Human Population Notes

The Human Population

• Cueva de las Manos, Argentina: Painted between 7300 BC - 700 AD

Origin and Expansion of Homo Sapiens

• Homo sapiens originated around 200,000 years ago.
• By 50,000 years ago, they had developed language, culture, and complex tools.
• Map showing locations and ages of early human sites:
  • Komsa: 12 kya
  • Kostenki: 40 kya
  • Ahrensburg: 30 kya
  • Aurignacian: 45 kya
  • Mal'ta: 25 kya
  • Emiran: 70 kya
• Key time periods:
  • 150 kya
  • Eemian: 125 kya.
  • Out of Africa (OOA): 75 kya
  • Last Glacial Maximum (LGM): 25 kya
  • Holocene
  • Clovis: 14 kya

Independent Origins of Agriculture

• Agriculture originated independently at least 12 times, starting 12,000 years ago.
• Examples of agricultural origins:
  • Eastern North America: sunflower, sumpweed, pitseed goosefoot.
  • Fertile Crescent: wheats, barley, sheep, goat.
  • North China: proso & foxtail millets, soybean, pig.
  • Eastern Tibet: buckwheat, yak, cattle.
  • West Sahel: pearl millet, African rice, fonio.
  • North Japan: barnyard millet, burdock, soybean, rice (japonica).
  • New Guinea: banana, yams, taro.
  • Mesoamerica: maize, beans, squash.
  • N. Peru/Equador: lima bean, sword bean, squash.
  • Western Savanna: cowpea.
  • Eastern Savanna: mungbean, sorghum, horsegram, browntop millet, cattle.
  • Amazonia: manioc, peanut.
  • North/High Andes: potato, oca, llama, guinea pig.
  • Mid Andes: quinoa, amaranth.
• Archaeological documentation varies, with some regions better documented than others.

Effects of Agriculture on Human Population

• Food storage leads to greater food security.
• Transition to a less diverse diet.
• Aggregation of populations results in greater density.
• Higher disease rates.
• Stratified society.
• Population growth: Higher birth rates offset by higher death rates.

World Population Size Over Time

• The size of the world population over the last 12,000 years is visualized.
• 7.9 billion in 2022.
• 7 billion in 2011.
• 6 billion in 1999.
• 5 billion in 1987.
• 4 billion in 1975.
• 3 billion in 1960.
• 2 billion in 1928.
• 1.65 billion in 1900.
• 990 million in 1800.
• 600 million in 1700.
• Mid-14th century: The Black Death pandemic killed between a quarter and half of all people in Europe.
• 190 million in the year 0.
• 4 million in 10,000 BCE.
• Average growth rate from 10,000 BCE to 1700 was 0.04% per year.
• Global life expectancy increased significantly:
  • Before 1800: less than 30 years.
  • In 2019: 73 years.
• Demographers expect rapid population growth to end by the end of the 21st century, with the UN projecting about 11 billion in 2100.

Demographic Transition

• Demographic transition ( 1780s to 1960s):
  • Phase 1: High birth and death rates.
  • Phase 2: Death rates fall due to improvements in sanitation and agriculture; population growth soars.
  • Phase 3: Birth rates fall; population growth slows.

Historical Mortality Rates

• Average mortality rate across 21 historical societies: 48%
• Examples of mortality rates in historical societies:
  • Roman Egypt (around the year 0): 60%
  • Teotihuacan (Mexico) (550-700): 57%
  • Wari (Peru) (600-1100): 62%
  • Poland 1875: 53%
  • Teotihuacan (Mexico) (300-550): 49%
  • Rome (200 BCE-200): 50%
  • Nasca (Peru): 48%
  • Average across 17 hunter-gatherer societies: 49%
  • Japan (1776-1875): 45%
  • Venice (1800-1900): 50%
  • Sweden (1600-1700): 51%
  • Japan (1300-1400): 51%
  • Mallorca (Spain) (400-200 BCE): 40%
  • France (1600-1700): 40-50%
  • China (1700-1800): Higher than 40%
  • Bavaria (Germany) (1750-99): 50%
  • West Indies (1820-32): 47%
  • Imperial China (1650-1800): 45%
  • France (1816-50): 44%
  • Belgium (1800-1900): 41%
  • Italy (1700-1800): Higher than 40%
  • Sweden (1750-80): 40%
• Global mortality rates:
  • In 1950: 2.7%
  • In 2020: 0.3%
• Somalia has the highest mortality rate in the world.
• Iceland, Finland, Norway, Japan, and Slovenia have the lowest mortality rates.

Demographic Transition in Britain

• Britain's demographic transition from 1700 to 2020 is examined.
• Britain's population doubled from 1801 - 1841 (Phase 2).
• Key phases and events:
  • Phase 2: Population boom.
  • World War 1 (WW1).
  • World War 2 (WW2).
  • Post-war baby boom.

Transition to Phase 3

• Transition to Phase 2 has occurred throughout the world.
• Transition to Phase 3 through much of the world.
• Examples:
  • Sweden.
  • Mexico.

Reasons for Transition to Phase 3

• Decline in infant mortality.
• Shift away from subsistence farming.
• Greater access to birth control.
• Increasing economic opportunities for women.

Fertility Rates and Education

• Correlation between women's education and the number of children per woman.
• Countries with higher average years of schooling for women in reproductive age tend to have lower fertility rates.
• Examples of countries and their fertility rates:
  • Niger: 7 children per woman.
  • Mali, Democratic Republic of Congo, Afghanistan: 6 children per woman.
  • Uganda, Benin, Malawi, Tanzania, Zambia, Sudan, Yemen: 5 children per woman.
  • Congo, Pakistan, Kenya: 4 children per woman.
  • Gabon, Zimbabwe, Papua New Guinea, Tonga, Jordan, Namibia, Guatemala, Tajikistan, Egypt, Philippines, India: 3 children per woman.
  • Algeria, Nepal, Indonesia, Bangladesh, Mexico, Vietnam, China, Colombia, Kyrgyzstan, Israel, Kazakhstan, United States, Thailand, Russia, Italy, South Korea, Macao, Taiwan: lower fertility rates.

Impact of Delaying Age of First Reproduction

• Delaying the age of first reproduction slows population growth rate.
• Formula to describe the correlation: $r \approx (\ln R_0)/T$
• Data from different years (1963, 1980, 1991, 2007) shows a declining percentage of first births occurring at younger ages.

Additional Reasons for Transition to Phase 3

• Delay in age of first child.
• Increase in average spacing between children.

Trends in Yearly Growth Rate

• Growth rate for the human population peaked in the early 1960s and has been declining since then.

Demographic Transitions and China

• In 2019, China's birthrate fell to 10.48 per thousand people.
• One Child Policy (1980s - 2015) impacted birth rates.

Fertility Rates Below Replacement Level

• Many countries now have birth rates below replacement level ( 2.1 births per woman).
• The total fertility rate is the number of children that would be born to a woman if she were to live to the end of her child-bearing years and give birth to children at the current age-specific fertility rates.

Median Age and Fertility Rates

• As fertility rates decrease, the median age of a population increases.
• Countries with low fertility rates tend to have higher median ages.
• Countries with high birth rates have a lot of younger people.

Population by Age Group

• Examples of population distribution by age group in Japan and Nigeria.
• Japan: aging population with a larger proportion of older individuals.
• Nigeria: younger population with a larger proportion of younger individuals.

Carrying Capacity (K) for the Human Population

• Estimates and projections of the human population size.
• Different scenarios based on UN projections (High, Medium, Low).
• What is K for the human population?
  • 10 billion?
  • 1 billion?

Limits to Population Growth

• What are the inescapable limits to population growth?
• Essential resources:
  • Food (and land to grow it).
  • Fresh water.
  • Energy.

Resource Consumption and Renewal

• Relationship between input (supply rate) and output (consumption rate).
• Whether a resource is "renewable" or not depends on rates of supply and consumption.

Impact of Lifestyle on Carrying Capacity

• Formula: $I = N A T$
  • I = environmental impact of the human population.
  • N = human population size.
  • A = affluence = material standard of living.
  • T = technology used to acquire that standard of living.
• I (not N) will determine how quickly resources are depleted.

Role of Technology in Reducing Environmental Impact

• Technology reduces environmental impact because better technology provides the same standard of living more efficiently.
• $I = N A T$