The morphological basis of the arm-to-wing transition

Human-powered flight has fascinated scientists, artists, and physicians for centuries. This history includes Abbas Ibn Firnas, a Spanish inventor who attempted the first well-documented human flight; Leonardo da Vinci and his flying machines; the Turkish inventor Hezarfen Ahmed Celebi; and the modern aeronautical pioneer Otto Lilienthal. These historic figures held in common their attempts to construct wings from man-made materials, and though their human-powered attempts at flight never came to fruition, the ideas and creative elements contained within their flying machines were essential to modern aeronautics. Since the time of these early pioneers, flight has continued to captivate humans, and recently, in a departure from creating wings from artificial elements, there has been discussion of using reconstructive surgery to fabricate human wings from human arms. This article is a descriptive study of how one might attempt such a reconstruction and in doing so calls upon essential evidence in the evolution of flight, an understanding of which is paramount to constructing human wings from arms. This includes a brief analysis and exploration of the anatomy of the 150-million-year-old fossil Archaeopteryx lithographica, with particular emphasis on the skeletal organization of this primitive bird's wing and wrist. Additionally, certain elements of the reconstruction must be drawn from an analysis of modern birds including a description of the specialized shoulder of the European starling, Sturnus vulgaris. With this anatomic description in tow, basic calculations regarding wing loading and allometry suggest that human wings would likely be nonfunctional. However, with the proper reconstructive balance between primitive (Archaeopteryx) and modern (Sturnus), and in attempting to integrate a careful analysis of bird anatomy with modern surgical techniques, the newly constructed human wings could function as cosmetic features simulating, for example, the nonfunctional wings of flightless birds.