21
Fossil finds changed ideas about
how life began. The first example of an
articulated plesiosaur—Plesiosaurus
dolichodeirus—was discovered in 1823
by Mary Anning in Dorset, England.See also: Extinction and change 22 ■ Uniformitarianism 23 ■ Evolution by
natural selection 24–31 ■ The rules of heredity 32–33THE STORY OF EVOLUTION
History in Paris, he argued that
traits acquired by a creature during
its lifetime could be inherited by
its offspring—and that a buildup
of such changes over many
generations could radically alter
an animal’s anatomy.
Lamarck wrote several books
in which he developed this idea
of transmutation. He argued, for
instance, that the use or nonuse of
body parts eventually resulted in
such features becoming stronger,
weaker, bigger, or smaller in a
species. For example, the ancestors
of moles probably had good
eyesight, but over generations
this deteriorated because moles did
not require vision as they burrowed
underground. Similarly, giraffes
gradually developed longer necks
to enable them to reach leaves
growing high up in trees.Drivers of evolution
Larmarck’s ideas about inherited
acquired traits were part of a wider
early theory of evolution. He also
believed that the earliest, simplest
forms of life had emerged directly
from nonliving matter. Lamarck
identified two main “life forces”
driving evolutionary change. One,
he believed, made organismsdevelop from simple to more
complex forms in a “ladder” of
progress. The other, via the
inheritance of acquired traits,
helped them adapt better to their
environment. When Charles Darwin
developed his theory of evolution
by means of natural selection, he
would reject many of Lamarck’s
ideas, but both men shared the
belief that complex life evolved
over an immense period of time. ■Jean-Baptiste
LamarckBorn in 1744, Jean-Baptiste
Lamarck attended a Jesuit
college before joining the
French army. Forced by an
injury to resign, he studied
medicine and then pursued
his passion for plants, working
at the Jardin du Roi (Royal
Garden) in Paris. Supported
by the Comte de Buffon,
Lamarck was elected to the
Academy of Sciences in 1779.
When the Jardin’s main
building became the new
National Museum of Natural
History during the French
Revolution (1789–99), Lamarck
was placed in charge of the
study of insects, worms, and
microscopic organisms. He
coined the biological term
“invertebrate” and often used
the relatively simpler forms of
such species to illustrate his
“ladder” of evolutionary
progress. However, Lamarck’s
work was controversial and
he died in poverty in 1829.Key works1802 Research on the
Organization of Living Bodies
1809 Zoological Philosophy
1815–22 Natural History of
Invertebrate Animals...continuous use of
any organ gradually
strengthens, develops
and enlarges that organ.
Jean-Baptiste LamarckUS_020-021_Early_theories.indd 21 12/11/18 6:24 PM