“You can’t expect a tiger to change its stripes.” Or so the adage goes.
Nor, apparently, can a leopard change its spots. Even the writers of
the Bible said so, centuries ago (Jeremiah 13:23). Namely, people
widely believe that every species has its own special “nature.” This
immutable essence is supposed to guide how the organism functions.
Indeed, an organism that does not fully express its “inner nature” is
considered by many as somehow unhealthy or incomplete. Only negative consequences can ensue (Griffiths, 2002, p. 79). Biologists
observe otherwise, of course. Yet this intuition – call it species essentialism (this month’s Sacred Bovine) – is widespread and can persist even
after evolution education. It is deeply rooted in our intuitive teleology
(Keleman & Rosset, 2009). Yet a few fascinating – and sometimes
playful – cases of color patterns in animals might prompt reflection,
questioning, and learning.
What Makes a Tiger a “Tiger”
The belief that a tiger’s stripes or a leopard’s spots are essential is
based foremost on a view that they exhibit an intended purpose.
In this case, the predator “must” be inconspicuous to prey. That
seemed clear even to Rudyard Kipling (no biologist himself), who
described it in one of his now classic Just So Stories, “How the Leopard Got His Spots.” The Leopard character moves from the fields to the jungle,
which is all “speckled and sprottled
and spottled, dotted and splashed and
slashed and hatched and cross-hatched
with shadows.” A bystander observes
his new spots and notes: “You can lie
out on a leafy branch and look like sunshine sifting through the leaves; and you
can lie right across the centre of a path
and look like nothing in particular.
Think of that and purr!” (Kipling, 1912,
p. 59). That is, the leopard’s spots – as
much as the tiger’s stripes – fulfill a
All the traits of a tiger apparently
Do All Tigers Have Stripes?
contribute to its “nature.” For amuse-
ment, imagine a tiger munching a tasty
salad: a vegetarian tiger?! No, the claws,
the huge canine teeth, the roar, the
stalking, the padded paws all seem to speak to its imagined “natural
purpose” of hunting animals.
Essentialism is based, first, on perceived purpose, but also
involves two other concepts: universality and fixity. Namely, all tigers
have stripes. And, as the adage indicates, they cannot change. They are
innate. Nowadays, that is viewed in terms of genetic determinism.
Purpose, universality, and fixity: together these features foster essen-
tialist views. Biologists, of course, know better. The essentialist view
is nowhere justified. Rather, it emerges from psychological tendencies.
So, to address the deep preconceptions, one needs startling images to
provoke awareness and reflection.
Ironically, essentialism fits comfortably with the evolutionary
notions of adaptation and genetic “blueprints.” So the strategy here is
to focus on developmental factors and variation at the population level.
Under intuitive thinking, the tiger’s stripes are essential, so all tigers
must have them. Or else they fail to be “true” tigers.
So, what should one say about a stripeless tiger (Figures 1 and 2)?
These are not just white tigers with stripes (which are also found).
Nor are they albinos. These are tigers without stripes. One lounges comfortably with her siblings, who exhibit the more common pattern. That
Figure 1. Not all tigers have stripes. Here, a stripeless tiger sits with her two siblings
(photo courtesy of Cango Wildlife Ranch).
The American Biology Teacher, Vol. 81, No. 8, pp. 599–604, ISSN 0002-7685, electronic ISSN 1938-4211. © 2019 National Association of Biology Teachers. All rights
reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Reprints and Permissions web page,
www.ucpress.edu/journals.php?p=reprints. DOI: https://doi.org/10.1525/abt.2019.81.8.599.
THE AMERICAN BIOLOGY TEACHER SACRED BOVINES
HOW THE TIGER CHANGED ITS STRIPES
DOUGLAS ALLCHIN, DEPARTMENTAL EDITOR