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Zoos have existed in some form since at least 2500 bce in Egypt and Mesopotamia, where records indicate that giraffes, bears, dolphins, and other animals were kept by aristocrats. These private collections of wild and exotic animals for exhibition, called menageries, were precursors to modern zoos; a menagerie is now a general term for any unusual and varied collection of things. The oldest zoo still operating is Austria’s Vienna Zoo (Tiergarten Schönbrunn), which began as a menagerie in 1752 in the gardens and park of the Schönbrunn Palace, the Habsburg rulers’ summer residence. The zoo was opened to the public in 1779.[1] [2]

France’s king at this time, Louis XVI (1774–92), also had a royal menagerie at his residence, the Palace of Versailles, outside of Paris. When the king was ousted and the palace abandoned during the French Revolution, the royal animals were transferred to the Paris Jardin des Plantes (Garden of Plants), which opened its menagerie to the public in 1794.[45]

These menageries and early zoos were a perfect reflection of the ongoing Enlightenment intellectual movement, during which the spirit of curiosity enveloped Europe and scholars sought to better to understand the natural world through science, reason, and observation. Studying animals was a key aspect of the Enlightenment.[46]

The word zoo evolved as a popular shortened form of “zoological garden,” and was first used by the founders of the London Zoological Society in 1826. They modeled their society after the Jardin des Plantes in Paris.[42] The London society opened its own “zoological garden” (later called the London Zoo) two years later, in 1828.[43]

This zoological connection between Paris and London made history again in 1865, when the Jardin des Plantes gave the London zoo a small male African elephant named Jumbo, who grew into the largest elephant in the world and whose name became a worldwide symbol and synonym for anything huge. The London Zoo received another animal destined for fame in 1914, when it inherited an American black bear cub called “Winnie,” named after its owner’s home in Winnipeg, Canada. The cub became a favorite of zoo visitors, inspiring English writer A. A. Milne’s creation of Winnie-the-Pooh.[44] [53]

By the mid-19th century, zoos were opening around the world. Largely modeled after the London Zoo, these facilities were intended for “genteel amusement and edification,” according to Emma Marris, environmental writer and Institute Fellow at the UCLA Institute of the Environment and Sustainability. As such, reptile houses, aviaries, and insectaries (a place for keeping and raising insects) were soon added to zoos, to move them beyond the mere spectacle of showcasing big scary animals.[40]

Carl Hagenbeck (1844-1913), an internationally famous German animal dealer and trainer, introduced the prototype of the modern open-air zoo at his Animal Park in Hamburg in 1907. There animals were exhibited not in cages but in artificial environments more akin to their natural habitat. Hagenbeck also instituted more humane methods of caring for and training zoo animals and deemphasized the beating of the animals. This change prompted the shift in zoo narrative from entertainment to the protection of animals.[40]

Controversy has long shadowed exhibitions of live animals, from displays of “exotic” humans in exhibits offensively called “freak shows” to zoos ignorant on how to properly care for their animals. For example, a gorilla from the French Congo named Madame Ningo, the first gorilla in North America and the first to arrive and be exhibited in the United States (1911), lived at the Bronx Zoo in New York City—she was fed hot dinners with cooked meat from a nearby restaurant, though gorillas are herbivores (plant eaters). The gorilla refused to eat and died in two weeks. The zoo director was furious with the animal, saying she “deserved to be [dead], for its obstinacy.”[3] [4]

In the contemporary debate over zoos, both sides tend to focus on animal welfare—whether zoos protect animals or imprison them. So, should zoos exist? Explore the debate below.

Pros and Cons at a Glance

PROSCONS
Pro 1: Zoos educate the public about animals and conservation efforts. Read More.Con 1: Zoos don’t educate the public enough to justify keeping animals captive. Read More.
Pro 2: Zoos produce helpful scientific research. Read More.Con 2: Zoos are detrimental to the animals’ physical health. Read More.
Pro 3: Zoos save species from extinction and other dangers. Read More.Con 3: Zoo confinement is psychologically harmful to animals. Read More.

Pro Arguments

 (Go to Con Arguments)

Pro 1: Zoos educate the public about animals and conservation efforts.

As of September 2025, there were 254 accredited zoos, aquariums, and related facilities in 13 countries. At last count, in 2024, the zoos attracted over 209 million visitors annually, which is 54 percent more than the approximately 135.3 million spectators of games played in 2024 by the MLB (71.3 million), NBA (22.3 million), NFL (18.6 million), and NHL (23.0 million) combined.[5] [6] [7] [8] [9] [10]

According to a study of 26 zoos worldwide published in Conservation Biology, visitors to zoos increased their knowledge of biodiversity and efforts to protect it. [11]

Robin Ganzert, president and CEO of American Humane, said,

Zoos provide people, especially impressionable children, with the opportunity to see these remarkable animals up close. People won’t protect what they don’t love, and they can’t love what they don’t know. No matter how closely programs like Planet Earth depict animals, nothing will match the bond of seeing them in real life. Just look at a child’s eyes at the zoo when he or she encounters a tiger or similarly majestic animal.[12]

Furthermore, zoos have incredible reach via social media. Pygmy hippos Moo Deng (at Thailand’s Khao Kheow Open Zoo) and Mars (Tanganyika Wildlife Park in Goddard, Kansas), king penguin Pesto (Sea Life Melbourne), giant panda Fu Bao (China Conservation and Research Center for the Giant Panda), Asian elephant Kirby (Houston Zoo), and orangutan Rocky (Indianpoilis zoo) are just a few of the viral zoo stars that capture the public’s heart and imagination, leading to increased knowledge and support for the species. [47] [48] [49] [50] [51] [52] [13]

Pro 2: Zoos produce helpful scientific research.

In 2024, the Association of Zoos and Aquariums reported member institutions spent $30.3 million on research over 1,839 projects and 435 peer-reviewed publications that studied 652 species and subspecies (148 of which were endangered). [14]

Because so many diseases can be transmitted from animals to humans, such as Ebola, hantavirus, and bird flu, zoos frequently conduct disease surveillance research in wildlife populations and their own captive populations that can have a direct impact on human health. For example, the veterinary staff at the Bronx Zoo alerted health officials to the presence of West Nile virus. [15]

Zoos and zoo research are used in other ways, too, such as promoting legislation like the Sustainable Shark Fisheries and Trade Act, helping engineers build a robot to move like a sidewinder snake (so the robots can move uphill and on slippery and sandy slopes), and encouraging with workshops and programs more minority students to enter STEM careers . [37] [38] [39]

Pro 3: Zoos save species from extinction and other dangers.

Corroboree frogs, eastern bongos, regent honeyeaters, Panamanian golden frogs, Bellinger River snapping turtles, golden lion tamarins, and Amur leopards, among others, have been saved from extinction by zoos.[16]

Zoos are also working to save polar bears, tigers, and wild African elephants from habitat loss, apes and rhinos from poachers, dolphins and other whales from hunters, and bees and butterflies from population declines, among many other efforts.[17] [18] [19] [20]

According to researchers, 23 percent of birds and 47 percent of small mammals (weighing less than about 2.2 pounds) are being harmed by climate change. By keeping populations of animals and conducting wild re-population, zoos can help preserve species in danger from climate change. There were only 9 California condors in the wild in 1985. However, by 2016 a joint conservation effort between the San Diego and Los Angeles zoos with other organizations had increased the population of condors in the wild to 276 and in captivity to 170. [21] [22] [23]  

Przewalski’s horses, the last wild horses, were declared extinct in the wild in the 1960s when about 12 lived in zoos. By 2018, breeding programs at zoos had increased the number to 2,400 horses, and 800 were reintroduced to the wild. [24] [25]

Con Arguments

 (Go to Pro Arguments)

Con 1: Zoos don’t educate the public enough to justify keeping animals captive.

A review published in Animal Studies Repository concluded that “there is no compelling or even particularly suggestive evidence for the claim that zoos and aquariums promote attitude change, education, and interest in conservation in visitors.” Even a study widely cited to justify the argument that zoos educate the public stated that “there was no overall statistically significant change in understanding [of ecological concepts] seen,” because visitors know a lot about ecology before going to the zoo.[26] [27]

TV shows such as Planet Earth bring wild animals into living rooms, allowing people to see the animals in their natural habitats without causing harm to animals such as the endangered snow leopard. As British comedian Romesh Ranganathan stated,

It still slightly surprises me that anybody thinks that we should have zoos at all. The animals always look miserable in captivity.
The idea that kids only get excited about things they can see in the flesh is ridiculous. My kids are obsessed with dinosaurs that no longer exist, and Skylanders, which have never existed.[28]

Con 2: Zoos are detrimental to the animals’ physical health.

A study of 35 species of carnivores, including brown bears, cheetahs, and lions, found that zoo enclosures were too small for the animals to carry out their normal routines, which led to problems such as pacing and increased infant deaths. Polar bears, for example, had an infant mortality rate of 65 percent due to small enclosures.[29]

About 70 percent of adult male gorillas in North America have heart disease, the leading cause of death among gorillas in captivity, although the condition is almost completely absent in the wild. Other great apes have similar health problems in captivity.[4]

Captive elephants (for exhibition) live about half as long as wild elephants—16.9 years versus 35.8 years (for African elephants)—and about half as long as working elephants—18.9 years versus 41.7 years (for Asian elephants). Of 77 elephants in 13 zoos, 71 were overweight and spent 83 percent of their time indoors, contributing to early death.[30]

Con 3: Zoo confinement is psychologically harmful to animals.

Animal behaviorists often see zoo animals suffering from behavioral problems not seen in the wild, such as clinical depression in clouded leopards and gibbons, obsessive-compulsive disorder (OCD) in brown bears, and anxiety in giraffes. The animals experience these issues due to smaller enclosures, changes in diet and activities, and the introduction of things not seen in the wild, such as medical exams and people with cameras. The Toledo Zoo in Ohio ran a psychiatric program in which a gorilla with premenstrual depression was prescribed Prozac. To ease them into new habitats, an agitated tiger was given Valium, and anxious zebras and wildebeests were given Haldol.[31] [32] [33]

A study of captive chimpanzees found that “abnormal behavior is endemic in the population” and includes such actions as eating feces, twitching, rocking back and forth, plucking hair, pacing, vomiting, and self-mutilation. The study concluded that the cause of such behavior could be mental health issues.[34]

According to one study, 24 percent of captive orcas (killer whales) had “major” to “extreme” tooth wear, and 60 percent had tooth fractures as a result of stress-induced teeth grinding. The 2013 documentary Blackfish highlighted Tilikum, a male orca captured at age two off the coast of Iceland in 1983 and kept at SeaWorld Orlando in Florida until his death in 2017. Confined for nearly his whole life, Tilikum grew increasingly aggressive, eventually killing three people, including two trainers. The deaths led to many ethical discussions about captive animals and even spurred legislation concerning marine mammals in captivity. The breeding of captive orcas was subsequently outlawed in certain states, zoos, and theme parks.[35] [36]

Slideshow: Animals in zoos

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Assessment quiz

After reading the above debate, take our assessment quiz to test your knowledge of this issue. Good luck!

1-minute survey

After reading this debate, take our quick survey to see how this information affected your opinion of this topic. We appreciate your feedback.

Discussion questions

  1. Should zoos exist? If you believe they should, consider whether they should remain the same or change. If you believe they should not, consider how else to accomplish zoo’s conservation efforts. Explain your answers.
  2. Extend the debate to other artificial animal habitats, such as safari parks and animal sanctuaries. Should they exist? Why or why not?
  3. What other conservation efforts are important to saving wildlife? Explain your answer.
  4. Consider how you felt about the issue before reading this article. After reading the pros and cons on this topic, has your thinking changed? If so, how? List two to three ways. If your thoughts have not changed, list two to three ways your better understanding of the other side of the issue now helps you better argue your position.
  5. Push for the position and policies you support by writing U.S. senators and representatives.

Sources

  1. National Geographic Education, “Zoo” (accessed May 8, 2019), education.nationalgeographic.org
  2. Schönbrunn Palace, “Zoo” (accessed April 23, 2019), schoenbrunn.at
  3. CBC, “Trapped in a Human Zoo” (accessed April 23, 2019), cbc.ca
  4. Krista Langlois, “Something Mysterious Is Killing Captive Gorillas” (March 5, 2018), theatlantic.com
  5. Association of Zoos and Aquariums, “AZA-Accredited Members,” (accessed December 2, 2025), aza.org
  6. Association of Zoos and Aquariums, “Zoo and Aquarium Statistics” (accessed December 2, 2025), aza.org
  7. ESPN, “MLB Attendance Report - 2024,”4” (accessed December 2, 2025), espn.com
  8. NHL Records, “Attendance (1946-47 through 2024-25)4” (accessed December 2, 2025), records.nhl.com
  9. ESPN, “NBA Attendance Report - 20244” (accessed December 2, 2025), espn.com
  10. ESPN, “NFL Football Attendance Report - 2024” (accessed December 2, 2025), espn.com
  11. Andrew Moss, Eric Jensen, and Markus Gusset, “Evaluating the Contribution of Zoos and Aquariums to Aichi Biodiversity Target 1” (August 22, 2014), Conservation Biology, pubmed.ncbi.nlm.nih.gov
  12. Robin Ganzert, “Zoos Save Species—Visit One This World Wildlife Day” (March 3, 2018) thehill.com
  13. Indianapolis Zoo (September 25, 2023), instagram.com
  14. Association of Zoos and Aquariums, “Research and Science” (accessed December 2, 2025), aza.org
  15. C. Robinette et al., “Zoos and Public Health: A Partnership on the One Health Frontier” (November 23, 2016), One Health, pmc.ncbi.nlm.nih.gov
  16. Taronga Conservation Society Australia, “10 Endangered Species Saved from Extinction by Zoos” (May 18, 2017), medium.com
  17. Association of Zoos and Aquariums, “AZA and Animal Program Conservation Initiatives” (accessed April 17, 2019), aza.org
  18. Association of Zoos and Aquariums, “Pollinator Conservation” (accessed April 17, 2019), aza.org
  19. Association of Zoos and Aquariums, “Climate Change and Wildlife” (accessed April 17, 2019), aza.org
  20. Association of Zoos and Aquariums, “Marine Mammal Conservation” (accessed April 17, 2019), aza.org
  21. Michela Pacifici et al., “Species Traits Influenced Their Response to Recent Climate Change” (2017), nature.com
  22. Association of Zoos and Aquariums, “Conservation Success Stories in AZA-Accredited Zoos and Aquariums” (April 20, 2017), aza.org
  23. U.S. Fish and Wildlife Service, “California Condor Population Information” (May 7, 2018) fws.gov
  24. Jan Flemr, “Long Way Home as Przewalski’s Horses Fly to Mongolia” (July 19, 2018), phys.org
  25. Jane Palmer, “The World’s Last Truly Wild Horse” (November 11, 2015), bbc.com
  26. Lori Marino et al., “Do Zoos and Aquariums Promote Attitude Change in Visitors? A Critical Evaluation of the American Zoo and Aquarium Study” (2010), animalstudiesrepository.org
  27. John H. Falk et al., “Why Zoos and Aquariums Matter: Assessing the Impact of a Visit to a Zoo or Aquarium” (2007) docplayer.net
  28. Romesh Ranganathan, “Zoos Are Prisons for Animals—No One Needs to See a Depressed Penguin in the Flesh” (March 13, 2017, theguardian.com
  29. Edna Francisco, “Zoo Carnivores Need More Space” (October 1, 2003), sciencemag.org
  30. Ian Sample, “Stress and Lack of Exercise Are Killing Elephants, Zoos Warned” (December 11, 2008), theguardian.com
  31. Alex Halberstadt, “Zoo Animals and Their Discontents” (July 3, 2014), nytimes.com
  32. Daniel Engber, “The Tears of a Panda” (September 14, 2006), slate.com
  33. Jenni Laidman, “Zoos Using Drugs to Help Manage Anxious Animals” (September 12, 2005), toledoblade.com
  34. Lucy Birkett and Nicholas E. Newton-Fisher, “How Abnormal Is the Behavior of Captive, Zoo-Living Chimpanzees?” (June 16, 2011), journals.plos.org
  35. John Jett et al., “Tooth Damage in Captive Orcas” (May 2018), sciencedirect.com
  36. Natasha Daly, “Orcas Don’t Do Well in Captivity. Here’s Why” (March 25, 2019), nationalgeographic.com
  37. Shelby Isaacson, “Mote Ranked No. 1 Nonprofit in Published Research by Top Zoos and Aquariums” (April 4, 2018), mote.org
  38. Zoo Atlanta, “Representative Research” (accessed May 8, 2019), zooatlanta.org
  39. Bronx Zoo, “Bridging the Gap” (accessed May 8, 2019) bronxzoo.com
  40. Emma Marris, “Modern Zoos Are Not Worth the Moral Cost” (June 11, 2021) nytimes.com
  41. Association of Zoos and Aquariums, “Zoo and Aquarium Statistics” (July 2024), aza.org
  42. Henry Scherren, The Zoological Society of London (1905), archive.org
  43. London Zoo, “The History of ZSL” (accessed May 15, 2025), londonzoo.org
  44. London Zoo, “Winnie the Pooh at London Zoo” (accessed May 16, 2025), londonzoo.org
  45. Place Valhubert, “La MĂ©nagerie, Le Zoo du Jardin Des Plantes – MusĂ©um National D’histoire Naturelle” (accessed May 16, 2025) parisjetaime.com
  46. Brian Duignan, “Enlightenment” (March 14, 2025), britannica.com
  47. Tanganyika Wildlife Park (August 23, 2025) instagram.com
  48. Pattaya Mail, “Pygmy Hippo Calf Captures Hearts at Khao Kheow Open Zoo; Fans Show Interests in Pants” (September 11, 2024), pattayamail.com
  49. Tanganyika Wildlife Park, “Baby Hippo Mars Mission Control” (accessed December 2, 2025), twpark.com/mars-mission-control
  50. Sea Life Melbourne, Visit Our Viral King Penguin Pesto!” (accessed December 2, 2025), visitsealife.com
  51. Global Times, “S.Korea-Born Panda Fu Bao Returns to Public View After Rehabilitation of Over 100 Days” (March 25, 2025), globaltimes.cn
  52. Houston Zoo (April 23, 2025), instagram.com
  53. London Zoo, “Jumbo the Elephant” (accessed May 16, 2025), londonzoo.org