The arthropod head problem is a long-standing zoological dispute concerning the segmental composition of the heads of the various arthropod groups, and how they are evolutionarily related to each other. While the dispute has historically centered on the exact make-up of the insect head, it has been widened to include other living arthropods such as the crustaceans and chelicerates; and fossil forms, such as the many arthropods known from exceptionally preserved Cambrian faunas. While the topic has classically been based on insect embryology, in recent years a great deal of developmental molecular data has become available. Dozens of more or less distinct solutions to the problem, dating back to at least 1897, have been published, including several in the 2000s.
The arthropod head problem is popularly known as the "endless dispute", the title of a famous paper on the subject by Jacob G. Rempel in 1975, referring to its apparently intractable nature. Although some progress has been made since that time, the precise nature of especially the labrum and the pre-oral region of arthropods remain highly controversial.
Read more about Arthropod Head Problem: Background, Head Components, The Acron Concept, Molecular Development and The Arthropod Head Problem, Areas of Agreement, Areas of Disagreement, The Head of Onychophorans, Fossil Evidence, Assessment
Famous quotes containing the words head and/or problem:
“So long as you write what you wish to write, that is all that matters; and whether it matters for ages or only for hours, nobody can say. But to sacrifice a hair of the head of your vision, a shade of its colour, in deference to some Headmaster with a silver pot in his hand or to some professor with a measuring-rod up his sleeve, is the most abject treachery, and the sacrifice or wealth and chastity, which used to be said to be the greatest of human disasters, a mere flea-bite in comparison.”
—Virginia Woolf (1882–1941)
“If a problem is insoluble, it is Necessity. Leave it alone.”
—Mason Cooley (b. 1927)