Download Theories on Origin and Change

NAME ______________________________________
Period___________
Theories on Origin and Change Outline
Change Over Time
Most scientists agree that organisms have changed over a long period of time
– from ____________ to ______________.
Scientists do not know how life first began or how evolutionary changes
occurred.
To explain these events, scientists have proposed various theories.
Some theories have been totally rejected because of lack of supporting evidence.
Other theories have been modified (changed) based on new evidence.
Spontaneous Generation
An Early attempt to explain the origin of life.
The concept that living things come from __________________ things.
People believed, for example, that toads came from mud, flies came from the
rotting bodies of animals, and mice came from cheese.
This theory was widely accepted until the late 1800’s when it was disproved by
___________________________.
Today, we know that life comes from other living things although some
scientists believe the first cell must have come from nonliving materials.
Theory of Use and Disuse
In the early 1800’s ______________________________ presented this theory.
He thought that organisms were able to develop new structures
because they _______________ the structures.
He also believed that the size of an organ is determined by how much the organ is
used.


According to this theory, ballet dancers have big, strong muscles because they use their muscles a
lot.
When a dancer stops using a certain muscle, the muscle gets smaller and weaker.
Inheritance of Acquired Characteristics
________________________ also stated that the useful traits an individual
developed during its lifetime can be ______________ on to its offspring.
An ____________________________ is a trait that is produced during an
individual’s lifetime.
 Lamarck would have said that the children of dancers would inherit strong muscles.
Lamarck’s theories were widely accepted for a long time.
As time went on, scientists began to challenge his theories by showing that there
was no data to support his hypothesis.
Disproving Lamarck’s Theory
The idea that acquired traits could be inherited was officially disproved in
the late 1800s by the experiments of __________________________.
 Weismann _________________ the tails from mice.
 He then ___________ the tailless mice.
 He did this for many generations.
 The offspring of the tailless mice were always born with
___________________.
 This experiment proved that acquired traits are __________ inherited by
offspring.
Darwin’s Theory
In the 1850’s the theory of _________________________ was proposed by
__________________________.
In his travels he noticed that a certain species in one geographic area was
different from the same species in another area.
His theory of evolution was developed to explain the ___________ change in
species.
Alfred Wallace
___________________ (The environment) acts as the selecting agent of an
organism’s traits.
Darwin believed organisms better adapted to the environment survive and
reproduce more successfully than organisms not as well adapted.
Natural Selection suggests that _____________ that help an organism survive in
a changing environment are _________________ on to the next generation.
Although Darwin is given credit for the theory of natural selection, another
scientist, __________________________, proposed a theory of evolution that was
quite similar to Darwin’s Theory.
Darwin’s Theory of Natural Selection
1.Overproduction:
•For example: a fish must lay millions of eggs to reproduce a small number of
new fish.
2.Competition:
3.Variations:
•Differences in structure, size, and color are examples of variations.
4.Natural Selection:
5.Survival of the Fittest:
•In a woodland environment, brown fur color would be a helpful variation and
white fur color would not be helpful.
6.Inheritance of Variations:
7.Evolution of New Species:
Mutation Theory
In 1901, ____________________, suggested that inherited mutations caused
____________________.
He believed that ______________________ (changes in genetic material)
occurred randomly and those mutations that were favorable were
______________________ by offspring.
DeVries based his theory on his reproduction experiments with the evening
primrose plant.
Modern Theory of Natural Selection
The genes of inherited variations that give an organism a better chance for
survival tend to be passed on from _______________ to _________________.
These favorable genes tend to _______________ in numbers within a population.
________________ for traits with ____________ survival value _____________
in numbers from generation to generation.
If the _____________________ changes, genes that previously were neutral or
had low survival value may become ________________ and increase in numbers.
Evolution In Our Time
Staphylococcus bacteria
When the antibiotic was first used, these bacteria had __________ that made
them _____________________ to antibiotics.
When the use of antibiotics became widespread, these ___________
increased in numbers, producing a ________________ of bacteria that was
not _________________ by antibiotics.
Today, scientists continuously develop new _________________ because
the bacteria population ___________________ and produces new antibioticresistant strains.
Mutations are not caused by environmental change. Mutations occur
________________________.
Mutations with __________________ survival value allow organisms to be
better __________________ to their ______________________.
The _______________________ selects those variations, or adaptations,
that may have ____________________ value.
English Peppered Moth
Peppered moths have two basic colors: light color with dark markings or
dark color with light markings.
Before the industrial revolution, most peppered moths were light colored.
This enabled them to blend with their light-colored environment, such as the
trunks of trees and the side of buildings.
By blending with the environment, the light-colored moths were almost
invisible.
Insect eating birds could not see them.
The soot and other air pollutants from the industrial revolution gradually
changed the environment from light to dark.
The light-colored moths became visible and were eaten by birds.
The dark-colored moths could not be seen against the dark background.
These moths reproduced more dark moths and the population shifted from
light to dark-colored.
Recently, as a result of environmental pollution laws, the moth population is
slowly changing back to light-colored moths.
Artificial Selection
Sometimes plant and animal breeders purposely ________________ organisms by
mating plants and animals that have certain desirable traits.
By selective breeding, ____________ may cause evolution.
Example: racehorses and greyhounds have been produced that are faster than their
predecessors.
Geographic Isolation
Occurs when a population is physically separated into smaller populations by
____________________________.
Mountain ranges, deserts, oceans, rivers, other bodies of water, big expressways, or
shopping malls.
Changes may occur in these separated populations that, over a long period of time
may result in the production of different species. The production of a _______
species is known as ___________________.
___________________________ occurs when members of the
_________________ population and the _______________ populations can no
longer interbreed, even if the barriers are removed.
Adaptive Radiation
The process by which __________________________________________
______________________________________________________________
The new species evolve and fill different environmental ____________ where
there is less _____________________.
Organisms move into new _________________ in the environment through
chance ___________________ that have _______________ adaptive _________.
A ___________________ adaptation would be one that allows an organism to
live successfully in a new ____________. If there is little ________________ in
the niche, the organism has a better chance to ____________
and ______________.
Rate of Change
Gradualism
A theory that evolutionary change is slow, gradual, and continuous.
New species would arise by the very gradual collection of minor changes in
a population.
Punctuated Equilibrium
A theory that species are relatively stable for long periods of time (several
million years).
This stability is interrupted by brief periods during which major changes
occur. These changes result in the evolution of new species.
The minor changes that occur in a population over time might produce new
varieties of an existing species, but not a new species.
Heterotroph Hypothesis
This theory, proposed by A.I. Oparin in the late 1930’s, stated that groups of
organic molecules were formed from the chemical elements in the Earth’s primitive
ocean.
These organic molecules combined, using energy from heat, lightning, solar
radiation, and radioactive materials in the rocks.
The first living things were thought to be heterotrophs. Since no free oxygen gas
existed in the atmosphere, these forms of life carried on anaerobic respiration.
They used the free organic molecules in the sea for food.
Over time, genetic changes occurred in the first organisms.
As a result of the genetic changes, photosynthetic forms of life evolved.
These organisms, Autotrophs, released oxygen into the atmosphere.
Aerobic forms of life evolved from the anaerobic forms.
Human Evolution
Scientists know very little about human evolution, because there is very little
_____________________________.
Some people incorrectly think that Darwin proposed that humans evolved from
apes.
Darwin only suggested that humans, along with other mammals, could have
shared a ____________________________.
There is no evidence that humans are the direct descendants of organisms living
today.
Some human-like fossil forms
have been discovered.
Their exact place in human
ancestry has yet to be determined.
Out of Africa Theory
Human Evolution
Modern scientists assume that human evolution, like evolution in other animals,
is continuing.
Because of their superior reasoning ability, _____________ are able to control
their ________________________.
Because of this, the evolutionary effect of natural selection is _______________
as in other organisms.
Factors That May Affect Human Evolution
Medical Knowledge – permits the survival of individuals with genetic traits such
as diabetes, hemophilia, and PKU. Without medical knowledge these people would
die and the genes for these diseases would decrease in number in the population.
With modern medicine the number of genes are maintained or increased.
Modern Transportation – humans are less affected by the evolutionary force of
geographic isolation.
Advanced Technology – gives humans better nutrition and greater control over
their reproductive process. It has also increased the number and kinds of mutagenic
agents in the environment.
Genetic Engineering – may possibly lead to the appearance of new traits and the
elimination of others.
What is Evolution?
The process of gradual (slow) ______________ through ________________.
Helps to explain the differences in structure, function and behavior among living
things.
–
Geologic Evolution:
–
Organic Evolution:
•
•
Geologic Time
The oldest living thing, a bacteria-like organism, is estimated to be 3.4
billion years old.
Each time period is identified by its dominant (common) animal and plant
life.
4 Major Eras

Cenozoic Era

Mesozoic Era

Paleozoic Era

Precambrian Era
Fossil Evidence
 Fossils–

Paleontologists–
The study of fossils in the earth provides evidence to support the idea that life
changed over time from __________________ to _____________________.
Fossil distribution shows that life began in the _____________ and then
moved to ________________.
It also provides evidence for the time of _________________________ of various
forms of life.
Fossils help scientists understand how ________________ and land surfaces
have __________________.
By the process of _________________________________, scientists
determine the _________________ of the earth’s rocks and its fossils.
Fossil Evidence In Sedimentary Rock
 Many Fossils are found in sedimentary rock.
 Where the crust of earth is undisturbed, the oldest rock layers lie
under the younger layers.
 Sedimentary rock is formed from layers of slowly deposited
sediments.
o Rock particles
o Silt
o Mud
 After long periods of time and great amounts of heat and pressure,
sediments harden into rock forming visible layers.
Fossilization

Amber -

Tar

Ice

Mold -

Cast -

Petrification -

Imprints –
Skeletal Evidence

Comparative Anatomy

The science that studies the ______________________
_____________________ of plants and animals.

When scientists compare skeletal structures of different
vertebrates, they see a ___________________________.

This observation shows that organisms with similar bone structures may have evolved
from a ____________________________________________.
 Organs or structural parts that seem to have a common evolutionary origin are
referred to as _____________________________________________.

Although homologous structures are similar in __________________________, they
do not always have the same _______________________.
Vestigial Structures
Parts of an animal’s body that are not ____________________________.
These structures look like structures that are fully developed and used by other
animals.
Example: Human Appendix - Scientists think that perhaps some ancestor of
humans used their appendix and, as evolution continued, humans stopped using this
organ.
Other Examples: human ear muscles, and the leg bones of the python and porpoise
Comparing Cell Structure
Cells and cell organelles are basically __________________ from one group of
organisms to another.
For example, all cells have a nucleus, cell membrane, cytoplasm, ribosomes,
mitochondria, chromosomes, and other organelles.
This is evidence that different kinds of living things may share a
___________________________________.
Comparing Embryos
Comparisons of early stages of embryonic development show the possibility
of ___________________________ and ______________________________.
The science that studies the structural similarities among vertebrate embryos
is called _______________________________________.
At early stages, vertebrate embryos show gill slits, tails and two-chambered hearts.
Similarities in Biochemistry
Similarities in the body ___________________ (______________________)
of living things, such as DNA, hormones, and enzymes, show a close
_______________________ between various forms of life.
Organisms that are closely related, like the cat and the lion, have a greater
similarity in their _________________________________.
Greater differences in _____________________________ are thought to show a
________________ evolutionary ______________________________.
Examples of Evolution
The
ancient ancestor of the horse was
about the size of a fox. It had four toes on
its front feet and three toes on its hind feet.
The
horse gradually got bigger and the
length of its feet increased.

As
time passed, some of the toes
disappeared, until today the modern horse
is one-toes.

The
middle toe is the one that remains,
but the horse retains tiny splints of two
other toes.

The
skull grew longer and the teeth
became flat-topped.
The
ancestor of the present elephant was
the size of a pig and had no tusks.
Over
time, the size of the elephant’s body
and head increased tremendously.
The
two upper incisor teeth increased in size and length and gradually developed into tusks.
The
early trunk was much shorter than the trunk of today’s elephant.