Like humans, gorillas can strengthen their relationships by cuddling. Rare footage released by the Wildlife Conservation Society has shown two sibling western lowland gorillas locked in a tender embrace.

The two gorillas, named Avatar and Jingles, live in a forest clearing in the Republic of Congo's Nouabale Ndoki National Park known as Mbeli Bai.

They were hugging as part of a play session. Gorillas can be quite physical in their play behaviour, engaging in wrestling, hitting and biting each other but also in touching, kissing and hugging.

Researchers have tried to understand the science behind cuddles for years. Studies have shown that hugs can help humans in many situations, from showing appreciation to beating loneliness and stress at work.

Cuddling is thought to be the human form of primate grooming, and is used to create and maintain our relationships.

Recently, scientists studying primates have also uncovered growing evidence that primates don't resort only to grooming to strengthen their links - they also hug like humans.

Researchers have shown that chimps can console each other by hugging and stroking, and that this can reduce stress levels after a fight. Both humans and chimpanzees have also been found to hug victims of violent crimes to console them.

This behaviour of 'sympathetic concern' has been observed in gorillas and bonobos as well.

Here, Jingles and Avatar don't appear to console each other, but they reinforce the fraternal bond that unites them. It's thus possible that just like grooming, hugging is also a way for gorillas to form and reinforce social bonds.

The Wildlife Conservation Society will continue to monitor the two gorillas as well as the other animals in the park, such as forest elephants, to protect them from poaching.