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Evolution
By Fehmi Alkas
What is evolution ?
• Evolution is the change in
the inherited traits of
a population of organisms through successive
generations.(1)
• Primary mechanism by which evolution occurs
is natural selection.
Charles Robert Darwin
•Born in England in 1809.
•Developed the Theory of Evolution with
contributions from Alfred Russell
Wallace.
•Differentiation among birds in different
zones gave him the idea that in a
particular environment, only the species
that are best adapted to that
environment are likely to survive. This is
known as natural selection.
•Published On The Origin of Species in
1859.
•Widely criticised by the Fundametalists.
Mutations
• Mutations are random changes in an
organism’s DNA that can have various effects.
• Mutations can have a wide range of effects :
Some of them are fatally impairing but most
have no or little effect on the organism.
• A little proportion of mutations actually cause
a change that will make the organism more fit
to survive. It is these mutations that evolution
mainly depends on.
Natural Selection
• In any environment, there will
be some subspecies that will
have superior traits to the
mainstream population e.g.
Better vision or hearing.
• These subspecies will have a
lower probability of being
predated as they can sense
predators from a greater
distance and run away more
easily.
• In time, all the members of
the species will be the better
type.
• Example
X : Normal, Y: Better Sight
90 X, 10 Y
Y: 10 %
Predation or Next Generation
70 X, 8 Y
Y: 10.3 %
Predation or Next Generation
50 X, 7 Y
Y: 12.3 %
Key points to natural selection
• Not all of the offspring produced by a generation
survives. In fact, most of the offspring produced by a
generation is going to die before producing any
offspring themselves.
• It does not mean that the better organisms will
always survive and the less functional ones will die.
• An almost perfect organism can still die sue to factors
purely dependent on luck e.g. Velociraptor,
Tyrannosaurus Rex and Carcharodon Megalodon
were among the deadliest predators ever roamed
the Earth but nonetheless they are extinct.
• Evolution does not happen overnight : It takes
thousands, even million years for a small change in the
general population to happen.
• It does not advance in definitive steps : It rather
advances in small, smooth steps that eventually give
result to something fundamentally different. Therefore,
it’s a continuous process.(2)
• It does not result in freak creatures : An intermediate
between an ape and a human is NOT an ape with the
arm of a human. It is more likely to be an ape with the
ability to stand on two feet or an ape with decreased
fur.
References
• http://en.wikipedia.org/wiki/Charles_Darwin
• http://en.wikipedia.org/wiki/Evolution
• http://www.wisegeek.com/contest/how-doesevolution-work.htm
• http://necsi.org/projects/evolution/evolution/5parts
/evolution_5parts.html