified it as a “landmark” case that would set legal and political precedents affecting animal research across the country.
But nobody on either side could have foreseen that in 1991, a decade later, the case would still be alive and still causing controversy. And no one could possibly have predicted the bizarre twists and turns that the saga of the Silver Spring Monkeys would take over the next decade: The monkeys would be kidnapped. Several monkeys would be subjected to an experiment involving electrodes stuck into the brain. There would be two criminal trials, two libel suits and countless legal battles over custody of the monkeys. The two sides would dispute virtually every fact, accuse each other of “exploiting” the animals for political gain and call each other liars. Congress would battle the National Institutes of Health over the fate of the monkeys. Nature, a British scientific magazine, would call the animals “the most celebrated icons of the U.S. animal rights movement.” Doris Day would call them “political prisoners.” Protests about the monkeys would swamp the White House switchboard. A pro-monkey crusade by the National Enquirer would dump 46,000 letters on Barbara Bush. And, perhaps most importantly, the activist who infiltrated the Silver Spring lab would build a large and militant movement against not only cruelty to lab animals but virtually any use of animals by human beings.

Although the Supreme Court ultimately rejected PETA’s appeal for custody, resulting in the July 1991 euthanasia of the remaining monkeys, PETA emerged from the legal struggle stronger than ever.

Dozens of other high-profile cases followed: dogs shot during a Department of Defense medical training program, cosmetics companies recorded testing their products on rabbits, car manufacturers caught using live pigs in crash tests.

Over the years, the organization’s advertisements have become almost as shocking and controversial as the practices they seek to prevent.

The organization has launched lengthy and lurid campaigns against fur, fast food chains and circuses, to name just a few of its targets. Not even popular brands like NASA, Sea World and POM — that’s right, pomegranate juice — could escape PETA’s wrath.

A 2000 PETA poster showed a cow’s severed, bloody head above the words: “Do you want fries with that? McCruelty to go.”

Another poster seven years later featured a mouse trapped inside of a POM bottle. “POM Kills Animals,” the poster claimed. “Don’t buy while animals die.”

In 2011, just four days after a shark bit a 21-year-old while he was spear fishing in the Gulf of Mexico, PETA released a poster of a shark devouring a human above the slogan: “Payback is hell. Go vegan.”

PETA readily admits that its ads are often obnoxious.

“Unlike our opposition — which is mostly composed of wealthy industries and corporations — PETA must rely largely on free ‘advertising’ through media coverage,” the organization explains on its Web site. “We will do extraordinary things to get the word out about animal cruelty because we have learned from experience that the media, sadly, do not consider the terrible facts about animal suffering alone interesting enough to cover. It is sometimes necessary to shake people up in order to initiate discussion, debate, questioning of the status quo, and, of course, action.

“Thus, we try to make our actions colorful and controversial, thereby grabbing headlines around the world and spreading the message of kindness to animals to thousands — sometimes millions — of people,” PETA said.

(PETA, it should be pointed out, has itself been accused of animal cruelty for “killing over 99 percent” of the dogs in its shelters, according to the Atlantic. PETA said it euthanized animals it could not place into loving homes.)

Given PETA’s prior advertising, it’s perhaps no surprise that Newkirk came out swinging on Tuesday when Palmer was identified as Cecil’s executioner.

But her written statement calling for the dentist’s own execution still struck some as excessive.

More about the death of Cecil the lion: