Human Population

People Over Time Humans have interacted with their environment in several distinct ways in the past. The technologies of the time have dramatically influenced these interactions

Early Humans Up until about 500 years ago the human population was relatively stable Limiting Factors: Disease Scarce Food 50% survival of children During this time frame, human populations had two main modes of life

1. Hunter-gatherer Characteristics: small, migratory groups Effects: Hunted for game animals Foraged for seeds, fruits, a vegetables subsistence - place very few demands on environment, harvest at low levels Effects: Sustained prairies with fire, built small dams Transport of non-native species Population growth limited by food availability

Population was stable

2. Agricultural After hunter gatherer societies, agricultural societies arose Agriculture is the practice of growing, breeding, and tending plants and animals (domestication) for consumption or use by humans. Producing their own plants and animals provided a more dependable supply of food to early humans. People began living in larger settlements Effects human population growth rate increased slightly selective breeding for desirable traits of crops and animals habitat destruction for farm land soil and water degradation as farms replaced forests

Slight population increases

Industrial Revolution (1800-1900s) Characteristics: Energy sources shifted from animals & water to fossil fuels Mass production of goods rather than small local producers Increased use of artificial substances… plastics, pesticides, fertilizers Transportation of goods & people increased

Industrial Revolution Effects: increased agricultural productivity improved nutrition, sanitation, medical care Urban Development- movement of people from agriculture based society to a industry and city based society. Industrial Growth- increase in the production rates, transport, and consumption rates of goods increased pollution, growth, and habitat loss … improved quality of life???

Large increase in population

Green Revolution By the 1950’s the world population was growing faster than the food supply Scientists and Governments got together and developed new, intensive farming practices that increased production of rice, wheat and other key crops- Green Revolution Monoculture- large fields planted with a single crop year after year Large irrigation and fertilization and pesticide programs needed to support this type of farming Allowed food production to more than double, supporting a larger population

Population Sky rockets

Human population explosion Just passed 7 Billion last Fall!!! Characteristics: Increasing life expectancy Increasing fertility rates Increasing need for food/natural resources Effects: Human population is 10X larger than 300ya average population growth rate is increasing pollution is increasing pressure on Earth’s environment is increasing

Human population growth Population of… China: 1.3 billion India: 1.1 billion 1650500 million 20056 billion Industrial Revolution Significant advances in medicine through science and technology Bubonic plague "Black Death" adding 82 million/year ~ 200,000 per day! Doubling times 250m  500m = y () 500m  1b = y () 1b  2b = 80y (1850–1930) 2b  4b = 75y (1930–1975) The population doubled to 1 billion within the next two centuries, doubled again to 2 billion between 1850 and 1930, and doubled still again by 1975 to more than 4 billion. The global population now numbers over 6 billion people and is increasing by about 73 million each year. The population grows by approximately 201,000 people each day, the equivalent of adding a city the size of Amarillo, Texas, or Madison, Wisconsin. Every week the population increases by the size of San Antonio, Milwaukee, or Indianapolis. It takes only four years for world population growth to add the equivalent of another United States. Population ecologists predict a population of 7.3–8.4 billion people on Earth by the year 2025.

Key Factors What are the key factors that have led to the growth? Reliable food supply Improved Sanitation Improved Medication and Health care= decreased death rates and increased longevity Basically, the limiting factors were removed from the population

Demography In order to better understand how and why our population is changing, scientists study the: Demographics- study of the characteristics of the population and attempts to explain how the population will change over time Demographics examines the age-structure of the population Age Structure- illustrations of the number of people occupying different age groups in the population Age structures can be used to determine whether a population is likely to grow or shrink in the future.

Age Structure Diagrams

Age Structure Diagrams

Demographic Transition As countries become more developed their demographics tend to change Historically, societies had birth rates = death rates Recently many developing countries have had birth rates > death rates Most of world population growth is occurring in India and China Eventually, as countries modernize both birth and death rates fall, and population tends to stabilize Has happened in a few countries such as Japan, the US and much of Europe

Fertility Rates Replacement level fertility: The number of children per couple that would result in a stable population 2.1 (not all children live to adult hood) Current: World 2.47 US 2.06 Japan 1.39 Somalia 6.25 Rwanda 4.81

Future? Will this growth continue? How are humans impacting the environment? What is the solution?