Artificial Selection, also called selective breeding, is the process in which humans select traits in other species and breed
the species in a way to make that trait more prevalent. This is often performed by selecting two individuals who display the
selected trait and then breeding them in hoping to pass the trait to their offspring. For example, artificial selection is
widely prevalent in agriculture, where cows have been bred to produce more beef and wheat has produce to be hardier.
A chromosome is an organized structure of packaged DNA that is used to efficiently transport the DNA during cell replication.
As DNA is far less organized during the other stages of a cell’s life cycle, chromosomes are used in biology as a convenient way to
organize gene loci.
Directional Selection is the concept that the most extreme, and thus rarest, versions of a trait, are the most beneficial to an organism. As a result,
the more extreme versions of the trait become more and more common, and evolution is driven in a certain direction.
DNA, or deoxyribonucleic acid, is the molecule in a cell that carries the genetic information for development,
growth, function and reproduction of an organism. DNA is made up of four different nucleotides: adenine, cytosine,
guanine and thymine, which together make up the “genetic code” of an organism. DNA is usually found as two strands
that come together to form a double helix.
Evolution in its most basic form is “descent of life with modification.” More precisely,
evolution is the change in genetic composition of a population over successive generations. On the small scale, this
happens when the frequency of genes changes in a population from one generation to the next. On the large scale this
leads to the descent of different species from a common ancestor over many generations. Evolution is shaped by five forces:
1. Mutation: a permanent change in the DNA of an organism so that the change is different from the majority of the population
2. Genetic Recombination: the production of different traits observed in offspring than those that are observed in the parents
3. Gene Flow/Migration: the transfer of a gene from one population to another. This usually occurs when an organism migrates and becomes part of a different
4. Genetic Drift: when a gene becomes more or less prevalent in a population due to random chance
5. Natural Selection: the process through which organisms that are best adapted for the environment are able to survive and reproduce better than other organisms
Fitness, more specifically biological fitness, is the ability of an organism to survive, mate and reproduce. Generally,
when an organism has traits that enable it reproduce so, it will have more offspring over its lifetime and as a result,
have greater fitness.
A gamete is a mature germ cell. When a gamete unites with the germ cell of the opposite sex during sexual reproduction it
forms a zygote. In humans, gametes are haploid meaning that they contain half the number of chromosomes that
a mature cell does. When the gametes unite, the chromosomes come together to form the full genome, yielding a
This refers to the succession of a species from parent to offspring. All plants and animals must reproduce to
continue their species, and by doing so they pass down genetic and physical traits. The genetic material from each
parent is combined to create new, unique individuals.
In evolution, this is how populations adapt to changing environments and competition. The strongest individuals
from each generation will pass down their competitive advantage to the next.
Genetic Drift is the process under which an allele becomes more or less frequent in a population due to chance. This is
possible because while it is true that individuals with higher fitness tend to reproduce more, there are always organisms
that manage to reproduce even though they are the not the most adapted to an environment. Because it is random, Genetic Drift
does not work to bring about adaptations in an environment, simply changes to the population.
A genome is the complete collection of an organism’s DNA. This means that the genome of an organism contains all the
necessary information for the organism to develop, grow, survive, and reproduce. Genomes are divided up into different
chromosomes. The number of chromosomes vary based on the species.
A genotype is the genetic makeup of a cell or organism which determines the physical traits, or phenotype, of the organism.
Even though the genotype makes up the genetic basis of a trait, it is not the sole factor that determines the phenotype.
A haploid cell is a cell containing half the number of chromosomes as a normal, mature cell. In humans, germ cells are haploid. This means
that because the normal, mature human cell has 46 chromosomes, haploid cells have 23.
A heterozygous gene locus is one where an individual has two different alleles for the same gene. For example; gene B has
two alleles (versions), “B” and “b.” An individual who has the two different versions of gene B and is “Bb,” is heterozygous.
A homozygous gene locus is one where an individual’s alleles for that gene are the same. For example; gene B has two
alleles (versions), “B” and “b.” An individual who has two of the same alleles for gene B, such as “BB” or “bb,” is
Inheritance is the process of parents passing genetic material to their offspring. It is through inheritance that individual
organisms who are better adapted to the environment are able to ensure that their genes are more widely dispersed in the next
A mutation is a permanent change in the nucleotide sequence of an organism’s genome. Mutations can occur as a result of:
errors in DNA replication, errors in DNA repair, or in the insertion or deletion of DNA by mobile genetic elements (such
as viruses). It is estimated that 70% of mutations that cause changes in proteins are harmful.
Natural Selection is the process under which species that are better adapted to their environment will reproduce at a higher
rate than those that are less adapted to the environment. As a result, the next generation should have a higher frequency of
traits that are adapted to the environment. The four factors that govern natural selection:
1. Variation: differences between individuals of the same species
2. Overproduction: species produce far more offspring than could possibly survive
3. Competition: since there is a finite number of resources, offspring must compete with others to survive
4. Selection: certain traits are better adapted to the environment, individuals with those traits are more likely to survive and reproduce
Reproduction is the process through which a new organism, or offspring, is generated from their parent. Reproduction is
one of the six characteristics of life, and as a result, all known living organisms carry out reproduction. Organisms
can either reproduce by themselves, called asexual reproduction, or with another member of their species, called sexual
A species is usually defined as the largest group of organisms that are still able to reproduce and produce viable,
fertile, offspring. This usually occurs through sexual reproduction. For example, while horses and donkeys can reproduce
to produce a living offspring, a mule, mules are not fertile, thus it is not a species. There is believed to have been
over 5 billion species to have ever lived, with over 99% of those species being extinct.
Traits are characteristics that can change over time during the process of evolution. For example, utilizing specific poisons
against creatures may result in the survivor’s offspring having an immunity to the poison. Creatures exposed to cold may develop
more traits that enable them to resist the cold, like a thick coat of fur. Others may result in total defense, like a hard shell
of armor, or even wings for flight.
Variation is the idea that any biological system will vary across time and space. Variation is present in both individuals
and among different populations. Individuals vary based on their alleles of their genes while populations vary based on the
frequency of genes in the gene pool.
About Polymorphic Games
Polymorphic Games is a game design studio focusing on using evolutionary principles to build better video games.
Based at the University of Idaho in Moscow, Idaho, this highly interdisciplinary team includes students and professors
from nearly every discipline on campus from Visual Design and English to Biology and Computer Science.