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Human Population Growth
Dr. Mark A. McGinleyHonors College and Department of Biological
SciencesTexas Tech University
Human Population Growth
• Reached 1 Billion – 1830• Reached 2 Billion – 1930• Reached 3 Billion – 1960• Reached 4 Billion – 1975• Reached 5 Billion – 1987• Reached 6 Billion – 1999• Reached 7 Billion – 2011
Current Estimated Human Population
• Monday February 4, 2013– 1:40 PM
• World 7,064,109,760 people
• http://www.census.gov/main/www/popclock.html
Approximate EstimatesWorldwide
• 5 births per second• 2 deaths per second
• dN/dt = 3 individuals per second
• = 10,800 inviduals per hour
• Add new Lubbock (N = 230,000 ind) in less than 1 day!!!
Human Population Growth
• As human population size has increased there has not been a decline in the per capita growth rate– As populations have gotten larger humans have
not been forced to have lower per capita birth rates
– As populations have gotten larger humans have not been forced to have higher per capita death rates
What’s Up With Humans?
• Humans can alter the world in ways that no other species on the planet can.– 1. increase food production• Agriculture
– Irrigation, fertilization, farm more area, mechanization, crop improvement
• Interestingly, the proportion of people who are starving on the planet is about the same to day as it was in the mid 1800s (20%)
What’s Up With Humans?
– 2. Modern medicine• Decreased juvenile mortality• Increased longevity
– 3. Better public health• Waste disposal• Clean water
– 4. Don’t worry too much about predators• Occasional shark or cougar attack
Human Population Growth Problem?
• Benefits of Population Growth??
• Disadvantages of Population Growth??
Human Numbers Through Time
• http://www.globalchange.umich.edu/globalchange2/current/lectures/human_pop/human_pop.html
•http://www.youtube.com/watch?v=4BbkQiQyaYc
Where is Human Population Growth Occurring?
• Most population growth is occurring in developing countries.
Potential Problems With High Human Population Growth Occurring in Developing Countries
• Environmental problems– Most developing countries located in the tropical
regions– Habitat destruction, overharvesting, and pollution
can cause extinction in the two most diverse ecosystems on the Earth• Tropical Rainforests• Coral Reefs
Deforestation in Borneo
Hunger
Food-related Problems?
Childhood Obesity in the USA
Weight Loss Products
• Weight Loss is a 60 Billion Dollar industry in the USA
Pudgy Pets
Access to Freshwater
World Poverty
Child Labor
Urbanization
Urbanization- India
Photo by Honey Blakeman
Human Population Growth
• Human populations have basically stabilized in developed countries but are still increasing in developing nations
• Why??
Demographic Transition
Demographic Transition
• Pre-industrial societies– High per capita death rates offset by high per capita birth
rates• Slow population growth
• Transitional societies– Per capita birth rates have remained high while per capita
death rates have fallen• Rapid population growth
• Post-industrial societies– Low per capita death rates and per capita birth rates
• Slow population growth
What Causes Per Capita Birth Rates to Decline in Industrialized Societies?
Literacy Rate vs. Birth rate
Worldwide Literacy
Fertility Rate vs GDP
What Will Happen to Human Population Size in the Future???
• Human demographers predict that once all countries have completed the demographic transition that Earth’s population will stabilize.– When and how large?
Factors Increasing Mortality RatesHIV/AIDS
HIV in Africa
