The earliest point where scientists can make reasonable estimates for the population of global regions is around 10,000 years before the Common Era (or 12,000 years ago). Estimates suggest that Asia has consistently been the most populated continent, and the least populated continent has generally been Oceania (although it was more heavily populated than areas such as North America in very early years). Population growth was very slow, but an increase can be observed between most of the given time periods. There were, however, dips in population due to pandemics, the most notable of these being the impact of plague in Eurasia in the 14th century, and the impact of European contact with the indigenous populations of the Americas after 1492, where it took almost four centuries for the population of Latin America to return to its pre-1500 level. The world's population first reached one billion people in 1803, which also coincided with a spike in population growth, due to the onset of the demographic transition. This wave of growth first spread across the most industrially developed countries in the 19th century, and the correlation between demographic development and industrial or economic maturity continued until today, with Africa being the final major region to begin its transition in the late-1900s.

Between 1500 and 1800, London grew to be the largest city in Western Europe, with its population growing almost 22 times larger in this period. London would eventually overtake Constantinople as Europe's largest in the 1700s, before becoming the largest city in the world (ahead of Beijing) in the early-1800s.

The most populous cities in this period were the capitals of European empires, with Paris, Amsterdam, and Vienna growing to become the largest cities, alongside the likes of Lisbon and Madrid in Iberia, and Naples or Venice in Italy. Many of northwestern Europe's largest cities in 1500 would eventually be overtaken by others not shown here, such as the port cities of Hamburg, Marseilles or Rotterdam, or more industrial cities such as Berlin, Birmingham, and Munich.

In the year 1500, the share of Western Europe's population living in urban areas was just six percent, but this rose to 31 percent by the end of the 19th century. Despite this drastic change, development was quite slow between 1500 and 1800, and it was not until the industrial revolution when there was a spike in urbanization. As Britain was the first region to undergo the industrial revolution, from around the 1760s until the 1840s, these areas were the most urbanized in Europe by 1890. The Low Countries Prior to the 19th century, Belgium and the Netherlands had been the most urbanized regions due to the legacy of their proto-industrial areas in the medieval period, and then the growth of their port cities during the Netherlands' empirical expansion (Belgium was a part of the Netherlands until the 1830s). Belgium was also quick to industrialize in the 1800s, and saw faster development than its larger, more economically powerful neighbors, France and Germany. Least-urban areas Ireland was the only Western European region with virtually no urbanization in the 16th and 17th century, but the industrial growth of Belfast and Dublin (then major port cities of the British Empire) saw this change by the late-1800s. The region of Scandinavia was the least-urbanized area in Western Europe by 1890, but it saw rapid economic growth in Europe during the first half of the following century.

In the past four centuries, the population of the United States has grown from a recorded 350 people around the Jamestown colony of Virginia in 1610, to an estimated 331 million people in 2020. The pre-colonization populations of the indigenous peoples of the Americas have proven difficult for historians to estimate, as their numbers decreased rapidly following the introduction of European diseases (namely smallpox, plague and influenza). Native Americans were also omitted from most censuses conducted before the twentieth century, therefore the actual population of what we now know as the United States would have been much higher than the official census data from before 1800, but it is unclear by how much. Population growth in the colonies throughout the eighteenth century has primarily been attributed to migration from the British Isles and the Transatlantic slave trade; however it is also difficult to assert the ethnic-makeup of the population in these years as accurate migration records were not kept until after the 1820s, at which point the importation of slaves had also been illegalized. Nineteenth century In the year 1800, it is estimated that the population across the present-day United States was around six million people, with the population in the 16 admitted states numbering at 5.3 million. Migration to the United States began to happen on a large scale in the mid-nineteenth century, with the first major waves coming from Ireland, Britain and Germany. In some aspects, this wave of mass migration balanced out the demographic impacts of the American Civil War, which was the deadliest war in U.S. history with approximately 620 thousand fatalities between 1861 and 1865. The civil war also resulted in the emancipation of around four million slaves across the south; many of whose ancestors would take part in the Great Northern Migration in the early 1900s, which saw around six million black Americans migrate away from the south in one of the largest demographic shifts in U.S. history. By the end of the nineteenth century, improvements in transport technology and increasing economic opportunities saw migration to the United States increase further, particularly from southern and Eastern Europe, and in the first decade of the 1900s the number of migrants to the U.S. exceeded one million people in some years. Twentieth and twenty-first century The U.S. population has grown steadily throughout the past 120 years, reaching one hundred million in the 1910s, two hundred million in the 1960s, and three hundred million in 2007. In the past century, the U.S. established itself as a global superpower, with the world's largest economy (by nominal GDP) and most powerful military. Involvement in foreign wars has resulted in over 620,000 further U.S. fatalities since the Civil War, and migration fell drastically during the World Wars and Great Depression; however the population continuously grew in these years as the total fertility rate remained above two births per woman, and life expectancy increased (except during the Spanish Flu pandemic of 1918).

Since the Second World War, Latin America has replaced Europe as the most common point of origin for migrants, with Hispanic populations growing rapidly across the south and border states. Because of this, the proportion of non-Hispanic whites, which has been the most dominant ethnicity in the U.S. since records began, has dropped more rapidly in recent decades. Ethnic minorities also have a much higher birth rate than non-Hispanic whites, further contributing to this decline, and the share of non-Hispanic whites is expected to fall below fifty percent of the U.S. population by the mid-2000s. In 2020, the United States has the third-largest population in the world (after China and India), and the population is expected to reach four hundred million in the 2050s.

BackgroundIt is not known whether equity-oriented primary care investment that seeks to scale up the delivery of effective care in disadvantaged communities can reduce health inequality within high-income settings that have pre-existing universal primary care systems. We provide some non-randomised controlled evidence by comparing health inequality trends between two similar jurisdictions–one of which implemented equity-oriented primary care investment in the mid-to-late 2000s as part of a cross-government strategy for reducing health inequality (England), and one which invested in primary care without any explicit equity objective (Ontario, Canada).MethodsWe analysed whole-population data on 32,482 neighbourhoods (with mean population size of approximately 1,500 people) in England, and 18,961 neighbourhoods (with mean population size of approximately 700 people) in Ontario. We examined trends in mortality amenable to healthcare by decile groups of neighbourhood deprivation within each jurisdiction. We used linear models to estimate absolute and relative gaps in amenable mortality between most and least deprived groups, considering the gradient between these extremes, and evaluated difference-in-difference comparisons between the two jurisdictions.ResultsInequality trends were comparable in both jurisdictions from 2004–6 but diverged from 2007–11. Compared with Ontario, the absolute gap in amenable mortality in England fell between 2004–6 and 2007–11 by 19.8 per 100,000 population (95% CI: 4.8 to 34.9); and the relative gap in amenable mortality fell by 10 percentage points (95% CI: 1 to 19). The biggest divergence occurred in the most deprived decile group of neighbourhoods.DiscussionIn comparison to Ontario, England succeeded in reducing absolute socioeconomic gaps in mortality amenable to healthcare from 2007 to 2011, and preventing them from growing in relative terms. Equity-oriented primary care reform in England in the mid-to-late 2000s may have helped to reduce socioeconomic inequality in health, though other explanations for this divergence are possible and further research is needed on the specific causal mechanisms.

It is only in the past two centuries where demographics and the development of human populations has emerged as a subject in its own right, as industrialization and improvements in medicine gave way to exponential growth of the world's population. There are very few known demographic studies conducted before the 1800s, which means that modern scholars have had to use a variety of documents from centuries gone by, along with archeological and anthropological studies, to try and gain a better understanding of the world's demographic development. Genealogical records One such method is the study of genealogical records from the past; luckily, there are many genealogies relating to European families that date back as far as medieval times. Unfortunately, however, all of these studies relate to families in the upper and elite classes; this is not entirely representative of the overall population as these families had a much higher standard of living and were less susceptible to famine or malnutrition than the average person (although elites were more likely to die during times of war). Nonetheless, there is much to be learned from this data. Impact of the Black Death In the centuries between 1200 and 1745, English male aristocrats who made it to their 21st birthday were generally expected to live to an age between 62 and 72 years old. The only century where life expectancy among this group was much lower was in the 1300s, where the Black Death caused life expectancy among adult English noblemen to drop to just 45 years. Experts assume that the pre-plague population of England was somewhere between four and seven million people in the thirteenth century, and just two million in the fourteenth century, meaning that Britain lost at least half of its population due to the plague. Although the plague only peaked in England for approximately eighteen months, between 1348 and 1350, it devastated the entire population, and further outbreaks in the following decades caused life expectancy in the decade to drop further. The bubonic plague did return to England sporadically until the mid-seventeenth century, although life expectancy among English male aristocrats rose again in the centuries following the worst outbreak, and even peaked at more than 71 years in the first half of the sixteenth century.

In 1800, the population of the region of present-day India was approximately 169 million. The population would grow gradually throughout the 19th century, rising to over 240 million by 1900. Population growth would begin to increase in the 1920s, as a result of falling mortality rates, due to improvements in health, sanitation and infrastructure. However, the population of India would see it’s largest rate of growth in the years following the country’s independence from the British Empire in 1948, where the population would rise from 358 million to over one billion by the turn of the century, making India the second country to pass the billion person milestone. While the rate of growth has slowed somewhat as India begins a demographics shift, the country’s population has continued to grow dramatically throughout the 21st century, and in 2020, India is estimated to have a population of just under 1.4 billion, well over a billion more people than one century previously. Today, approximately 18% of the Earth’s population lives in India, and it is estimated that India will overtake China to become the most populous country in the world within the next five years.

Site indices, as a relative measure of the actual population size, for UK butterfly species calculated from data from the UK Butterfly Monitoring Scheme (UKBMS). Site indices are a relative rather than an absolute measure of the size of a population, and have been shown to relate closely to other, more intensive, measures of population size such as mark, release, recapture (MRR) methods. The site index can be thought of as a relative measure of the actual population size, being a more or less constant proportion of the number of butterflies present. The proportion seen is likely to vary according to species; some butterfly species are more conspicuous and thus more easily detected, whereas others are much less easy to see. Site indices are only calculated at sites with sufficient monitoring visits throughout the season, or for targeted reduced effort surveys (timed observations, larval web counts and egg counts) where counts are generally obtained as close to the peak of the flight period as possible and are subsequently adjusted for the time of year and size of the site (area of suitable habitat type for a given species). Wider Countryside Butterfly Survey (WCBS) sites are thus excluded because they are based on very few visits from which accurate indices of abundance cannot currently be calculated. For transect sites a statistical model (a General Additive Model, 'GAM') is used to impute missing values and to calculate a site index. Each year most transect sites (over 90%) produce an index for at least one species and in recent years site indices are calculated for almost 1,500 sites across the UK. Site indices are subsequently collated to contribute to the overall 'Collated Index' for each species, which are relative measures of the abundance of each species across a geographical area, for example, across the whole UK or at country level in England, Scotland, Wales or Northern Ireland. Individual site indices are important in informing conservation management as not all sites show the same patterns for each species and likely reflect a combination of local climate and habitat management at the site. Although the Centre for Ecology & Hydrology (CEH) and Butterfly Conservation (BC) are responsible for the calculation and interpretation of site indices, the collection of the data used in its creation is ultimately reliant on a large volunteer community. The UKBMS is run by Butterfly Conservation (BC), the Centre for Ecology & Hydrology (CEH) and the British Trust for Ornithology (BTO), in partnership with the Joint Nature Conservation Committee (JNCC), and supported and steered by Forestry Commission (FC), Natural England(NE), Natural Resources Wales (NRW), Northern Ireland Environment Agency (NIEA), and Scottish Natural Heritage (SNH). The UKBMS is indebted to all volunteers who contribute data to the scheme.

The Rural Definition was introduced in 2004 as a joint project between the Commission for Rural Communities (CRC - formerly the Countryside Agency), the Department for Environment, Food and Rural Affairs (Defra), the Office for National Statistics (ONS), the Office of the Deputy Prime Minister (ODPM) and the Welsh Assembly. It was delivered by the Rural Evidence Research Centre at Birkbeck College (RERC).A) This new 'spectrum', or graded system, replaces the earlier Oxford/CA binary ward classification and adopts a settlement-based approach.B) It is available for England and Wales at:Census Output Area (COA or OA)Census Super Output Area (CSOA or SOA)Ward[OAs consist of ~125 households and have a population of ~300. SOAs are built of OAs, typically 5, and so contain ~625 households or a mean population of ~1500. OAs therefore vary greatly in size and shape between urban and rural regions, for example a single tower block may consist of more than one OA, whereas a large area of remote moorland may be covered by a single OA.] More information on OAs and SOAs.C) Output areas are classified by morphology and context:MorphologyUrban (over 10,000)Rural townVillageDispersed (hamlets and isolated dwellings)And contextSparseLess sparseThis gives 8 Urban/Rural Classification (1 urban and 6 rural):Urban (Sparse)Urban (Less Sparse)Town (Less Sparse)Town (Sparse)Village (Less Sparse)Village (Sparse)Dispersed (Less Sparse)Dispersed (Sparse)In April 2009 significant changes in the structure of local government came into force. These changes, especially the creation of 9 new unitary authorities, have necessitated an update to the Local Authority Classification. The Government Statistical Service Regional and Geography Group (GSSRG) commissioned a working group to look at this issue, and the outcome of this working group is a revised LA Classification. Detailed information about the changes can be found here, with guidance on how to use the Definition and Classification here.

This file contains the boundaries, names and codes for 2021 Census Lower Layer Super Output Areas (LSOA) in Cheshire East as at 31 December 2021. These boundaries are created by the Office for National Statistics. Nationally, Lower Layer Super Output Areas have an average population of 1500 people or 650 households. They were updated following the 2021 Census, to reflect changes in local population. In Cheshire East, the 234 former LSOAs were updated - 11 LSOAs were abolished to become 21 new LSOAs, which were sub-divisions of the former LSOA boundaries.The whole of England and Wales can be broken down into these constituent areas. Output areas (OAs) nestle within the boundaries of Lower Super Output Areas (LSOAs), LSOAs nestle within the boundaries of Middle Layer Super Output Areas (MSOAs) and MSOAs nestle within the boundaries of Local Authorities.Boundary data sources used by permission of relevant providers © Crown Copyright Ordnance Survey and National Statistics.

While the European colonization and settlement of other world regions largely began in the 16th and 17th centuries, it was not until the 19th century when the largest waves of migration began to take place. In early years, migration rates were comparatively low; in all of the Americas, the slave population actually outnumbered that of Europeans for most of the given period. Then, with the development of steam ships, intercontinental travel became more affordable and accessible to the masses, and voluntary migration from Europe rose significantly. Additionally, larger numbers of Asian migrants, especially from India and China, migrated to Australia, the Caribbean, and U.S. from the mid-1800s; although the U.S. and Australia both introduced policies that limited or prevented Asian immigration throughout most of the early 1900s. International migration between 1913 and 1950 was also comparatively low due to the tumultuous nature of the period, which involved both World Wars and the Great Depression.

In 1498, Vasco da Gama became the first known European to sail to India by circumventing Africa, which ushered in a new age of European sea trade with Asia. Initially, Indian rulers were unimpressed and wary of the Portuguese, and Muslim traders in the region were hostile, but the Portuguese were able to assess what could be traded for exotic goods (mostly spices) and lucrative trade routes were established after subsequent journeys. Additionally, the Portuguese quickly learned that they had the technological advantage in conflict, and repelled attacks from their Muslim rivals. Fortified trading posts, known as factories, were then established along the African and Asian coasts to protect these trade routes, and these became the foundation upon which the Portuguese Empire (Europe's longest-lasting) was built.

Colonization and competition In 1494, the Treaty of Tordesillas saw Portugal and Spain draw a line through the Atlantic, with each crown laying claim to all non-Christian lands on their respective side. No other European power acknowledged these claims, but it would take almost a century for the British, Dutch, or French to begin establishing their own maritime empires; this meant that the Portuguese had a near-monopoly on the Indian spice trade for almost 100 years, and this was the century when their trade with Asia was most active. Portuguese traders not only did business with merchants in India, but they also explored further, and established trade routes with present-day China, Indonesia, and Japan, and even facilitated trade between these cultures. In the 1590s, the Dutch then followed the Portuguese model of empire building and quickly emerged as Portugal's biggest rival in Asia. VOC The Dutch and Portuguese were in conflict for over 60 years, across four continents, and the Asian and African conflicts are often referred to as the "Spice War". The Netherlands eventually usurped Portugal as the strongest European trading power in Asia by the mid-1600s. Most of the Dutch trade was done through the Dutch East India Company (VOC), which is often considered the most valuable company to have ever existed. In the 17th century, 56 percent of all ships that travelled from the given countries to Asia were Dutch, and the figure was over 44 percent in the following century. Such companies were not only trading enterprises, but also acted in the military and political interests of their respective crowns. The VOC went into decline in the mid-1700s, as the British Empire gained the upper hand in its rivalry with the Netherlands. The British East India Company then consolidated its power on the Indian subcontinent, and Dutch interests were largely centered in the East Indies (present-day Indonesia), which remained a Dutch colony until the Second World War. For France, its primary colonial power in Asia was in French Indochina, made up of present-day Cambodia, Laos, and Vietnam, although the seven European powers had trade connections all over Asia, and all competed or cooperated with one another at various points in these 300 years.

During the eighteenth century, it is estimated that France's population grew by roughly fifty percent, from 19.7 million in 1700, to 29 million by 1800. In France itself, the 1700s are remembered for the end of King Louis XIV's reign in 1715, the Age of Enlightenment, and the French Revolution. During this century, the scientific and ideological advances made in France and across Europe challenged the leadership structures of the time, and questioned the relationship between monarchial, religious and political institutions and their subjects. France was arguably the most powerful nation in the world in these early years, with the second largest population in Europe (after Russia); however, this century was defined by a number of costly, large-scale conflicts across Europe and in the new North American theater, which saw the loss of most overseas territories (particularly in North America) and almost bankrupted the French crown. A combination of regressive taxation, food shortages and enlightenment ideologies ultimately culminated in the French Revolution in 1789, which brought an end to the Ancien Régime, and set in motion a period of self-actualization.

War and peace

After a volatile and tumultuous decade, in which tens of thousands were executed by the state (most infamously: guillotined), relative stability was restored within France as Napoleon Bonaparte seized power in 1799, and the policies of the revolution became enforced. Beyond France's borders, the country was involved in a series of large scale wars for two almost decades, and the First French Empire eventually covered half of Europe by 1812. In 1815, Napoleon was defeated outright, the empire was dissolved, and the monarchy was restored to France; nonetheless, a large number of revolutionary and Napoleonic reforms remained in effect afterwards, and the ideas had a long-term impact across the globe. France experienced a century of comparative peace in the aftermath of the Napoleonic Wars; there were some notable uprisings and conflicts, and the monarchy was abolished yet again, but nothing on the scale of what had preceded or what was to follow. A new overseas colonial empire was also established in the late 1800s, particularly across Africa and Southeast Asia. Through most of the eighteenth and nineteenth century, France had the second largest population in Europe (after Russia), however political instability and the economic prioritization of Paris meant that the entire country did not urbanize or industrialize at the same rate as the other European powers. Because of this, Germany and Britain entered the twentieth century with larger populations, and other regions, such as Austria or Belgium, had overtaken France in terms of industrialization; the German annexation of Alsace-Lorraine in the Franco-Prussian War was also a major contributor to this.

World Wars and contemporary France

Coming into the 1900s, France had a population of approximately forty million people (officially 38 million* due to to territorial changes), and there was relatively little growth in the first half of the century. France was comparatively unprepared for a large scale war, however it became one of the most active theaters of the First World War when Germany invaded via Belgium in 1914, with the ability to mobilize over eight million men. By the war's end in 1918, France had lost almost 1.4 million in the conflict, and approximately 300,000 in the Spanish Flu pandemic that followed. Germany invaded France again during the Second World War, and occupied the country from 1940, until the Allied counter-invasion liberated the country during the summer of 1944. France lost around 600,000 people in the course of the war, over half of which were civilians. Following the war's end, the country experienced a baby boom, and the population grew by approximately twenty million people in the next fifty years (compared to just one million in the previous fifty years). Since the 1950s, France's economy quickly grew to be one of the strongest in the world, despite losing the vast majority of its overseas colonial empire by the 1970s. A wave of migration, especially from these former colonies, has greatly contributed to the growth and diversity of France's population today, which stands at over 65 million people in 2020.

The share of households owning a pet in the United Kingdom remained relatively stable between 2012 and 2018, hovering around an estimated percentage of 47 to 45 percent. However, pet ownership levels peaked to an unprecedented high of 62 percent in 2022, likely as a result of the coronavirus pandemic and increased time spent at home. In 2023, this figure shrank to 57 percent.

Pet ownership in the UK With more than half of UK households owning at least one pet in 2021/22, dogs and cats were the most common household pets in that year, with an estimated 13 million dogs and 12 million cats living in homes. As of 2020, the United Kingdom was the second highest-ranking European country in terms of its dog population, preceded only by Germany.

Consumer spending on pets in the UK As the pet population in the United Kingdom increased in size, so did consumer spending on pet food and pet-related products and services. Spending on pets and related products reached almost eight billion British pounds in 2020, a notable increase from a mere 2.9 billion British pounds in 2005. Among the most expensive pet-related expenditures are veterinary and pet services, which constituted almost four billion British pounds in 2020.

In 1800, the population of the island of Sri Lanka was approximately 1.2 million. This figure would begin to grow following the island’s complete annexation into the British Empire with the end of the Second Kandyan War in 1815. Population growth then increased much faster towards the end of the 19th century, as child mortality rates dropped and large numbers of Indian migrants were imported to work on British plantations. These migrants were largely Tamil migrants from southern India, and by 1911, this group would make up almost 13 percent of the island’s population (on top of the existing 13 percent Sri Lankan Tamil population).

Population growth would expand rapidly in the years immediately following the island’s independence from the British Empire in 1948. However, this growth would slow in the 1950s, as legislation passed by the Sinhalese-dominated government immediately following independence resulted in the removal of citizenship for an estimated 700,000 Indian Tamils, and the deportation of over 300,000 to India over the following three decades. Growth would slow even further after the ethnic clashes of Black July in 1983, which marked the beginning of a civil war in Sri Lanka which would last from 1983 to 2009 and result in the death of over 80,000 people, and the displacement of an estimated 800,000. However, since the end of the civil war in 2009, the population of Sri Lanka has continued to grow, and in 2020, the population of Sri Lanka is estimated to be over 21 million.

Between 1500 and 1820, an estimated 2.58 million Europeans migrated to the Americas, namely from the British Isles, Portugal, Spain, France and Germany. Until the mid-1600s, the majority of European migrants were from the Iberian Peninsula, as Portugal and Spain had a 150 year head start over other European powers when building their overseas empires. However, by the end of the century, more settlers from the British Isles had emigrated to the New World than from Spain or Portugal; the majority of which migrated to British colonies in the Caribbean as indentured servants or prisoners. The 18th century also saw migrants from other European nations begin to migrate en masse, particularly those from France and the German states, although migration from the British Isles and Portugal remained at the highest levels.

In comparison to the almost 2.6 million Europeans migrants, it is estimated that over 8.6 million Africans were forced across the Atlantic during this time period, as part of the transatlantic slave trade. The first half of the 19th century saw the demise of the transatlantic slave trade, which was followed by an influx of white migration to the Americas from across Europe; this contributed heavily to reversing demographic trends and making those with African ancestry an ethnic minority in most American countries today.

Life expectancy in India was 25.4 in the year 1800, and over the course of the next 220 years, it has increased to almost 70. Between 1800 and 1920, life expectancy in India remained in the mid to low twenties, with the largest declines coming in the 1870s and 1910s; this was because of the Great Famine of 1876-1878, and the Spanish Flu Pandemic of 1918-1919, both of which were responsible for the deaths of up to six and seventeen million Indians respectively; as well as the presence of other endemic diseases in the region, such as smallpox. From 1920 onwards, India's life expectancy has consistently increased, but it is still below the global average.