Shifting balance theory Shifting balance theory The shifting balance theory is a theory of evolution proposed in 1932 by Sewall Wright, suggesting that adaptive evolution may proceed most quickly when a population divides into subpopulations with restricted gene flow. The name of the theory is borrowed from Wright's metaphor of fitness landscapes (evolutionary landscapes), attempting to explain how a population may move across an adaptive valley to a higher adaptive peak. According to the theory, this movement occurs in three steps: Although shifting balance theory has been influential in evolutionary biology, inspiring the theories of quantum evolution and punctuated equilibrium, little empirical evidence
The Evolution of Beauty The Evolution of Beauty The Evolution of Beauty: How Darwin's Forgotten Theory of Mate Choice Shapes the Animal World—and Us is a 2017 book by the ornithologist and evolutionary biologist Richard O. Prum about the power of aesthetic mate choice arguing it to be an important independent agent in evolution. Prum indicates that while Charles Darwin made this argument in "The Descent of Man" published in 1871, the concept was sidelined and forgotten, and the notion of natural selection being the sole driver of evolution took over. As an ornithologist, Prum describes many examples in avian evolution where aesthetics are