The Science Book

74

NATURE DOES NOT

PROCEED BY LEAPS

AND BOUNDS

CARL LINNAEUS (1707–1778)

T

he classification of the

natural world into a clear

hierarchy of groups of

named and described organisms is

a foundation stone of the biological

sciences. These groupings help

to make sense of life’s diversity,

allowing scientists to compare

and identify millions of individual

organisms. Modern taxonomy—

the science of identifying, naming,

and classifying organisms—began

with the Swedish naturalist, Carl

Linnaeus. He was the first to devise

a systematic hierarchy, based on

his wide-ranging and detailed

study of physical characteristics

of plants and animals. He also

pioneered a way of naming different

organisms that is still in use today.

The most influential of early

classifications was that of the

Greek philosopher Aristotle. In his

History of Animals, he grouped

similar animals into broad genera,

distinguished the species within

each group, and ranked them on a

scala naturae or “ladder of life” with

11 grades of increasing complexity

in form and purpose, from plants at

the base to humans at the apex.

Over the ensuing centuries, a

chaotic multiplicity of names and

descriptions of plants and animals

Linnaeus’s system groups organisms

according to shared characteristics. A

tiger belongs to the cat family Felidae,

which in turn belongs to the order

Carnivora, in the class Mammalia.

IN CONTEXT

BRANCH

Biology

BEFORE

c.320 BCE Aristotle groups

similar organisms on a scale

of increasing complexity.

1686 John Ray defines a

biological species in his

Historia Plantarum.

AFTER

1817 French zoologist Georges

Cuvier extends the Linnaean

hierarchy in his study of fossils

as well as living animals.

1859 Charles Darwin’s On the

Origin of Species sets out how

species arise and are related in

his theory of evolution.

1866 German biologist Ernst

Haeckel pioneers the study of

evolving lineages, known as

phylogenetics.

1950 Willi Hennig bases a

new system of classification

on cladistics, which looks for

evolutionary links.

appeared. By the 17th century,

scientists were striving to set out

a more coherent and consistent

system. In 1686, English botanist

John Ray introduced the concept

of the biological species, defined

by the ability of plants or animals

to reproduce with one another,

and this remains the most widely

accepted definition today.

SPECIES

Panthera

tigris

KINGDOM

Animalia

PHYLUM

Chordata

CLASS

Mammalia

ORDER

Carnivora

FAMILY

Felidae

GENUS

Panthera