118
See also: William Smith 115 ■ Mary Anning 116–17 ■ Charles Darwin 142–49 ■
Gregor Mendel 166–71 ■ Thomas Hunt Morgan 224–25 ■ Michael Syvanen 318–19I
n 1809, French naturalist
Jean-Baptiste Lamarck
introduced the first major theory
that life on Earth has evolved over
time. The impetus to his theory
was the discovery of fossils of
creatures unlike any alive today.
In 1796, French naturalist Georges
Cuvier had shown that fossilized
elephant-like bones were markedly
different in anatomy from the bones
of modern elephants, and must
come from extinct creatures now
called mammoths and mastodons.
Cuvier explained the vanished
creatures of the past as victims of
catastrophes. Lamarck challenged
this idea, and argued that life
had “transmutated,” or evolved,
gradually and continuously through
time, developing from the simplest
life forms to the most complex. A
change in the environment, he
suggested, could spur a change in
the characteristics of an organism.
Those changes could then be
inherited through reproduction.
Characteristics that were useful
developed further; those that were
not useful might disappear.Lamarck believed characteristics
were acquired during a creature’s
life and passed on. Later, Darwin
showed that changes occur because
mutations at conception survive
to be passed on through natural
selection, and the idea of “acquired
characteristics” was ridiculed. But
recently, scientists have argued that
the environment—chemicals, light,
temperature, and food—can in fact
alter genes and their expression. ■THE INHERITANCE
OF ACOUIRED
CHARACTERISTICS
JEAN-BAPTISTE LAMARCK (1744–1829)
IN CONTEXT
BRANCH
BiologyBEFORE
c.1495 Leonardo da Vinci
suggests in his notebook that
fossils are relics of ancient life.1796 Georges Cuvier proves
that fossil bones belong to
extinct mastodons.1799 William Smith shows the
succession of fossils in rock
strata of different ages.AFTER
1858 Charles Darwin
introduces his theory of
evolution by natural selection.1942 The “modern synthesis”
reconciles Gregor Mendel’s
genetics with Darwin’s natural
selection, paleontology, and
ecology in trying to explain
how new species arise.2005 Eva Jablonka and Marion
Lamb claim that nongenetic,
environmental, and behavioral
changes can affect evolution.What nature does in the
course of long periods we do
every day when we suddenly
change the environment in
which some species of living
plant is situated.
Jean-Baptiste Lamarck