Germany was buzzing in late June with news that a long-awaited giant panda pair had arrived at the Berlin Zoo. The zoo had been without a panda since the death of Bao Bao five years earlier, and panda mania gripped the nation as the public waited to see Meng Meng and Jiao Qing.

On July 5, the day before the new $10 million Chinese-themed enclosure would open, the zoo held a welcoming ceremony for the pandas. Visiting President Xi Jinping toured the enclosure with German Chancellor Angela Merkel.

Merkel was overjoyed with the arrival of the "special envoys", telling Xi they were a "symbol of the relationship between our two countries".

How right she was.

"Panda diplomacy" has been around for years.

In February 1972, US president Richard Nixon traveled with his wife, Pat, and adviser Henry Kissinger to Beijing to meet Mao Zedong and Zhou Enlai, dramatically ending Washington's diplomatic cold shoulder toward New China. Beijing, to underscore its goodwill toward the United States, sent two giant pandas to Washington the following month.

It's a gesture that China has often repeated in various countries.

In March, for instance, two pandas were sent to the Netherlands. Fourteen foreign countries now have giant pandas, sent as a token of friendship by the People's Republic.

It's such a heartwarming diplomatic gesture, you have to wonder why other countries haven't followed suit.

Sure, after the National Zoo in Washington received the gift in 1972, Nixon reciprocated by sending a pair of Alaskan muskoxen to China. But it's not the same.

A muskox just doesn't say "Greetings from the US".

For that you'd need the bald eagle, the US national bird, as seen on dollar bills, or the American bison, the national mammal.

Most countries have a designated national animal, such as Russia's Eurasian brown bear or India's Bengal tiger. Some chose birds, like France's Gallic rooster and Colombia's Andean condor, and some reptiles, like Indonesia's Komodo dragon.

One could imagine a pair of any of these creatures serving as a diplomatic greeting card to a foreign country.

Still, the panda seems to have an inexplicable universal charm.

In the excitement leading up to the arrival of Xing Ya and Wu Wen at Ouwehands Zoo in the Netherlands, de Volkskrant newspaper in Amsterdam published an explanation of the phenomenon.

According to de Volkskrant, human beings are psychologically wired to feel tenderness for pandas.

It's called the "baby effect". As with human infants, the pupils of a panda's eyes appear proportionately too big.

"The panda's eye patches, moreover, sit just right, with the corner of the eye lower, a shape that people associate with supplication and subservience," the newspaper quoted psychologist Mariska Kret of Leiden University as saying. "Turn them the other way around and you get an angry looking face."

Add the round ears, small snout and head that looks proportionately too big, de Volkskrant added, and it's like a baby, huggable.

I can't imagine saying that about a bald eagle.

Contact the writer at lydon@chinadaily.com.cn