An example of
evolution resulting from natural
selection was discovered among "peppered" moths living near English industrial
cities. These insects have varieties that vary in wing and body coloration from
light to dark. During the 19th century, sooty smoke from coal burning furnaces
killed the lichen on trees and darkened the bark. When moths landed on these trees
and other blackened surfaces,
the dark colored ones were harder to spot by birds who ate them and, subsequently, they
more often lived long enough to reproduce. Over generations, the environment
continued to favor darker moths. As a result, they progressively became more
common. By 1895, 98%
of the moths in the vicinity of English cities like Manchester
were mostly black. Since the 1950's, air pollution controls have significantly reduced the amount of
heavy particulate air pollutants reaching the trees, buildings, and other
objects in the environment. As a result, lichen has grown back, making trees
lighter in color. In addition, once blackened buildings were cleaned
making them lighter in color. Now, natural selection favors lighter moth varieties so they have
become the most common. This trend has been well documented by field
studies undertaken between 1959 and 1995 by Sir Cyril Clarke from the University
of Liverpool. The same pattern of moth wing color evolutionary change in
response to increased and later decreased air pollution has been
carefully documented by other researchers for the countryside around Detroit, Michigan.
While it
is abundantly clear that there has been an evolution in peppered moth
coloration due to the advantage of camouflage over the last two centuries, it
is important to keep in mind that this story of natural selection in action
is incomplete.
There may have been additional natural selection factors
involved.
Jaryn Olson on 30 Jan 13"Description of efforts by some criminal defendants to negate criminal responsibility by showing that they could not tell right from wrong due to abuse by their spouses or parents. Although this defense is not specifically recognized in substantive Criminal Law, it has been used successfully in some cases to prove, for example, the Insanity Defense. Using prior sexual or other physical abuse as evidence in a criminal defense is largely a result of research regarding mental disorders caused by such abuse. Psychologists and other researchers have identified disorders, including post-traumatic stress disorder and battered woman syndrome, as causes for severe emotional instability that can lead to violent acts by the victim against his or her abuser. Some writers have advocated more widespread use of such evidence to mitigate the punishment of victims who commit violent acts. Other scholars and writers disagree, noting that substantive criminal law does not recognize the abuse excuse as a legitimate defense except in some limited circumstances, such as those involving the insanity defense. Harvard law professor alan dershowitz coined the term in his 1994 book, The Abuse Excuse, where he deems the studies regarding psychological disorders caused by abuse as "psychobabble." Dershowitz and other critics disagree not only with the use of abuse as mitigating evidence of criminal intent, but also with the results of the studies themselves. According to these critics, especially Dershowitz, the abuse excuse fails to distinguish between the reasons why a person committed a crime and the responsibility for committing the crime. In a few high profile cases during the late 1980s and 1990s, defendants sought to avoid criminal responsibility for their crimes by introducing evidence of prior abuse. In 1989, Lyle and Erik Menendez, ages 21 and 18 respectively, brutally killed their parents in the family's California home. At their first trial for murder in 1993, the brothers' defen
