The Basics of Population About 12,000 years ago, several cultures of other species' populations continue to look shifted from hunting and gathering to to this day. The graph of recent human farming. Humans became the first and only species ever to control our own food supply. Steady population growth was the result of controlling the food supply. In population growth is referred to as a "J the absence of other limiting factors, any curve," because it starts out low and population will expand to the limit of its food skyrockets straight up. supply. This happens so reliably that it is considered a law of ecology. Present Technology World population reached 6.6 billion people By about 1800, major advances referred to as in 2007. At the present rate of growth nearly the “Industrial Revolution” were occurring. 77 million people are added per year. The Improvements to agriculture, settlement world adds a New York City every month, a planning, division of labor, mathematics, Germany every year and a Europe each literacy and science were all foundations of decade. The United States, with over 301 the industrial revolution. million people, is growing by nearly 3 million people each year. At this rate, we are one of Breakthroughs in medicine, nutrition and the fastest growing industrialized nations in sanitation brought down child mortality rates the world. We have the third largest and led to longer life spans. The population of all nations, preceded only by mechanization of agriculture and China and India. At 5% per year, the U.S. also improvements in food preservation led to has the highest teen pregnancy rate of any even greater increases in food production and modern industrialized country. availability. Human numbers began doubling at an unprecedented pace. Future With a current annual growth rate of 1.14%, Rates of Growth Past world population is projected to double in just A graph of human population before the 61 years. Our doubling times will be realized agricultural revolution would likely have if and only if growth rates remain constant. suggested a wave, reflecting growth in times Doubling time is the amount of time it takes of plenty and decline in times of want. Graphs a population to double its number. Today, the world's birth rate is almost three times its 1 death rate. The closer these two rates are, the What is Overpopulation? slower population growth will be. Most people equate overpopulation with Zero population growth (ZPG) is the crowding, but, in fact, density is largely demographic term for the state of equilibrium irrelevant to questions of overpopulation. reached when birth and death rates are the What is relevant is carrying capacity. An area same. Birth rate is the number of live births is overpopulated when its long-term carrying per thousand people. Death rate is the capacity is being degraded by its current number of people that die per thousand human occupants. people. Momentum is also a factor in population growth. Some countries, like the Degree of Impact U.S., are growing even though the average The impact of any human group on its woman has just two children. In such cases, a environment has to do with three equally population can still take 60-70 years to important factors. The first is the number of stabilize, and will do so only when the people. The second factor encompasses the percentage of elderly people is equal to the ways in which we manufacture goods, design percentage at child-bearing age. communities and use technology. The third is the actual amount of resources consumed by Density vs. Consumption, Space vs. each person. Carrying Capacity "The entire world's population could fit into Unfortunately, the rate at which industrialized the state of Texas." This statement is nations consume resources makes their frequently cited by people who don't populations' effect on the planet vastly greater understand the difference between land not than that of developing countries. currently occupied by humans and the amount and type of land required to support human Population growth and rapid consumption of life. People are only able to live in densely resources are equal parts in the problem of populated areas if enough space elsewhere is environmental degradation. For example, the left much less densely populated. For United States could reduce our consumption instance, arable land must be available to of resources and generation of pollution by grow the food for people living in cities and half today. But if we did so without slowing suburbs. Trees and other plants must be left to our growth rate, the difference would be made produce the oxygen we all need. up in 72 years, when our population is expected to double. An area's carrying capacity is the number of a given species that area can support without The Environment and the Importance of impairing its ability to continue supporting Biodiversity that population. The land within Texas could An ecosystem will be more robust with a not provide enough food, water or energy to greater the variety of species within it. It is meet the needs of 6.6 billion people. It could the biodiversity, the variety of life, on Earth not accommodate all the waste generated by that makes our survival possible. Biodiversity so many either. Because that area could not provides crucial "ecosystem services", such come close to sustaining all of the world's as, clean water, breathable atmosphere and people, the fact that we could all physically fit natural climate control, upon which all into that space is virtually meaningless. species depend. The extermination of plant populations changes climates locally and has severe regional effects through disturbance of 2 the water cycle. Food, medicine and shelter industrialization, economic development, are all derived from the abundant organic availability of quality medical care, the resources of the Earth. In fact, more than 50% educational level of the population and the of the prescription drugs dispensed worldwide status of women. are derived from wild plant species. The Industrial Revolution in Western Europe We demand more space and resources from and North America improved living the Earth as human numbers grow. Taking conditions through advances in medicine, more for people means leaving less for other sanitation and nutrition. These changes led to species. Loss of wildlife habitat results in the declines in death rates, especially among extinction of countless numbers of plant and infants and small children. However, birth animal species every year. Currently, 20-75 rates remained high and soon the population plant and animal species are lost every day as swelled. a result of deforestation. It is estimated that by 2015 some 6-14% of all species will have As these regions gradually moved away from gone extinct. an agricultural way of life and became more urbanized, large families became less Doubling Time practical and more expensive. Machinery was The world's current population is estimated at used more frequently to plant and harvest 6.6 billion, with an annual growth rate of 1.14 food reducing the need for children as farm percent. 1.14 percent may not sound like a workers. Urban families bought food instead large number, but, at this rate, almost 77 of harvesting it. Over the course of the 19th million people will be added to the population and early 20th centuries, birth rates dropped this year. dramatically in these areas. Another way to see the impact of growth rates Developing areas, such as Africa, Latin is to consider the doubling time of a America and parts of Asia are still primarily population. Doubling time for a population agriculturally based. Therefore, incentives for can be calculated by dividing 70 by the having larger families still exist. Technology growth rate. For example, 70 divided by 1.14 imported from industrialized countries not is 61.4. This means that if present growth only improved living conditions but caused rates continue, our world population would death rates to plunge dramatically. As a result, double in about 61 years. Twice as many these populations are growing rapidly. people would need twice as much food, water, roads, houses, schools, churches, sanitation In many countries, the low status of women is facilities, etc. Many ecologists worry that our another contributing factor to higher birth planet can't support another doubling of rates. Women are often denied educational population. and employment opportunities and have few alternatives to their childbearing roles. Many Why are developing countries experiencing people wish to limit their family size but lack rapid population growth while developed access to family planning education and countries are growing slowly or not at all? health services. Both developed and developing countries have experienced significant declines in their Are areas of high population density bad? death rates and prolonged life expectancies. No. To the contrary, urban areas hold hope for Developing nations continue to have higher human development and protection of natural birth rates than developed countries. A resources because they can efficiently support country's birth rate is strongly linked to large numbers of people thus limiting their 3 impact on the natural environment. One of the U.S. consumption patterns are dramatically reasons that cities are growing rapidly is different from those in the developing world. because they offer more economic and social Although Americans comprise only 5 percent benefits than do rural areas. of the world's population, we use 25 percent This contrasts to poorly planned areas of of its resources and produce more trash and urban and suburban sprawl, which are fast- pollution than citizens of most other nations. growing, low-density developments typically The average American's energy use is found outside major urban areas.