C. Creation and Evolution
We begin with a brief scientific overview of evolutionary
biology.
Science minisummary: evolutionary biology.
Evolutionary biology rests on two principles: variation and selection. Natural selection was
proposed by Charles Darwin in his 1859 publication, The Origin of Species.It is a process that promotes or maintains adaptation by filtering out among
the variations in progeny those most fit to survive, and thus gives creatures
the appearance of purpose or design. What was missing for Darwin was a theory
of inheritance that would explain the basis and preservation of variations on
which natural selection could act. Simultaneous with Darwins work, but unknown
to him, the Augustinian monk Gregor Mendel developed just what was needed in
his study of peas. In 1900, Mendels genetic theory of heredity was
rediscovered by evolutionary biologists. After several decades of research by
geneticists such as R. A. Fisher, J. B. S. Haldane, and Sewall Wright, and
culminating in the work of Theodosius Dobzhansky in 1937, Mendelian genetics
was fully integrated into Darwins theory of natural selection in what is now
called the modern or synthetic theory of evolution. In 1953, James Watson and
Francis Crick discovered the molecular structure of DNA, the hereditary
material contained in the chromosomes of the nucleus of each cell. DNA in turn
consists of two long chains of nucleotides coiled into a double helix. A gene
is a sequence of nucleotides required for the production of a specific protein;
the information needed is encoded in the specific sequence of these
nucleotides. The DNA molecule is copied during routine cell division (mitosis)
as well as during sexual reproduction (meiosis), thus preserving and
transmitting hereditary information. Miscopying and other forms of genetic
mutation constitute a major source of biological variation.
In recent decades, the modern synthesis has been extended to
include paleontology, comparative anatomy, biogeography, embryology and
molecular genetics. Research areas include the processes of speciation, gradual
versus punctuated evolution, protein evolution, the neutrality theory of
molecular evolution, the molecular evolutionary clock, multiple forms of
selection at the level of gene, organism, kin, group, and species, and the
possibility of additional sources of biological novelty besides mutation and
selection. There are also a variety of scientific theories pushing the
frontiers of evolutionary and molecular biology from the perspective of
physics, including chaos, complexity, and self-organization, particularly
through the work of Stuart Kauffman. Moreover, research on human evolution is
focusing on what distinguishes our species from other early hominids, including
such possibilities as bipedalism, brain size, language and tools, as well as on
the biological basis of morality.
Contributed by: Dr. Robert Russell
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