This is Marius the giraffe. Wasn't he cute? Photographer: Keld Navntoft/AFP/Getty Images
This is Marius the giraffe. Wasn't he cute? Photographer: Keld Navntoft/AFP/Getty Images

Yesterday morning, an 18-month-old giraffe named Marius died at the hands of his keepers at the Copenhagen Zoo. From a scientific perspective, it's possible to understand why zoos must cull "surplus" animals, even incredibly cute ones like Marius, with long eyelashes and soft lips. Emotionally, it still feels like a particularly heartless crime.

It was because of his bloodline that Marius became one of several dozen animals euthanized each year at Copenhagen Zoo. His genes were apparently too abundant among animals in the breeding program, a situation that could have led to genetic defects in his progeny. "Giraffes today breed very well, and when they do you have to choose and make sure the ones you keep are the ones with the best genes," the zoo's scientific director, Bengt Holst, told the BBC.

Holst is a venerable zoologist and author of works such as "Palpebral myiasis in a Danish traveler caused by the human bot-fly (Dermatobia hominis)" and "International Studbook for Muskox." He is also well versed in the Code of Practice of the European Association of Zoos and Aquaria, which says this about killing off extra animals: "Members having considered alternative solutions may cull animals in a manner that ensures a quick death without suffering. This may be controlled by local customs and laws but should always be used in preference to keeping an animal alive under conditions which do not allow it to experience an appropriate quality of life." It was EAZA that recommended the euthanasia.

Whether Holst really considered all the alternatives is debatable. He rejected options such as contraception and neutering because they could lead to diseases and a poor quality of life for Marius. He turned down a Swedish zoo because it could not guarantee it would not resell Marius -- and that, too, could be a life-worsening scenario. "You don't prostitute what you're trying to save by selling it," as Steve Graham, the former director of the Detroit Zoo, put it.

Holst's refusal to hand over Marius to two other zoos appears more arbitrary. Yorkshire Wildlife Park in England, Holst said, should keep any available space for a giraffe with a more useful genetic makeup. A Dutch zoo was turned down for unspecified reasons. Both establishments were unconvinced and saddened by the Danish scientist's decision. Despite Holst's qualifications, it appears that he was stubbornly proving the point that culling was normal. The international campaign to save Marius, which included an online petition signed by more than 21,000 people, had gone "too far," he felt.

It is only natural for experts to hate being pushed around by laymen or to deny their emotional motivations. "Zoos often do not cull favored animals when they become surplus to the needs of a program," University of Chicago biologist Robert Lacy wrote. "Decisions about which animals to kill are based on considerations of human feelings, although the justifications are often couched in terms of animal welfare or animal rights. The continued maintenance of favored animals, after no further progeny are desired and no other uses for the animals can be identified, uses resources that are needed to prevent the suffering and death of other animals, both currently living and yet to be born."

That is a powerful argument: Consider the suffering of Marius's inbred, possibly deformed would-be progeny. Still, I cannot help but feel that arrangements could have been made to keep him alive in some zoo where his gene pool would not be a problem. Too many people wanted to save him for Holst to go ahead with the euthanasia. After all, Lacy, for all his pragmatism, admits that not all "surplus" animals should be culled.

"The emotional bonds we feel to animals near us, with which we feel that we share experiences, are essential motivators behind the care we give to animals," he wrote. "I have three cats in my house. ... They serve no purpose but to increase my happiness. Maybe zoos can keep a favorite tiger or gorilla long past the end of his breeding lifetime for the same reason."

Zoos are more than scientific institutions. They are open to the public; 140 million people a year visit EAZA member establishments. A zoo is often the only place where children can see a lion or a giraffe. They are also places where kids learn how to treat animals.

Marius's post-mortem and the feeding of his meat to lions were open to the public at the Copenhagen Zoo. Some parents treated their children to the spectacle. For my part, I shudder to think how I could have explained that sight to my 4-year-old daughter. I may be squeamish, old-fashioned and unscientific, but I would rather explain to her that killing animals is basically wrong. That would make house cats' lives a little safer.

As Lacy suggests, zoo workers should consider emotional arguments against culling and openly admit them. Science does not have all the answers.

(Leonid Bershidsky writes on Russia, Europe and technology for Bloomberg View. Follow him on Twitter.)

To contact the writer of this article: Leonid Bershidsky at lbershidsky@bloomberg.net.

To contact the editor responsible for this article: Mark Whitehouse at mwhitehouse1@bloomberg.net.