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Examples of human phenotypic variability: people with different levels of skin colors, a normal distribution of IQ scores, the tallest recorded man in history - Robert Wadlow - with his father. Human variability , or human variation , is the range of possible values for any characteristic, physical or mental , of human beings .
Population bottleneck followed by recovery or extinction. A population bottleneck or genetic bottleneck is a sharp reduction in the size of a population due to environmental events such as famines, earthquakes, floods, fires, disease, and droughts; or human activities such as genocide, speciocide, widespread violence or intentional culling.
The study of human genetic variation has evolutionary significance and medical applications. It can help scientists reconstruct and understand patterns of past human migration. In medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in certain population groups.
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
The variability hypothesis, also known as the greater male variability hypothesis, is the hypothesis that males generally display greater variability in traits than females do. It has often been discussed in relation to human cognitive ability , where some studies appear to show that males are more likely than females to have either very high ...
Varieties of maize in the office of the Russian plant geneticist Nikolai Vavilov. A study conducted by the National Science Foundation in 2007 found that genetic diversity (within-species diversity) and biodiversity are dependent upon each other — i.e. that diversity within a species is necessary to maintain diversity among species, and vice versa.
Research has shown that non-SNP variation accounts for more human genetic variation than single nucleotide diversity. Structural variation includes copy-number variation and results from deletions, inversions, insertions and duplications. It is estimated that approximately 0.4 to 0.6 percent of the genomes of unrelated people differ.
For example, in 2001 Wolpoff and colleagues published an analysis of character traits of the skulls of early modern human fossils in Australia and central Europe. They concluded that the diversity of these recent humans could not "result exclusively from a single late Pleistocene dispersal", and implied dual ancestry for each region, involving ...