How the bat beats the lifespan rule
From the elephant to the mayfly, biologists say there is a general rule about longevity: the bigger the animal, the longer it lives.
From the elephant to the mayfly, biologists say there is a general rule about longevity: the bigger the animal, the longer it lives.
Plants & Animals
Aug 20, 2013
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Long-and-low dwarf breeds are prone to painful and debilitating slipped discs, and a new study from The Royal Veterinary College published on 24th July 2013 in the journal PLoS ONE, reveals that dogs with longer backs relative ...
Plants & Animals
Jul 25, 2013
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(Phys.org) —Ever since the discovery of the remains in 2003, scientists have been debating whether Homo floresiensis represents a distinct Homo species, possibly originating from a dwarfed island Homo erectus population, ...
Archaeology
Jul 11, 2013
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How do bone-eating worms reproduce? A new study by Norio Miyamoto and colleagues from the Japan Agency for Marine-Earth Science and Technology sheds light on this question through a detailed observation of the postembryonic ...
Plants & Animals
Mar 12, 2013
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Plants grow upward from a tip of undifferentiated tissue called the shoot apical meristem. As the tip extends, stem cells at the center of the meristem divide and increase in numbers. But the cells on the periphery differentiate ...
Biotechnology
Dec 3, 2012
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(Phys.org)—A new multidisciplinary study on the enigmatic large Horseshoe bat – found widespread throughout South and East Africa – has revealed that instead of just one species as previously believed, the bat is in ...
Plants & Animals
Sep 14, 2012
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(Phys.org) -- The smallest mammoth known to have ever lived has been identified by Natural History Museum scientists, and is reported in the journal Proceedings of the Royal Society B today.
Archaeology
May 9, 2012
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Four new species of miniaturized lizards have been identified in Madagascar. These lizards, just tens of millimeters from head to tail and in some cases small enough to stand on the head of a match, rank among the smallest ...
Plants & Animals
Feb 15, 2012
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Plants leaves are sealed with a gas-tight wax layer to prevent water loss. Plants breathe through microscopic pores called stomata (Greek for mouths) on the surfaces of leaves. Over 40% of the carbon dioxide, CO2, in the ...
Biotechnology
Feb 5, 2012
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Scientists have for the first time measured how fast large-scale evolution can occur in mammals, showing it takes 24 million generations for a mouse-sized animal to evolve to the size of an elephant.
Evolution
Jan 30, 2012
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Dwarfism ( /ˈdwɔrfɪzəm/) is short stature resulting from a medical condition. It is sometimes defined as an adult height of less than 4 feet 10 inches (147 cm), although this definition is problematic because short stature in itself is not a disorder.
Dwarfism can be caused by about 200 distinct medical conditions, such that the symptoms and characteristics of individual people with dwarfism vary greatly. In the United States, Canada and New Zealand, many people with dwarfism prefer to be called little people.
Disproportionate dwarfism is characterized by one or more body parts being relatively large or small in comparison to those of an average-sized adult, with growth variations in specific areas being apparent. In cases of proportionate dwarfism, the body appears normally proportioned, but is unusually small. Historically, the term midget was used to describe "proportionate dwarfs"; however, this term has now become offensive and pejorative (see terminology). Hypotonia, or low muscle tone, is common in dwarfs, but intelligence and lifespan are usually normal.
Achondroplasia is a bone-growth disorder responsible for 70% of dwarfism cases. With achondroplasia, one's limbs are proportionately shorter than one's trunk (abdominal area), with a larger head than average and characteristic facial features. Conditions in humans characterized by disproportional body parts are typically caused by one or more genetic disorders in bone or cartilage development. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth-hormone deficiency, once called pituitary dwarfism.
There is no single treatment for dwarfism. Individual differences, such as bone-growth disorders, sometimes can be treated through surgery, and some hormone disorders can be treated through medication, but usually it is impossible to treat all the symptoms of dwarfism. Individual accommodations, such as specialized furniture, are often used by people with dwarfism. Many support groups provide services to aid individuals with dwarfism in facing the challenges of an ableist society.
Dwarfism is a highly visible condition and often carries negative connotations in society. Because of their unusual height, people with dwarfism are often used as spectacles in entertainment and portrayed with stereotypes. For a person with dwarfism, heightism can lead to ridicule in childhood and discrimination in adulthood.
Short stature can be inherited without any coexisting disease. Short stature in the absence of a medical condition is not generally considered dwarfism. For example, a short man and a short woman with average health will tend to produce children who are also short and with average health. While short parents tend to produce short children, persons with dwarfism may produce children of average height, if the cause of their dwarfism is not genetically transmissible or if the individual does not pass on the genetic variation.
This text uses material from Wikipedia, licensed under CC BY-SA