Historians divide history into periods and eras to study the past in an organized way. Prehistory began over 5,500 years ago before writing was invented. The Paleolithic Age started 2.5 million years ago and lasted until 8000 BCE, during which early humans hunted and gathered food using basic stone tools. Neolithic times began around 8000 BCE and saw the development of agriculture, settled communities, and early technological advances like pottery and shelters.

1. Unit 1: PREHISTORY

2. MeasuringTime
• To study the past, historians must have a way to identify and describe when
things happened.
• They do that by measuring and labeling time in different ways.

3. Periods of History
• A group of 10 years is called a decade.
• A group of 100 years is known as a century.
• Ten centuries grouped together is called a millennium.

4. • Historians also divide the past into larger blocks of time known as eras.
• Prehistory is the time before people developed writing.

5. • Writing was invented about 5,500 years ago.
• The period known as Ancient History comes next.
• It ends c. A.D. 500 (c., or circa, means “about).

6. • Historians call the time period between about A.D. 500 and aboutA.D. 1400
the Middle Ages, or the medieval period.

7. • Modern History begins about A.D. 1400. It continues to the present day.

8. Calendars
• A calendar is a system for arranging days in order.
• The calendar we use today is the Gregorian Calendar.
• Pope Gregory XIII started counting from the birth of Jesus.
• Our calendar includes leap years and took more than three centuries to be
recognized around the world.

9. Dating Events
• In the Gregorian calendar, the years before the birth of Jesus are known as
“B.C.” (before Christ).The years after are called “A.D.” (anno domini, “in the
year of the Lord”).
• Years were written 1 B.C., A.D. 1.

10. • To avoid a religious reference in dating, many historians prefer to use the
initials B.C.E. (“before the common era”) and C.E. (“common era”).

11. Timelines
• Time lines show the order of events within a period of time.
• They also show the amount of time between events.

12. Archaeology
• The study of the past by looking at what people left behind.
• Discover artifacts (objects made by people).
• Include: tools, pottery, weapons, and jewelry.

13. Paleontology
• Paleontologists study fossils (remains of plant and animal life that has been
preserved).

14. Human Discoveries
• 1974: Paleontologist Donald Johnson made an exciting find in Africa.
• They discovered a partial skeleton of a human ancestor who lived more than
3.2 million years ago.
• Lucy was 3.5 feet tall and weighed 60 lbs.
• She had long arms and short legs and walked upright.

15. • Lucy belonged to the species Australopithicus afarensis.
• A species is a class of individuals with similar physical characteristics.
• We are Homo sapiens (“wise man”).
• Scientists believe that Homo sapiens probably developed about 150,000 to
195,000 years ago.

16. The Paleolithic Age
• Earliest part of the Stone Age.
• Began about 2.5 million years ago and lasted until around 8000 B.C.E.

17. • People often moved around in search of food.
• They were nomads (people who regularly move from place to place to
survive).
• Survived by hunting and gathering.

18. • Men hunted large animals.
• Women looked after the children and gathered (berries, fruit, grain, etc.).

19. • Men and women worked together in monogamous pairs (the first families).

20. The Invention ofTools
• Technology (tools and methods to perform tasks) was first used by
Paleolithic people.
• Before this time, sticks, stones, and tree branches served as tools.
• By the end of the Paleolithic Age, people were making smaller and sharper
tools.

21. Changing to Survive
• Climate affected how Paleolithic people lived.
• They sought protection in available natural shelters (caves, rock overhangs).
• They began to build tents and huts of animal skin, brush, and wood.

22. • Life became less difficult for Paleolithic people once they discovered how to
make fire.

23. • Paleolithic cave paintings have been found all around the world.
• Scholars believe that the paintings may have been created to record the
group’s history.

24. The Ice Ages
• Long periods of extreme cold that affected all of Earth.
• To survive, humans had to change many areas of their lives.
• Began eating meals with fat, building sturdier shelters, making warm
clothing using animal furs.
• Ice Age lasted about 90,000 years, ending between about 9,000 and 8,000
B.C.E.

25. NeolithicTimes
• Began about 8,000 B.C.E. and lasted until around 4,000 B.C.E.
• Shifted from hunting and gathering to systematic agriculture (growing food
on a regular basis).
• Caused the population to grow at a faster rate.
• People began to settle into communities.

26. • Neolithic farming villages developed throughout Europe, India, Egypt,
China, and Mexico.
• One of the oldest communities was Jericho (between present-day Israel and
Jordan).
• Established by around 8,000 B.C.E.

27. • During this time period, people made more technological advances.

28. Civilizations Emerge
• Humans continued to develop more complex cultures, or ways of life.
• One characteristic of the early civilizations was that they developed cities and
formed governments.
• Religions emerged in the new civilizations to help people explain their lives.
• People in society were organized into groups.
• People invented ways of writing in order to pass on information.
• Artists created paintings and sculptures for entertainment and practical purposes.