The Ecology Book

90

ORGANISMS

CLEARLY CLUSTER

INTO SEVERAL

PRIMARY KINGDOMS

A MODERN VIEW OF DIVERSITY

B

efore biologists had the

equipment and techniques

needed to scrutinize the

microscopic structure of living

things, biological diversity was

split simply into animal-like and

plant-like organisms. Then, in the

20th century, better microscopes

began to reveal deeper differences

that could not be seen with the

naked eye. By the 1960s, picking

up on an idea first proposed by

Edouard Chatton in the 1930s, the

need for a new division of living

things emerged, placed between

prokaryotes (such as bacteria,

with simple nucleus-free cells),

and eukaryotes (such as animals

and plants with larger, more

complex cells).

In the 1970s, the American

biologist Carl Woese claimed that

even this system failed to account

for the diversity among microbes—

the smallest living things. He

focused on ribosomes—minuscule

IN CONTEXT

KEY FIGURE

Carl Woese (1928–2012)

BEFORE

1758 Systema Naturae (10th

edition) by Carl Linnaeus

classifies known life into two

kingdoms: animals and plants.

1937 French biologist Edouard

Chatton divides life into

prokaryotes (bacteria) and

eukaryotes (organisms with

complex cells).

1966 German biologist Willi

Hennig establishes a system

of classification based on

clades—groups of organisms

based on common ancestry.

1969 American ecologist

Robert Whittaker divides

life into five kingdoms:

bacteria, protists, fungi,

plants, and animals.

AFTER

2017 A consensus among

biologists accepts a seven-

kingdom classification of life.

Sulfur-dependent archaea

organisms thrive in the hot geothermal

pools of Yellowstone National Park,

Wyoming, in conditions that would

kill most other organisms.

US_090-091_Modern_view_of_diversity.indd 90 12/11/2018 17:34