Photo of baby gorilla Okanda. Credit: Twycross Zoo

When zoo keepers at the Twycross Zoo in England care for a baby Western Lowland gorilla named Okanda, they feed him and grumble at him like a mother gorilla would do to keep him calm, but the hardest part is they are not allowed to smile.

Here’s why: When gorillas smile, or bare their teeth, it means they are hopping mad and keepers don’t want the baby gorillas to learn how to smile so they can be reintroduced into their families. Baring teeth or smiling shows a fear face, according to gorilla handler Sharon Redrobe.

“They’ll say, ‘who are you, what on Earth are you doing, you’re wrong, there’s something wrong with you,’ and kill him,” Redrobe said.

One baby gorilla named Tiny was killed by his foster father Kesho just a few months ago at the London zoo. Male silverback gorillas are temperamental and prone to violence, and a smile from Okanda could set them off.

Okanda was born at the Twycross zoo, but he was taken away from his parents a month ago because he was starving to death. There was something wrong with his mother’s milk. So zoo keepers launched a grueling round-the-clock human parenting that could continue for months until Okanda has moved on to solid food.

Redrobe said it was important to save the baby gorilla because there are only 100,000 Western Lowland gorillas left on the planet. Zoo keepers want Okanda to grow up, breed and have a family of his own to keep this critically endangered species alive.

That’s why they can never ever smile at this beautiful little creature.

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For more information, visit the Twycross Zoo website:   http://www.twycrosszoo.org/home.aspx