Encyclopedia of Evolution.pdf - Online Reading Center

0 Cenozoic era
opens the way to an understanding of mass extinctions,
followed by rapid evolution, that punctuate the history of life
on Earth (see punctuated equilibria). Modern geology, by
presenting a background of uniformitarian processes punctuated
by catastrophes such as asteroid impacts (see Permian
extinction; Cretaceous extinction), has preserved the
best of both 19th-century approaches: uniformitarianism and
catastrophism.
Further Reading
Benton, Michael. “The death of catastrophism.” Chap. 3 in When
Life Nearly Died: The Greatest Mass Extinction of All Time.
London: Thames and Hudson, 2003.
Gould, Stephen Jay. “Uniformity and catastrophe.” Chap. 18 in Ever
Since Darwin: Reflections in Natural History. New York: Norton,
1977.
Cenozoic era The Cenozoic era (the era of “recent life”)
is the third era of the Phanerozoic Eon, or period of visible
multicellular life, which followed the Precambrian time in
Earth history (see geological time scale). The Cenozoic
era, which is the current era of Earth history, began with the
mass extinction event that occurred at the end of the Cretaceous
period of the Mesozoic era (see mass extinctions;
Cretaceous extinction). The Cenozoic era is traditionally
divided into two geological periods, the Tertiary period
and the Quaternary period.
The Cretaceous extinction left a world in which many
organisms had died and much space and many resources were
available for growth. The dinosaurs had become extinct,
as well as numerous lineages within the birds, reptiles, and
mammals (see birds, evolution of; reptiles, evolution
of; mammals, evolution of). The conifers that had dominated
the early Mesozoic forests came to dominate only the
forests of cold or nutrient-poor mountainous regions in the
Cenozoic (see gymnosperms, evolution of). The flowering
plants evolved in the Cretaceous period but proliferated during
the Cenozoic era, into the forest trees that dominate the
temperate and tropical regions, and many shrubs and herbaceous
species (see angiosperms, evolution of). The explosive
speciation of flowering plants paralleled that of insect
groups such as bees, butterflies, and flies, a pattern most scientists
attribute to coevolution.
The Cenozoic world was cooler and drier than most of
previous Earth history. Climatic conditions became cooler and
drier during the late Cenozoic than they had been early in the
Cenozoic. During the middle of the Tertiary period, dry conditions
allowed the adaptation of grasses and other plants to aridity,
and the spread of grasslands and deserts. Grazing animals
evolved from browsing ancestors, taking advantage of the grass
food base (see horses, evolution of). Five million years ago,
the Mediterranean dried up into a salt flat. The coolest and driest
conditions began with the Quaternary period. About every
hundred thousand years, glaciers build up around the Arctic
Ocean and push southward over the northern continents (see
ice ages). Meanwhile, lower sea levels and reduced evaporation
result in drier conditions in the equatorial regions.
Many evolutionary scientists and geologists now divide
the Cenozoic era into the Paleogene (Paleocene, Eocene, Oligocene)
and the Neogene (Miocene, Pliocene, Pleistocene,
Holocene) rather than the traditional Tertiary and Quaternary
periods.
Chambers, Robert (1802–1871) British Publisher Born
July 10, 1802, Robert Chambers was a British publisher,
whose role in the development of evolutionary theory was
not widely known until after his death. Long before Darwin
(see Darwin, Charles) wrote his famous book (see origin
of species [book]), evolutionary thought was in the air in
Europe. The naturalist Buffon (see Buffon, Georges) had
presented a limited evolutionary theory in France in the 18th
century. Charles Darwin’s grandfather (see Darwin, Erasmus)
had speculated about the possibility, and the French scientist
Lamarck had proposed a scientific evolutionary theory
(see Lamarckism). In October of 1844, an anonymous British
book, Vestiges of the Natural History of Creation, presented
an evolutionary history of the Earth, from the formation of
the solar system and plant and animal life, including even
the origins of humankind. More than 20,000 copies sold in
a decade. Political leaders like American president Abraham
Lincoln, British Queen Victoria, and British statesmen William
Gladstone and Benjamin Disraeli read it. Poets, such as Alfred
Tennyson, and philosophers like John Stuart Mill did also.
Many scientists also read it (see Huxley, Thomas Henry).
The purpose of the book, said its author, was to provoke scientific
and popular discussion about evolution.
It certainly succeeded in this objective. Responses ranged
from enthusiasm to condemnation. A British medical journal,
Lancet, described Vestiges as “a breath of fresh air.” Physicist
Sir David Brewster wrote that Vestiges raised the risk of “poisoning
the fountains of science, and sapping the foundations
of religion.” Scottish geologist Hugh Miller published an
entire book, Foot-Prints of the Creator, as a rebuttal to Vestiges.
Charles Darwin called it a “strange, unphilosophical,
but capitally-written book,” and noted that some people had
suspected him of being the author. Huxley recognized it as
the work of an amateur whose author could “indulge in science
at second-hand and dispense totally with logic.” A professional
scientist would have dismissed the fraudulent claim
of the amateur scientist, Mr. W. H. Weekes, who claimed to
have created living mites by passing electric currents through
a solution of potassium ferrocyanate, a claim that the Vestiges
author was credulous enough to believe.
It was not until 1884, after Darwin’s death and evolutionary
science had become respectable, that the author was
officially revealed to be Robert Chambers, one of Britain’s
most successful publishers. Chambers had chosen to remain
anonymous because he feared the reputation of Vestiges
would hurt his business. (His company published, among
many other things, Bibles.) Because of Chambers’s interest in
science, some people, including Darwin, had already guessed
the identity of the notorious “Mr. Vestiges.”
Chambers and his older brother had begun their publishing
business by selling cheap Bibles and schoolbooks from