Study: Having 6 fingers on each hand is better than having 5

FREIBURG, Germany — People who are born with more than five fingers or toes, a condition known as polydactyly, may often feel embarrassed or ashamed by what the medical community considers a limb malformation. But a new study shows that individuals with six fingers are actually at an advantage in many ways when it comes to fine motor skills and capabilities, with the ability to perform movements that would otherwise require individuals to use two hands.

According to a 2017 study, polydactyly is reported in approximately 1 in 700-1,000 live births.

Researchers from the University of Freiburg say that the first study to examine the motor skills and sensorimotor brain areas in people with polydactyly shows that these individuals have areas of the brain specifically dedicated to using their additional limbs.

“We wanted to know if the subjects have motor skills that go beyond people with five fingers and how the brain is able to control the additional degrees of freedom,” explains study co-author Prof. Dr. Carsten Mehring from the University of Freiburg and the Bernstein Center Freiburg, in a statement.

For their research, researchers studied two people who have six fingers on each hand — a fully-formed additional digit between their thumb and index finger. The authors had the participants perform numerous movements while monitoring their brains using using functional magnetic resonance imaging (fMRI).

They found that these additional fingers were moved by their own muscles, giving the participants an extraordinary ability to use their hands in many beneficial ways.

“Our subjects can use their extra fingers independently, similar to an additional thumb, either alone or together with the other five fingers, which makes manipulation extraordinary versatile and skillful,” says Mehring. “For instance, in our experiments subjects can carry out a task with one hand, for which we normally need two hands.”

In fact, researchers say there doesn’t seem to be any handicap associated with the condition when compared to people with five fingers.

“Despite the extra finger increasing the number of degrees of freedom that the brain has to control, we found no disadvantages relative to five-finger people,” says co-author Prof. Dr. Etienne Burdet, of Imperial College London. “In a nutshell, it is amazing that the brain has enough capacity to do it without sacrificing elsewhere. That’s exactly what our subjects do.”

The authors say the findings could lead to a science fiction-like development of additional artificial limbs to give people the ability to do more in various specialized fields, such as surgeons given an extra arm to complete operations without an assistant. They note, though, that people with polydactyly have had the condition since birth, meaning their brains were naturally “trained” to use the additional limb.

The study is published in the journal Nature Communications.