Llamas at a llama breeding farm in Germany. (Hannelore Foerster/Getty Images)

We humans began domesticating animals at least 15,000 years ago, when somehow or another, wolves became dogs — and eventually became, as the saying goes, man’s best friend. Cats became our buddies many millennia later, and look at them now: They’re pillow-warmers and YouTube stars.

But maybe we’ve been too narrow-minded. In a new study, Dutch scientists analyzed 90 mammal species for pet “suitability” and came up with five animals for which PetSmart probably hasn’t yet stocked supplies. Those animals, starting with the most suitable, are: Sika deer, Agile wallaby, Tamar Wallaby, llama and Asian palm civet.


About 1,200 Sika deer live in Nara Park, in Nara City, Japan. The animals follow visitors, who can purchase and feed them specially-made deer snacks. (EPA/EVERETT KENNEDY BROWN)

The researchers’ work wasn’t just whimsy, and it wasn’t actually an endorsement of ordering a wallaby from a shady online exotic pet dealer. It was in response to a Dutch national animal welfare policy that took effect in 2013 to address a growing trend in the Netherlands of owning exotic pets.

The policy said people could own “production animals,” a category that includes pigs and gerbils, or pets that are “suitable” for keeping by anyone without special knowledge or skills. The study’s goal was to use statistical methods to determine in an “objective and nondiscriminatory” way what animals should qualify for that second category.

A swamp wallaby joey at Symbio Wildlife Park in Australia poked its head out of its mother's pouch for the first time after it was born six months ago. (Facebook/Symbio Wildlife Park)

The scientists who took on this task, led by Paul Koene at the Wageningen University and Research center, were specialists in animal ecology, ethology, veterinary science and husbandry. After gathering information on animals kept as pets in the Netherlands and eliminating production animals and dogs and cats from their pool, they had 90 mammals to judge.

They then came up with short summaries — “oneliners” — on each animal for each of 24 behavior and needs criteria, including their food, shelter and reproductive needs, as well as their risk to humans and other animals. Two other teams of scientists reviewed those summaries and ranked the animals for pet suitability.


The Budapest Zoo’s male Tamar wallaby, “Frodo,” rested in a handbag carried by an animal keeper in 2011. (AP/Bela Szandelszky)

It should be noted that none of the mammals on the list of 90 — which included the bactrian camel and a several small animals like voles and gerbils — got a pass from all the scientists on the team that did the ranking. But somehow, a couple of wallabies and a deer got a majority vote. (The study, published in Frontiers in Veterinary Science, did include the caveat that assessors’ judgments might be influenced by an animal’s ugliness or cuteness.)


A llama crosses a road near Argentina’s Tolillar salt flat Tolillar, more than 12,000 feet above sea level. (Reuters/Enrique Marcarian)

Koene, for the record, said in a statement that he does not expect the list-toppers to be seen walking around the Netherlands on leashes anytime soon. “Dogs and cats are a special kind of pets,” he said, adding: “Wallabies will certainly not replace them.”


Tara, a 2-month-old Asian palm civet cub, sit on the shoulder of a Royev Ruchei Zoo employee in the Siberian city of Krasnoyarsk. (Reuters/Ilya Naymushin)

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