Laterality

The term laterality refers to asymmetric preference, usage, skill, or specialization of symmetric body parts in an organism. Humans exhibit laterality in many ways, including limb dominance such as left and right handedness and footedness as well as specialization of one brain hemisphere over the other for certain functions such as language. Many other animals have also been shown to exhibit laterality in their own ways.

The term laterality refers to asymmetric preference, usage, skill, or specialization of symmetric body parts in an organism. Humans exhibit laterality in many ways, including limb dominance such as left and right handedness and footedness as well as specialization of one brain hemisphere over the other for certain functions such as language. Many other animals have also been shown to exhibit laterality in their own ways. ===Different expressions=== Board footedness: The stance in a boardsport is not necessarily the same as the normal-footedness of the person. In skateboarding and other board sports, a "goofy footed" stance is one with the right foot leading. A stance with the left foot forward is called "regular" or "normal" stance. Jump and spin: Direction of rotation in figure skating jumps and spins is not necessarily the same as the footedness or the handedness of each person. A skater can jump and spin counter-clockwise (the most common direction), yet be left-footed and left-handed. Ocular dominance: The eye preferred when binocular vision is not possible, as through a keyhole or monocular microscope. ====In marsupials==== Marsupials are fundamentally different from other mammals in that they lack a corpus callosum. However, wild kangaroos and other macropod marsupials have a left-hand preference for everyday tasks. Left-handedness is particularly apparent in the red kangaroo (Macropus rufus) and the eastern gray kangaroo (Macropus giganteus). The red-necked wallaby (Macropus rufogriseus) preferentially uses the left hand for behaviours that involve fine manipulation, but the right for behaviours that require more physical strength. There is less evidence for handedness in arboreal species. ===In birds=== Parrots tend to favor one foot when grasping objects (for example fruit when feeding). Some studies indicate that most parrots are left footed. The Australian magpie (Gymnorhina tibicen) uses both left-eye and right-eye laterality when performing anti-predator responses, which include mobbing. Prior to withdrawing from a potential predator, Australian magpies view the animal with the left eye (85%), but prior to approaching, the right eye is used (72%). The left eye is used prior to jumping (73%) and prior to circling (65%) the predator, as well as during circling (58%) and for high alert inspection of the predator (72%). The researchers commented that "mobbing and perhaps circling are agonistic responses controlled by the LE[left eye]/right hemisphere, as also seen in other species. Alert inspection involves detailed examination of the predator and likely high levels of fear, known to be right hemisphere function." Yellow-legged gull (Larus michahellis) chicks show laterality when reverting from a supine to prone posture, and also in pecking at a dummy parental bill to beg for food. Lateralization occurs at both the population and individual level in the reverting response and at the individual level in begging. Females have a leftward preference in the righting response, indicating this is sex dependent. Laterality in the begging response in chicks varies according to laying order and matches variation in egg androgens concentration. ===In fish=== Laterality determines the organisation of rainbowfish (Melanotaenia spp.) schools. These fish demonstrate an individual eye preference when examining their reflection in a mirror. Fish which show a right-eye preference in the mirror test prefer to be on the left side of the school. Conversely, fish that show a left-eye preference in the mirror test or were non-lateralised, prefer to be slightly to the right side of the school. The behaviour depends on the species and sex of the school. ===In amphibians=== Three species of toads, the common toad (Bufo bufo), green toad (Bufo viridis) and the cane toad (Bufo marinus) show stronger escape and defensive responses when a model predator was placed on the toad's left side compared to their right side. Emei music frogs (Babina daunchina) have a right-ear preference for positive or neutral signals such as a conspecific's advertisement call and white noise, but a left-ear preference for negative signals such as predatory attack. ===In invertebrates=== The Mediterranean fruit fly (Ceratitis capitata) exhibits left-biased population-level lateralisation of aggressive displays (boxing with forelegs and wing strikes) with no sex-differences. In ants, Temnothorax albipennis (rock ant) scouts show behavioural lateralization when exploring unknown nest sites, showing a population-level bias to prefer left turns. One possible reason for this is that its environment is partly maze-like and consistently turning in one direction is a good way to search and exit mazes without getting lost. This turning bias is correlated with slight asymmetries in the ants' compound eyes (differential ommatidia count). ==See also== Dextrocardia Situs inversus Handedness Footedness Ocular dominance Lateralization of brain function Cross-dominance Semantic processing ==References== ==External links== Limb preferences in non-human vertebrates: A new decade Is laterality adaptive? Pitfalls in disentangling the laterality–performance relationship The Flinders Handedness survey (FLANDERS): A brief measure of skilled hand preference

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