Bully for Brontosaurus: Reflections in Natural History by Gould Stephen Jay

Author:Gould, Stephen Jay [Gould, Stephen Jay]
Language: eng
Format: epub
Publisher: Norton
Published: 2010-11-29T05:00:00+00:00

Man…has escaped the need for specialization because his evolution has been projected outside himself into an evolution of tools and weapons. Other animals in need of tools and weapons must evolve them from their own bodily parts; we therefore frequently find a specialized adaptation to environmental needs grafted on to primitive simplicity of structure.

You can’t win in such a world. You are either primitive prima facie or specialized as a result of lurking and implicit simplicity! From such a Catch-22, platypuses can only be rescued by new concepts, not additional observations.

As a supreme irony, and ultimate defense of adaptation versus ineptitude, the structure that built the myth of primitivity—the misnamed duckbill itself—represents the platypus’s finest special invention. The platypus bill is not a homologue of any feature in birds. It is a novel structure, uniquely evolved by monotremes (the echidna carries a different version as its long and pointed snout). The bill is not simply a hard, inert horny structure. Soft skin covers the firm substrate, and this skin houses a remarkable array of sensory organs. In fact, and strange to tell, the platypus, when under water, shuts down all its other sensory systems and relies entirely upon its bill to locate obstacles and food. Flaps of skin cover tiny eyes and nonpinnate ears when a platypus dives, while a pair of valves closes off the nostrils under water.

E. Home, in the first monograph of platypus anatomy (1802), made an astute observation that correctly identified the bill as a complex and vital sensory organ. He dissected the cranial nerves and found almost rudimentary olfactory and optic members but a remarkably developed trigeminal, carrying information from the face to the brain. With great insight, Home compared the platypus bill to a human hand in function and subtlety. (Home never saw a live platypus and worked only by inference from anatomy.) He wrote:

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