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to evolutionary science. He also applied his scientific viewpoint to religion and ethics. Born May 4, 1825, into a large and not affluent family, Thomas Huxley had limited formal education. However, he read voraciously in many scholarly fields. He won a scholarship to study medicine at a hospital in London. At age 21, he became the assistant surgeon on HMS Rattlesnake, during a voyage to map the seas around Australia. Huxley collected and studied marine invertebrates (see invertebrates, evolution of). He became an expert in natural history the same way that Charles Darwin had on HMS Beagle and Joseph Hooker had on HMS Erebus. Huxley sent specimens and notes back to England, and when he returned in 1850 he found that these specimens and notes had made him a celebrity among English scientists, just as had happened with Darwin. He became acquainted with the leading natural scientists of his day (see Lyell, Charles; Hooker, Joseph Dalton). Huxley supported himself on a Navy stipend and by writing popular scientific articles. In 1854 he was hired by the School of Mines as a lecturer, a position he retained until retirement. Although he initially opposed evolution, especially the version proposed in the Vestiges of Creation (see Chambers, Robert), Huxley became convinced of evolution by reading the Origin of Species. His reaction to it was something like, “How stupid of me not to have thought of that.” Accustomed to lecturing and to popular writing, Huxley was ready to champion the theory that Charles Darwin was, due to a quiet nature and illness, reluctant to defend in public. Huxley’s most famous public moment was at the 1860 meeting of the British Association at Oxford University, where he debated Bishop Samuel Wiberforce, known as “Soapy Sam” because of the slippery debate maneuvers for which he was famous. Wilberforce knew little about science but had been coached by a famous paleontologist (see Owen, Richard). Wilberforce could not resist a jab at Huxley, asking him whether he traced his descent from the apes on his mother’s side or his father’s side. Huxley muttered, “The Lord hath delivered him into my hands,” referring to the harm Wilberforce had done to his own position by this statement. Huxley said, according to his own account, “If then the question is put to me would I rather have a miserable ape for a grandfather or a man highly endowed by nature and possessed of great means of influence and yet who employs these faculties and that influence for the mere purpose of introducing ridicule into a grave scientific discussion, I unhesitatingly affirm my preference for the ape.” The debate was just one part of a series of speeches, and its importance was dramatically exaggerated in 20th-century accounts. Wilberforce has been portrayed as a vicious attacker of evolutionary scientists, while in reality Darwin and Wilberforce were on reasonably good terms. Wilberforce referred to Darwin as “a capital fellow.” Furthermore, the main defense of Darwin’s theory at this meeting was made by Joseph Hooker, not Huxley. However, the audience saw this meeting as much Huxley, Thomas Henry 0 more than a scientific debate about zoology. The captain with whom Charles Darwin had sailed around the world walked around, holding up a Bible, saying, “The Book! The Book!” (see FitzRoy, Robert). Although he was a bulldog, Huxley was ready to admit mistakes and correct his viewpoints. He visited the United States to present lectures on the evolution of horses (see horses, evolution of). Fossil horses from Europe seemed to indicate that the modern horse genus, Equus, had evolved there. American paleontologist Othniel C. Marsh, however, showed Huxley evidence that horses had evolved in North America, and some of them had migrated to Europe. Huxley completely and immediately rewrote his speeches. In another instance, Huxley became convinced that the ocean floor was covered with a formless ooze that might have been an amoebalike primitive organism, which he called Bathybius haeckelii, named after another famous paleontologist (see Haeckel, Ernst). It turned out that the ooze was simply a chemical product of the reaction of mud with alcohol (used to preserve the specimens). Huxley also admitted this error. Huxley took Darwin’s theory further than Darwin had dared to propose in writing. Darwin wrote in the Origin of Species that “Much light will be thrown on the origin of man and his history.” In 1963 Huxley published Man’s Place in Nature, which explicitly presented the fossil evidence for the evolutionary place of humankind among the apes. Because little was known about human prehistory, aside from recently discovered skull fragments of Neandertals, most of Huxley’s evidence was to show the many anatomical similarities between humans and other primates. This brought him into conflict with Richard Owen, who insisted that the human brain had a structure, the hippocampus minor, that was not present in the brains of other primates. As more evidence became available about gorillas and chimpanzees, both recently discovered by Europeans, it became obvious that Owen was wrong. Especially in his later years, Huxley gave much attention to ethics. He had rejected organized religion, yet was unwilling to conclude that God could not exist. The term agnostic, referring to someone who believes the existence of God cannot be known, was Huxley’s invention. In Evolution and Ethics, Huxley claimed an evolutionary origin for human behavior but also noted that large brains give humans the ability to behave differently than other animals (see evolutionary ethics). In saying that good ethics consists of resisting rather than embracing the tendencies of evolution, he placed his philosophy firmly against those of the social Darwinists (see Spencer, Herbert) and the eugenicists (see eugenics). Huxley’s passion for science and scholarship established a tradition in his family. One of his grandchildren (see Huxley, Julian) was one of the scientists who established the modern synthesis of evolution; another grandson, Andrew Huxley, won the Nobel Prize for his study of nerve impulses and muscle contraction; another grandson, Aldous Huxley, was a writer, most famous for Brave New World. Thomas Henry Huxley died June 29, 1895.
0 hybridization Examples of Interspecific Crosses in Animals and Plants (within Genera) Parent Parent Hybrid Jackass (Equus asinus) Mare (E. caballus) Mule Jenny (Equus asinus) Stallion (E. caballus) Hinny Male tiger (Panthera tigris) Lioness (P. leo) Tigon Tigress (Panthera tigris) Male lion (P. leo) Liger Leopard (Panthera pardus) Lion (P. leo) Leapon Bluegill (Lepomis macrochirus) Green sunfish (L. cyanellis) Hybrid sunfish Larkspur (Delphinium hesperium) Larkspur (D. recurvatum) D. gypsophilium Penstemon (Penstemon centrantifolius) Penstemon (P. grinnellii) P. spectabilis Japanese larch (Larix kaempferi) European larch (L. decidua) Dunkeld larch Magnolia (Magnolia denudata) Magnolia (M. liliiflora) M. soulangeana American sycamore (Platanus occidentalis) European sycamore (P. orientalis) London plane Elm (Ulmus glabra) Elm (U. minor) U. × hollandica Wingnut (Pterocarya fraxinifolia) Wingnut (P. stenoptera) P. × rehderiana Linden (Tilia cordata) Linden (T. platyphyllos) T. × europaea White poplar (Populus alba) Aspen (P. tremula) Gray poplar Arbutus (Arbutus unedo) Arbutus (A. andrachne) A. × andrachnoides Horse chestnut (Aesculus hippocastanum) Horse chestnut (A. pavia) A. × carnea Further Reading Gould, Stephen Jay. “Bathybius and Eozoon.” Chap. 23 in The Panda’s Thumb: More Reflections in Natural History. New York: Norton, 1980. Huxley, Thomas Henry. Man’s Place in Nature. London: Williams and Norgate, 1863. Reprinted with Introduction by Stephen Jay Gould. New York: Random House, 2001. ———. Evolution and Ethics and Other Essays. New York: Appleton, 1898. Irvine, William. Apes, Angels, and Victorians: Darwin, Huxley, and Evolution. New York: McGraw-Hill, 1955. hybridization Hybridization is the crossbreeding between different species of organisms. The term hybrid has also been used for crosses between varieties within a species (as in hybrid corn within the species Zea mays). The offspring with many heterozygous traits (see Mendelian genetics) produced by intraspecific crosses may produce hybrid vigor. However, evolutionary biologists generally restrict the term hybrid to crosses between species. According to the biological species concept (see speciation), distinct species do not normally produce fertile offspring. This is most obviously the case with crosses between donkeys and horses, resulting in mules, which are very strong but are sterile. Crosses between lions and tigers (such as ligers and tigons) have also occurred in zoos (see table above). It is possible that the elusive “marozi” of Africa is a naturally occurring hybrid between leopards and lions. Many other hybridizations are possible between feline species. While even fertile hybrids may be produced between different feline species, they are rare in the wild, which suggests that either the species nearly always avoid one another when mating and/ or the hybrid offspring have reduced health or fertility (see isolating mechanisms). Hybrids have also been reported between species of fishes. The bluegill (Lepomis macrochirus) can cross with the green sunfish (L. cyanellis). Intergeneric hybrids, such as between pumas and leopards, and between dromedaries and llamas, have also been reported (see table on page 203). When a scientific name is assigned to a hybrid species, an × often precedes the specific name. Hybrids between plant species in the same genus occur more often than hybrids between animal species. Hybridization in plants is not usually successful, for at least two reasons: • The two species may pollinate at different times of the year. Among the oaks of North America, hybridization can occur among species of white oaks, and among species of red and black oaks (genus Quercus). However, all of the white oaks have acorns that mature during the same year, while most of the red and black oaks have acorns that mature the following year, after pollination. Because of these differences in reproductive pattern, hybrids between the two groups of oaks cannot occur. Hybridization between species of pine (the bishop pine Pinus muricata and the Monterey pine P. radiata), and between species of alders (the seaside alder Alnus maritima and the hazel alder A. serrulata) cannot occur, as pollination occurs at different times of the year. • The two species may specialize on different habitats. Hybrids can and do occur within the white oak and within the black-red oak groups. Hybridization usually produces solitary unusual trees or scattered clusters with characteristics intermediate between the species. Occasionally there will be a widespread zone of hybridization between oak species. The oak species remain distinct probably because the hybrids are not adapted to either of the habitats of the parents. For example, even though post oak (Q. stellata) and bur oak (Q. macrocarpa) are both white oaks, hybrids between them would probably not grow well under natural
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ENCYCLOPEDIA OF Evolution
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Encyclopedia of Evolution Copyright
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Contents Foreword ix Acknowledgment
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Foreword The theory and facts of ev
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IntroduCtIon What you do not know a
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other issues coming along with it.
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adaptation Adaptation is the fit of
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from the allometric patterns of gro
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considered as an example. (The taxo
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English) were a resounding success,
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Some Centers of the Evolution of Ag
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helps the DNA insert into the host
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Even within a single patient, HIV e
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then into the insect body; carbon d
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chromosomes (they are diploid) whil
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genetic basis. About 35,000 years a
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emained dormant and sprouted after
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Further Reading Wise, Steven M. Rat
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Because the DNA of many archaebacte
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Koi and goldfish have been bred tha
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Barringer Crater, Arizona, was form
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y a silent wall of darkness advanci
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Skeleton of “Lucy,” the Austral
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Further Reading Alemseged, Zerxenay
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acteria, evolution of Examples of t
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0 Bates, Henry Walter advantage. Th
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ehavior, evolution of In another sp
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ig bang make nests with horizontal
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iodiversity How Much Do Genes Contr
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iodiversity Biodiversity (as indica
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0 biogeography Another problem with
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iogeography Biogeography of Selecte
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iogeography their species through d
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iology design) or adaptation to the
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iology D. Response to environment.
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0 birds, evolution of • The foot.
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irds, evolution of • doves and pi
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Burgess shale early career. By heat
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Burgess shale jointed legs, Anomalo
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Cambrian period occurred when anima
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0 Cenozoic era opens the way to an
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Chicxulub Pritchard, J., and Dolph
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cladistics The above examples used
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coevolution descent, and that scien
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coevolution Coevolution of Organism
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0 coevolution What Are the “Ghost
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coevolution What Are the “Ghosts
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commensalism Wilson, Michael. Micro
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continental drift was an animal tha
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continental drift During geological
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0 convergence bee-pollinated flower
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convergence Both birds and bats hav
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creationism explained these observa
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creationism used to justify militar
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creationism • In the early 21st c
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00 Cretaceous period however, other
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0 Cro-Magnon evolution had occurred
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0 Cro-Magnon areas, perforated shel
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0 Cuvier, Georges Cuvier held stron
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0 Darwin Awards Darwin Awards “Th
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0 Darwin, Charles forever. It would
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Darwin, Charles and animals did hav
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Darwin’s finches has its own uniq
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Dawkins, Richard ate the pulp. More
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developmental evolution Part II. In
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0 Devonian period gene from an inve
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dinosaurs what DeVries thought were
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diseases, evolution of • Thyreoph
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disjunct species have happened? Som
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DNA (evidence for evolution) genes,
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0 DNA (evidence for evolution) seco
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DNA (raw material of evolution) DNA
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DNA (raw material of evolution) The
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Dobzhansky, Theodosius Mice have tw
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duplication, gene prominent brow ri
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0 ecology Second, organisms can con
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Eldredge, Niles they possess no str
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eugenics grieving, or experiencing
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eugenics because government officia
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eukaryotes, evolution of of the sor
Page 169 and 170: 0 Eve, mitochondrial within cells,
Page 171 and 172: evolutionary ethics the ability to
Page 173 and 174: evolutionary ethics Can an Evolutio
Page 175 and 176: evolutionary medicine Can an Evolut
Page 177 and 178: evolutionary medicine variable in t
Page 179 and 180: 0 extinction past (a genetic bottle
Page 181 and 182: fishes, evolution of his obvious vi
Page 183 and 184: Flores Island people Christopher St
Page 185 and 186: fossils and fossilization The grain
Page 187 and 188: founder effect Further Reading Fort
Page 189 and 190: 0 Gaia hypothesis nitrogen oxide (N
Page 191 and 192: Galton, Francis constituted a premi
Page 193 and 194: gene pool Cocos Island is too small
Page 195 and 196: Gould, Stephen Jay animals, and the
Page 197 and 198: Gray, Asa he had long accepted Lyel
Page 199 and 200: 0 group selection used the carbon t
Page 201 and 202: gymnosperms, evolution of began per
Page 204 and 205: Haeckel, Ernst (1834-1919) German E
Page 206 and 207: The initial divergence between homi
Page 208 and 209: Although Homo ergaster, the presume
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Page 212 and 213: Selected Examples of Homo heidelber
Page 214 and 215: sunlight of tropical regions, and t
Page 216 and 217: win, Hooker could not pay his own w
Page 218 and 219: gene transfer from a bacterium, per
Page 222 and 223: Examples of Intergeneric Crosses Re
Page 224 and 225: ice ages The term ice ages usually
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Page 228 and 229: migrated into Europe and displaced
Page 230 and 231: ence their intelligence. There is a
Page 232 and 233: This does not mean that all of the
Page 234 and 235: e exactly the right ones. Bovine in
Page 236 and 237: Van Till, Howard J. “E. coli at t
Page 238 and 239: food particles with whiplike struct
Page 240 and 241: would readily interbreed and produc
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Page 244 and 245: isotopes When evaporation from the
Page 246: Java man See Homo erectus. Johanson
Page 249 and 250: 0 Kenyanthropus chemist Henri Becqu
Page 251 and 252: language, evolution of is not consi
Page 253 and 254: language, evolution of Italian, Por
Page 255 and 256: Lascaux caves Some of the original
Page 257 and 258: Leakey, Richard Richard Leakey, in
Page 259 and 260: 0 life history, evolution of it inv
Page 261 and 262: life history, evolution of is: sele
Page 263 and 264: life history, evolution of Why Do H
Page 265 and 266: life history, evolution of Why Do H
Page 267 and 268: Linnaean system The tree of life us
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Lysenkoism about evolution. When Da
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Malthus, Thomas intelligent design)
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mammals, evolution of the reptilian
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markers another precocious and crea
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0 Mars, life on • The spacecraft
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Maynard Smith, John producing a 200
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meiosis Zoology. He became director
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Mendel, Gregor of the fertilized eg
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Mendelian genetics an American gene
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0 Mendelian genetics the environmen
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microevolution Stanley Miller did o
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missing links Batesian mimicry. Nam
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mitochondrial DNA Hominin skulls ha
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molecular clock these scientists di
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0 mutualism function of the protein
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natural selection Fact 1. Populatio
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natural selection Three types of na
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natural theology different kinds of
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Neandertals different species of hu
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0 Neolithic Neandertals lived short
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new synthesis In contrast to progen
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noncoding DNA Some regulatory molec
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origin of life they refer to life t
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origin of life Are Humans Alone in
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00 origin of life It is often said
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0 Origin of Species (book) ribose);
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0 Orrorin ———. On the Origin
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0 Paley, William in the Chordata) e
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0 peppered moths There remained som
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0 Permian extinction produced in la
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Permian period upon the exploitatio
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Piltdown man found in slightly diff
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plate tectonics The Earth’s surfa
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population Percent of Mammal Genera
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0 population genetics Vandermeer, J
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population genetics If allele A is
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Precambrian time at least some gene
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progress, concept of arboreal prima
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promoter Each chromosome contains t
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0 punctuated equilibria and persist
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punctuated equilibria Gradualism wa
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Quaternary period epoch of the Quat
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ecapitulation would cause some of t
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eligion, evolution of pathogens nev
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0 reproductive systems Catkins of m
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eproductive systems Scobell has inv
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eproductive systems fact, there is
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eptiles, evolution of Blanckenhorn,
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esistance, evolution of ineffective
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0 respiration, evolution of There i
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Sagan, Carl (1934-1996) American As
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tain features are universally recog
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The testing of hypotheses accumulat
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the results are sufficiently intere
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een wrong: His hypothesis of the co
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Comparison of Inherit the Wind with
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and others form more complex struct
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endonuclease gene is then used as a
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e able to do the same thing. Second
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mosomes come in groups of five rath
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eliminated—that is, if sexual rec
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one, free of parasites, is likely t
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nesses of resource acquisition and
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Zahavi, Amotz. The Handicap Princip
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and it is not happening extensively
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this, too, is a genetically based u
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monkeyflowers of the genus Mimulus)
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Further Reading Abrahamson, Warren
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comes from the unfertilized egg, ra
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of the bacteriophages. Therefore, h
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technology Technological and Cultur
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thermodynamics • Plants. The flow
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thermodynamics return to their orig
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00 Triassic period more resulting l
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unconformity An unconformity is a g
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sissippi River is getting shorter e
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ago. This was the birth of the Sun.
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0 vestigial characteristics algae.
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Wallace, Alfred Russel (1823-1913)
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genetic inferiority of the lower cl
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that point onward he questioned the
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Carl R. Woese pioneered the use of
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Darwin’s “One LOng argument”:
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the young seedlings must compete wi
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Traits can reappear after even hund
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ated: It has been an advantage in o
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chapter 10. On the imperfection of
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out in competition with the species
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languages. Linguists classify all R
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My theory has been much maligned. T
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Index Note: Boldface page numbers i
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asexual propagation 370-371 Ashfall
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Bryan, William Jennings creationism
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ird evolution 62-63 cladistics 72-7
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divergence molecular clock 278-279
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extinction 159-160. See also mass e
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Gondwana (Gondwanaland) 68, 84, 86,
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Huxley, Julian S. 200 eugenics 146
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Mendelian genetics and 268 Spencer,
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Origin of Species (Darwin) 433-434
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ocean currents 179, 207 Oceanian re
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polar cells 368 Polkinghorne, John
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Sanger, Frederick 55 Sanger, Margar
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spores 264, 370 spotted hyena (Croc
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useless characteristics 409 Ussher,
show all

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