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NAME: ______________________________________ DATE: ____________ BLOCK: ____
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Evolution - ___________________________ over generations
Organisms change over time – this is a fact. How organisms have changed throughout
earth’s history is theory.
EVIDENCE OF EVOLUTION
 ____________________________
 Comparative anatomy
 Embryology
 ____________________________
 Genetics
 Direct observation
FOSSILS
 Fossils - a __________________ of an organism that lived long ago
 Fossil records- use radiometric dating or rock layers to date fossils
 Fossil records are incomplete:
o soft tissues
o weather
 Geographic distribution of species
o Similar organisms in different areas
 Fossils of extinct organisms
COMPARATIVE ANATOMY
 Comparative anatomy- the study of structures of different organisms
 Homologous structures - __________________________________ modified between
different organisms
o The more similar the structures, the closer the relationship between two
organisms
o Example: a bat’s wing, a horse’s leg and a human forearm
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Vestigial Organs - structures that have _____________________________ in present
organisms, but may have been used in ancestors
Example in animals
o pelvic bone in some snakes and whales
Examples of Vestigial Organs in Humans
o _________________________________
o wisdom teeth
o _________________________________
o pointed canines
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EMBRYOLOGY
 Comparative embryology - the study of embryos (early stages of life) of different
organisms
o The more similar the embryos, the more closely related two organism are
o ex. human and pig embryos appear very ________________________ to each
other
BIOCHEMISTRY and GENETICS
 Chemicals (like proteins, DNA, mRNA etc) in different organisms show similarities.
 More similar chemicals means more closely related
 Example- Hemoglobin in chimpanzees is very similar to hemoglobin in humans
GENETICS
 How are offspring genetically different from their parents? In other words, how can
evolution occur from one generation to the next?
o Meiosis – remember, individuals can make lots of genetically different sex cells
o Mutations – DNA can change!
o Sex – combines two individuals’ DNA together
 DNA sequences of all living things have many similarities
 Base sequences of DNA
o DNA of humans and chimpanzees is ___________ identical
o DNA of humans and other mammals is ___________ identical
DIRECT OBSERVATION
 Direct observation - evolutionary changes are happening ____________
o Example - bacteria becoming resistant to antibiotics
CHARLES DARWIN
 Charles Darwin – an Englishman credited for first describing natural selection
o HMS Beagle – a British survey _______________on which Darwin was a
naturalist. This ship sailed around the world in 1831.
 Galapagos Islands – located 600 miles west of South America. The islands have very
different climates and thus the organisms adapt according to the environment.
o Giant tortoise, marine iguanas, and finches vary from island to island due to
different environments
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Artificial Selection – __________ chose particular species to breed (selective breeding)
o Artificial selection helped to explain that variations in species could make them
better adapted.
o Dog breeders, farmers, gardeners have been using artificial selection for years.
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NATURAL SELECTION
The _____________________________of the _________________________________
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Darwin wondered why there were so many different species of finches on the Galapagos
Islands. He proposed the concept of natural selection.
Natural Selection - the __________________________________ individuals in a
population survive and reproduce offspring that are also well adapted
The least adapted produce fewer offspring and are less likely to survive.
Among the various traits that _____________________, certain traits may benefit a
population
The environment typically does _____________cause the variation!
o Examples
 Virus from outer space – kills blue-eyed people (but does not change a
person’s eyes to blue)
 Spadefoot toad – must bury itself in the ground and mate quickly when it
comes to the surface, therefore, it has a loud croak and long toes!
TYPES OF SELECTION
 Directional Selection – when individuals at one ___________ of the curve have higher
fitness than individuals in the middle.
o Example: birds with larger beaks are better able to survive food shortages than
those with small and medium beaks
 Stabilizing Selection - when individuals at ______________ of the curve have higher
fitness than individuals at the ends.
o Example: average-sized babies are most likely to survive compared to really big
and really small babies
 Disruptive selection - when individuals at _____________________ of the curve have
higher fitness than individuals in the middle.
o Example: due to small and large seeds, birds with small and large beaks are
most fit compared to birds with medium beaks
Some vocab…
 Gene Pool - the entire collection of genes among a _____________________________
 Population - All organisms within a breeding group (same species)
 Gene Frequency - The _____________________________ an allele appears in a gene
pool
 ______________ in gene ________________ mean that the population has evolved.
 An entire population evolves, not an individual!
 A specific gene may be “selected” for by the environment.
GENETIC DRIFT
 Genetic Drift - _______________ changes in gene frequency of a _____________,
___________ population
o Ex. in small populations, a recessive allele can become much more common
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o In the Amish population, certain genetic disorders are more common than in the
general population.
ADAPTATIONS
 Adaptations - _____________________________ of a living organism that help it to
survive in its environment
 Adaptations evolve by ______________________________!
TYPES OF ADAPTATIONS
 ________________________ - physical parts
o Ex. woodpecker’s tongue, anglerfish, anteater’s snout, hummingbird’s beak
 ________________________ - chemicals made by organisms
o Ex. poison venom of a snake, ink of a squid
 ________________________
o Ex. migration of birds, mating dances
TYPES OF EVOLUTION
 Convergent Evolution – species that are _______closely related evolve similar traits (two
species look like they are closely related and they are not)
o Example: dolphins (mammals) and sharks (fish)
 Divergent evolution – one species evolves into two or more species with
__________________ characteristics (speciation)
o Example: lions and tigers evolved from a common ancestor
SPECIATION
 Speciation – _________________ of two different _____________________ from one
common ancestor.
 What keeps two species apart so that they evolve differently?
 Isolating mechanisms – keep groups apart
o Geographic Isolation – ______________ changes occur that isolate individuals
of a population
 Ex. Squirrels separated by Grand Canyon and Darwin’s finches separated
by being on different islands
o Genetic Isolation – genes don’t mix right
 Donkeys and horses make mules, but mules are sterile.
o Temporal isolation – timings off
 Different species of skunks that mate at different times of the year.
o Behavioral isolation – behaviors don’t match
 Certain species of lightning bugs use different blinking patterns to attract
mates.
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THEORY OF ORIGIN OF LIFE
 Theory - a major hypothesis that has withstood the test of time
o Based on observations and evidence
o The closest to a complete explanation that science can offer
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ORIGINAL ATMOSPHERE
 Hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and
water.
 __________________________ gas
FIRST ORGANISMS
 Prokaryotes [__________________] - first cells; have genetic material (RNA or DNA);
starting 3.5 byaFirst prokaryotes
 First prokaryotes were __________________________(eat food)
 Later, some bacteria became ____________________________(make own food)
o Chemosynthesis - using energy from chemicals to make food
o Photosynthesis - using CO2 and light to make food
 Cyanobacteria put ___________________________ in atmosphere.
 Oxygen drove some life forms to extinction, while other life forms evolved
new ways to use oxygen (_______________respiration)
 Oxygen formed ____________________________- shielded earth from
harmful UV and allowed an explosion of life (2.7 bya)
Big steps…
 Eukaryotes (cells with nuclei) about 2.2 bya
 Plants and animals begin in water
 ____________________ and sexual reproduction in plants and animals
o Increased genetic diversity
 _______________ and later ____________________ colonize land around 4.5 mya.
 First ____________________ and then first ______________________ (245 mya)
 Dinosaurs go extinct around 65 mya and this allows for evolution of larger mammals.
 Extinctions are often followed by explosions of new life forms!
 Remember your eras: Precambrium. Paleozoic, Mesozoic, and Cenozoic.
HUMAN EVOLUTION
 Did man come from monkey???
o NO!
 Humans and monkeys evolved from a ____________________________ that lived
approximately 65 million years ago and was a tree dweller (roughly the size of a cat). This
was not a monkey like the monkeys today.
Evolution of Primates
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Anthropoids developed into 3 groups:
o New World Monkeys – includes squirrel and spider monkeys; have prehensile
tail (can coil around branches) and lived in trees; found in central and S. America
o Old World Monkeys – include giant apes, baboons, and macaques; do not have
prehensile tail, but spend a lot of time in trees; found in Africa and Asia
o Hominoids (great apes) – include orangutans, _________________,
__________________, and ______________________
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HOMINIDS
 Hominid family includes modern humans and several distinctly different extinct species
 Bipedal – ____________________ locomotion
o Freed hands to use tools
 Opposable thumb – allowed hand to _____________________ objects and tools
 Increased ___________________________
Australopithecus afarensis
 Very small brain capacity
 ~3.9-3.0 million years ago (mya)
 “________________”
 Bipedal apes that spent some time in trees
 ____________________ (Lucy is 1m)
Homo habilis
 “_________________ man”
 ~2.5 mya
 Increased brain size
 Began to make and use _______________
 1.3 meters tall (4 feet tall)
Homo erectus
 “__________________ man”
 ~ 1.8 mya - 250,000 years ago
 Taller
 __________________brain capacity (comparable to modern humans)
 Built fires
 Migrated out of Africa into China and Asia
Homo sapiens (“wise man”)
 Homo sapiens neanderthalis
o _____________________________
o Overlapped in existence with modern humans
o Heavier brow ridge
o Slightly larger brain capacity than modern human
o Lived ~200,000 – 30,000 years ago
 Homo sapiens sapiens
o First arose in Africa around 100,000 years ago.
o Lived with Neanderthals for ~50,000 years.
o Tools, art, and buried dead with rituals
o One group became __________________________(in Europe) ~40,000 years
ago.
o We are Homo sapiens sapiens
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