Unit 1: The Earliest Humans

Unit 1: The Earliest Humans

• Covers the period from 13.8 billion years ago to 6,000 years ago
• The unit will look at the Big Bang, Our Hominin Ancestors, and the Rise of Homo Sapiens
• The unit includes major questions:
  • What distinguished Homo sapiens from their ancestors?
  • How did global migration affect cultural and genetic diversity?

Start of Class Task

• Students should put phones and laptops away
• Gather a notebook and writing utensil
• Submit homework before the icebreaker
• Use index cards to write down information from the reading

A Look Ahead

• The Big Bang (13.8 Billion Years Ago)
• Our Hominin Ancestors (1.2 Billion Years Ago - 400,000 Years Ago)
• Rise of Homo sapiens (300,000 to 200,000 Years Ago)

Major Questions

• What were the distinguishing traits of Homo sapiens compared to their ancestors?
• How did the global migration of Homo sapiens contribute to the diversification of cultures and genetics?

Where Did Modern Humans Come From?

• The origin of life was a single-celled organism (3.5-3.8 billion years ago)

• Some produced oxygen

• Evolved into multicellular organisms (1.2 billion years ago)

• Dinosaurs and small mammals existed around 240 million years ago, but not humans

• An asteroid impact, specifically from the Chicxulub impactor, is believed to have caused mass extinction events that wiped out approximately 75% of all Earth's species, including the non-avian dinosaurs in what is now known as the Yucatan Peninsula, around 66 million years ago. This event led to drastic changes in the Earth's climate and ecosystems, paving the way for mammals to thrive in the absence of dinosaurs.

  • Approximately 25 million years ago, during the Miocene epoch, primates that we classify as apes appeared in Africa. This period marked a significant evolutionary milestone, as these early apes eventually branched off, leading to the emergence of hominins, which are our more immediate ancestors in the evolutionary tree.
  • Two notable examples of early hominins include Ardipithecus ramidus, dating back to about 4.4 million years ago, and Australopithecus afarensis, commonly known as "Lucy," who lived around 3.2 million years ago. These species showcase the transition in traits such as bipedalism and increased brain size that are vital in the evolutionary lineage leading to modern humans.
  • Current genetic research indicates that humans share approximately 98-99% of their DNA with chimpanzees, our closest living relatives. This remarkable genetic similarity highlights not only our shared ancestry but also the evolutionary processes that have shaped both species over millions of years.

Timeline of the Universe

• Shows major thresholds in the history of the universe, like the Big Bang, stars igniting, the formation of the Earth and solar system, the emergence of life, and later developments like collective learning and the modern revolution.

Where Did Modern Humans Come From (additional info)?

• Humanity originated in the Afar Depression, Ethiopia, in Africa.

Where Did Modern Humans Come From (additional info)?

• Apes appeared in Africa approximately 25 million years ago
• Multiple hominin branches existed over the past 7 million years

Where Did Modern Humans Come From (additional info)?

• The human lineage chart and information on human genetic relation and shared genetic material with chimpanzees.

Group Activity: Uncovering Lucy

• Students will create a 4-slide presentation on "Lucy"
• Research using reputable websites (such as National Geographic, Wikipedia, PBS, and Smithsonian)

Homework

• Read “Bipedalism” and “Brains” (pages 8-11)
• Fill in the corresponding worksheet
• The material in this reading segment will appear on the quiz

BBC Earth Video on Lucy

• Link provided to a BBC Earth video about Lucy

Where Did Modern Humans Come From?

• Homo sapiens share DNA and traits with earlier hominins
• Certain skills were retained through the process of natural selection, which is a fundamental mechanism of evolution that promotes the survival and reproduction of individuals with advantageous traits.
  • Bipedalism: This is the ability to stand and walk upright on two legs, a characteristic that distinguishes humans and some other species from most mammals. Bipedalism offers numerous advantages, including the ability to see over tall grass, freeing the hands for tool use, and improved energy efficiency in long-distance travel.
  • Big Brains: These are highly complex and capable organs that facilitate advanced cognitive functions, such as creative thinking, strategic planning, complex social interactions, and the development of sophisticated tools. The expansion of brain size in early humans has been linked to increased social cooperation, problem-solving skills, and adaptability to changing environments.

Why Do We Migrate?

• Migration is the movement of animals or people from one region to another.

The Migration of Early Humans

• Shows the path of early human migration

The Final Four

• Explains the timeline and development of hominin species

Sapiens Migrated Due To Climate Change

• During the ice age (75,000 years ago), climate conditions forced hominins to migrate
• Sea levels decreased, exposing land bridges (like the Bering Strait), which facilitated migration

So It's Now Just Homo Sapiens...

• Reason behind the extinction of other hominin species remains unknown but theories include resource conflicts and interbreeding.

Migration Encourages Genetic & Cultural Diversity

• Genetic diversity increased as humans migrated across the globe
• Different environments led to varied physical traits
• New environments led to advancements in clothing, hunting, and tool-making
• Big Game Hunting became advantageous for humans facing novel environments

First Messages Written in Stone

• Example: Petroglyphs (ancient carvings)

The Paleolithic Era

• The prehistoric period known as the "Old Stone Age" (up to 13,000 years ago)
• Identified by the stone tools used

Paleolithic Culture & Art

• Discuss Paleolithic art and culture

STUDY DAY – TEST ON MONDAY

• The test format includes 10 multiple-choice/true/false questions, 2 identification responses (choose 2 from 4), and 1 short answer question focusing on major traits of Homo sapiens or global migration

How to Study For The Test

• Materials to help study for the test

STUDY DAY – TEST ON MONDAY

• Vocabulary practice using crossword puzzles.

Major Questions (reiteration)

• Again, what distinguished Homo Sapiens and their ancestors?
• How did global migration influence cultural and genetic diversification?