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From Wikipedia, the free encyclopedia

The distribution of human world population in 2018
The distribution of human world population in 2018
Key
Key

In biology, a population is all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding.[1][2] The area of a sexual population is the area where inter-breeding is potentially possible between any pair within the area, and where the probability of interbreeding is greater than the probability of cross-breeding with individuals from other areas.[3]

In sociology, population refers to a collection of humans. Demography is a social science which entails the statistical study of human populations. Population in simpler terms is the number of people in a city or town, region, country or world; population is usually determined by a process called census (a process of collecting, analyzing, compiling and publishing data)

This article refers mainly to human population.

YouTube Encyclopedic

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  • Defusing the Population Bomb
  • Overpopulation – The Human Explosion Explained
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  • Japan's Population Problem
  • DON'T PANIC — Hans Rosling showing the facts about population

Transcription

Hey guys, Joe here. I’ve been thinking... if you sang happy birthday to every person who will be born today, you’d be singing for nearly six and a half weeks without stopping. That’s adding 386,000 more birthday cakes and humans, every day. It’s estimated that 1 in 15 humans ever born is alive right now. When I was growing up there were only 5 billion of us, but now Earth is home to 7.6 billion people. And some folks are worried what will happen if things continue at this rate. Space isn’t the problem. If we all lived as densely as people in Manhattan, every human could fit inside Norway, with a fjord or two to spare. But our species’ true footprint is much, MUCH larger. For many, today’s climate and ecological imbalances are proof there’s simply too many people on this planet. But are there really? What IS overpopulation? And how did it get this way? No one really asked these questions until recently, because for tens of thousands of years, our species’ numbers only hovered in the millions. But by the year 1800 or so, there were finally one billion of us, and then things really started to change. While it took tens of thousands of years for the human population to hit 1 billion, it only took 123 years to double that, and just 47 to double again. Since the 1970s the 5th, 6th, and 7th billion have arrived every 12 years. So when does population growth become overpopulation? The answer? It depends. Way back in 1798, Thomas Malthus warned that unchecked population growth would, as a rule, outpace food supply, leading to global mass starvation and violent conflict. Many environmentalists in the 20th century predicted the incoming population bomb would send shockwaves of disease, poverty, and environmental destruction rippling around the globe, basically ruining everything. This hasn’t proven to be the case. Malthus underestimated humanity’s ability to increase Earth’s capacity using good ol’ science. But one thing is true: The way we feed 7 billion people today won’t scale to feed 10 billion tomorrow. I don’t know if you’ve noticed, but many parts of the world have too much food. Maybe we aren’t getting it where it’s needed, because we let imaginary lines on maps make too many rules. A lot of what we grow doesn’t go into our own stomachs. A third of crops go to feeding livestock. Animals raised for food occupy 80% of Earth’s agricultural land, yet provide only 20% of our calories. Beef alone requires ten times as much land per unit of protein as produce, grains, even eggs. We’ve been able to scale up food production so far, but there is SOME upper limit to how many people Earth can feed, no matter how we grow it, and we can’t exactly eat the moon. But what makes populations grow–or not grow? The reality for most of history was that many children would die before adulthood, so you’d better have plenty. Lots of births balanced by lots of deaths kept populations low, but steady, for a long time. But beginning in the 1700s, advances in agriculture and transportation meant fewer people starved. Later, during the Industrial Revolution, public health and economic advancements translated into less disease and higher living standards. Death rates went down, but old habits die hard, so people continued to have lots of babies, which led to rapid population growth. Eventually people caught on that more of their kids were going to survive, and as education and opportunities for women improved, families started having fewer children, and population growth slowed. Eventually, when birth and death rates remain low, populations level off, and become stable, or even start shrinking. Things had gotten a lot better for a lot of people… if they lived in Europe or North America. Not every country moves through these demographic transitions at the same time, so while population growth was slowing or coming to an end in many developed countries, it was just picking up in other places. But developing nations are moving more rapidly through these transitions. It took the United Kingdom 95 years to halve birth rates, while Brazil did it in 26, and Iran just 10. Today birth rates are falling almost everywhere. The less time a country spends in stages of rapid growth, the quicker Earth’s population stops increasing. It’s unlikely that the 12 billionth human will ever be born. And by 2100 our population will most likely peak between 9 and 12 billion. Instead of one big population bomb, the challenge today is defusing a few population “cluster bombs” in pockets of the developing world. There are two big ways to accomplish this. Increasing women’s access to education is the most effective way to lower birth rates. It improves children’s health and leads to better family planning. Empowering women leads to slower population growth. This alone could reduce greenhouse gas emissions as much as all wind energy by 2050. Today, the richest 10% of humans are responsible for almost half of climate emissions, while the poorest half of people are only responsible for a tenth. Developed nations will have to reduce their impact and meet developing nations in a cleaner middle. Populations can’t grow forever without consequences, but under the right circumstances populations control themselves. But 10 billion people is still a lot of mouths to feed, and doing it without ruining nature or anything like that won’t be easy. But it’s not impossible, and it won’t take some apocalyptic robot army of forced population control to do it. While history has taught us that population growth has natural checks and balances, we have yet to find a limit when it comes to creating new ways to live. Stay curious.

Contents

Population genetics (ecology)

In population genetics a sexual population is a set of organisms in which any pair of members can breed together. This means that they can regularly exchange gametes to produce normally-fertile offspring, and such a breeding group is also known therefore as a Gamo deme. This also implies that all members belong to the same species.[4] If the Gamo deme is very large (theoretically, approaching infinity), and all gene alleles are uniformly distributed by the gametes within it, the Gamo deme is said to be panmictic. Under this state, allele (gamete) frequencies can be converted to genotype (zygote) frequencies by expanding an appropriate quadratic equation, as shown by Sir Ronald Fisher in his establishment of quantitative genetics.[5]

This seldom occurs in Nature: localization of gamete exchange – through dispersal limitations, preferential mating, cataclysm, or other cause – may lead to small actual Gamo demes which exchange gametes reasonably uniformly within themselves but are virtually separated from their neighboring Gamo demes. However, there may be low frequencies of exchange with these neighbors. This may be viewed as the breaking up of a large sexual population (panmictic) into smaller overlapping sexual populations. This failure of panmixia leads to two important changes in overall population structure: (1) the component Gamo demos vary (through gamete sampling) in their allele frequencies when compared with each other and with the theoretical panmictic original (this is known as dispersion, and its details can be estimated using expansion of an appropriate binomial equation); and (2) the level of homozygosity rises in the entire collection of Gamo demes. The overall rise in homozygosity is quantified by the inbreeding coefficient (f or φ). Note that all homozygotes are increased in frequency – both the deleterious and the desirable. The mean phenotype of the Gamo demes collection is lower than that of the panmictic original – which is known as inbreeding depression. It is most important to note, however, that some dispersion lines will be superior to the panmictic original, while some will be about the same, and some will be inferior. The probabilities of each can be estimated from those binomial equations. In plant and animal breeding, procedures have been developed which deliberately utilize the effects of dispersion (such as line breeding, pure-line breeding, backcrossing). It can be shown that dispersion-assisted selection leads to the greatest genetic advance (ΔG=change in the phenotypic mean), and is much more powerful than selection acting without attendant dispersion. This is so for both allogamous (random fertilization)[6] and autogamous (self-fertilization) Gamo demes.[7]

In ecology, the population of a certain species in a certain area can be estimated using the Lincoln Index.

World human population

As of today's date, the world's population is estimated by the United States Census Bureau to be 7.651 billion.[8] The US Census Bureau estimates the 7 billion number was surpassed on 12 March 2012. According to a separate estimate by the United Nations, Earth’s population exceeded seven billion in October 2011, a milestone that offers unprecedented challenges and opportunities to all of humanity, according to UNFPA, the United Nations Population Fund.[9]

According to papers published by the United States Census Bureau, the world population hit 6.5 billion on 24 February 2006. The United Nations Population Fund designated 12 October 1999 as the approximate day on which world population reached 6 billion. This was about 12 years after world population reached 5 billion in 1987, and 6 years after world population reached 5.5 billion in 1993. The population of countries such as Nigeria, is not even known to the nearest million,[10] so there is a considerable margin of error in such estimates.[11]

Researcher Carl Haub calculated that a total of over 100 billion people have probably been born in the last 2000 years.[12]

Predicted growth and decline

The years taken for every billion people to be added to the world's population, and the years that population was reached (with future estimates).
The years taken for every billion people to be added to the world's population, and the years that population was reached (with future estimates).

Population growth increased significantly as the Industrial Revolution gathered pace from 1700 onwards.[13] The last 50 years have seen a yet more rapid increase in the rate of population growth[13] due to medical advances and substantial increases in agricultural productivity, particularly beginning in the 1960s,[14] made by the Green Revolution.[15] In 2007 the United Nations Population Division projected that the world's population will likely surpass 10 billion in 2055.[16]

PRB 2017 Data Sheet Largest Populations
PRB 2017 Data Sheet Largest Populations

In the future, the world's population is expected to peak,[17] after which it will decline due to economic reasons, health concerns, land exhaustion and environmental hazards. According to one report, it is very likely that the world's population will stop growing before the end of the 21st century. Further, there is some likelihood that population will actually decline before 2100.[18][19] Population has already declined in the last decade or two in Eastern Europe, the Baltics and in the Commonwealth of Independent States.[20]

The population pattern of less-developed regions of the world in recent years has been marked by gradually declining birth rates. These followed an earlier sharp reduction in death rates.[21] This transition from high birth and death rates to low birth and death rates is often referred to as the demographic transition.[21]

Control

Human population control is the practice of altering the rate of growth of a human population. Historically, human population control has been implemented with the goal of increasing the rate of population growth. In the period from the 1950s to the 1980s, concerns about global population growth and its effects on poverty, environmental degradation, and political stability led to efforts to reduce population growth rates. While population control can involve measures that improve people's lives by giving them greater control of their reproduction, a few programs, most notably the Chinese government's one-child per family policy, have resorted to coercive measures.

In the 1978s, tension grew between population control advocates and women's health activists who advanced women's reproductive rights as part of a human rights-based approach.[22] Growing opposition to the narrow population control focus led to a significant change in population control policies in the early 1980s.[23]

See also

References

  1. ^ "Population". Biology Online. Retrieved 5 December 2012. 
  2. ^ "Definition of population (biology)". Oxford Dictionaries. Oxford University Press. Retrieved 5 December 2012. a community of animals, plants, or humans among whose members interbreeding occurs 
  3. ^ Hartl, Daniel (2007). Principles of Population Genetics. Sinauer Associates. p. 45. ISBN 978-0-87893-308-2. 
  4. ^ Hartl, Daniel (2007). Principles of Population Genetics. Sinauer Associates. p. 95. ISBN 978-0-87893-308-2. 
  5. ^ Fisher, R. A. (1999). The Genetical Theory of Natural Selection. Oxford University Press. ISBN 0-19-850440-3. 
  6. ^ Gordon, Ian L. (2000). "Quantitative genetics of allogamous F2 : an origin of randomly fertilized populations". Heredity. 85: 43–52. doi:10.1046/j.1365-2540.2000.00716.x. PMID 10971690. 
  7. ^ Gordon, Ian L. (2001). "Quantitative genetics of autogamous F2". Hereditas. 134 (3): 255–262. doi:10.1111/j.1601-5223.2001.00255.x. PMID 11833289. 
  8. ^ U.S. Census Bureau – World Pop Clock Projection Archived 1 February 2008 at WebCite
  9. ^ to a World of Seven Billion People Archived 13 January 2012 at the Wayback Machine. UNFPA 12 September 2011
  10. ^ "Cities in Nigeria: 2005 Population Estimates – MongaBay.com". Retrieved 1 July 2008. 
  11. ^ "Country Profile: Nigeria". BBC News. 24 December 2009. Retrieved 1 July 2008. 
  12. ^ Haub, C. 1995/2004. "How Many People Have Ever Lived On Earth?" Population Today, "Archived copy". Archived from the original on 24 April 2013. Retrieved 29 April 2013. 
  13. ^ a b As graphically illustrated by population since 10,000BC and population since 1000AD
  14. ^ "The end of India's green revolution?". BBC News. 29 May 2006. Retrieved 29 November 2009. 
  15. ^ Food First/Institute for Food and Development Policy Archived 14 July 2009 at the Wayback Machine.
  16. ^ "World population will increase by 2.5 billion by 2050; people over 60 to increase by more than 1 billion" (Press release). United Nations Population Division. 13 March 2007. Retrieved 14 March 2007. The world population continues its path towards population ageing and is on track to surpass 9 billion persons by 2050. 
  17. ^ World Population Development Statistics: Forecast, United Nations, 2011.
  18. ^ "The End of World Population Growth". Nature. 412: 543–545. doi:10.1038/35087589. Retrieved 4 November 2008. 
  19. ^ Ojovan, M.I.; Loshchinin, M.B. (2015). "Heuristic Paradoxes of S.P. Kapitza Theoretical Demography" (PDF). European Researcher. 92 (3): 237–248. doi:10.13187/er.2015.92.237. 
  20. ^ Shackman, Gene, Xun Wang and Ya-Lin Liu. 2011. Brief review of world population trends. Available at http://gsociology.icaap.org/report/demsum.html
  21. ^ a b "Archived copy". Archived from the original on 30 March 2009. Retrieved 7 April 2009. 
  22. ^ Knudsen, Lara (2006). Reproductive Rights in a Global Context. Vanderbilt University Press. p. 2. ISBN 978-0-8265-1528-5. 
  23. ^ Knudsen, Lara (2006). Reproductive Rights in a Global Context. Vanderbilt University Press. pp. 4–5. ISBN 978-0-8265-1528-5. 

External links

This page was last edited on 17 September 2018, at 15:03
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