Unit 1: The Earliest Humans

Unit 1: The Earliest Humans

The unit covers a time period from 13.8 billion years ago to 6,000 years ago, encompassing the vast history of cosmic, geological, and biological evolution that shaped our planet and ultimately led to the emergence of humans.

A look ahead at the unit's content includes discussions surrounding the Big Bang, which marks the beginning of the universe around 13.8 billion years ago, and details on our Hominin Ancestors, which span from 1.2 billion years ago to about 400,000 years ago. Additionally, the unit will delve into the Rise of Homo sapiens, which occurred approximately 300,000 to 200,000 years ago, detailing the ecological, social, and technological changes that influenced this pivotal moment in human history.

Key questions for the unit include: What distinguished Homo sapiens and their ancestors in terms of physical and cognitive traits? How did global migration of early humans influence cultural practices and genetic diversity across various populations worldwide?

Start of Class Task

Students should turn off their phones and laptops to minimize distractions and foster an environment conducive to learning.

Each student is required to have a notebook and writing utensil ready for notetaking and class activities.

They need to submit their homework assignment before the class activity begins to ensure timely review and engagement with the material.

Students should obtain an index card and write down as much information as they can recall from the assigned homework reading, enabling them to actively engage with the content and assess their understanding.

Timeline of the Universe

The timeline illustrates significant events from the Big Bang to the present day, providing a visual representation of the history of the universe and key milestones in the development of life on Earth.

This timeline tracks important thresholds, such as the emergence of stars lighting up the cosmos, the formation of the Earth and solar system approximately 4.5 billion years ago, and the subsequent appearance of the first signs of life on Earth around 3.8 billion years ago.

Other crucial thresholds highlighted on the timeline include the advent of collective learning among early humans, the agricultural revolution, which fundamentally changed human societies, and the modern revolution that has drastically reshaped human existence and environment.

Origin of Life and Evolutionary Importance

Life originated on Earth as single-celled organisms between 3.5 and 3.8 billion years ago, marking the first step in a long evolutionary journey that would eventually give rise to complex multicellular life forms.

Some of these early life forms served as oxygen producers, significantly altering the atmosphere and making it conducive to further biological evolution.

Multicellular organisms evolved approximately 1.2 billion years ago, paving the way for greater complexity and diversity in life forms.

Dinosaurs and small mammals emerged around 240 million years ago, but modern humans did not appear until much later, during the late stages of the Earth's evolution.

Where Did Modern Humans Come From? — Asteroid Impact

An asteroid struck the Yucatan Peninsula 66 million years ago, marking one of the most significant events in Earth's geological history. The impact released energy equivalent to the explosion of billions of atomic bombs, leading to catastrophic environmental changes, including wildfires, tsunamis, and a "nuclear winter" effect.

This devastating event resulted in the mass extinction of approximately 75% of Earth's species, including all non-avian dinosaurs which had dominated terrestrial ecosystems for millions of years. The loss of such dominant terrestrial creatures created opportunities for the evolution of new species and ecological dynamics.

In the aftermath, the extinction of dinosaurs allowed mammals, which had been relatively small and inconspicuous during the reign of the dinosaurs, to diversify rapidly and expand into ecological niches that had previously been occupied by reptiles, ultimately leading to the evolution of early primates that would eventually give rise to modern humans.

Humanity Originated in the Afar Depression

Humanity originated in the Afar Depression in Ethiopia, Africa, a region that is significant for its geological activity and fossil discoveries that provide insight into early human evolution.

Ape and Hominin Appearance

Apes appeared in Africa around 25 million years ago, marking the beginning of a lineage that eventually led to the emergence of humanity. This period illustrates the evolutionary diversification of primates.

Hominins encompass all extinct branches of early humans and apelike ancestors, a lineage that has been traced back over the past 7 million years to understand the roots of modern human anatomy and behavior.

Ardipithecus ramidus and Australopithecus afarensis are notable examples of hominin species known from fossil evidence, which provide valuable insights into the evolutionary adaptations that occurred during this time.

Humans share approximately 98-99% of their genetic material with chimpanzees, highlighting a recent common ancestry and offering important clues about our evolution and shared traits with other primates.

The Human Lineage (Evolution)

The illustration displays the progression from early human ancestors to modern humans (Homo sapiens), allowing for a visual understanding of evolutionary relationships and adaptations over time.

Significant species along this lineage include Australopithecus afarensis, known for its bipedal locomotion; Homo habilis, often considered one of the first members of the genus Homo; Homo erectus, recognized for its use of tools and control of fire; and Homo neanderthalensis, which coexisted with early Homo sapiens and contributed to their genetic heritage.

Group Activity: Uncovering Lucy

Groups will create a 4-slide presentation on Lucy, a famous Australopithecus afarensis fossil that has provided significant insights into early bipedalism and human evolution.

They will need to investigate reputable websites and academic sources for reliable information to ensure the accuracy and depth of their presentation.

The presentation serves as an educational tool and is not for formal evaluation, allowing students to explore their creativity while learning.

Homework

Students are assigned readings on Bipedalism and Brains, covering pages 8-11 in the textbook, to deepen their understanding of the critical adaptations that define early human evolution.

They are to fill in a worksheet provided by the teacher, which will help reinforce concepts learned and assess comprehension of the material.

This material related to bipedalism and neurological development will be included on the upcoming quiz, highlighting its importance in the evolution of modern humans.

Students are also encouraged to use additional resources such as slides, readings, notes, and handouts from the week to create a thorough study preparation.

BBC Earth Video on Lucy

A video covering the insights and discoveries related to Lucy is available for review, providing a multimedia approach to learning about this iconic figure in human evolution.

The link is provided for students to access the video conveniently, encouraging them to engage with the material in a dynamic way.

Homo Sapiens and Other Hominins

Homo sapiens share DNA and important physical and behavioral traits with other hominins, particularly those that represent our closest evolutionary relatives, shedding light on the shared heritage of modern humans.

Natural selection played a crucial role in preserving certain skills and abilities such as bipedalism and advanced cognitive functions across various hominin species, allowing for successful adaptation to diverse environments.

Bipedalism and Big Brains in Defining Modern Humans

The presentation identifies bipedalism (the ability to stand upright and walk on two legs) as a critical characteristic that distinguishes modern humans from earlier ancestors, highlighting the importance of this adaptation in relation to locomotion and social behavior.

The evolution of big brains provided a significant evolutionary advantage, allowing for complex capabilities such as social cooperation, intricate toolmaking, and the development of language, which are foundational traits of modern human societies.

Skills via Natural Selection

Modern humans developed a variety of skills through natural selection that significantly contributed to survival and social organization, including bipedalism, large brains that facilitate cooperation and bonding, as well as advanced techniques in toolmaking, fire control, and language acquisition.

PBS Documentary: First People of Africa

A PBS documentary on the earliest people of Africa should be watched in conjunction with a viewing guide that helps students to analyze content and foster discussion about this crucial aspect of human history.

Major Questions:

What distinguished Homo sapiens from other hominins in terms of anatomical and cultural traits that can be identified through fossil evidence and archaeological findings?

How did migrations of Homo sapiens influence cultural practices, societal structures, and genetic diversity among populations across different regions of the world?

Everything Changes When We Stand Up

Homo erectus is identified as the first species to exhibit habitual bipedalism, a change that fundamentally altered the evolutionary trajectory of humans, influencing everything from environmental interaction to social dynamics.

The Migration of Early Humans

Maps displaying early human migrations illustrate the complex pathways taken by our ancestors as they spread across continents, exploring and adapting to various environments.

The paths of human migration demonstrate a blend of exploration and adaptation, showcasing how early humans responded to environmental challenges and opportunities in new habitats.

The Final Four

Homo erectus and Neanderthals are recognized as part of the final four major human evolutionary lines, each contributing uniquely to the story of human evolution.

Denisovans and "Hobbits" (Homo floresiensis) also represent key evolutionary branches, highlighting the diversity of human ancestors and their adaptations to varying ecological niches.

The presentation includes detailed descriptions, skull reconstructions, timelines, and other characteristics of these hominin species to enrich students' understanding of human evolution.

Ice Age and Human Migration

Human migration during the Ice Age was significantly influenced by climatic changes occurring between approximately 130,000 to 12,000 years ago, altering habitats and resources accessible to early humans.

Migrations were closely linked to changes in sea levels, which exposed land bridges such as the Bering Strait, enabling easy movement between continents and facilitating dispersal of human populations.

These climate changes prompted innovations in survival strategies, learning, the crafting of new tools, and adaptability required for humans to thrive in challenging environments.

Vanishing Species (Homo sapiens)

The presentation discusses various reasons contributing to the disappearance of other hominin species, exploring multiple factors that may have led to their extinction.

The theories surrounding these extinctions include conflicts over resources with Homo sapiens and other hominins, as well as the possibility of interbreeding, which may have influenced genetic contributions.

Migration Encourages Genetic and Cultural Diversity

Through migration, genetic diversity among populations was fostered, as new genetic variations were introduced and mixed, leading to enhanced adaptability to varied environments.

This process also encouraged the development of cultural differences across environments, as groups adapted their lifestyles, beliefs, and survival strategies to the distinct challenges of their surroundings.

New environments necessitated unique adaptations, including advancements in clothing, tools, and hunting techniques, which provided competitive advantages, particularly in activities such as big game hunting that played a critical role in sustenance and survival.

Paleolithic Era and Tools

The Paleolithic Era, which extends up to approximately 13,000 years ago, is defined by the use and creation of stone tools, a defining characteristic of early human technology.

Petroglyphs, which are examples of early artistic expressions and communication, are included for review, illustrating the intellectual and cultural developments of early humans during this era.

Paleolithic Culture & Art

Discoveries related to art and culture during the Paleolithic Era have proven to be crucial in understanding the cognitive abilities and social behaviors of early humans, marking a significant leap in human expression and identity formation.

Practice Writing IDs

Students need to answer ID questions as a means to clarify their understanding of key concepts and figures from the unit, emphasizing critical thinking and analytical skills.

ID responses should encompass comprehensive details including when a significant event occurred, who was involved, what the event entails, where it took place, why it is important historically, and its significance to our understanding of human evolution.

Short Response Prompts (for Test Review)

The review includes two significant test questions that will aid in students’ preparation for upcoming assessments, focusing on fundamental concepts outlined in the unit.

Major traits that distinguished Homo sapiens and their ancestors can be explored through anatomical features and behavioral practices.

Examining how global migration contributed to both cultural and genetic diversity, highlighting the interconnectedness of human populations over time, will also be pivotal.

How to Study for the Test

A comprehensive list of important materials to study will include textbooks, handouts, worksheets, videos, timelines, and additional resources to ensure thorough preparation.

The presentation emphasizes the importance of utilizing various resources, such as the Lucy slideshow, notes on human traits, maps detailing migrations, and viewing guides to enhance understanding and retention of the material covered in the unit.