The Theory of Human Evolution
Team Pegasus Ancient Civ.
Name:
Class: Y R G B
Table #: 1 2 3 4 5
Section 1 - Introduction
Prehistoric humans left clues about their lives in cave paintings. Scientists call these
prehistoric humans hominids. In this unit, you will learn about five important groups of
hominids.
Three kinds of “history detectives” that study the past are archaeologists, historians, and
geographers. The study of hominids involves a fourth type, paleoanthropologists.
Paleoanthropologists specialize in studying the development and culture of the earliest
hominids. (Paleo means “ancient.”)
In 1974, an American paleoanthropologist named Donald Johanson made an exciting
discovery. While searching for artifacts under a hot African sun, he found a partial skeleton.
The bones included a piece of skull, a jawbone, a rib, and leg bones. After careful study,
Johanson determined that the bones had come from a female hominid who had lived more
than 3 million years ago. She is one of the earliest hominids ever discovered. Johanson
nicknamed her “Lucy,” from the Beatles’ song “Lucy in the Sky with Diamonds,” which was
playing at his celebration party.
What have scientists found out about Lucy and other hominids? How were these hominids
like us? How were they different? What abilities did each of the five hominid groups have?
Section 2 - Evolution and Natural Selection
When we study Lucy and other hominids, we use the scientific theory of Evolution.
Evolution is the process by which biological organisms develop new traits and pass them on
from one generation to the next. Evolution by natural selection is a concept that was
popularized by British biologist Charles Darwin in the 1800s. Natural Selection is the idea
that organisms with advantageous traits tend to survive long enough to pass on those traits
to future generations, while organisms without those traits are more likely to die out. Over
time, the advantageous traits become more and more frequent in a particular population of
plant or animal. Most scientists believe that evolution is what’s responsible for the rise and
fall of species—more specifically, that species evolve because certain environments favor
certain traits. When an environment changes, sometimes species that were once highly
suited to live there die out and go extinct because they can no longer survive.
A perfect example is the dinosaurs. Dinosaurs once roamed the earth millions of years ago.
But at some point the environment changed so much that they could no longer survive.
Many of them died and most of them went extinct—but not all of them! Some bird-like
dinosaurs had traits that allowed them to survive the environmental change that killed the
rest of the dinos. Many scientists believe these bird-like dinos survived and evolved into the
birds we see today.
Section 3 - Scientific Hypotheses and Theories
In the scientific method, a hypothesis is an educated guess about an explanation for a set of
observations. A hypothesis may be proven false through experimentation. When looking at
cave art, you came up with your own hypotheses, and sometimes your hypotheses were
proven wrong.
A scientific theory is a hypothesis that has been repeatedly tested and not disproven. For
example, Charles Darwin’s theory of natural selection has been tested over and over again
since it was introduced in 1859, and it has yet to be disproven.
Often, a well-established theory is basically accepted as a fact over time, even though it’s
rarely, if ever, called a “fact” or “law.”
Not everyone accepts the scientific theory of evolution. In the United States, some people
don’t believe that one can accept the scientific reality of evolution while still believing in God.
They believe that the Bible is accurate in all respects, and that the account of Creation in
the Book of Genesis describes how the universe began. Freedom of religion in our country
allows people to choose what they want to believe.
The Theory of Human Evolution
Notes and Vocabulary
Team Pegasus Ancient Civ.
Name:
Class: Y R G B
Table #: 1 2 3 4 5
Directions: Use this two-column note taker to record information about important ideas from
the reading.
Topics
Section 1
Types of “history
detectives”
Work of Donald
Johanson
Section 2
Theory of Human
Evolution
Charles Darwin and
Natural Selection
Notes
Topics
Section 3
Hypothesis
Notes
Scientific Theory
Based on the reading, come up with a detailed definition for each of the following terms:
Hominid
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Paleoanthropologist
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Evolution
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Natural Selection
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Scientific theory
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