Snap Your Fingers about Design
Finger snapping and other wonders of the human body should
make evolutionists snap awake to failures of Darwinian theory.
Snap your fingers right now. Did you know you just performed one of the fastest accelerations in vertebrates?
We take it for granted, but finger snapping is an amazing feat. It’s also an action with little to no “survival value” for evolution. Watch this talented finger-snapping practitioner on YouTube and see if your local Darwinist can come up with a just-so story for why this ability evolved. Are they going to claim that without this ability, the first hairless hominid would have gone extinct? Obviously not.
When you examine your own finger snap, you see that several things have to be just right for the action and resulting sound to work: arrangement of the fingers, friction of the skin, muscle tension, bone strength and flexibility of the “sounding board” among them. Were all these specifications the result of chance mutations?
Many aspects of organisms are not required for survival, but add interest, novelty and wonder to life. This is a good example.
Inspired by art, researchers find the finger snap to have the highest acceleration the human body produces (Georgia Institute of Technology). This press release from Nov 15, 2021 starts with historic artwork showing that “Through the ages, the snap of a finger has been used by people to communicate.” That doesn’t make it required for survival. There are louder ways to communicate, and many go most of their lifetimes without communicating that way. The finger snap is useful, and seems instinctive, although some learning is involved when children first try it. Researchers at Georgia Tech applied “curiosity-driven science” wherein “everyday occurrences and biological behaviors can serve as data sources for new discoveries.” Darwinism is not required for that.
As the Georgia Tech team researched the history and biology of the finger snap, they found that the earliest depiction of it dates from Greece in 300 BC, although they know the skill is undoubtedly as old as the first humans. What they found was quite surprising.
Using an intermediate amount of friction, not too high and not too low, a snap of the finger produces the highest rotational accelerations observed in humans, even faster than the arm of a professional baseball pitcher. The results were published Nov. 17 in the Journal of the Royal Society Interface.
Assistant professor Saad Bhamla became more intrigued as he considered all the details that go into a finger snap.
“For the past few years, I’ve been fascinated with how we can snap our fingers,” Bhamla said. “It’s really an extraordinary physics puzzle right at our fingertips that hasn’t been investigated closely.”
In earlier work, Bhamla, Ilton, and other colleagues had developed a general framework for explaining the surprisingly powerful and ultrafast motions observed in living organisms. The framework seemed to naturally apply to the snap. It posits that organisms depend on the use of a spring and latching mechanism to store up energy, which they can then quickly release.
Watch the slow-motion finger snap in an embedded video clip. CEH has reported ultra-fast motions in other organisms, like the mantis shrimp’s club (13 June 2012), the chameleon tongue (8 March 2004) and the dracula ant’s pincers (15 Dec 2018). Here’s one right at our fingertips, and scientists hadn’t thought it about it much before. The team determined that skin friction is a key aspect of a finger snap, more than the spring-and-latch mechanism.
For an ordinary snap with bare fingers, the researchers measured maximal rotational velocities of 7,800 degrees per second and rotational accelerations of 1.6 million degrees per second squared. The rotational velocity is less than that measured for the fastest rotational motions observed in humans, which come from the arms of professional baseball players during the act of pitching. However, the snap acceleration is the fastest human angular acceleration yet measured, almost three times faster than the rotational acceleration of a professional baseball pitcher’s arm.
“When I first saw the data, I jumped out of my chair,” said Bhamla, who studies ultrafast motions in a variety of living systems, from single cells to insects. “The finger snap occurs in only seven milliseconds, more than twenty times faster than the blink of an eye, which takes more than 150 milliseconds.“
The finger snap cannot be done when wearing gloves, thimbles and other materials. Human skin is just right:
Surprisingly, increasing the friction of the fingertips with rubber coverings also reduced speed and acceleration. The researchers concluded that a Goldilocks zone of friction was necessary—too little friction and not enough energy was stored to power the snap, and too much friction led to energy dissipation as the fingers took longer to slide past each other, wasting the stored energy into heat.
Their measurements led to a mathematical model that can be useful for robot designers and for explaining other fast actions in the animal kingdom. Did evolution contribute to the study? Only with respect to assumption and futureware:
The researchers believe that the results open a variety of opportunities for future study, including understanding why humans snap at all, and if humans are the only primates to have evolved this physical ability.
The open-access paper in the Journal of the Royal Society Interface says nothing about Darwin, evolution, fitness, survival, or natural selection, but it does say something about design and complexity in artificial and natural systems:
Our work reveals how friction between surfaces can be harnessed as a tunable latch system and provides design insight towards the frictional complexity in many robotic and ultra-fast energy-release structures. [See another quotation below.]*
Acharya et al., “The ultrafast snap of a finger is mediated by skin friction,” Journal of the Royal Society Interface (17 Nov 2021), https://doi.org/10.1098/rsif.2021.0672.
See also last month’s report about how fingertips can detect single atom differences in surfaces (24 Dec 2021).
Impress your friends. Snap your fingers and tell them you just demonstrated intelligent design in action.
*Although the snapping behaviour of various biological organisms differs in terms of purpose and function, the mechanism behind snapping may be classified as a latch-mediated spring-actuated (LaMSA) system. A LaMSA system is one where energy is loaded in a mass–spring system by an external motor over a relatively long period of time before being held in place with a latch. Ultrafast movement is achieved when the latch is rapidly released, allowing the stored potential energy to explosively launch the mass in a relatively short period of time. Many biological organisms exploit this principle using biological springs and latches to achieve various functionalities. Some of these organisms include trap jaw ants, froghoppers, mantis shrimps, and the aforementioned snapping ant and termite species. While the roles of the latch geometry and spring structures in snap-based LaMSA systems have been explored, one key aspect of snapping systems that has yet to be explored in detail is that of friction. Friction has been hypothesized to play a key role in ensuring successful loading and unlatching of LaMSA systems but it has not been analysed.
In the case of the finger snap, we hypothesize that the arm muscles act as a motor to load potential energy in the tendons of the fingers and arms, which act as springs (figure 1b). The skin friction between the middle finger and thumb assists in the latching of the middle finger but also hinders unlatching and motion, playing a dual role in the dynamics of the snap. We begin analysis of the role of friction by experimentally varying the friction coefficient and compressibility of the materials covering the skin. We then develop a mathematical model that incorporates friction with a LaMSA system that can qualitatively capture the trends observed experimentally. Using this model, we reveal the role that friction plays in mediating the finger snap.