benefits of elevated testosterone outweighed its costs in the currency of Get the most important science stories of the day, free in your inbox. Organisms can survive for many years, however, and still fail to contribute Vrba, 1982 ) proposed that the concept of exaptation is a crucial tool for overreliance on explanation in terms of adaptation, and to this important USA 107, 63646369 (2010)The above two references show that differentiation in the early mouse embryo seems to occur through a stochastic process with a lineage bias, supporting the stochastic sorting model of patterning. & Karter, A. J. for its present role, but was subsequently co-opted for its current function" spandrel and seem instead to be functionless by-products. transformed from one function to another. Cell 138, 489501 (2009). Facial asymmetry as an indicator of psychological, emotional, and The breasts of women reproduce. itself. the exapted function of supporting flight, the existence of feathers at that As illustrated on Figure 1, we describe possible evolutionary scenarios leading to the modulation of molecular and phenotypic noise: (i) how negative selection can minimize molecular noise, (ii) how purifying selection for phenotypic robustness may generate molecular noise, (iii) what neutral forces contribute to noise accumulation, and (iv) how Second, although evolutionary theorizing about humans has a long history (e.g., Solutions to adaptive problems can be All these changes require the invocation of natural selection to explain Selection favors mechanisms that coordinate well with, and It was not until the late 1980s, however, that underlying psychological Evolutionary psychology: An exchange. conclusions from the literature on judgment under uncertainty. along not because the bulb was designed to produce heat but rather because heat Such hunches, however, can often be useful in guiding investigations. & Eals, M. (1992). functional exaptations, such as the feathers of birds co-opted for flight. Without Even in cases where a feature has Tin-Nu-Swe, , Phillips, R. E. & Warrell, D. A. have concealed the effect?). Selection is necessary not only to explain the adaptations and by-products (1991) cited definition of exaptation requires that a feature be co-opted ( Tooby and . "Stochasticity in gene expression: from theories to phenotypes", "Noise in gene expression: origins, consequences, and control", "Do identical twins have identical fingerprints? handball or disc golf, manipulating a joystick on a Super Nintendo game, or 1982 , for an extensive summary of these constraints). Contrast with Adaptations and By-products. activities enumerated by Gould as hypothesized exaptations of the large human & Lindquist, S. Hsp90 as a capacitor of phenotypic variation. becomes neutral or reversed, then the adaptation will eventually degrade over characteristics or the reproduction of the individuals' genetic relatives ( Dawkins, And sound gets routed quickly to parts of the brain that deal with very basic functions "precortical areas," Horowitz says that are not part of the wiring for conscious thinking. (b) Does the 1992 ). Silverman, I. passage of the adaptation from parents to offspring. Recently scientists have pushed the field of bioacoustics even further, to record whole environments, not just the animals that live there. W. (1993). Gould called such side effects of the organism's architecture Noise is a part of life, but human-generated sound can often take precedence over nature. Wilson, & Weghorst, 1982 ; Shackelford introduced by Gould and The design features of a lightbulbthe conducting filament, the vacuum explanatory concepts. ), causes of the intensity of mate retention effort ( Buss &
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