FREE ESSAY ON DARWIN BEAGLES

DARWIN BEAGLES

Biology came of age on November 24, 1859, the day Charles Darwin published On The Origin 
of Species by Means of Natural Selection. His book presented the first convincing case
for 
evolution and led the way in the emergence of biology from a bewildering chaos of facts
into a 
cohesive science. In biology, evolution refers to all the changes that have transformed
life on 
Earth from its earliest beginnings to the seeningly infinite diversity that characterizes
it today. 
Darwin addressed the sweeping issues of biology: the great diversity of organisms, their
origins 
and relationships, their similarities and differences, their geographical distribution,
and their 
adaptations to the surrounding environment. 
Darwin made two points in The Origin of Species. First, he argued from the evidence that

species were not specifically created in their present forms, but had evolved from
ancestral 
species. Second, Darwin described a mechanism for evolution, which he termed natural
selection. 
Evolutionary change is based mainly on the interactions between populations of organisms
and 
their environments. The Origin of Species was truly radical, for not only did it
challenge 
prevailing scientific views, but it also shook the deepest roots of Western culture.
Darwin's view 
of life contrasted sharply with the conventional paradigm of an Earth only a few thousand
years 
old, populated by immutable (unchanging) forms of life that had been individually made by
the 
Creator during the single week in which he formed the entire universe. Darwin's ideas
subverted a 
world view that had been taught for centuries.
THE VOYAGE OF THE BEAGLE --- Darwin was 22 years old when he sailed from England 
with the Beagle in December 1831. The primary mission of the voyage was to chart poorly 
known stretches of the South American coastline. While the crew of the ship surveyed the
coast, 
Darwin spent most of his time on shore, collecting thousands of specimens of the exotic
and 
exceedingly diverse fauna and flora of South America. 
As the ship worked its way around the continent, Darwin was able to observe the various 
adaptations of plants and animals that inhabited such diverse environments as the
Brazilian 
jungles, the expansive grasslands of the Argentine pampas, the desolate lands of Tierra
del Fuego 
near Antartica, and the towering heights of the Andes Mountains. He realized that the
fauna and 
flora were very distinct from the life forms of Europe. The plants and animals living in
temperate 
regions of South America were taxonomically closer to species living in tropical regions
of that 
continent than to species in temperate regions of Europe. Furthermore, the South American

fossils that Darwin found, though clearly different from modern species, were distinctly
South 
American in their resemblance to the living plants and animals of that continent. Darwin
was 
perplexed by the peculiarities of the geographical distribution of species. 
A particularly puzzling case of geographical distribution was the fauna of the Galapagos

Islands, which lie on the Equator about 900 km. west of the South American coast. Most of
the 
animal species on the Galapagos live nowhere else in the world, although they resemble
species 
living on the South American mainland. Among the birds Darwin collected on the Galapagos

were 14 types of finches that, although quite similar, seemed to be different species.
Some were 
unique to individual islands, while other species were distributed on two or more islands
that were 
close to each other. Darwin wondered about the relationships of the island finches to one
another 
and to the finches on the mainland, which were different. 
By the time the Beagle sailed from the Galapagos, Darwin had read Lyell's Principles of 
Geology. Darwin was doubting the church's position that the Earth was static and had been

created only a few thousand years ago. By acknowledging that the Earth was very old and 
constantly changing, Darwin had taken an important step toward recognizing that life on
Earth 
had also evolved. He would soon realize that evolution was the only rational explanation
for the 
relationships between the species he had collected, particularly those from the Galapagos
Islands.
At the time Darwin collected the Galapagos finches, he was not sure whether they were 
actually different species or merely varieties of a single species. Soon after returning
to England in 
1836, he learned from ornithologists (bird specialists) that the finches were indeed
separate 
species. He began to reassess all that he had observed during the voyage of the Beagle
and in 
1837 began the first of several notebooks on the origin of species.
Darwin began to perceive the origin of new species and adaptation as closely related 
processes. A new species would arise from an ancestral form by the gradual accumulation
of 
adaptations to a different environment. For example, if one species became fragmented
into 
several localized populations isolated in different environment by geographical barriers,
the 
populations would diverge more and more in appearance as each adapted to local
conditions, 
gradually, over many generations, becoming dissimilar enough to be designated separate
species. 
This is apparently what happened to the Galapagos finches. Among the differences between
the 
birds are their beaks, which are adapted to the specific foods available on their home
islands. 
Darwin anticipated that explaining how such adaptations arise was essential to
understanding 
evolution.
Bibliography
1. Biology by Neil A. Campbell C.1986
2. Aol.www.charlesdarwin.com