1. Human Population Growth
Dr. Mark A. McGinley
Honors College and Department of
Biological Sciences
Texas Tech University

3. 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

4. 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

5. Approximate Estimates
Worldwide
• 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!!!

6. 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

7. 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%)

8. 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

9. Human Population Growth Problem?
• Benefits of Population Growth??
• Disadvantages of Population Growth??

11. Human Numbers Through Time
• http://www.globalchange.umich.edu/globalch
ange2/current/lectures/human_pop/human_
pop.html
•
http://www.youtube.com/watch?v=4BbkQiQy
aYc

12. Where is Human Population Growth
Occurring?
• Most population growth is occurring in
developing countries.

13. 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

14. Deforestation in Borneo

15. Hunger

16. Food-related Problems?

17. Childhood Obesity in the USA

18. Weight Loss Products
• Weight Loss is a 60
Billion Dollar
industry in the USA

19. Pudgy Pets

20. Access to Freshwater

21. World Poverty

22. Child Labor

23. Urbanization

24. Urbanization- India
Photo by Honey Blakeman

25. Human Population Growth
• Human populations have basically stabilized in
developed countries but are still increasing in
developing nations
• Why??

26. Demographic Transition

27. 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

28. What Causes Per Capita Birth Rates to
Decline in Industrialized Societies?

29. Literacy Rate vs. Birth rate

30. Worldwide Literacy

31. Fertility Rate vs GDP

32. 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?

33. Factors Increasing Mortality Rates
HIV/AIDS

34. HIV in Africa