Some rabbits walk on their front legs; science finds the reason. Illustration: Petepop / Condutta
A defective gene can turn rabbits into professional acrobats that only walk on their front legs, according to a new study.
To move quickly, a breed of domesticated rabbit called Sauteur d’Alfort raises its hind legs and walks on its front legs. This strange habit may be the result of a gene related to limb movement, researchers report in a study published in PLOS Genetics.
The Sauteur d’Alfort rabbits are not the only animals that adopt a strange walk if there is a mutation in this gene, called RORB. Mice with a mutation in this gene also perform handstands when they start running, says Stephanie Koch, a neuroscientist at University College London who was not involved in the rabbit study. Even while walking, mice raise their hind legs to waddle forward, almost like a duck.
“I spent four years watching these mice do little handstands, and now I see a rabbit do the same handstand. It’s incredible,” said Koch, who led a 2017 study published in Neuron that explored the mechanism behind the “duck walk” in mice.
According to Leif Andersson, molecular geneticist at Uppsala University in Sweden, understanding why rabbits move in such a strange way may help researchers learn more about how the spinal cord works. “The study is contributing to our basic knowledge of a very important function in humans and all animals: how we are able to move.”
In the rabbit study, Andersson and colleagues bred male Sauteur d’Alfort rabbits without hopping with white New Zealand rabbits that can hop. The team then scanned the genetic designs of the offspring that couldn’t hop and looked for mutations that didn’t appear in the offspring that could.
A mutation in the RORB gene appeared as a likely candidate for the rabbits’ handstand acrobatics. This change creates defective versions of the genetic instructions that cells use to produce proteins, the researchers found. As a result, there seems to be less RORB protein in nerve cells in rabbits with the mutation compared to rabbits that don’t have it.
These nerve cells in the spinal cord, called interneurons, help coordinate the left and right sides of the body and are crucial for normal gait, explained Andersson. Without RORB protein in the interneurons, rabbits may not have the ability to coordinate what their hind limbs are doing, which limits their ability to hop.
While moving slowly from one place to another, rabbits with the defective gene can walk normally, alternating their front and hind legs. But the rabbits that hop use this technique to move fast or travel long distances. And hopping requires synchronized hind legs to jump at the same time, emphasized study co-author Miguel Carneiro, a molecular geneticist at the University of Porto, Portugal.
Without this coordination, some rabbits that can’t hop may perform a more drastic handstand than others. But all rabbits with the RORB mutation use their front legs to move quickly, Carneiro explained.
Discovering how this genetic defect affects the body on a larger scale could be important for understanding how all animals move, just as humans cannot run without harmonious movements of all four limbs.
Illustration: Petepop / Condutta. This content was created with the help of AI and reviewed by the editorial team.
