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116-423: Ontogeny (also ontogenesis ) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny , which refers to

232-591: A Lamarckian heredity, made unscientific pronouncements on agriculture, used his influence to destroy classical genetics in Russia and to move genuine scientists from their posts. In 1940, the leading botanical geneticist Nikolai Vavilov was arrested, and Lysenko replaced him as director of the Institute of Genetics. In 1941, Vavilov was tried, found guilty of 'sabotage' and sentenced to death. Reprieved, he died in jail of malnutrition in 1943. Lysenko's machinations were

348-492: A zygote changes the surrounding membrane to not allow any more sperm to penetrate the egg, so multiple fertilizations can be prevented. Fusion of a zygote also activates the egg so it can begin undergoing cell division. Each animal species might not have specifically a sperm and an egg, but two gametes that contain half of the species' typical genetic material and the membranes of these gametes fuse to start creating an offspring. Not long after successful fertilization by sperm,

464-601: A Soviet mental hospital, and Vavilov's reputation was posthumously restored in 1955. In the 1950s Huxley played a role in bringing to the English-speaking public the work of the French Jesuit - palaeontologist Pierre Teilhard de Chardin , who he believed had been unfairly treated by the Catholic and Jesuit hierarchy. Both men believed in evolution, but differed in its interpretation as Teilhard de Chardin

580-447: A blastocyst. Other species such as sea stars , frogs , chicks , and mice have all the same structures in this stage, yet the orientation of these features differs, plus these species have additional types of cells in this stage. After blastulation, the single-layered blastula expands and reorganizes into multiple layers, a gastrula (seen in the figure to the right). Reptiles , birds and mammals are triploblastic organisms, meaning

696-486: A butterfly. Adulthood is the stage of when physical and intellectual maturity have been achieved and this differs between species. In humans , adulthood is thought to be around 20 or 21 years old and is the longest stage of life, but in all species it ends with death. In dogs , small breeds (e.g., Yorkshire Terrier , Chihuahua , Cocker Spaniel , etc.) physically mature faster than large breeds (e.g., Saint Bernard , Great Dane , Golden Retriever , etc.), so adulthood

812-420: A cavity and fuse with the central canal of the neural tube. Secondary neurulation occurs in the small region starting at the spinal tail bud up to the posterior neuropore, which is the open neural folds near the tail region that don't close through primary neurulation. As canalization progresses over the next few weeks, neurons and ependymal cells (cells that create cerebral spinal fluid) differentiate to become

928-763: A close association with the British rationalist and secular humanist movements. He was an Honorary Associate of the Rationalist Press Association from 1927 until his death, and on the formation of the British Humanist Association in 1963 became its first President, to be succeeded by A. J. Ayer in 1965. He was also closely involved with the International Humanist and Ethical Union . Many of Huxley's books address humanist themes. In 1962 Huxley accepted

1044-451: A cluster of nerve bodies positioned along the spinal cord at the dorsal and ventral roots of a spinal nerve, which is a pair of nerves that correspond to a vertebra of the spine. In secondary neurulation, caudal and sacral regions of the spine are formed after primary neurulation is finished. This process initiates once primary neurulation is finished and the posterior neuropore closes, so the tail bud can proliferate and condense, then create

1160-569: A few enzymes and molecules like those in living organisms, they have no metabolism of their own; they cannot synthesize the organic compounds from which they are formed. In this sense, they are similar to inanimate matter. Viruses have their own genes , and they evolve . Thus, an argument that viruses should be classed as living organisms is their ability to undergo evolution and replicate through self-assembly. However, some scientists argue that viruses neither evolve nor self-reproduce. Instead, viruses are evolved by their host cells, meaning that there

1276-636: A fortnight he dashed off a 60-page booklet on the purpose and philosophy of UNESCO, eventually printed and issued as an official document. There were, however, many conservative opponents of his scientific humanism. His idea of restraining population growth with birth control was anathema to both the Catholic Church and the Comintern / Cominform . In its first few years UNESCO was dynamic and broke new ground; since Huxley it has become larger, more bureaucratic and stable. The personal and social side of

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1392-398: A group could be viewed as a superorganism , optimized by group adaptation . Another view is that attributes like autonomy, genetic homogeneity and genetic uniqueness should be examined separately rather than demanding that an organism should have all of them; if so, there are multiple dimensions to biological individuality, resulting in several types of organism. A unicellular organism

1508-695: A half-salary cut at the start of the war, and no salary at all whilst he was in America, the council's action was widely read as a personal attack on Huxley. A public controversy ensued, but eventually the Council got its way. In 1943 he was asked by the British government to join the Colonial Commission on Higher Education. The commission's remit was to survey the West African Commonwealth countries for suitable locations for

1624-427: A hollow sphere of cells, which is a blastula . These outer cells form a single epithelial layer, the blastoderm, that essentially encases the fluid-filled inside that is the blastocoel. The figure to the right shows the basic process that is modified in different species. Blastulation differs slightly in different species, but in mammals, the eight-cell stage embryo forms into a slightly different type of blastula, called

1740-401: A larval form of an animal is the caterpillar of butterflies and moths . Caterpillars keep growing and feeding in order for enough energy during the pupal stage, when necessary body parts for metamorphosis are grown. The juvenile phase is different in plants and animals, but in plants juvenility is an early phase of plant growth in which plants can't flower. In animals, the juvenile stage

1856-640: A lifelong internationalist with a concern for education, got involved in the creation of the United Nations Educational, Scientific and Cultural Organization ( UNESCO ), and became the organization's first director-general in 1946. His term of office, six years in the Charter, was cut down to two years at the behest of the American delegation. The reasons are not known for sure, but his left-wing tendencies and humanism were likely factors. In

1972-420: A new method of evolution: the transmission of organized experience by way of tradition, which… largely overrides the automatic process of natural selection as the agent of change." Both Huxley and his grandfather gave Romanes Lectures on the possible connection between evolution and ethics (see evolutionary ethics ). Huxley's views on God could be described as being that of an agnostic atheist . Huxley had

2088-489: A parallel manner but branch off to develop more specific features for the organism such as hooves, a tail, or ears. In developing vertebrate offspring, a neural tube is formed through either primary or secondary neurulation . Some species develop their spine and nervous system using both primary and secondary neurulation, while others use only primary or secondary neurulation. In human fetal development, primary neurulation occurs during weeks 3 and 4 of gestation to develop

2204-500: A process of recombination (a primitive form of sexual interaction ). Julian Huxley Sir Julian Sorell Huxley FRS (22 June 1887 – 14 February 1975) was an English evolutionary biologist , eugenicist , and internationalist . He was a proponent of natural selection , and a leading figure in the mid-twentieth century modern synthesis . He was secretary of the Zoological Society of London (1935–1942),

2320-670: A scholarship in Zoology to Balliol College, Oxford and took up the place in 1906 after spending the summer in Germany. He developed a particular interest in embryology and protozoa and developed a friendship with the ornithologist William Warde Fowler . In the autumn term of his final year, 1908, his mother died from cancer at the age of 46. In his final year he won the Newdigate Prize for his poem "Holyrood". In 1909 he graduated with first class honours, and spent that July at

2436-676: A series of sub-species with continuous change in characters over a geographical area. The classic example of a cline is the circle of subspecies of the gull Larus round the Arctic zone. This cline is an example of a ring species . Some of Huxley's last contributions to the evolutionary synthesis were on the subject of ecological genetics . He noted how widespread polymorphism is in nature, with visible morphism much more prevalent in some groups than others. The immense diversity of colour and pattern in small bivalve molluscs, brittlestars, sea-anemones, tubicular polychaetes and various grasshoppers

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2552-454: A slightly different journey through these stages, since some stages might be shorter or longer when compared to other species, and where the offspring develops is different for each animal type (e.g., in a hard egg shell, uterus, soft egg shell, on a plant leaf, etc.). In humans, the process of fetal development starts after sperm fertilizes an egg and they fuse together, kickstarting embryonic development . The fusion of egg and sperm into

2668-411: Is metamorphosis . For example, amphibian tadpoles have a maturation of liver enzymes, hemoglobin , and eye pigments, in addition to their nervous, digestive, and reproductive systems being remodeled. In all species, molting and juvenile hormones appear to regulate these changes. The figure to the right shows the stages of life in butterflies and their metamorphosis transforms the caterpillar into

2784-445: Is a microorganism such as a protist , bacterium , or archaean , composed of a single cell , which may contain functional structures called organelles . A multicellular organism such as an animal , plant , fungus , or alga is composed of many cells, often specialised. A colonial organism such as a siphonophore is a being which functions as an individual but is composed of communicating individuals. A superorganism

2900-401: Is a teleonomic or goal-seeking behaviour that enables them to correct errors of many kinds so as to achieve whatever result they are designed for. Such behaviour is reminiscent of intelligent action by organisms; intelligence is seen as an embodied form of cognition . All organisms that exist today possess a self-replicating informational molecule (genome), and such an informational molecule

3016-741: Is a colony, such as of ants , consisting of many individuals working together as a single functional or social unit . A mutualism is a partnership of two or more species which each provide some of the needs of the other. A lichen consists of fungi and algae or cyanobacteria , with a bacterial microbiome ; together, they are able to flourish as a kind of organism, the components having different functions, in habitats such as dry rocks where neither could grow alone. The evolutionary biologists David Queller and Joan Strassmann state that "organismality" has evolved socially, as groups of simpler units (from cells upwards) came to cooperate without conflicts. They propose that cooperation should be used as

3132-535: Is an argument for viewing viruses as cellular organisms. Some researchers perceive viruses not as virions alone, which they believe are just spores of an organism, but as a virocell - an ontologically mature viral organism that has cellular structure. Such virus is a result of infection of a cell and shows all major physiological properties of other organisms: metabolism , growth, and reproduction , therefore, life in its effective presence. The philosopher Jack A. Wilson examines some boundary cases to demonstrate that

3248-415: Is discontinuous and can start at different points along the cranial-caudal axis necessary for it to close. After the neural crest closes, the neural crest cells and ectoderm cells separate and the ectoderm becomes the epidermis surrounding this complex. The neural crest cells differentiate to become components of most of the peripheral nervous system in animals. Next, the notochord degenerates to become only

3364-568: Is inadequate in biology; that the concept of individuality is problematic; and from a philosophical point of view, question whether such a definition is necessary. Problematic cases include colonial organisms : for instance, a colony of eusocial insects fulfills criteria such as adaptive organisation and germ-soma specialisation. If so, the same argument, or a criterion of high co-operation and low conflict, would include some mutualistic (e.g. lichens) and sexual partnerships (e.g. anglerfish ) as organisms. If group selection occurs, then

3480-472: Is likely intrinsic to life. Thus, the earliest organisms also presumably possessed a self-replicating informational molecule ( genome ), perhaps RNA or an informational molecule more primitive than RNA. The specific nucleotide sequences in all currently extant organisms contain information that functions to promote survival, reproduction , and the ability to acquire resources necessary for reproduction, and sequences with such functions probably emerged early in

3596-522: Is most commonly found in social mammals, such as wild dogs , monkeys , apes , lions , wolves , and more. In humans, puberty marks the end of this stage and adolescence follows. Some species begin puberty and reproduction before the juvenile stage is over, such as in female non-human primates. The larval and pupal stages can be seen in the figure to the right. The process of an organism's body undergoing structural and physical changes after birth or hatching to become suitable for its adult environment

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3712-426: Is no basic cleavage between science and religion;… I believe that [a] drastic reorganization of our pattern of religious thought is now becoming necessary, from a god-centered to an evolutionary-centred pattern." Some believe the appropriate label for these views is religious naturalism . Many people assert that this abandonment of the god hypothesis means the abandonment of all religion and all moral sanctions. This

3828-422: Is perhaps maintained by making recognition by predators more difficult. Although Huxley believed that on a broad view evolution led to advances in organisation, he rejected classical Aristotelian teleology : "The ordinary man, or at least the ordinary poet, philosopher and theologian, always was anxious to find purpose in the evolutionary process. I believe this reasoning to be totally false.". Huxley coined

3944-422: Is reached anywhere from 12 to 24 months or 1 to 2 years. In contrast, many insect species have long larval stages and the adult stage is only for reproduction. The silkworm moths don't have mouthparts and don't feed, so they have to consume enough food during the larval stage for energy to survive and mate. Senescence is when cells stop dividing but don't die, but these cells can build up and cause problems in

4060-469: Is unquestionable. Their lesser weight in Huxley's citations was caused by the early publication date of his book. Huxley's book is not strong in palaeontology, which illustrates perfectly why Simpson's later works were such an important contribution. Huxley coined the terms the new synthesis and evolutionary synthesis ; he also invented the term cline in 1938 to refer to species whose members fall into

4176-556: Is used in anthropology as "the process through which each of us embodies the history of our own making". The word ontogeny comes from the Greek on meaning a being, individual; and existence, and from the suffix -geny from the Greek - geniea , meaning genesis, origin, and mode of production. The term ontogeny was coined by Ernst Haeckel , a German zoologist and evolutionist in the 1860s. Haeckel, born in Germany on February 16, 1834,

4292-651: The American Humanist Association 's annual "Humanist of the Year" award. Huxley also presided over the founding Congress of the International Humanist and Ethical Union and served with John Dewey , Albert Einstein and Thomas Mann on the founding advisory board of the First Humanist Society of New York. Huxley wrote that "There is no separate supernatural realm: all phenomena are part of one natural process of evolution. There

4408-494: The University of Oxford , and started on the systematic observation of the courtship habits of water birds, such as the common redshank (a wader) and grebes (which are divers). Bird watching in childhood had given Huxley his interest in ornithology , and he helped devise systems for the surveying and conservation of birds. His particular interest was bird behaviour, especially the courtship of water birds. His 1914 paper on

4524-696: The battle of the Somme on the Western Front . The ecological geneticist E. B. Ford always remembered his openness and encouragement at the start of his career. In 1925 Huxley moved to King's College London as Professor of Zoology , but in 1927, to the amazement of his colleagues and on the prodding of H. G. Wells whom he had promised 1,000 words a day, he resigned his chair to work full-time with Wells and his son G. P. Wells on The Science of Life ( see below ). For some time Huxley retained his room at King's College, continuing as Honorary Lecturer in

4640-559: The ectoderm is the outer layer of cells that become the epidermis and hair while being the precursor to the mammary glands, central nervous system , and the peripheral nervous systems . The figure above shows how the development of a pig , cow , rabbit , and human offspring are similar when compared to one another. This figure shows how the germ layers can become different organs and tissues in evolutionarily higher life-forms and how these species essentially develop very similarly. Additionally, it shows how multiple species develop in

4756-955: The evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes (see evolutionary developmental biology and recapitulation theory ), individual organisms develop (ontogeny), while species evolve (phylogeny). Ontogeny, embryology and developmental biology are closely related studies and those terms are sometimes used interchangeably. Aspects of ontogeny are morphogenesis ,

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4872-570: The great crested grebe , later published as a book, was a landmark in avian ethology ; his invention of vivid labels for the rituals (such as 'penguin dance', 'plesiosaurus race' etc.) made the ideas memorable and interesting to the general reader. In 1912 Huxley was asked by Edgar Odell Lovett to set up the Department of Biology at the newly created Rice Institute (now Rice University ) in Houston , Texas, which he accepted, planning to start

4988-400: The nucleus pulposus of the intervertebral discs and the mesoderm cells differentiate to become the somites and skeletal muscle later on. Also during this stage, the neural crest cells become the spinal ganglions, which function as the brain in organisms like earthworms and arthropods . In more advanced organisms like amphibians , birds and mammals ; the spinal ganglions consists of

5104-642: The "defining trait" of an organism. Samuel Díaz‐Muñoz and colleagues (2016) accept Queller and Strassmann's view that organismality can be measured wholly by degrees of cooperation and of conflict. They state that this situates organisms in evolutionary time, so that organismality is context dependent. They suggest that highly integrated life forms, which are not context dependent, may evolve through context-dependent stages towards complete unification. Viruses are not typically considered to be organisms, because they are incapable of autonomous reproduction , growth , metabolism , or homeostasis . Although viruses have

5220-473: The "defining trait" of an organism. This would treat many types of collaboration, including the fungus / alga partnership of different species in a lichen , or the permanent sexual partnership of an anglerfish , as an organism. The term "organism" (from the Ancient Greek ὀργανισμός , derived from órganon , meaning instrument, implement, tool, organ of sense or apprehension) first appeared in

5336-566: The 1930s Huxley visited Kenya and other East African countries to see the conservation work, including the creation of national parks . In 1933, he was one of eleven people involved in the appeal that led to the foundation of the British Trust for Ornithology (BTO), an organisation for the study of birds in the British Isles. From 1933 to 1938 he was a member of the committee for Lord Hailey's African Survey. In 1935 Huxley

5452-457: The English language in the 1660s with the now-obsolete meaning of an organic structure or organization. It is related to the verb "organize". In his 1790 Critique of Judgment , Immanuel Kant defined an organism as "both an organized and a self-organizing being". Among the criteria that have been proposed for being an organism are: Other scientists think that the concept of the organism

5568-589: The Huxley family grave in Watts Cemetery, Compton. Huxley grew up at the family home in Shackleford , Surrey , England, where he showed an early interest in nature, as he was given lessons by his grandfather, Thomas Henry Huxley . When he heard his grandfather talking at dinner about the lack of parental care in fish, Julian piped up with "What about the stickleback , Gran'pater?". His grandfather also took him to visit Joseph Dalton Hooker at Kew. At

5684-605: The US, without success. As the 1930s started, Huxley travelled widely and took part in a variety of activities which were partly scientific and partly political. In 1931 Huxley visited the USSR at the invitation of Intourist , where initially he admired the results of social and economic planning on a large scale. Later, back in the United Kingdom, he became a founding member of the think tank Political and Economic Planning . In

5800-725: The United States should join World War II : a few weeks later came the attack on Pearl Harbor . When the US joined the war, he found it difficult to get a passage back to the UK, and his lecture tour was extended. The Council of the Zoological Society—"a curious assemblage… of wealthy amateurs, self-perpetuating and autocratic" —uneasy with their secretary, used this as an opportunity to remove him. This they did by abolishing his post "to save expenses". Since Huxley had taken

5916-512: The United States. He was therefore able to learn from and influence other scientists, naturalists and administrators. In the US he was able to meet other evolutionists at a critical time in the reassessment of natural selection . In Africa he was able to influence colonial administrators about education and wildlife conservation . In Europe, through UNESCO , he was at the centre of the post- World War II revival of education. In Russia, however, his experiences were mixed. His initially favourable view

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6032-560: The Zoo Magazine. Fellows and their guests had the privilege of free entry on Sundays, a closed day to the general public. Today, that would be unthinkable, and Sundays are now open to the public. Huxley's mild suggestion (that the guests should pay) encroached on territory the Fellows thought was theirs by right. In 1941 Huxley was invited to the United States on a lecturing tour, and generated some controversy by saying that he thought

6148-724: The Zoology Department, and from 1927 to 1931 he was also Fullerian Professor of Physiology at the Royal Institution , where he gave an annual lectures series, but this marked the end of his life as a university academic. In 1929, after finishing work on The Science of Life , Huxley visited East Africa to advise the Colonial Office on education in British East Africa (for the most part Kenya , Uganda and Tanganyika ). He discovered that

6264-399: The age of thirteen Huxley attended Eton College as a King's Scholar , and continued to develop scientific interests; his grandfather had influenced the school to build science laboratories much earlier. At Eton he developed an interest in ornithology, guided by science master W. D. "Piggy" Hill. "Piggy was a genius as a teacher ... I have always been grateful to him." In 1905 Huxley won

6380-408: The biologists and Nobel laureates Konrad Lorenz and Niko Tinbergen , and taught and encouraged many others. In general, he was more of an all-round naturalist than his famous grandfather, and contributed much to the acceptance of natural selection. His outlook was international, and somewhat idealistic: his interest in progress and evolutionary humanism runs through much of his published work. He

6496-488: The body. These cells can release substances that cause inflammation and can damage healthy nearby cells. Senescence can be induced by un-repaired DNA damage (e.g., from radiation, old age, etc.) or other cellular stress and also is the state of being old. Most organisms undergo allometric changes in shape as they grow and mature , while others engage in metamorphosis . Even reptiles (non-avian sauropsids, e.g., crocodilians , turtles , snakes , and lizards ), in which

6612-399: The brain and spinal cord. Then during weeks 5 and 6 of gestation, secondary neurulation forms the lower sacral and coccygeal cord. The diagram to the right illustrates primary neurulation, which is the process of cells surrounding the neural plate interacting with neural plate cells to proliferate, converge, and pinch off to form a hollow tube above the notochord and mesoderm. This process

6728-523: The category Planned Parenthood – World Population . Huxley came from the Huxley family on his father's side and the Arnold family on his mother's. His great-grandfather was Thomas Arnold of Rugby School , his great-uncle Matthew Arnold , and his aunt, Mrs Humphry Ward . His grandfather Thomas Henry Huxley was raised Anglican but eventually became an advocate of Agnosticism , a word he coined. Thomas

6844-586: The cause of his arrest. Worse still, Lysenkoism not only denied proven genetic facts, it stopped the artificial selection of crops on Darwinian principles. This may have contributed to the regular shortage of food from the Soviet agricultural system ( Soviet famines ). Huxley, who had twice visited the Soviet Union, was originally not anti-communist, but the ruthless adoption of Lysenkoism by Joseph Stalin ended his tolerant attitude. Lysenko ended his days in

6960-414: The change of behavioral machinery during development was distinct from the change in behavior during development. We can conclude that the thrush itself, i.e. its behavioral machinery, has changed only if the behavior change occurred while the environment was held constant...When we turn from description to causal analysis, and ask in what way the observed change in behavior machinery has been brought about,

7076-678: The concept of organism is not sharply defined. In his view, sponges , lichens , siphonophores , slime moulds , and eusocial colonies such as those of ants or naked molerats , all lie in the boundary zone between being definite colonies and definite organisms (or superorganisms). Scientists and bio-engineers are experimenting with different types of synthetic organism , from chimaeras composed of cells from two or more species, cyborgs including electromechanical limbs, hybrots containing both electronic and biological elements, and other combinations of systems that have variously evolved and been designed. An evolved organism takes its form by

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7192-496: The courtship takes place mostly after mate selection, not before. Huxley tackled the subject of evolution at full length, in what became the defining work of his life. His role was that of a synthesiser, and it helped that he had met many of the other participants. His book Evolution: The Modern Synthesis was written while he was secretary to the Zoological Society, and made use of his collection of reprints covering

7308-412: The creation of universities. There he acquired a disease, went down with hepatitis , and had a serious mental breakdown. He was completely disabled, treated with ECT , and took a full year to recover. He was 55. In 1945, Huxley proposed to melt the polar ice caps by igniting atomic bombs to moderate the world climate in the northern hemisphere, and permit shipping across the top of the world. Huxley,

7424-407: The developing organism have been established. He proposed that individual development followed developmental stages of previous generations and that the future generations would add something new to this process, and that there was a causal parallelism between an animal's ontogeny and phylogeny. In addition, Haeckel suggested a biogenetic law that ontogeny recapitulates phylogeny, based on the idea that

7540-457: The development of form and shape of an organism; tissue growth; and cellular differentiation . The term ontogeny has also been used in cell biology to describe the development of various cell types within an organism. Ontogeny is a useful field of study in many disciplines, including developmental biology , cell biology , genetics , developmental psychology , developmental cognitive neuroscience , and developmental psychobiology . Ontogeny

7656-447: The digestive system and the lungs. The mesoderm gives rise to other tissues not formed by the ectoderm, such as the heart, muscles, bones, blood, dermis of the skin, bone marrow, and the urogenital system. This germ layer is more specific for species, as it is the distinguishing layer of the three that can identify evolutionarily higher life-forms (e.g., bilateral organisms like humans) from lower-life forms (with radial symmetry). Lastly,

7772-408: The early days… [and in] the far-reaching influence he exerted [on] the international community." In addition to his international and humanist concerns, his research interests covered evolution in all its aspects, ethology , embryology , genetics , anthropology and to some extent the infant field of cell biology . Julian's eminence as an advocate for evolution, and especially his contribution to

7888-422: The evolution of life. It is also likely that survival sequences present early in the evolution of organisms included sequences that facilitate the avoidance of damage to the self-replicating molecule and promote the capability to repair such damages that do occur. Repair of some of the genome damages in these early organisms may have involved the capacity to use undamaged information from another similar genome by

8004-432: The figure below, human germ cells are able to differentiate into the specific organs and tissues they become later on in life. Germ cells are able to migrate to their final locations to rearrange themselves and some organs are made of two germ layers; one for the outside, the other for the inside. The endoderm cells become the internal linings of organisms, such as the stomach, colon, small intestine, liver, and pancreas of

8120-545: The first director of UNESCO , a founding member of the World Wildlife Fund , the president of the British Eugenics Society (1959–1962), and the first president of the British Humanist Association . Huxley was well known for his presentation of science in books and articles, and on radio and television. He directed an Oscar-winning wildlife film. He was awarded UNESCO's Kalinga Prize for

8236-591: The first part of the century. It was published in 1942. Reviews of the book in learned journals were little short of ecstatic; the American Naturalist called it "The outstanding evolutionary treatise of the decade, perhaps of the century. The approach is thoroughly scientific; the command of basic information amazing". Huxley's main co-respondents in the modern evolutionary synthesis are usually listed as Ernst Mayr , Theodosius Dobzhansky , George Gaylord Simpson , Bernhard Rensch , Ledyard Stebbins and

8352-607: The following year. Huxley made an exploratory trip to the United States in September 1912, visiting a number of leading universities as well as the Rice Institute. At T. H. Morgan 's fly lab ( Columbia University ) he invited H. J. Muller to join him at Rice. Muller agreed to be his deputy, hurried to complete his PhD and moved to Houston for the beginning of the 1915–1916 academic year. At Rice, Muller taught biology and continued Drosophila lab work. Before taking up

8468-500: The gastrula comprises three germ layers ; the endoderm (inner layer), mesoderm (middle layer), and ectoderm (outer layer). As seen in the figure below, each germ layer will become multi-potent stem cells that can become a specific tissue depending on the germ layer and is what happens in humans. This differentiation of germ layers differs slightly, because not all of the organs and tissues below are in all organisms, but corresponding body systems can be substituted in place of these. In

8584-439: The hereditary modification of embryonic development. Marine biologist Walter Garstang reversed Haeckel's relationship between ontogeny and phylogeny, stating that ontogeny creates phylogeny, not recapitulates it. A seminal 1963 paper by Nikolaas Tinbergen named ontogeny as one of the four primary questions of biology, along with Julian Huxley's three others: causation, survival value and evolution. Tinbergen emphasized that

8700-487: The international gathering for the centenary of Darwin's birth, held at the University of Cambridge . Huxley was awarded a scholarship to spend a year at the Naples Marine Biological Station, where he developed his interest in developmental biology by investigating sea squirts and sea urchins . In 1910 he was appointed as Demonstrator in the Department of Zoology and Comparative Anatomy at

8816-468: The latter part of the twentieth century with objections from Cladists , among others, to any suggestion that one group could be scientifically described as "advanced" and another as 'primitive'. Modern assessments of these views have been surveyed in Nitecki and Dawkins. Huxley's humanism came from his appreciation that mankind was in charge of its own destiny (at least in principle), and this raised

8932-434: The lumbar and tail vertebrae of frogs and chicks and in both instances, this process is like a continuation of gastrulation. In most species, the young organism that is just born or hatched is not sexually mature yet and in most animals, this young organism looks quite different than the adult form. This young organism is the larva and is the intermediate form before metamorphosing into an adult. A well known example of

9048-525: The mere microscopic eye-spots of early forms of life. [Over] the whole range of evolutionary time we see general advance—improvement in all the main properties of life, including its general organization. 'Advance' is thus a useful term for long-term improvement in some general property of life. [But] improvement is not universal. Lower forms manage to survive alongside higher". Huxley's views on progressive evolution were similar to those of G. Ledyard Stebbins and Bernhard Rensch , and were challenged in

9164-617: The minority of biologists who believed that natural selection was the main driving force of evolution, and that evolution occurred by small steps and not by saltation (jumps). These opinions are now standard. Though his time as an academic was quite brief, he taught and encouraged evolutionary biologists at the University of Oxford in the 1920s. Charles Elton (ecology), Alister Hardy ( marine biology ) and John Baker ( cytology ) all became highly successful, and Baker eventually wrote Huxley's Royal Society obituary memoir. Perhaps

9280-429: The modern evolutionary synthesis which took place around the time of World War II . The synthesis of genetic and population ideas produced a consensus which reigned in biology from about 1940, and which is still broadly tenable. "The most informative episode in the history of evolutionary biology was the establishment of the 'neo-Darwinian synthesis'." The synthesis was brought about "not by one side being proved right and

9396-667: The modern evolutionary synthesis, led to his awards of the Darwin Medal of the Royal Society in 1956, and the Darwin–Wallace Medal of the Linnaean Society in 1958. 1958 was the centenary anniversary of the joint presentation On the tendency of species to form varieties; and the perpetuation of varieties and species by natural means of selection by Darwin and Wallace. Huxley was a friend and mentor of

9512-459: The modern synthesis shows indirectly those whom Huxley regarded as the most important contributors to the synthesis up to 1941 (the book was published in 1942, and references go up to 1941). The authorities cited 20 or more times are: Darlington , Darwin , Dobzhansky , Fisher , Ford , Goldschmidt , Haldane , J. S. Huxley, Muller , Rensch , Turrill , Wright . Goldschmidt was an influential geneticist who advocated evolution by saltation, and

9628-747: The most significant was Edmund Brisco Ford , who founded a field of research called ecological genetics , which played a role in the evolutionary synthesis. Another important disciple was Gavin de Beer , who wrote on evolution and development , and became director of the Natural History Museum . Both these scholars had attended Huxley's lectures on genetics , experimental zoology (including embryology ) and ethology . Later, they became his collaborators, and then leaders in their own right. In an era when scientists did not travel so frequently as today, Huxley travelled widely in Europe, Africa and

9744-553: The natural first step is to try and distinguish between environmental influences and those within the animal...In ontogeny the conclusion that a certain change is internally controlled (is 'innate') is reached by elimination . Tinbergen was concerned that the elimination of environmental factors is difficult to establish, and the use of the word innate is often misleading. Development of an organism happens through fertilization, cleavage, blastulation, gastrulation, organogenesis, and metamorphosis into an adult. Each species of animal has

9860-418: The need for a sense of direction and a system of ethics. His grandfather T. H. Huxley , when faced with similar problems, had promoted agnosticism, but Julian chose humanism as being more directed to supplying a basis for ethics. Julian's thinking went along these lines: "The critical point in the evolution of man… was when he acquired the use of [language]… Man's development is potentially open… He has developed

9976-458: The offspring are often viewed as miniature adults, show a variety of ontogenetic changes in morphology and physiology . Organism The evolutionary biologists David Queller and Joan Strassmann state that "organismality", the qualities or attributes that define an entity as an organism, has evolved socially as groups of simpler units (from cells upwards) came to cooperate without conflicts. They propose that cooperation should be used as

10092-538: The others wrong, but by the exchange of the most viable components of the previously competing research strategies". Ernst Mayr, 1980. Huxley's first "trial run" was the treatment of evolution in the Science of Life (1929–30), and in 1936 he published a long and significant paper for the British Association . In 1938 came three lengthy reviews on major evolutionary topics. Two of these papers were on

10208-739: The pairs displaying to each other, and with secondary sexual characteristics equally developed in both sexes. In September 1916 Huxley returned to England from Texas to assist in the war effort. He was commissioned a temporary second lieutenant in the Royal Army Service Corps on 25 May 1917, and was transferred to the General List, working in the British Army Intelligence Corps from 26 January 1918, first in Sussex , and then in northern Italy. He

10324-501: The partially understood mechanisms of evolutionary developmental biology , in which the genome directs an elaborated series of interactions to produce successively more elaborate structures. The existence of chimaeras and hybrids demonstrates that these mechanisms are "intelligently" robust in the face of radically altered circumstances at all levels from molecular to organismal. Synthetic organisms already take diverse forms, and their diversity will increase. What they all have in common

10440-551: The phrase Progress without a goal to summarise his case in Evolution the modern synthesis that evolutionary progress was "a raising of the upper level of biological efficiency, this being defined as increased control over and independence of the environment." In Evolution in action he wrote that Natural selection plus time produces biological improvement… 'Improvement' is not yet a recognised technical term in biology … however, living things are improved during evolution… Darwin

10556-531: The popularisation of science in 1953, the Darwin Medal of the Royal Society in 1956, and the Darwin–Wallace Medal of the Linnaean Society in 1958. He was also knighted in the 1958 New Year Honours , a hundred years after Charles Darwin and Alfred Russel Wallace announced the theory of evolution by natural selection. In 1956 he received a Special Award from the Lasker Foundation in

10672-440: The population geneticists J. B. S. Haldane , Ronald Fisher and Sewall Wright . However, at the time of Huxley's book several of these had yet to make their distinctive contribution. Certainly, for Huxley, E. B. Ford and his co-workers in ecological genetics were at least as important; and Cyril Darlington , the chromosome expert, was a notable source of facts and ideas.An analysis of the "authorities cited" index of Evolution

10788-670: The post of assistant professor at the Rice Institute , Huxley spent a year in Germany preparing for his demanding new job. Working in a laboratory just months before the outbreak of World War I , Huxley overheard fellow academics comment on a passing aircraft, "It will not be long before those planes are flying over England." One pleasure of Huxley's life in Texas was the sight of his first hummingbird , though his visit to Edward Avery McIlhenny 's estate on Avery Island in Louisiana

10904-443: The subject of sexual selection , an idea of Darwin's whose standing has been revived in recent times. Huxley thought that sexual selection was "…merely an aspect of natural selection which… is concerned with characters which subserve mating, and are usually sex-limited ". This rather grudging acceptance of sexual selection was influenced by his studies on the courtship of the great crested grebe (and other birds that pair for life):

11020-480: The successive and progressive origin of new species was based on the same laws as the successive and progressive origin of new embryonic structures. According to Haeckel, development produced novelties, and natural selection would eliminate species that had become outdated or obsolete. Though his view of development and evolution wasn't justifiable, future embryologists tweaked and collaborated with Haeckel's proposals and showed how new morphological structures can occur by

11136-409: The tail end of the spinal cord. Next, the closed neural tube contains neuroepithelial cells that immediately divide after closure and a second type of cell forms; the neuroblast. Neuroblast cells form the mantle layer, which later becomes the gray matter , which then gives rise to a marginal layer that becomes the white matter of the spinal cord. Secondary neurulation is seen in the neural tube of

11252-601: The wildlife on the Serengeti plain was almost undisturbed because the tsetse fly (the vector for the trypanosome parasite which causes sleeping sickness in humans) prevented human settlement there. He tells about these experiences in Africa view (1931), and so does his wife. She reveals that he fell in love with an 18-year-old American girl on board ship (when Juliette was not present), and then presented Juliette with his ideas for an open marriage: "What Julian really wanted

11368-516: The years in Paris are well described by his wife. Huxley's internationalist and conservation interests also led him, with Victor Stolan , Sir Peter Scott , Max Nicholson and Guy Mountfort , to set up the WWF ( World Wide Fund for Nature under its former name of the World Wildlife Fund ). Another post-war activity was Huxley's attack on the Soviet politico-scientist Trofim Lysenko , who had espoused

11484-447: The zygote undergoes many mitotic divisions , which are also non-sexual cell divisions. Cleavage is the process of cell division, so the starting zygote becomes a collection of identical cells which is a morula and contains cells called blastomeres. Cleavage prepares the zygote to become an embryo, which is from 2 weeks to 8 weeks after conception (fertilization) in humans. After the zygote has become an embryo, it continues dividing into

11600-407: Was a Christian, whilst Huxley was an atheist. Huxley wrote the foreword to The Phenomenon of Man (1959) and was bitterly attacked by his rationalist friends for doing so. On Huxley's death at 87 on 14 February 1975, John Owen (Director of National Parks for Tanganyika ) wrote, "Julian Huxley was one of the world's great men … he played a seminal role in wild life conservation in [East] Africa in

11716-400: Was a pupil at Prior's Field, Compton, the school his mother had founded and run. During 1913 the relationship broke down and Huxley had a nervous breakdown which a biographer described as caused by 'conflict between desire and guilt'. In the first months of 1914 Huxley had severe depression and lived for some weeks at The Hermitage, a small private nursing home. In August 1914 while Huxley

11832-551: Was advanced in grade within the Intelligence Corps on 3 May 1918, relinquished his intelligence appointment on 10 January 1919 and was demobilised five days later, retaining his rank. After the war he became a Fellow at New College, Oxford , and was made Senior Demonstrator in the University Department of Zoology. In fact, Huxley took the place of his old tutor Geoffrey Smith, who had been killed in

11948-482: Was also a friend and supporter of Charles Darwin and proponent of evolution. Huxley's father was writer and editor Leonard Huxley and his mother was Julia Arnold , a graduate of Somerville College, Oxford, who had gained a First in English Literature there in 1882. Julia and Leonard married in 1885 and they had four children: Margaret (1899–1981), the novelist Aldous , Trevenen and Julian. Huxley

12064-527: Was also a strong supporter of Darwinism . Haeckel suggested that ontogeny briefly and sometimes incompletely recapitulated or repeated phylogeny in his 1866 book, Generelle Morphologie der Organismen ("General Morphology of Organisms"). Even though his book was widely read, the scientific community was not very convinced or interested in his ideas, so he turned to producing more publications to get more attention. In 1866, Haeckel and others imagined development as producing new structures after earlier additions to

12180-488: Was appointed secretary to the Zoological Society of London , and spent much of the next seven years running the society and its zoological gardens, the London Zoo and Whipsnade Park , alongside his writing and research. The previous Director, Peter Chalmers Mitchell , had been in post for many years, and had skillfully avoided conflict with the Fellows and Council. Things were rather different when Huxley arrived. Huxley

12296-513: Was born on 22 June 1887, at the London house of his aunt. His mother opened a school in Compton, Guildford in 1902 and died in 1908, when he was 21. In 1912, his father married Rosalind Bruce, who was the same age as Julian, and he later acquired half-brothers Andrew Huxley and David Huxley. In 1911, Huxley became informally engaged to Kathleen Fordham, whom he had met some years earlier when she

12412-517: Was changed by his growing awareness of Stalin's murderous repression, and the Lysenko affair. There seems little evidence that he had any effect on the Soviet Union , and the same could be said for some other Western scientists. "Marxist-Leninism had become a dogmatic religion… and like all dogmatic religions, it had turned from reform to persecution." Huxley was one of the main architects of

12528-459: Was co-evolution of viruses and host cells. If host cells did not exist, viral evolution would be impossible. As for reproduction, viruses rely on hosts' machinery to replicate. The discovery of viruses with genes coding for energy metabolism and protein synthesis fuelled the debate about whether viruses are living organisms, but the genes have a cellular origin. Most likely, they were acquired through horizontal gene transfer from viral hosts. There

12644-475: Was in Scotland, his brother Trevenen also had a nervous breakdown and stayed in the same nursing home. Trevenen was worried about how he had treated one of his women friends and committed suicide whilst there. In 1919, Huxley married Juliette Baillot (1896–1994) a French Swiss woman whom he had met while she was employed as a governess at Garsington Manor , the country house of Lady Ottoline Morrell . Huxley

12760-677: Was later unfaithful to Baillot and told her that he wanted an open marriage. One of his affairs was with the poet May Sarton who in turn fell in love with Baillot and had a brief affair with her as well. Huxley described himself in print as suffering from manic depression, and his wife's autobiography suggests that Julian Huxley suffered from a bipolar disorder . He relied on his wife to provide moral and practical support throughout his life. Sir Julian and Lady Juliette Huxley had two sons: Anthony Huxley (1920–1992) and Francis Huxley (1923–2016), who both became scientists. His ashes are buried with his wife, son Anthony, parents and brother at

12876-469: Was more significant. The McIlhennys and their Avery cousins owned the entire island, and the McIlhenny branch used it to produce their famous Tabasco sauce . Birds were one of McIlhenny's passions, however, and around 1895 he had set up a private sanctuary on the island, called Bird City. There Huxley found egrets , herons and bitterns . These water birds, like the grebes, exhibit mutual courtship, with

12992-529: Was not a skilled administrator; his wife said "He was impatient… and lacked tact". He instituted a number of changes and innovations, more than some approved of. For example, Huxley introduced a whole range of ideas designed to make the Zoo child-friendly. Today, this would pass without comment; but then it was more controversial. He fenced off the Fellows' Lawn to establish Pets Corner; he appointed new assistant curators, encouraging them to talk to children; he initiated

13108-407: Was not afraid to use the word for the results of natural selection in general… I believe that improvement can become one of the key concepts in evolutionary biology. Can it be scientifically defined? Improvements in biological machinery… the limbs and teeth of grazing horses… the increase in brain-power… The eyes of a dragon-fly, which can see all round [it] in every direction, are an improvement over

13224-475: Was one of the signers of the Humanist Manifesto . Huxley and biologist August Weismann insisted on natural selection as the primary agent in evolution . Huxley was a major player in the mid-twentieth century modern evolutionary synthesis. He was a prominent populariser of biological science to the public , with a focus on three aspects in particular. In the early 20th century he was one of

13340-399: Was sometimes mentioned in disagreement. Turrill provided Huxley with botanical information. The list omits three key members of the synthesis who are listed above: Mayr , Stebbins the botanist and Simpson the palaeontologist. Mayr gets 16 citations and more in the two later editions; all three published outstanding and relevant books some years later, and their contribution to the synthesis

13456-414: Was … a definite freedom from the conventional bonds of marriage." The couple separated for a while; Julian travelled to the US, hoping to land a suitable appointment and, in due course, to marry Miss Weldmeier. He left no account of what transpired, but he was evidently not successful, and returned to England to resume his marriage in 1931. For the next couple of years Huxley still angled for an appointment in

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