Biology Reference
In-Depth Information
species had a separate origin by some unspecified natural mechanism and does not
change with time, but may become extinct.
Transformism
supposes that species have separate origins, possibly at different
times, but can change with time, and may become extinct.
Evolutionism
supposes that all species have a common origin, can change with
time and may become extinct.
Each red line in Fig. 3.5 represents a single species. Vertical red lines indicate
that species do not change with time between generations, while red lines sloping
either to the left or to the right indicate that species do change with time between
generations. If you compare these three hypotheses in terms of Occam's razor, you
see that evolution is simpler because it supposes only one origin of life, while the
other two suppose as many origins as there are species. None of these hypotheses
however, explains either how life originated or how the diversity arose. Explaining
the origin of the first living cells is one of the most challenging unsolved problems in
biology, but explaining the origin of life's diversity is one of the intellectual triumphs
of science. This explanation is called the theory of evolution by natural selection,
proposed by Charles Darwin.
Prior to Darwin, most people thought that each species was created separately
and persisted unchanged. Religious people thought in addition, that the act of cre-
ation was performed by a supernatural entity of some sort, but remember, science
works within a naturalistic framework and looks for natural causes of natural events.
So the problem is to find a testable natural explanation of the huge diversity found
in the living world. The explanation that is accepted by biologists today was sug-
gested by Charles Darwin in a topic, the full title of which is
On the Origin of
Species by Means of Natural Selection.
The first edition was published in 1859 and
the sixth edition in 1872. The 200th anniversary of Darwin's birth and the 150th
anniversary of the first publication of his famous topic occurred in 2009, and these
anniversaries were celebrated around the world. The publication of
On the Origin
of Species
marks a turning point in the history of science - the point where nature
study became the unified discipline that we now call biology.
The Early Life of Charles Darwin
Charles Darwin was an English naturalist born into a wealthy family living in
Shrewsbury. When young, he had a passion for all things outdoors, and collected
birds' eggs and minerals. At the age of nine he entered Shrewsbury Grammar School
where he was taught Greek and Latin, which he hated and learnt very badly, but
received no tuition in either science or sports. The headmaster described him as
“a very ordinary boy, rather below the common standard in intellect” so his father
withdrew him from school at the age of 16. His father was a popular and successful
doctor, and wanted Charles to follow in his footsteps, so he sent him to Edinburgh
University where Charles' brother was studying medicine. Unlike today, you did
not need any exam passes or any qualifications at all to enter university - all you
