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:
“A man whose mind feels that it is captive would prefer to blind himself to the fact. But if he hates falsehood, he will not do so; and in that case he will have to suffer a lot. He will beat his head against the wall until he faints. He will come to again and look with terror at the wall, until one day he begins afresh to beat his head against it; and once again he will faint. And so on endlessly and without hope. One day he will wake up on the other side of the wall.”
—Simone Weil (1909–1943)
“If a problem is insoluble, it is Necessity. Leave it alone.”
—Mason Cooley (b. 1927)