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Humans Change the World

Human Characteristics: Humans Change the World

Modern humans evolve in Africa.  Image courtesy of Karen Carr Studio.For millions of years all humans, early and modern alike, had to find their own food. They spent a large part of each day gathering plants and hunting or scavenging animals.  Then, within just the past 12,000 years, our species, Homo sapiens, made the transition to producing food and changing our surroundings. We have been so successful that we have inadvertently created a turning point in the history of life on Earth.


200,000 Years Ago

Modern Humans Evolve in Africa

During a time of dramatic climate change, modern humans (Homo sapiens) evolved in Africa. Like early humans, modern humans gathered and hunted food. They evolved behaviors that helped them respond to the challenges of survival.

The first modern humans shared the planet with at least three species of early humans. Over time, as modern humans spread around the world, the other three species became extinct. We became the sole survivors in thehuman family tree.

Modern humans exchange resources over long distances. Image courtesy of Karen Carr Studio.


By 164,000 years ago

Modern humans collect and cook shellfish


By 130,000 years ago

Modern humans exchange resources over long distances


By 90,000 years ago

Modern humans make special tools for fishing


Between 80,000 and 60,000 years ago

Modern humans spread to Asia


By 77,000 years ago

Modern humans almost become extinct. Image courtesy of Karen Carr Studio.

Modern humans record information on objects


About 74,000 years ago


Modern humans almost become extinct; as a result of extreme climate changes, the population may have been reduced to about 10,000 adults of reproductive age.


By 70,000 years ago


Homo erectus becomes extinct


By 60,000–40,000 years ago

Modern humans create permanent drawings


Homo neanderthalensis becomes extinct. Image courtesy of Karen Carr Studio.

By 50,000 years ago

Modern humans reach Australia


By 40,000 years ago

Modern humans reach Europe


By 28,000 years ago


Neanderthals (Homo neanderthalensis) become extinct


By 17,000 years ago


Homo floresiensis becomes extinct, leavingmodern humans (Homo sapiens) as the sole survivor in the once diverse human family tree


By 15,000 years ago

Modern humans reach the Americas

Humans grow their own food.  Image courtesy of Karen Carr Studio.


12,000 Years Ago

The Turning Point

Eventually, humans found they could control the growth and breeding of certain plants and animals. This discovery led to farming and herding animals, activities that transformed Earth’s natural landscapes—first locally, then globally.

As humans invested more time in producing food, they settled down. Villages became towns, and towns became cities. With more food available, the human population began to increase dramatically.


11,200 years ago

Figs cultivated in Lower Jordan Valley, Middle East


11,000 years ago

Jericho, West Bank, begins to grow into a city


9,500 years ago. Image courtesy of Karen Carr Studio.

10,000 years ago

Cows domesticated in Africa and Middle East

Squash cultivated in Central America


9,500 years ago

Wheat cultivated in Middle East

Çatalhöyük, Turkey, begins to grow into a city


9,000 years ago

Sheep domesticated in Middle East

Rice cultivated in China

Corn cultivated in North America


4,400 years ago. Image courtesy of Karen Carr Studio.8,000 years ago

Chickens domesticated in Southeast Asia


7,000 years ago

Potatoes cultivated in South America

Bananas cultivated in Southeast Asia


5,600 years ago

Horses domesticated in Eurasia


4,400 years ago

Caral, Peru, begins to grow into a city


3,600 years ago

Cacao (chocolate) cultivated in Central America


3,100 years ago. Image courtesy of Karen Carr Studio.

3,400 years ago

Athens, Greece, begins to grow into a city


3,100 years ago

Xi’an, China, begins to grow into a city


2,760 years ago

Rome, Italy, begins to grow into a city


2,000 years ago

Tea cultivated in China



Smallpox kills millions of citizens in ancient Rome



Coffee cultivated in Africa



Bubonic plague kills up to 10,000 people a day in Europe, North Africa, and the Near East



Bubonic plague (“The Plague”) kills at least a third of Europe’s population



Influenza kills up to 40 million people worldwide, about 5% of the entire human population.



Humans Change the World: Today

Modern humans have spread to every continent and grown to huge numbers. Producing our own food, rather than tracking it down daily, has freed us to enrich our lives in many ways—to become artists, inventors, scientists, politicians, and more.

We have altered the world in ways that benefit us greatly. But this transformation has unintended consequences for other species as well as for ourselves, creating new survival challenges.

By 1995, at least 83% of Earth’s land surface had been directly affected by humans.

In 2004, the International Union for Conservation of Nature (IUCN) reported that current bird, mammal, and amphibian extinction rates were at least 48 times greater than natural extinction rates—possibly 1,024 times higher.

As of 2005, humans had built so many dams that nearly six times as much water was held in storage as flowed freely in rivers.


World population growth. Image courtesy of Karen Carr Studio.


Benefits and Costs of Our Success



By settling down and producing our own food, we created:

●enough food to feed billions of people and respond to catastrophes;

●buildings that protect us from extreme weather;

●technologies that enable us to extend our lives, communicate worldwide, and venture into space;

●time to think, create, play, socialize, and much more.



By settling down and producing our own food, we created:

●piles of waste that form natural breeding grounds for contagious diseases;

large concentrations of people, enabling diseases to spread and become epidemics;

●domesticated landscapes that displace wild habitats;

●loss of wild species that depend on natural habitats.


Technologies enabling plant and animal domestication, as seen in by these stone sickle blades from Dynastic Egypt and Ali Kosh, Iran, represent a turning point of human interaction with the environment. Image courtesy of Chip Clark, Smithsonian Institution.

Changing the World:

Great Moments in Food Technology

1928 - Sliced bread

1791 - Artificial teeth

63 BCE - Water-powered grist mill

500 BCE - Iron plow

9500 BCE - Grain storehouse


Changing the World:

Animal Domestication

FACT: From 1961 to 2004, the population of cattle, pigs, sheep, and goats increased from 2.7 to 4.1 billion. The number of domesticated fowl grew from 3 to 16 billion.

FACT: Of the estimated 15,000 species of mammals and birds, only about 30–40 have been used for food.

FACT: Fewer than 14 species of animals account for 90% of global livestock production today.


Changing the World:


FACT: About a quarter of Earth’s surface is used to grow crops.

FACT: Fewer than 20 plant species produce most of the world’s food.

FACT: Most of the world’s population is dependent on 4 main crops: wheat, corn, rice, and potatoes.


Changing the World:

Growing Numbers of People

FACT: Between 1959 and 1999, just 40 years, the human population doubled from 3 billion to 6 billion people.

FACT: Today the population continues to grow by over 90 million people a year.

FACT: By 2042, the world population may reach 9 billion, an increase of 50% in 43 years.


Changing the World:  

Unintended Consequences

FACT: A cholera pandemic that began in 1961 is still ongoing in Asia, Africa, and the Americas. The number of cases reported in 2006 was 79% more than in 2005.

FACT: Every year between 3 and 5 million people get “the flu,” and between 250,000 and 500,000 people die from it.

FACT: A child dies of malaria every 30 seconds. About 40% of the world’s population is at risk of malaria.

FACT: Every second someone in the world is infected with tuberculosis. One-third of the world’s population is infected.

Page last updated: September 14, 2018