Ontogeny (also ontogenesis or morphogenesis) is the origination and development of an organism, usually from the time of fertilization of the egg to the organism's mature form—although the term can 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 the evolutionary history of a species. In practice, writers on evolution often speak of species as "developing" traits or characteristics. This can be misleading. While developmental (i.e., ontogenetic) processes can influence subsequent evolutionary (e.g., phylogenetic) processes[1] (see evolutionary developmental biology), individual organisms develop (ontogeny), while species evolve (phylogeny).

Ontogeny, embryology and developmental biology are closely related studies and the terms are sometimes used interchangeably. The term ontogeny has also been used in cell biology to describe the development of various cell types within an organism.[2]

Ontogeny is a useful field of study in many disciplines, including developmental biology, developmental psychology, developmental cognitive neuroscience, and developmental psychobiology.

Ontogeny is also a concept used in anthropology as "the process through which each of us embodies the history of our own making".[3]

The initial stages of human embryogenesis
Human embryo 8 weeks 2
Parts of a human embryo


The word ontogeny comes from the Greek ὄν, on (gen. ὄντος, ontos), i.e. "being; that which is", which is the present participle of the verb εἰμί, eimi, i.e. "to be, I am", and from the suffix -geny from the Greek -γένεια -geneia, which expresses the concept of "mode of production".[4]

Nature and nurture

A seminal paper named ontogeny as one of the four primary questions of biology, along with Huxley's three others: causation, survival value and evolution.[5] Tinbergen emphasized that 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, 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. " (p. 424) Tinbergen was concerned that the elimination of environmental factors is difficult to establish, and the use of the word "innate" is often misleading.

Ontogenetic allometry

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,[6] lizards[7]), in which the offspring are often viewed as miniature adults, show a variety of ontogenetic changes in morphology and physiology.[8]

Anthropological application

Comparing ourselves to others is something humans do all the time. "In doing so we are acknowledging not so much our sameness to others or our difference, but rather the commonality that resides in our difference. In other words, because each one of us is at once remarkably similar to, and remarkably different from, all other humans, it makes little sense to think of comparison in terms of a list of absolute similarities and a list of absolute differences. Rather, in respect of all other humans, we find similarities in the ways we are different from one another and differences in the ways we are the same. That we are able to do this is a function of the genuinely historical process that is human ontogeny".[3]

See also

Notes and references

  1. ^ Gould, S.J. (1977). Ontogeny and Phylogeny. Cambridge, Massachusetts: The Belknap Press of Harvard University Press
  2. ^ Thiery, Jean Paul (1 December 2003). "Epithelial–mesenchymal transitions in development and pathologies". Current Opinion in Cell Biology. 15 (6): 740–746. doi:10.1016/j.ceb.2003.10.006. PMID 14644200.
  3. ^ a b Toren, Christina. "Comparison and ontogeny." Anthropology, by comparison (2002): 187.
  4. ^ See -geny in the Oxford English Dictionary, second edition, 1989; online version March 2011, accessed 9 May 2011. Earlier version first published in New English Dictionary, 1898.
  5. ^ Niko Tinbergen (1963). "On aims and methods of ethology" (PDF). Zeitschrift für Tierpsychologie. 20: 410–433. doi:10.1111/j.1439-0310.1963.tb01161.x. See page 411.
  6. ^ Pough, F. H. (1978). "Ontogenetic changes in endurance in water snakes (Natrix sipedon): Physiological correlates and ecological consequences". Copeia. 1978: 69–75. doi:10.2307/1443823.
  7. ^ Garland Jr, T. (1985). "Ontogenetic and individual variation in size, shape and speed in the Australian agamid lizard Amphibolurus nuchalis". Journal of Zoology. 207: 425–439. doi:10.1111/j.1469-7998.1985.tb04941.x.
  8. ^ Garland Jr., T.; Else, P. L. (1987). "Seasonal, sexual, and individual variation in endurance and activity metabolism in lizards". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 252: R439–R449. doi:10.1152/ajpregu.1987.252.3.r439.

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Acari (or Acarina) are a taxon of arachnids that contains mites and ticks. The diversity of the Acari is extraordinary and its fossil history goes back to at least the early Devonian period. Acarologists (people who study Acari) have proposed a complex set of taxonomic ranks to classify mites. In most modern treatments, the Acari is considered a subclass of Arachnida and is composed of two or three superorders or orders: Acariformes (or Actinotrichida), Parasitiformes (or Anactinotrichida), and Opilioacariformes; the latter is often considered a subgroup within the Parasitiformes. The monophyly of the Acari is open to debate, and the relationships of the acarines to other arachnids is not at all clear. In older treatments, the subgroups of the Acarina were placed at order rank, but as their own subdivisions have become better understood, it is more usual to treat them at superorder rank.

Most acarines are minute to small (for example, 0.08–1.00 mm or 0.003–0.039 in), but the largest (some ticks and red velvet mites) may reach lengths of 10–20 mm (0.4–0.8 in). Over 50,000 species have been described (as of 1999) and it is estimated that a million or more species may exist. The study of mites and ticks is called acarology (from Greek ἀκαρί/ἄκαρι, akari, a type of mite; and -λογία, -logia), and the leading scientific journals for acarology include Acarologia, Experimental and Applied Acarology and the International Journal of Acarology.


Biomusicology is the study of music from a biological point of view. The term was coined by Nils L. Wallin in 1991 to encompass several branches of music psychology and musicology, including evolutionary musicology, neuromusicology, and comparative musicology.Evolutionary musicology studies the "origins of music, the question of animal song, selection pressures underlying music evolution", and "music evolution and human evolution". Neuromusicology studies the "brain areas involved in music processing, neural and cognitive processes of musical processing", and "ontogeny of musical capacity and musical skill". Comparative musicology studies the "functions and uses of music, advantages and costs of music making", and "universal features of musical systems and musical behavior".Applied biomusicology "attempts to provide biological insight into such things as the therapeutic uses of music in medical and psychological treatment; widespread use of music in the audiovisual media such as film and television; the ubiquitous presence of music in public places and its role in influencing mass behavior; and the potential use of music to function as a general enhancer of learning."Whereas biomusicology refers to music among humans, zoomusicology extends the field to other species.


The calcar, also known as the calcaneum, is the name given to a spur of cartilage arising from inner side of ankle and running along part of outer interfemoral membrane in bats.

This is to help spread the interfemoral membrane, which is part of the wing membrane between the tail and the hind legs.

Calcar (Femorale) also refers to the dense, vertically oriented bone present in the posteromedial region of the femoral shaft inferior to the lesser trochanter.


Calcaronea is a subclass in the class Calcarea.They are Calcarea with the triactines and the basal system of tetractines sagittal (i.e. the rays of the spicule make unequal angles with each other), exceptionally regular. In ontogeny the first spicules to be secreted are diactines. Choanocytes are apinucleate. Calcaronea have amphiblastula larvae

Culture and social cognition

Culture & Social Cognition is the relationship between human culture and human cognitive capabilities. Cultural cognitive evolution proposes that humans’ unique cognitive capacities are not solely due to biological inheritance, but are in fact due in large part to cultural transmission and evolution (Tomasello, 1999). Modern humans and great apes are separated evolutionarily by about six million years. Proponents of cultural evolution argue that this would not have been enough time for humans to develop the advanced cognitive capabilities required to create tools, language, and build societies through biological evolution. Biological evolution could not have individually produced each of these cognitive capabilities within that period of time. Instead, humans must have evolved the capacity to learn through cultural transmission (Tomasello, 1999). This provides a more plausible explanation that would fit within the given time frame. Instead of having to biologically account for each cognitive mechanism that distinguishes modern humans from previous relatives, one would only have to account for one significant biological adaptation for cultural learning. According to this view, the ability to learn through cultural transmission is what distinguishes humans from other primates (Tomasello, 1999). Cultural learning allows humans to build on existing knowledge and make collective advancements, also known as the “ratchet effect”. The ratchet effect simply refers to the way in which humans continuously add on to existing knowledge through modifications and improvements. This unique ability distinguishes humans from related primates, who do not seem to build collaborative knowledge over time. Instead, primates seem to build individual knowledge, in which the expertise of one animal is not built on by others, and does not progress across time.

Ernst Haeckel

Ernst Heinrich Philipp August Haeckel (German: [ˈʔɛɐ̯nst ˈhɛkl̩]; 16 February 1834 – 9 August 1919) was a German biologist, naturalist, philosopher, physician, professor, marine biologist, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, including anthropogeny, ecology, phylum, phylogeny, and Protista. Haeckel promoted and popularised Charles Darwin's work in Germany and developed the influential but no longer widely held recapitulation theory ("ontogeny recapitulates phylogeny") claiming that an individual organism's biological development, or ontogeny, parallels and summarises its species' evolutionary development, or phylogeny.

The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures, collected in his Kunstformen der Natur ("Art Forms of Nature"). As a philosopher, Ernst Haeckel wrote Die Welträthsel (1895–1899; in English: The Riddle of the Universe, 1901), the genesis for the term "world riddle" (Welträtsel); and Freedom in Science and Teaching to support teaching evolution.

Evolutionary developmental psychology

Evolutionary developmental psychology (EDP) is a research paradigm that applies the basic principles of Darwinian evolution, particularly natural selection, to understand the development of human behavior and cognition. It involves the study of both the genetic and environmental mechanisms that underlie the development of social and cognitive competencies, as well as the epigenetic (gene-environment interactions) processes that adapt these competencies to local conditions.EDP considers both the reliably developing, species-typical features of ontogeny (developmental adaptations), as well as individual differences in behavior, from an evolutionary perspective. While evolutionary views tend to regard most individual differences as the result of either random genetic noise (evolutionary byproducts) and/or idiosyncrasies (for example, peer groups, education, neighborhoods, and chance encounters) rather than products of natural selection, EDP asserts that natural selection can favor the emergence of individual differences via "adaptive developmental plasticity." From this perspective, human development follows alternative life-history strategies in response to environmental variability, rather than following one species-typical pattern of development.EDP is closely linked to the theoretical framework of evolutionary psychology (EP), but is also distinct from EP in several domains, including research emphasis (EDP focuses on adaptations of ontogeny, as opposed to adaptations of adulthood) and consideration of proximate ontogenetic and environmental factors (i.e., how development happens) in addition to more ultimate factors (i.e., why development happens), which are the focus of mainstream evolutionary psychology.


Foraminacephale (meaning "foramina head") is a genus of pachycephalosaurid dinosaur from Late Cretaceous (Campanian stage) deposits of Canada.

Hans Spemann

Hans Spemann (27 June 1869 – 9 September 1941) was a German embryologist who was awarded a Nobel Prize in Physiology or Medicine in 1935 for his discovery of the effect now known as embryonic induction, an influence, exercised by various parts of the embryo, that directs the development of groups of cells into particular tissues and organs.


Hymenomycetes was formerly the largest taxonomic group of fungi within the division Basidiomycota, but the term is no longer taxonomically relevant. Many familiar fungi belong to this class, including bracket fungi and toadstools. This class contained the orders Agaricales, Boletales, and Russulales.

The erstwhile class, now understood to be a polyphyletic assemblage of basidiomycetes, refers to fungi with fruit bodies whose hymenophore develops in an exposed manner, or only with a veil (velum). These forms are termed gymnocarpic or hemiangiocarpic ontogeny, respectively. A contrasting example of hymenophore development is the puffballs, which undergo gasterocarpic development (hymenophore enclosed).


Incisoscutum is a genus of arthrodire placoderm from the Late Frasnian Gogo Reef, from Late Devonian Australia. The genus contains two species I. ritchiei, named after Dr. Alex Ritchie, a palaeoichthyologist and senior fellow of the Australian Museum, and I. sarahae, named after Sarah Long, daughter of its discoverer and describer, Dr. John A. Long.

The genus is important in the study of early vertebrates as well-preserved fossilised embryos have been found in female specimens and ossified pelvic claspers found in males. This shows that viviparity and internal fertilisation was common amongst these primitive jawed vertebrates, which are outside the crown group Gnathostoma.

In a study of fossil remains, comparison of the ontogeny of fourteen dermal plates from Compagopiscis croucheri and the more derived species Incisoscutum ritchiei suggested that lengthwise growth occurs earlier in the ontogeny than growth in width, and that dissociated allometric heterochrony has been an important mechanism in the evolution of the arthrodires, which include placoderms.

These same fossil specimens also show that Incisoscutum was a predator, as muscle fibres from the tails of other placoderms have been found in the stomach regions.

Ontogeny (psychoanalysis)

Ontogeny (also ontogenesis or morphogenesis) is the origin and the development of an organism – for example: from the fertilized egg to mature form. It covers in essence, the study of an organism's lifespan. The word "ontogeny" comes from the Greek ὄντος, ontos, present participle singular of εἶναι, "to be"; and from the suffix -geny, which expresses the concept of "mode of production".

In more general terms, ontogeny is defined as the history of structural change in a unity, which can be a cell, an organism, or a society of organisms, without the loss of the organization which allows that unity to exist.

Ontogeny and Phylogeny (book)

Ontogeny and Phylogeny is a 1977 book on evolution by Stephen Jay Gould, in which the author explores the relationship between embryonic development (ontogeny) and biological evolution (phylogeny). Unlike his many popular books of essays, it was a technical book, and over the following decades it was influential in stimulating research into heterochrony, changes in the timing of embryonic development, which had been neglected since Ernst Haeckel's theory that ontogeny recapitulates phylogeny had been largely discredited.


Othnielia is a dubious genus of ornithischian dinosaur, named after its original describer, Professor Othniel Charles Marsh, an American paleontologist of the 19th century.

Pharyngeal slit

Pharyngeal slits are filter-feeding organs found in Invertebrate chordates (lancelets and tunicates) and hemichordates living in aquatic environments. Pharyngeal slits are repeated openings that appear along the pharynx caudal to the mouth. With this position, they allow for the movement of water in the mouth and out the pharyngeal slits. It is postulated that this is how pharyngeal slits first assisted in filter-feeding, and later with the addition of gills along their walls, aided in respiration of aquatic chordates. These repeated segments are controlled by similar developmental mechanisms. Some hemichordate species can have as many as 200 gill slits. Pharyngeal slits resembling gill slits are transiently present during the embryonic stages of tetrapod development. The presence of gill-like slits in the neck of the developing human embryo famously led Ernst Haeckel to postulate that "ontogeny recapitulates phylogeny"; this hypothesis, while false, contains elements of truth, as explored by Stephen Jay Gould in Ontogeny and Phylogeny. However, it is now accepted that it is the vertebrate pharyngeal pouches and not the neck slits that are homologous to the pharyngeal slits of invertebrate chordates. Gill slits are, at some stage of life, found in all chordates. One theory of their origin is the fusion of nephridia which opened both on the outside and the gut, creating openings between the gut and the environment.


In biology, phylogenetics (Greek: φυλή, φῦλον – phylé, phylon = tribe, clan, race + γενετικός – genetikós = origin, source, birth) is the study of the evolutionary history and relationships among individuals or groups of organisms (e.g. species, or populations). These relationships are discovered through phylogenetic inference methods that evaluate observed heritable traits, such as DNA sequences or morphology under a model of evolution of these traits. The result of these analyses is a phylogeny (also known as a phylogenetic tree) – a diagrammatic hypothesis about the history of the evolutionary relationships of a group of organisms. The tips of a phylogenetic tree can be living organisms or fossils, and represent the "end", or the present, in an evolutionary lineage. Phylogenetic analyses have become central to understanding biodiversity, evolution, ecology, and genomes.

Taxonomy is the identification, naming and classification of organisms. It is usually richly informed by phylogenetics, but remains a methodologically and logically distinct discipline. The degree to which taxonomies depend on phylogenies (or classification depends on evolutionary development) differs depending on the school of taxonomy: phenetics ignores phylogeny altogether, trying to represent the similarity between organisms instead; cladistics (phylogenetic systematics) tries to reproduce phylogeny in its classification without loss of information; evolutionary taxonomy tries to find a compromise between them.

Recapitulation theory

The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (ontogeny), goes through stages resembling or representing successive stages in the evolution of the animal's remote ancestors (phylogeny). It was formulated in the 1820s by Étienne Serres based on the work of Johann Friedrich Meckel, after whom it is also known as Meckel–Serres law.

Since embryos also evolve in different ways, the shortcomings of the theory had been recognized by the early 20th century, and it had been relegated to "biological mythology" by the mid-20th century.Analogies to recapitulation theory have been formulated in other fields, including cognitive development and art criticism.


Saurolophus (; meaning "lizard crest") is a genus of large saurolophine hadrosaurid dinosaurs that lived about 70.0–68.5 million years ago, in the Late Cretaceous of North America and Asia; it is one of the few genera of dinosaurs known from multiple continents. It is distinguished by a spike-like crest which projects up and back from the skull. Saurolophus was a herbivorous dinosaur which could move about either bipedally or quadrupedally.

The type species, S. osborni, was described by Barnum Brown in 1912 from Canadian fossils. A second valid species, S. angustirostris, is represented by numerous specimens from Mongolia, and was described by Anatoly Konstantinovich Rozhdestvensky.

Swamp rabbit

The swamp rabbit (Sylvilagus aquaticus), or swamp hare, is a large cottontail rabbit found in the swamps and wetlands of the southern United States. Other common names for the swamp rabbit include marsh rabbit and cane-cutter. The species has a strong preference for wet areas, and it will take to the water and swim.

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