The Ecology Book

F

or the earliest humans,

a rudimentary knowledge

of ecology—how organisms

relate to one another—was a matter

of life and death. Without having

a basic understanding of why

animals grazed in a certain place

and fruit-bearing plants grew in

another, our ancestors would not

have survived and evolved.

How living animals and plants

interact with each other, and

with the nonliving environment

interested the ancient Greeks.

In the 4th century BCE, Aristotle

and his student Theophrastus

developed theories of animal

metabolism and heat regulation,

dissected birds’ eggs to discover

how they grew, and described

an 11-level “ladder of life,” the first

attempt at classifying organisms.

Aristotle also explained how some

animals consume others—the first

description of a food chain.

In the Middle Ages (476–1500),

the Catholic Church discouraged

new scientific thought, and human

understanding of ecology advanced

very slowly. By the 16th century,

however, maritime exploration,

coupled with great technological

advances, such as the invention

of the microscope, led to the

discovery of amazing life forms and

a thirst for knowledge about them.

Swedish botanist Carl Linnaeus

developed a classification system,

Systema Naturae, the first scientific

attempt to name species and

group them according to

relatedness. Throughout this

time, essentialism—the idea that

each species had unalterable

characteristics—continued to

dominate Western thought.

Great breakthroughs

Geological discoveries in the late

17th and early 18th centuries began

to challenge the idea of essentialism.

Geologists noted that some fossil

species suddenly disappeared

from the geological record and were

replaced by others, suggesting that

organisms change over time, and

even become extinct. The

Frenchman Jean-Baptiste Lamarck

proposed the first cohesive theory

of evolution—the transmutation

of species by the inheritance of

acquired characteristics—in 1809.

However, some 50 years later it was

Charles Darwin—influenced by his

experiences on the epic expedition

of HMS Beagle—and Alfred Russel

Wallace, who developed the concept

of evolution by means of natural

selection, the theory that organisms

evolve over the course of generations

to adapt better to their environment.

Darwin and Wallace did not

understand the mechanism by

which this happened, but Gregor

Mendel’s experiments on peas

pointed at the role of hereditary

factors later known as genes,

representing another giant leap in

evolutionary theory.

Making connections

The relationships between

organisms and their environment,

and between species, dominated

ecological study in the early

20th century. The concepts of

food chains and food webs (who

eats what in a particular habitat)

and ecological niches (the role an

organism has in its environment)

developed, and in 1935, Arthur

INTRODUCTION

There are some 4 million

different kinds of animals and

plants in the world. Four

million different solutions to

the problems of staying alive.

David Attenborough

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