תנא דבי רבי ישמעאל מפני מה אוזן כולה קשה והאליה רכה? שאם ישמע אדם דבר שאינו הגון יכוף אליה לתוכה
A Baraisa was taught in the academy of Rabbi Yishmael: Why is the [upper part of the] ear hard, but the earlobe is soft? So that if a person overhears something inappropriate, he will be able to bend the lobe in the ear canal [and block out the sound].
In 1979 Stephen J. Gould (d. 2002) and Richard Lewontin published a paper that would rock the world of evolutionary biology. They suggested that evolution by natural selection could not explain every feature of an organism. Sometimes, a feature is a non-functional byproduct of evolution, rather than a direct result of it. Gould and Lewontin give an example from the world of architecture, from the spandrels in the church of San Marco in Venice. A spandrel is a by-product, formed when a dome sits upon a rounded arch, shown in the pictures below.
These spaces - these spandrels- are accidental spaces, and yet are intricately decorated, as if they were deliberately designed to have been there in the first place. The design of these spaces "is so elaborate, harmonious, and purposeful," wrote Gould and Lewontin, that
we are tempted to view it as the starting point of any analysis, as the cause in some sense of the surrounding architecture. But this would invert the proper path of analysis. The system begins with an architectural constraint: the necessary four spandrels and their tapering triangular form.
Just as spandrels are accidental, some features of an organism are not the result of natural selection, but instead are "spandrel-like"in their origin. This was not to suggest that natural selection was incorrect; only that it was not a complete explanation of an organism's form and behavior.
So what are earlobes for? Indeed, are they for anything? Perhaps they are just spandrels, and can now happily be pierced and used to hold rings, studs, and other decorative ornaments. The Academy of Rabbi Yishmael disagree with this premise. Earlobes are not a spandrel-like by-product of evolution, but a designed part of our anatomy. And they are designed to act as an ear-plug when it would be best not to hear what is being said. The Chofetz Chaim, Rabbi Yisrael Meir Kagan (d.1933) wrote a famous work on the laws of gossip, called ספר שמירת הלשון. In it, he cited today's passage, and wrote that the earlobe is better at blocking the sound than is a finger. Try it. Is he right? (I did. He isn't.)
A: Ear of a treeshrew (Tupia) B: Ear of a new world monkey (Cebus) C: Primate (& Human) ear and its constituent parts. From Friderun Ankel-Simons, Primate Anatomy: An Introduction. Academic Press 2010.