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Human Population: Demography
Transcript of Human Population: Demography
POPULATION & SOCIETY
And one more thing...
PRINCIPLES OF DEMOGRAPHY
Social and Economic factors affect Biodiversity:
Early European immigrants and their descendants viewed Costa Rica’s forests as an obstacle to agricultural and timber development.
Since 1945, Costa Rica’s population quadrupled and pressures on land increased.
Beginning in 1970, Costa Rica began protecting its land resources. Today over a quarter of the country’s area lies within national parks or other protected reserves.
Tourists now visit Costa Rica for ecotourism.
Hypothesis: Hot, dry climate conditions caused increased adult mortality and breeding problems among golden toads and other amphibians.
Evidence: Review of climate records revealed an increasing number of dry days from 1973 to 1998. Other observations note changes in the community from moisture-dependent species to more dry-tolerant species.
Climate Change, Disease, and the Amphibians of Costa Rica:
Local residents in Costa Rica’s mountainous Monteverde region told of an elusive golden toad that appeared only in the early rainy reason.
In 1964, Dr. Jay M. Savage and his colleagues encountered hundreds of these golden toads, which had never been formally discovered, during an expedition.
The newly discovered species went extinct 25 years later when global climate change caused drying of the forest.
Because all amphibians breathe and absorb water through their skin at some stage of their life, they are sensitive and vulnerable to individual or a combination of external environmental stressors.
Of the tigers that still survive in small pockets of their former range, those in the subspecies known as the Siberian tiger are the largest cats in the world.
For thousands of years, the Siberian tiger coexisted with the native people of what is today the Russian Far East, who equated the tiger with royalty and viewed it as a guardian.
The Russians who moved into and exerted control over the region in the early 20th century had no cultural traditions that expressed respect for the animal, causing the species to decline to as few as 30 animals.
Today, the population is in a range of 430 to 500 tigers, and 1,500 more survive in zoos around the world.
Saving the Siberian Tiger
One advantage of single-species conservation is in highlighting public awareness, especially if the organism in question is charismatic megafauna, such as a lion, tiger, or bear.
Typically, it’s the large mammals or birds, not the less charismatic vertebrates, invertebrates, or plants that are the focus of single-species conservation. Whereas, preserving and conserving habitats protects species that have yet to be discovered/studied and may be more economically feasible in the long term.
Single-Species Conservation: Pros and Cons
The lithosphere is everything that is solid earth beneath our feet.
The atmosphere is comprised of the air surrounding our planet.
The hydrosphere encompasses all water in surface bodies, underground, and in the atmosphere.
The biosphere consists of all the planet’s living organisms, or biotic components, and the abiotic portions of the environment with which they interact.
The number of dead zones has been rising globally.
Since 1975, the world’s population has added one billion humans every 12 years.
Our ongoing population growth has resulted from:
technological innovations improved sanitation
better medical care
increased agricultural output
decreased death rates and infant mortality rates
Environmental scientists (Thomas Malthus and Paul/Annie Ehrlich) believe that there are limits to human population growth.
Even if resource substitution could enable indefinite population growth, could we maintain the quality of life that we would desire?
Population is one of several factors that affect the environment.
Humans’ total impact results from the interaction among four factors:
sensitive a given environment is to human pressures
Modern-day China shows how all elements of human impact can result in tremendous environmental impact in very little time.
Impact can generally be boiled down to either pollution or resource consumption.
Earth has a carrying capacity for us.
Estimates of carrying capacity range from 1–2 billion people living prosperously in a healthy environment,
to 33 billion living in extreme poverty in a degraded world of intensive cultivation without natural areas.
Demographers study population size, density, distribution, age structure, and sex ratio, as well as birth and death rates, immigration and emigration.
Demography is the study of human population.
People are distributed unevenly over our planet. This uneven distribution means that certain areas bear far more environmental impact than others.
Age structure diagrams show the number of people in each age class.
The naturally occurring sex ratio in human populations at birth features a slight preponderance of males.
Total fertility rate influences population growth.
Demographic transition is a theoretical model of economic and cultural change that explains the trend of declining death and birth rates that occurs when nations become industrialized.
Birth control is a key approach for controlling population growth. Birth control limits the number of children one bears, by reducing the frequency of pregnancy.
Family planning is the effort to plan the number and spacing of one’s children, so as to assure children and parents the best quality of life possible.
Fertility rates have dropped most noticeably in nations where women have gained improved access to contraceptives and to family planning
Empowering women reduces fertility rates.
The causality is thought to operate in both directions:
Poverty exacerbates population growth, and rapid population growth worsens poverty.
Poverty is correlated with population growth.
This is unfortunate from a social standpoint, because these people will be added to the nations that are least able to provide for them.
Individuals in affluent societies leave a larger ―ecological footprint than those in less affluent societies.
We are running a global ecological deficit, gradually draining our planet of its natural capital and its long-term ability to support our civilization.
Of the world’s 33 million people infected with HIV/AIDS as of 2008, two-thirds live in sub-Saharan Africa.
Premature deaths, of both infants and young adults, are reducing the average life expectancy in African nations, and are taking away many of the youngest and most productive members of society.
HIV/AIDS is taking a major toll on African populations.
However, those of us living in the developed world must also be willing to reduce our consumption.
Sustainable development and population goals go hand-in-hand.
If humanity’s overarching goal is to generate a high standard of living and quality of life for all people, then developing nations must find ways to slow their population growth.
China is the world’s most populous nation.
Under Mao Zedong’s leadership, improved food production and medical care allowed China’s population to swell, causing environmental problems, and raising the TFR to 5.8.
In 1979, the government decided to institute a system that allowed one-child per family.
China’s growth rate is down to 0.5%.
Punishment for people who do not follow the policy.
Reduction in personal choice about family planning.
Pressure to favor one gender over another.
Fewer working-age people puts pressure on industry, health care, and military forces.
On Planet Earth, 25% of the land area, is devoted to the humanity.
A large concentration of individuals in young age groups portends a great deal of reproduction.
A greatly distorted sex ratio can lead to problems.
In China, selective abortion of female fetuses has skewed the natural sex ratio.
The total fertility rate (TFR) is the average number of children born per woman during her lifetime.
Many nations have experienced the demographic transition.
China's One-Child Policy