Science unravels the mystery of the head-walking rabbits

Sputnik / Bolivia newspaper

The rabbits known as ‘Alfort jumpers’ are famous for walking upright on their front legs, in the best style of a tightrope walker. Discovered in 1935, these rabbits have puzzled scientists for decades, and only in 2021 can they explain this behavior. The finding could be useful even for humans.

Rabbits walking supported only on their front legs, in the best style of an acrobat. The image does not belong to a circus but to nature itself and only in 2021, and after 85 years, science can explain it.

Indeed, not all rabbits jump and run at high speeds using all four legs.

In 1935, the French veterinarian Etienne Letard first described the behavior of these rabbits, known since then by the French name of sauteur d’Alfort, that is, Alfort jumpers. Despite documenting them, Letard could not conclusively explain the reasons why rabbits did this.

An explanation appeared in 2021. A group of researchers led by Miguel Carneiro, from the University of Porto, and Jennifer Viellard, from the University of Uppsala, managed to show that the particular gait of these rabbits is related to a genetic defect detected during the investigation.

The study, published on March 25 in the journal PLOS Genetics and cited by the specialized journal Science News, attributes the behavior of rabbits to a mutation of the gene known as RORB. The result indicates that the mutation in rabbits causes them to have a “drastic reduction” of the RORB gene in their spinal cord.

One of the findings of the study was that the presence of this gene is necessary for jumping locomotion, the usual way of gait of rabbits based on small jumps.

The researchers confirmed this with two experiments: first with mice, which also began to walk on their front legs after having a gene mutation; and then with the rabbits themselves, crossing rabbits with gene dysfunction with others without this condition. By analyzing their young, they found that the mutation was not found in rabbits that could jump.

Leif Andersson, one of the Swedish geneticists involved in the study, explained to Science News that the RORB gene mutation can affect interneurons located in the spinal cord, which help the body coordinate the left and right parts of the body. Lacking RORB proteins in their interneurons, rabbits are likely unable to coordinate what their hind legs are doing, losing the ability to jump.

The results of the study are not only decisive to understand these particular rabbits but, according to scientists, it could contribute elements to understand how all animals move, including humans, which require coordinating their limbs to run.