Dogs and More Dogs
To learn through an evolution card game how selective pressures can affect an organism's evolution.
- copy of the "From Wolf to Dog" student handout
- copy of the "Examining the Game" student handout
- copy of the "Wolf Deck" student handout
- 1 die
Scientists know all dogs descended from the gray wolf, but they don't know
exactly how that happened. Tell students that in this activity they are going
to engage in a simulation to learn how selective pressures can affect an
Review with students the concepts of gene, gene pool, selective pressure,
mutation, species, and genetic isolation (see Activity Answer for definitions).
Tell students that they will make a deck of cards that will represent the
entire gene pool for a hypothetical group of genes responsible for temperament
in a population of wolves. Each card will represent an individual gene and each
six-card hand will represent the collection of genes that contribute to
temperament for one wolf.
Organize students into teams of four and provide each team with a set of
materials (teams of smaller size will need to use dummy hands to complete the
activity). Have each team cut out and create a 24-card deck from the cards on
its "Wolf Deck" student handouts. Assign half of the teams to be Wolf Group A
and the other half to be Wolf Group B.
Have students do the activity as outlined on their student handouts.
Students will calculate the new deck average for the 5th,
10th, and 20th rounds. At the end of the game, compare
the final deck averages for each team. Have they all evolved from their
original average? How much do the final averages from Group A and Group B teams
differ from one another? Discuss with students how the selective pressures of
each of their groups contributed to each population's evolution.
To conclude, have a class discussion about the difference between the
conditions in this simulation and those occurring in nature. (Selective
pressures in the simulation occurred randomly; in nature, selective pressures
would occur as a result of specific environmental influences.)
As an extension, have students research and write a position paper
regarding the controversy involving wolf-dog hybrids. Find more information
may want to review the following terms with students:
gene: A segment of DNA that codes for a particular protein.
gene pool: All the genes of all the members in a population.
selective pressure: Any environmental factor that favors one trait over
mutation: A random change in a gene or a group of genes.
species: Any group of organisms, the members of which successfully breed
with each other, producing healthy, fertile offspring.
genetic isolation: What occurs when two groups of one species are
prevented from breeding with each other.
inherited trait: An inherited characteristic—such as hair and eye
color or muscle and bone structure—that has been passed on from a previous
acquired trait: An acquired characteristic—such as the ability to
ride a bike or do karate—that is attained throughout life. Acquired traits
are not passed on genetically.
This activity modeled the evolution of just one trait that contributes to
making dogs the species that they are; many additional anatomical,
physiological, and behavioral traits contribute to differentiating a dog from a
wolf. And while there are dogs that are bred for aggressiveness, the activity
addresses the evolution of genetic tameness in dogs as a species.
In the card game students played, higher hand totals represent wolves with
genes that contribute to tame behavior; lower hand totals indicate fewer genes
for tame behavior. Students were organized into two groups—Group A
students modeled a wolf population that continued to have an intermediate
temperament found in a wild wolf population. While this group underwent random
mutations, the selective pressures of the wild continued to select for the
average wolf. Group B students modeled a wolf population that evolved into
dogs. Random mutations allowed Group B wolves to evolve past what would have
been the tamest wolf in the wolf population (Canis lupus) and into the
subspecies of increasingly tamer dogs (Canis lupus familiaris).
Group A: Wild Wolf Population
Group B: Tamer Dog Population
Initial deck average
Initial deck average
In terms of the game, genetically isolating dogs and wolves means that the
cards from the wolves-evolving-into-dogs decks are never mixed with the
pure-wolf decks. If wolves and dogs were allowed to regularly interbreed, one
prediction might be that the dog's tameness would be reduced and the wolf's
tameness would be increased. In terms of real life, it would mean the two
groups would be prevented from breeding (e.g., exchanging genes) with each
If dogs and wolves had not been isolated, the small number of "tameness" genes
that arose in the population evolving into dogs would likely have been lost in
the much larger wolf gene pool, where they would be selected against by the
wolf's way of life. This would have made it very unlikely for dogs to ever
NOVA Web Site—Dogs and More Dogs
In this companion Web site for the NOVA program, discover why there are so many
breeds, read about why dogs are an evolutionary success, view a photo gallery
of working dogs, and match breeds with their countries of origin.
American Kennel Club
Contains information about purebred dogs, including a list of recognized
breeds, information on how to choose a puppy, and facts about DNA testing to
prove dog parentage.
Dog Breed Info Center
Provides an alphabetical listing of dog breeds with additional information
describing each breed and listing information about its temperament, living
conditions, exercise requirements, and health conditions.
The Dog Genome Project
Outlines the goals of the dog genome project, similar to the human genome
project, which is aimed at mapping all the chromosomes in dogs.
The Genetics of ... Dogs
Looks at some of the genetic problems faced by purebred dogs, such as
bulldogs with heads too large to fit through the birth canal and crippled
German shepherds, and humans' influence on these problems through artificial
The Human Role in Dog Evolution
Presents a lesson that asks students to investigate and consider the human role
in the domestication and evolution of ancient and modern dog breeds.
The Truth About Dogs
Presents author Stephen Budianski's view on how dogs have evolved into a
species uniquely adapted to getting food and shelter from people.
The Wolf-Dog Hybrid: An Overview of a Controversial Animal
Reviews some of the anatomical and physiological differences between dogs and
wolves and presents some of the breeding, genetic, and legal issues associated
with wolf-dog hybrids.
The Truth About Dogs: An Inquiry into the Ancestry, Social Conventions,
Mental Habits, and Moral Fiber of Canis Familiaris.
New York: Viking Press, 2000.
Draws on evidence from behavioral science, archeology, biology, and
neuroscience to probe how the relationship between humans and dogs
Coppinger, Raymond and Lorna.
Dogs: A Startling New Understanding of Canine Origin, Behavior, and
Evolution. New York: Scribner, 2001.
Focuses on how dog breeds have evolved and examines how the dog became a
distinct species from the wolf.
Padgett, George A.
Control of Canine Genetic Diseases.
New York: Howell Book House, 1998.
Includes chapters on modes of inheritance, tables and probabilities, genetic
disease predisposition by breed, and definitions of canine genetic
The Animal Estate: The English and Other Creatures in the Victorian
Age. Cambridge, Massachusetts: Harvard University Press, 1989.
Discusses the role of animals in Victorian England and looks at selective
Serpell, James (editor).
The Domestic Dog: Its Evolution, Behaviour and Interactions with People.
New York: Cambridge University Press, 1995
Explores the natural history of the dog and its evolution, behavior, and
interactions with humans.
The "From Wolf to Dog"" activity aligns with the following National Science
Science Standard C:
Reproduction and heredity:
Diversity and adaptation of organisms:
Science Standard C:
The molecular basis for heredity:
Species evolve over time. Evolution is the consequence of (1) the potential for
a species to increase its numbers, (2) the genetic variability of offspring due
to mutation and recombination of genes, (3) a finite supply of the resources
required for life, and (4) the ensuing selection by the environment of those
offspring better able to survive and leave offspring.
Classroom Activity Author
Low has taught biology at Malden High School in Massachusetts for 37 years. He
regularly participates in science research projects, and is currently involved
with a Tufts University School of Engineering program.