AP World History: Modern · Lesson 2 of 7 · Unit 9

Disease and debates about the environment after 1900

6 min read · about 1 h 30 min with practicePreview

You’re reading a preview of this lesson. Already on Pro? Sign in to read it all.

After 1900, rapid population growth, urbanization, and global travel reshaped human interactions with pathogens and the planet. On the AP exam, this topic frequently appears in data-based multiple-choice sets (charts on life expectancy, carbon emissions, or disease rates) and in short-answer or essay prompts assessing Humans and the Environment (ENV) and Technology and Innovation (TEC) through the lens of causation.

By the end you’ll be able to

Explain how diseases associated with poverty, such as malaria, tuberculosis and cholera, persisted while emergent epidemics, such as the 1918 influenza pandemic, Ebola and HIV/AIDS, threatened populations and in some cases caused social disruption.
Explain how disease outbreaks spurred technological and medical advances, and how some diseases, such as heart disease and Alzheimer’s disease, occurred at higher incidence because of increased longevity.

Preview

Upgrade to Pro to unlock the rest

You’ve read the first part of this lesson. The rest is part of Pro: about 4 more minutes of reading, plus the quick check.

Still to come

Core ideas (continued)
Worked examples
Exam technique
Common mistakes
Quick recap
Check your understanding (3 questions)

Upgrade to Pro

What the exam asks

Multiple Choice (MCQs): Expect graphs, maps, or public health posters. You will need to connect demographic or economic data to one of the three disease categories (poverty-related, emergent epidemics, or longevity-related) or link industrialization and population growth to environmental degradation.
Short Answer (SAQs) & Essays (DBQ/LEQ): Prompts often ask you to explain how globalization affected public health or the environment, or to evaluate the consequences of 20th-century technological and economic growth. Remember that SAQs and the DBQ stop at 2001, while MCQs can reach the present.

Core ideas

Three patterns of disease after 1900

Be ready to distinguish between the three specific categories of disease defined by the Course and Exam Description (CED) and know their causes and effects.

Disease Category	Illustrative Examples	Causes & Historical Context	Effects & Responses
Diseases associated with poverty	Malaria, tuberculosis (TB), cholera	Poor sanitation, lack of clean water, crowded housing, inadequate healthcare infrastructure in developing regions.	Persisted despite curable or preventable nature; widened the life-expectancy gap between wealthy and poor nations.
Emergent epidemics	1918 influenza pandemic, HIV/AIDS, Ebola	Rapid global transit (troop ships in 1918, commercial aviation later), human encroachment into wildlife habitats.	High mortality, severe social and economic disruption, spurred international medical cooperation (WHO) and new treatments (antiretrovirals, vaccines).
Diseases associated with longevity	Heart disease, Alzheimer’s disease	Antibiotics, vaccines, and better nutrition increased global life expectancy and altered diets/lifestyles.	Higher incidence in wealthier and aging populations; shifted medical research toward chronic and degenerative conditions.