Download 05 Evolutions Major Contributors

Major Contributors to
Modern Evolutionary
Theory
…even this theory evolved from
something!
Throughout history
there have been
many contributions to
theories involving the
origin and evolution of
species and the
earth…
 The
Ancient Greeks: they believed in the
transmutation of forms:
 Aristotle: proposed the ladder of gradual
transition, from inanimate objects to
perfect Greek men
 Christian Europeans: believed that all
animals were created by God and then
saved by Noah
Irish Archbishop James
Ussher of Armagh 15811656
 declared the earth was created on
Sunday, October 23rd, 4004 BC
 based estimate on astronomy, history, and
biblical sources
Ussher cont’d
Early beliefs held that organisms and the
earth were immutable
Immutable: unchanged and unchanging
Leonardo Da vinci
(15th century)
 Found
fossils of sea shells in the
mountains of Tuscany
 He postulated that they were deposited in
an ancient sea
 Concluded that the earth’s surface
changed dramatically over time
Nicolas Steno (Danish
scientist in Anatomy and
Geology) 1669
analysed fossils, showed that they were in
fact mineralized remains of living
organisms
 the idea that the earth’s surface changed
over time was burgeoning

Baron George Cuvier (French
zoologist/palaeontologist)18th
Century
 One
of the earliest palaeontologists, he
studied differences in species composition
between sedimentary strata
 He found that all strata contained fossils of
simple organisms but only younger strata
contained fossilized complex organisms
 Further…
The Baron cont’d
 Further,
fossils contained in younger strata
resembled living organisms
 In addition, each layer contained fossilized
species distinct from the layers above and
below
Catastrophism: local catastrophes cause
extinctions; extinct species are then
replaced by newly created species
 This did not account for the progressive
complexity of species throughout time
James Hutton (Scottish
scientist and medical
doctor) 1795
 Formally
proposed his theory of Actualism
which countered Cuvier’s Catastrophism
Actualism: the same geological processes
occurring in the present also occurred in
the past
Charles Lyell (English Lawyer
and Geologist) 1830
 Built
on Hutton’s Actualism with his
principles of Uniformitarianism
 In his now-famous book, The Principles of
Geology he proposed the following
arguments:
1. Wait for it….
cont’d
1.
2.
3.
The earth has been changed by the
same processes in the past as can be
observed in the present
Geological change is slow and gradual
rather than sudden and catastrophic
Natural laws are constant/eternal and
operated with the same intensity in both
the past and the present
 So,
the earth is really old, and things can
change dramatically over long periods of
time as the result of ongoing, slight
processes…got it.
The work of Hutton and Lyell
provided the foundation on which
other scientists could build theories
about the history of life on earth
Georges-Louis Leclerc,
Comte de Buffon
18th century
 Proposed
that species could change over
time and that these changes could lead to
new organisms
Carl Linnaeus
18th century
 The
founder of biological nomenclature
 Proposed that relatively few species had
formed many new species through
interbreeding
Erasmus Darwin
18th century
 Proposed
that all life originated from a
single cell
 Believed that humans may be closely
related to primates but could not suggest a
mechanism to explain how evolution might
have occurred
Jean Baptiste Pierre Antione de
Monet, Chevalier de La Marck
19th century
 Recognised
the influence of the
environment on evolution
 Proposed that species must be able to
adapt to the changing environment if they
are to survive
Lamarck cont’d
 Building
on others’ ideas, he postulated on
inheritance of acquired traits (or did he?)
 E.g.: over a giraffes’ lifetime, reaching high
for food may cause a slight elongation of
the neck
 he believed this trait could be passed on
 We now know this to be false but it paved
the way for future theories
Thomas Malthus
late 18th century
 His
Principle of Population Growth stated:
Populations increase geometrically while
food sources increase arithmetically; these
environmental conditions create
competition
Charles Darwin
19th century
 collected
and observed species mainly
from South America and the Galapagos
islands
 Incorporating elements from many of his
predecessors, including Lamarck, Malthus,
etc. he recognised that inheritable traits
which resulted in increased survival rates
contributed to the evolution of species
Darwin cont’d
 Darwin
entitled his theory, Natural
Selection
Alfred Russel Wallace
19th century
 Simultaneously
to Darwin postulated the
evolutionary theory: Survival of the Fittest
 The theory was fundamentally the same
as Natural Selection however, Darwin’s
extensive research elevated his work to
prominence