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Darwin's theory of evolution by natural selection is the only scientific explanation for why an animal's behaviour is usually well adapted for survival and reproduction in its environment. However, claiming that a particular mechanism is well suited to the present environment is different from claiming that this mechanism was selected for in ...
Trait theory tends to focus on the individual over the situation in which they are in. [10] This focus has relaxed within modern studies allowing for a consideration of the external factors outside of the self. As the focus becomes more relaxed (but still prominent as it is a main part of the theory) research expands.
For example, Brian Little's free trait theory [48] [49] suggests that people can take on "free traits", behaving in ways that may not be their "first nature", but can strategically advance projects that are important to them. Together, this presents an optimistic view of what extraversion is.
His studies on sex-limited traits have been further substantiated and supported over time, distinguishing sex-limited genes and sex-linked traits. Modern study of sex-limited genes includes research on epigenetics , which is the study of inheritable phentotypic changes with no change in DNA sequence.
Such traits, particularly body fat distribution, may represent sexual ornamentation, which is important in mating throughout the animal kingdom, for example, in birds. [ 113 ] [ 114 ] Humans also use bodily decoration, including jewelry, tattoos, scarification, and makeup to enhance appearance and desirability to potential mates.
In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype. [5] Atavisms are often seen as evidence of evolution. [6] In social sciences, atavism is the tendency of reversion: for example, people in the modern era reverting to the ways of thinking and acting of a former time.
Autosomal dominant A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
In evolutionary biology, an evolutionary tradeoff is a situation in which evolution cannot advance one part of a biological system without distressing another part of it. In this context, tradeoffs refer to the process through which a trait increases in fitness at the expense of decreased fitness in another trait.