60
ONE SPECIES NEVER
SPRINGS FROM THE
SEED OF ANOTHER
JOHN RAY (1627–1705)
T
he modern concept of a
plant or animal species
is based on reproduction.
A species includes all individuals
that can actually or potentially
breed together to produce offspring,
which in turn can do the same. This
concept, first introduced by English
natural historian John Ray in 1686,
still underpins taxonomy—the
science of classification, in which
genetics now plays a major role.Metaphysical approach
During this period, the term
“species” was in common usage,
but intricately connected with
religion and metaphysics—anapproach persisting from ancient
Greece. The Greek philosophers
Plato, Aristotle, and Theophrastus
had discussed classification and
used terms such as “genus” and
“species” to describe groups and
subgroups of all manner of things,
living or inanimate. In doing so,
they had invoked vague qualities
such as “essence” and “soul.” So
members belonged to a species
because they shared the same
“essence,” rather than sharing the
same appearance or the ability to
breed with one another.
By the 17th century, myriad
classifications existed. Many were
organized in alphabetical order, orIN CONTEXT
BRANCH
BiologyBEFORE
4th century BCE The Greeks
use the terms “genus” and
“species” to describe groups
of similar things.1583 Italian botanist Andrea
Cesalpino classifies plants
based on seeds and fruits.1623 Swiss botanist Caspar
Bauhin classifies more than
6,000 plants in his Illustrated
Exposition of Plants.AFTER
1690 English philosopher John
Locke argues that species are
artificial constructs.1735 Carl Linnaeus publishes
Systema Naturae, the first of
his many works classifying
plants and animals.1859 Charles Darwin proposes
the evolution of species by
natural selection in On the
Origin of Species.One species never
springs from the seed
of another.Plants make seeds that
grow into new plants.Seeds nearly always grow
into plants similar to the
parent plant.A plant seed does not
grow into an adult of
a different species from
its parent.