In 1821, Ireland's population was just over 6.8 million people. During this time, the entire island was a part of the United Kingdom of Great Britain and Ireland, after both islands were united by the Acts of Union in 1800. From the graph we can see that the population enjoyed steady growth between 1821 and 1841, and it rose by almost 1.4 million people in this time. However the Great Famine, which lasted from 1845 to 1849, had a devastating impact on the population, causing it to drop from 8.18 million in 1841 to 6.55 million in 1851. The Great Hunger The famine was caused by a Europe-wide potato blight that contributed to mass starvation and death throughout the continent, although it's impact on Ireland was much harsher than anywhere else. The potato blight affected Ireland so severely as the majority of potatoes in Ireland were of a single variety which allowed the disease to spread much faster than in other countries. As the potato blight spread, the population became increasingly dependent on dairy and grain products, however a lot of these resources were relocated by the British military to combat food shortages in Britain. Due to disproportional dependency on potatoes, and mismanagement by the British government, over one million people died and a further one million emigrated. The Great Famine lasted from just 1845 to 1849, but it's legacy caused almost a century of population decline, and to this day, the population of Ireland has never exceeded it's pre-famine levels. Road to recovery The population decline continued well into the twentieth century, during which time the Republic of Ireland achieved independence from the British Empire. After centuries of fighting and rebellion against British rule, Irish nationalists finally gained independence from Britain in 1921, although the six counties with the largest Protestant populations formed Northern Ireland, which is still a part of the United Kingdom today. In spite of the conflict that overshadowed Ireland for much of the twentieth century, which claimed the lives of thousands of people (particularly during the Northern Irish Troubles), and despite Ireland's high emigration rate, the population began growing again in the second half of the 1900s. The population was at it's lowest from 1926 to 1961, where it remained around 4.3 million, but in the following half-century the population grew by over two million people, reaching 6.4 million in 2011, although this number is still lower than in 1821. Gender stats The difference between the male and female populations throughout Ireland's recent history has also remained relatively low. The largest difference occurred in 1831, where there are 170,000 more women than men, although these figures do not include military personnel which would reduce the difference significantly. The gap then remains under 60,000 throughout the twentieth century.

In 1821, the population of the island of Ireland was just over 6.8 million people. During this time, the entire island was a part of the United Kingdom of Great Britain and Ireland, after both islands were united by the Act of Union in 1800. The population enjoyed steady growth between 1821 and 1841, and it rose by almost 1.4 million people in this time, however the Great Famine, which lasted from 1845 to 1849, had a devastating impact on the population, causing it to drop from 8.18 million in 1841 to 6.55 million in 1851. If applying modern-day borders, the population of Northern Ireland was not growing as fast as the population of the Republic of Ireland before 1841, however it was not as severely affected by the famine, which was hardest felt in the east and south. The Great Hunger The famine was caused by a Europe-wide potato blight that contributed to mass starvation and death throughout the continent, although it's impact on Ireland was much harsher than anywhere else. The potato blight affected Ireland so severely as the majority of potatoes in Ireland were of a single variety which allowed the disease to spread much faster than in other countries. As the potato blight spread, the population became increasingly dependent on dairy and grain products, however a lot of these resources were relocated by the British military to combat food shortages in Britain. Due to disproportional dependency on potatoes, and mismanagement by the British government, over one million people died and a further one million emigrated. The Great Famine lasted from just 1845 to 1849, but it's legacy caused almost a century of population decline, and to this day, the overall population of Ireland has never exceeded it's pre-famine levels. Decline continues through partition The population decline continued well into the twentieth century, during which time the Republic of Ireland achieved independence from the British Empire. After centuries of fighting and rebellion against British rule, Irish nationalists finally gained independence from Britain in 1921, although the six counties with the largest Protestant populations formed Northern Ireland, which is still a part of the United Kingdom today. Although there was much conflict in Ireland in the twentieth century which claimed the lives of thousands of people (particularly during the Northern Irish Troubles), and despite Ireland's high emigration rate, the overall population began growing again in the second half of the 1900s. Recovery The population of the Republic of Ireland was at it's lowest in 1961, with 2.8 million people, which is almost four million fewer people than before the famine. Since then it has grown consistently, reaching 4.6 million in 2011 and expected to reach 5 million people by 2020. In Northern Ireland, the population began growing again from the beginning of the 1900s, but growth has been very slow. The only time it fell was in the 1970s, at the peak of The Troubles, where high unemployment and violence contributed to a lower birth rate and an increase in emigration. From the 1980s onwards, living standards improved and the population began growing again, reaching 1.8 million people in 2011.

The island of Ireland is split into 32 different counties, and from 1800 until 1921 the whole island was a part of the United Kingdome of Great Britain and Ireland (although Britain had been a controlling presence on the island for considerably longer than this). In 1921 the island was split into two separate states, where the six counties with the highest population of Protestants formed part of the United Kingdom of Great Britain and Northern Ireland, and the other 26 counties became the Independent Republic of Ireland. From 1821 until 1841, the population of these 26 counties was growing steadily, until the Great Famine from 1845 to 1849 swept across the island, particularly devastating the west and south.

The famine was caused by a Europe-wide potato blight that contributed to mass starvation and death throughout the continent, although it's impact on Ireland was much harsher than anywhere else. The potato blight affected Ireland so severely as the majority of potatoes in Ireland were of a single variety which allowed the disease to spread much faster than in other countries. People in the west and south of Ireland were particularly dependent on potatoes, and these areas were affected more heavily than the north and west, where flax and cereals were the staple. As the potato blight spread, the population became increasingly reliant on dairy and grain products, however a lot of these resources were relocated by the British military to combat food shortages in Britain. Due to disproportional dependency on potatoes, and mismanagement by the British government, over one million people died and a further one million emigrated. The Great Famine lasted from just 1845 to 1849, but it's legacy caused almost a century of population decline, and to this day, the population of Ireland has never exceeded it's pre-famine levels.

The population decline continued well into the twentieth century, during which time the Republic of Ireland achieved independence from the British Empire. After centuries of fighting and rebellion against British rule, Irish nationalists finally gained some independence from Britain in 1921, establishing an Irish Republic in the 26 counties. There was a lot of conflict in Ireland in the early 1900s, through the War of Independence and Irish Civil War, however the population of the Republic began growing again from the 1960s onwards as the quality of life improved and the emigration rate declined. The population was at it's lowest from 1926 to 1971, where it remained at just under three million, but in the following fifty years the population has grown by over two million people.

Between 1821 and 1921, the entire island of Ireland was a part of the United Kingdom of Great Britain and Ireland, after both islands were united by the Act of Union in 1800. This graph shows only the population of the six counties of Ireland that would go on to become Northern Ireland. The population was just under 1.4 million in 1821 and grew to 1.7 million in the next twenty years.

Between 1845 and 1849 the Great Famine devastated the overall population of Ireland, causing the deaths of approximately one million people, and causing a further million to emigrate. Although the famine affected the population of the west and south of Ireland much more severely than the north, the population of the six counties still fell by over 200,000 people between 1841 and 1851. The population then continued to fall, reaching it's lowest point in the 1890s where it was 1.2 million. The Northern Irish population then grows slowly until the mid to late 1900s, during which time the state of Northern Ireland was founded in 1921. The population the reaches over 1.54 million in the 1960s, before it falls again in the 1970s. This drop in population coincides with the outbreak and the most violent decade of the Troubles in Northern Ireland, which was a conflict that dominated Northern Irish daily life for decades. However, from 1981 onwards the population grows by 70,000 to 12,000 every ten years, surpassing it's pre-famine level in the 1990s.

From 1821 until 2011, the male and female populations of the 26 counties of the modern-day Republic of Ireland grew at a relatively similar rate, however some fluctuations did occur. During this time, the entire island of Ireland was a part of the United Kingdom of Great Britain and Ireland, after both islands were united by the Acts of Union in 1800. This graph shows the populations of the 26 counties that would later form the Republic of Ireland in 1921, and does not include the six counties that became known as Northern Ireland.

As we can see, both populations follow a relatively similar trend throughout their respective histories. In the first three entries, women outnumber men by 70,000 to 120,000, although these figures do not include military personnel which would narrow this margin. Both populations fall at a similar rate during and after the famine, however the male population does fall slightly faster, possibly due to an increased rate of emigration among males. Another point where both populations differ is in the early twentieth century, where the female population declines in a relatively smooth curve, although the male populations peak in the census data before and after both world wars. From 1956 onwards both populations follow a very similar trend, and grow at the same rate. The difference in population sizes never exceeds 30,000 people, until the final entry in 2011 where the population of men is 2.27 million and the population of women is 2.31 million.

Cholera is one of the foremost water-borne diseases of citizens in developing countries without adequate access to clean water or sanitation facilities. Every year, 3 to 5 million people worldwide are infected by cholera, of which more than 100,000 die. Cholera is a re-emerging disease whose spread remains difficult to predict. One way to improve our ability to predict cholera epidemics is to learn from the dynamics of past epidemics. Studying historical cholera epidemics improves our understanding of the natural history of cholera before there were effective public health interventions or public understanding of transmission. Recent examples of studies that revisited cholera epidemics include Bingham and colleagues who studied the role of the water supply in the London outbreak of 1849, and Kuo and colleagues (5) who identified the changing geographical patterns of cholera in Fukushima from 1882 and 1895. Here, the 1848 – 1850 cholera epidemic in Ireland is investigated. This epidemic was part of the second cholera pandemic, during which more than 45,698 cases and 19,325 deaths were reported to Ireland’s Central Board of Health. It began during the Irish famine (1845 – 1852), when, between the censuses of 1841 to 1851, the population of Ireland dropped by 1,622,739 people through starvation, disease, and emigration, to a total population of 6,552,385. Epidemiology of the cholera epidemic of 1848 – 1850 in Ireland The second cholera pandemic began in 1829 in India, and first arrived in Ireland in Dublin in March, 1832. This first arrival of cholera in Ireland spread to the principal towns, but subsided quickly. The famine of Ireland began with the potato blight in 1845, which led to migration of Irish people to cities and workhouses in search of work and food. The first reported case of this epidemic was a man just arrived from Edinburgh and took place on December 4, 1848 in a workhouse in Belfast.

Pest and pathogen losses jeopardise global food security and ever since the 19th century Irish famine, potato late blight has exemplified this threat. The causal oomycete pathogen, Phytophthora infestans, undergoes major population shifts in agricultural systems via the successive emergence and migration of asexual lineages. The phenotypic and genotypic bases of these selective sweeps are largely unknown but management strategies need to adapt to reflect the changing pathogen population. Here, we used molecular markers to document the emergence of a lineage, termed 13_A2, in the European P. infestans population, and its rapid displacement of other lineages to exceed 75% of the pathogen population across Great Britain in less than three years. We show that isolates of the 13_A2 lineage are among the most aggressive on cultivated potatoes, outcompete other aggressive lineages in the field, and overcome previously effective forms of plant host resistance. Genome analyses of a 13_A2 isolate revealed extensive genetic and expression polymorphisms particularly in effector genes. Copy number variations, gene gains and losses, amino-acid replacements and changes in expression patterns of disease effector genes within the 13_A2 isolate likely contribute to enhanced virulence and aggressiveness to drive this population displacement. Importantly, 13_A2 isolates carry intact and in planta induced Avrblb1, Avrblb2 and Avrvnt1 effector genes that trigger resistance in potato lines carrying the corresponding R immune receptor genes Rpi-blb1, Rpi-blb2, and Rpi-vnt1.1. These findings point towards a strategy for deploying genetic resistance to mitigate the impact of the 13_A2 lineage and illustrate how pathogen population monitoring, combined with genome analysis, informs the management of devastating disease epidemics.

The main dataset ("ESB Mobility Database") contains occupational data on 1,200 Irish immigrants who arrived in the U.S. in the Famine years and could be tracked for at least a decade. We also present the most up-to-date version of our Emigrant Savings Bank Depositor Database, which contains data on all 15,000 people who opened accounts at the bank from 1850 to 1858. Also provided are data from the 1855 New York State census documenting the occupations of New York's entire Irish-born population as well as datasets documenting the occupations held by New York's Irish immigrants one year and ten years after their arrival in America,

Food and diet were class markers in nineteenth-century Ireland, which became evident as nearly one million people, primarily the poor and destitute, died as a consequence of the notorious Great Famine of 1845–1852. Famine took hold after a blight (Phytophthora infestans) destroyed the only means of subsistence—the potato crop—for a significant proportion of the population. This study seeks to elucidate the variability of diet in mid-nineteenth-century Ireland through microparticle and proteomic analysis of human dental calculus samples (n = 42) from victims of the Famine. The sample derives from remains of people who died between August 1847 and March 1851 while receiving poor relief as inmates in the union workhouse in the city of Kilkenny (52°39’N, -7°15’W). The results corroborate the historical accounts of food provisions before and during the Famine, with evidence of corn (maize), potato and cereal starch granules from the microparticle analysis and milk proteins from the proteomic analysis. Unexpectedly, there is also evidence of egg proteins—a food source generally reserved only for export and the better-off social classes—which highlights the variability of the Famine experience for those who died. Through historical contextualisation, this study shows how the notoriously monotonous potato diet of the nineteenth-century Irish poor was supplemented by other foodstuffs on an opportunistic basis. While the Great Irish Famine was one of the worst subsistence crises in history, it was foremost a social disaster induced by the lack of access to food and not the lack of food availability.

At the beginning of the 1840s, life expectancy from birth in Ireland was just over 38 years. However, this figure would see a dramatic decline with the beginning of the Great Famine in 1845, and dropped below 21 years in the second half of the decade (in 1849 alone, life expectancy fell to just 14 years). The famine came as a result of a Europe-wide potato blight, which had a disproportionally devastating impact on the Irish population due to the dependency on potatoes (particularly in the south and east), and the prevalence of a single variety of potato on the island that allowed the blight to spread faster than in other areas of Europe. Additionally, authorities forcefully redirected much of the country's surplus grain to the British mainland, which exacerbated the situation. Within five years, mass starvation would contribute to the deaths of over one million people on the island, while a further one million would emigrate; this also created a legacy of emigration from Ireland, which saw the population continue to fall until the mid-1900s, and the total population of the island is still well below its pre-famine level of 8.5 million people.

Following the end of the Great Famine, life expectancy would begin to gradually increase in Ireland, as post-famine reforms would see improvements in the living standards of the country’s peasantry, most notably the Land Wars, a largely successful series of strikes, boycotts and protests aimed at reform of the country's agricultural land distribution, which began in the 1870s and lasted into the 20th century. As these reforms were implemented, life expectancy in Ireland would rise to more than fifty years by the turn of the century. While this rise would slow somewhat in the 1910s, due to the large number of Irish soldiers who fought in the First World War and the Spanish Flu pandemic, as well as the period of civil unrest leading up to the island's partition in 1921, life expectancy in Ireland would rise greatly in the 20th century. In the second half of the 20th century, Ireland's healthcare system and living standards developed similarly to the rest of Western Europe, and today, it is often ranks among the top countries globally in terms of human development, GDP and quality of healthcare. With these developments, the increase in life expectancy from birth in Ireland was relatively constant in the first century of independence, and in 2020 is estimated to be 82 years.

Sustainably managing plant resistance to epidemic pathogens implies controlling the genetic and demographic changes in pathogen populations faced with resistant hosts. Resistance management thus depends upon the dynamics of local adaptation, mainly driven by the balance between selection and gene flow. This dynamics is best investigated with populations from locally dominant hosts in islands with long histories of local selection. We used the unique case of the potato late blight pathosystem on Jersey, where a monoculture of potato cultivar 'Jersey Royal' has been in place for over a century. We also sampled populations from the coasts of Brittany and Normandy, as likely sources for gene flow. The isolation by distance pattern and the absence of genetic differentiation between Jersey and the closest French sites revealed gene flow at that spatial scale. Microsatellite allele frequencies revealed no evidence of recombination in the populations, but admixture of two genotypic clusters. No local adaptation in Jersey was detected from pathogenicity tests on Jersey Royal and on French cultivars. These data suggest that long-distance gene flow (~ 50/100 km) prevents local adaptation in Jersey despite a century of local selection by a single host cultivar and emphasize the need for regional rather than local management of resistance gene deployment.

Between 1820 and 1957, over 4.6 million people emigrated from the island of Ireland to the United States. The period with the highest levels of migration came between 1845 and 1855 , as the Great Famine devastated Ireland's population, causing the deaths of roughly one million people and leading to the migration of one million more, most of which was to the United States. The period with the lowest levels of migration came in the 1930s and 40s, as the Great Depression and Second World War created an environment where migration to the US was difficult or impractical.

Genotyping of F2 mapping population with five EST-SSR markers.

Prior to 1921, the six counties that make up modern-day Northern Ireland were a part of the United Kingdom of Great Britain and Ireland, and the separate state of Northern Ireland did not exist until after the partition of Ireland in 1921. From 1821 until 1841, both the male and female populations grew by 130,000 each, until the Great Famine of 1845 to 1849 caused a sharp decline in the population in the 1840s. This decline continued until 1891, and the male population of the six counties fell at a slightly higher rate than the female population. The number of men fell by 310,000 between 1841 and 1891, and the number of women fell by 300,000. From 1891 to 1937 growth remains quite low, particularly among women, and then from 1937 the growth rate increases again. There is one more decade where the population dropped, which coincides with the most violent period of the Northern Irish Troubles. This was in the 1970s, where the number of men and women fell by approximately 30,000 each.

It is presumed that the first humans migrated from Siberia to North America approximately twelve thousand years ago, where they then moved southwards to warmer lands. It was not until many centuries later that humans returned to the north and began to settle regions that are now part of Canada. Despite a few short-lived Viking settlements on Newfoundland around the turn of the first millennium CE, the Italian explorer Giovanni Caboto (John Cabot), became the first European to explore the coast of North America in the late 1400s. The French and British crowns both made claims to areas of Canada throughout the sixteenth century, but real colonization and settlement did not begin until the early seventeenth century. Over the next 150 years, France and Britain competed to take control of the booming fur and fishing trade, and to expand their overseas empires. In the Seven Year's War, Britain eventually defeated the French colonists in North America, through superior numbers and a stronger agriculture resources in the southern colonies, and the outcome of the war saw France cede practically all of it's colonies in North America to the British.

Increased migration and declining native populations

The early 1800s saw a large influx of migrants into Canada, with the Irish Potato Famine bringing the first wave of mass-migration to the country, with further migration coming from Scandinavia and Northern Europe. It is estimated that the region received just shy of one million migrants from the British Isles alone, between 1815 and 1850, which helped the population grow to 2.5 million in the mid-1800s and 5.5 million in 1900. It is also estimated that infectious diseases killed around 25 to 33 percent of all Europeans who migrated to Canada before 1891, and around a third of the Canadian population is estimated to have emigrated southwards to the United States in the 1871-1896 period. From the time of European colonization until the mid-nineteenth century, the native population of Canada dropped from roughly 500,000 (some estimates put it as high as two million) to just over 100,000; this was due to a mixture of disease, starvation and warfare, instigated by European migration to the region. The native population was generally segregated and oppressed until the second half of the 1900s; Native Canadians were given the vote in 1960, and, despite their complicated and difficult history, the Canadian government has made significant progress in trying to include indigenous cultures in the country's national identity in recent years. As of 2020, Indigenous Canadians make up more than five percent of the total Canadian population, and a higher birth rate means that this share of the population is expected to grow in the coming decades.

Independence and modern Canada

Canadian independence was finally acknowledged in 1931 by the Statute of Westminster, putting it on equal terms with the United Kingdom within the Commonwealth; virtually granting independence and sovereignty until the Canada Act of 1982 formalized it. Over the past century, Canada has had a relatively stable political system and economy (although it was hit particularly badly by the Wall Street Crash of 1929). Canada entered the First World War with Britain, and as an independent Allied Power in the Second World War; Canadian forces played pivotal roles in a number of campaigns, notably Canada's Hundred Days in WWI, and the country lost more than 100,000 men across both conflicts. The economy boomed in the aftermath of the Second World War, and a stream of socially democratic programs such as universal health care and the Canadian pension plan were introduced, which contributed to a rise in the standard of living. The post war period also saw various territories deciding to join Canada, with Newfoundland joining in 1949, and Nunavut in 1999. Today Canada is among the most highly ranked in countries in terms of civil liberties, quality of life and economic growth. It promotes and welcomes immigrants from all over the world and, as a result, it has one of the most ethnically diverse and multicultural populations of any country in the world. As of 2020, Canada's population stands at around 38 million people, and continues to grow due to high migration levels and life expectancy, and a steady birth rate.

The 1981 Hunger Strike was one of the most significant events of the Troubles. On *************, Bobby Sands was the first of ** republican prisoners, all from the Irish Republican Army (IRA) or Irish Nationalist Liberation Army (INLA), in HM Prison Maze to begin their hunger strike, which would eventually result in the deaths of ** participants. Background In the late ***, the withdrawal of “Special Category” (Prisoner of War) status changed the rights of paramilitary prisoners, and led to; blanket protests, where prisoners refused to wear criminal uniforms; dirty protests, where prisoners refused to shower and smeared excrement on the cell walls (also to protest guard violence); and a hunger strike in 1980, although this was cancelled after ** days, without any deaths. The 1980 hunger strike ended as the strikers believed the government was ready to agree to some of their demands. The **** key demands were: 1. the right not to wear a prison uniform; 2. the right not to do prison work; 3. the right of free association with other prisoners (incl. educational and recreational pursuits); 4. the right to *** visit, *** letter, and *** parcel per week; and 5. full restoration of remission lost through the protest. 1981 Hunger strike When it became apparent that these demands would not be met without concessions, another strike began on *************. Bobby Sands was considered the leader of the movement, and was the first to go on hunger strike. Unlike the previous strike, participants in 1981 staggered their starting dates to prolong the strike for as long as possible, with **** men starting in March. During Sands' strike, a sitting member of parliament from Northern Ireland died suddenly, which resulted in a by-election, and Sands was put forward as the nationalist candidate for the "Anti H-Block" movement. Sands won the election with ** percent of the vote, although he died ** days later, triggering another by-election (again, won by the Anti H-Block candidate). Similarly, Kieran Doherty was also elected to the Irish Parliament in the ********* general election, but died two months later. Sands had been the first of the hunger strikers to die, after ** days, and his funeral in Belfast was attended by more than 100,000 people, showing the level of public support for the movement. As the first strikers died, they were then replaced by other participants; therefore, there were (almost) always between **** and *** men striking at any given time. ** of the first ** strikers died, before the families of the later strikers began ordering medical interventions when it became apparent that the government would not concede. Two of the strikes were also ended prematurely as the volunteers' conditions deteriorated much faster than expected. Eventually, the strike was ended after eight months, on *********, as the "special category" status and accompanying rights were gradually reintroduced, and all demands were met by 1983. Consequences The Thatcher government's defiance of the prisoners' demands, and the deaths of ** republicans, was painted as a victory by parts of the British press. However, the more lasting impact was that the hunger strikers became martyrs for the republican cause, and led to an uptick in paramilitary violence and IRA membership. The IRA's bombing of the Conservative Party conference in 1984 was also in retaliation for the deaths of the hunger strikers - Margaret Thatcher was the intended target but was unharmed, although **** others were killed and over ** injured. Sands' election also marked the first time a militant republican had achieved political success, and paved the way for Sinn Fein (then viewed as the political wing of the IRA) to take a significant role in British and Irish politics in the decades that followed.

In the nineteenth and twentieth centuries, the majority of documented migration to the United States of American came from European countries. Between 1820 and 1957, of the approximate 41 million migrants to the US, over 34 million of these came from Europe. The most commonly documented countries of origin during this time were Germany (6.6 million), Italy (4.9 million), Ireland (4.6 million), Great Britain (4.5 million), and Russia (3.4 million). The first wave of mass migration came in the 1850s, as the Great famine crippled Ireland's population, and many in rural areas of mainland Europe struggled to adapt to industrialization, and economic opportunities attracted many in the 1870s, following the American Civil War. The 1880s saw another wave, as steam powered ships and lower fares made trans-Atlantic journeys much more affordable. The first wave of mass migration from Eastern and Southern Europe also arrived at this time, as industrialization and agricultural advancements led to high unemployment in these regions.

The majority of migrants to the United States settled in major urban centers, which allowed the expansion of industry, leading to the United States' emergence as one of the leading global economies at the turn of the twentieth century. The largest wave of migration to the United states during this period came in the first fifteen years of the 1900s. The influx of migrants from Northern and Western Europe had now been replaced by an influx from Eastern and Southern Europe (although migration from the British Isles was still quite high during this time). European migration fell to it's lowest levels in eighty years during the First World War, before fluctuating again in the interwar period, due to the Great Depression. As the twentieth century progressed, the continent with the highest levels of migration to the US gradually changed from Europe to Latin America, as economic opportunities in Western Europe improved, and the US' relationship with the Soviet Union and other Eastern, communist states became complicated.