Unlike the Easter Bunny, these rabbits can't hop. Scientists have solved the mystery of the 'hand-standing' bunnies.

Sauteur d'Alfort rabbits hopping — The typical posture of a Sauteur d'Alfort rabbit when walking.
Carneiro et al, PLoS Genetics

Sauteur d'Alfort rabbits walk on their front legs, as opposed to hopping on their hind legs.
Scientists finally have an explanation as to why this species has such a peculiar gait.
The 'hand-standing' rabbits walk on their forelegs because of a genetic mutation, a PLoS study found.
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Sauteur d'Alfort rabbits, also known as Alfort jumping rabbits, have a peculiar way of moving.

Instead of hopping on their hind legs, like other bunnies, the Sauteur d'Alfort rabbits lift their back legs from the ground and 'hand-stand' on their forelegs.

They then scurry forward on their front paws, maintaining their balance.

Ever since the species was first discovered in 1935, scientists have been baffled as to why the furry creatures are unable to hop or jump like most other rabbits.

Academics from PLoS Genetics- a peer-reviewed scientific journal - now have an explanation, Gizmodo reported.

The unusual gait can be explained by a genetic mutation, the study found.

This species has a warped RORB gene, BBC Newsround said. "This was the only mutation that stood out as really striking," Miguel Carneiro, an academic at the University of Porto, told the media outlet.

A mutation in the RORB gene can result in the loss of spinal cord interneurons.

"When you move, these neurons fire all the time, they coordinate muscle contractions and know if the other limbs are in balance," Leif Andersson, a co-author of the study, told Gizmodo. "This coordination of muscle contraction is not correct in these rabbits."

In the Sauteur D'Alfort rabbits, these interneurons were either less abundant or totally absent, the study said. This, in turn, results in the loss of saltatorial locomotion - the ability to jump or hop.

The hand-standing is a result of the rabbits working around their inability to travel like other species, the study said.

Baby rabbits of this species learn, after a few months, to walk solely on their front legs to compensate for the genetic mutation and consequent spinal defects, the New Scientist said.

It's unlikely that the quirky gait causes the animals any pain, Gizmodo reported.

The team of 12 scientists solved the mystery of the hand-standing rabbits after an experiment involving the breeding of a Sauteur d'Alfort rabbit with another species that can hop and jump normally, Slate reported.

The scientists then sequenced the DNA of the 50 or so descendants, the Smithsonian Magazine said.

Some of the baby rabbits had hand-standing gaits and scientists were able to identify the mutation in the code at the RORB gene in these animals, the magazine added.

Previous studies have shown that RORB mutations in other animals, such as mice, can interfere with normal movement. RORB-deficient mice waddle like ducks, the PLoS study said.

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