Recent DNA studies of populations in Britain, Ireland, USA, Canada, Australia and New Zealand have produced genetic snapshots of the English-speaking world, reflecting thousands of years of migration history.
The proportion of genes that an individual can receive from any particular ancestral source can vary greatly. Y chromosome DNA tests trace direct paternal-line ancestry, Mitochondrial DNA tests trace the direct maternal line, while Autosomal DNA tests measure an individual’s mixed geographic heritage based on their overall ancestry.
The trends can be very revealing.
Here are 25 findings to think about. The genetic contribution by historical waves of migration across the Anglosphere may confirm what you already suspected, or throw up a few surprises.
United Kingdom – Population: 64 million. Ethnicity: White British 87% (mainly English, Scottish, Irish and Welsh), Asian 7% (mainly Indian subcontinent), Black (total or partial ancestry from Sub-Saharan Africa) 3%.
Republic of Ireland – Population: 4.8 million. Ethnicity: White Irish 84.5%, Other White 9.8%, Asian 1.9%, Black 1.4%.
1. The Y chromosome of men with Gaelic surnames from the west of Ireland shows a strong similarity with that of men from the Basque country in the north of Spain. The frequency of Y-DNA haplogroup R1b (the most common haplogroup in Europe) is highest in the populations of Atlantic Europe and, due to European emigration, in North America, South America, and Australia. In Ireland and the Basque Country its frequency exceeds 90% and approaches 100% in Western Ireland.
2. The Irish link to the Basques is thought to signify a common ancestry with hunter gatherers who survived the Last Glacial Maximum in an Iberian refuge in northern Spain/southern France. This genetic stock repopulated the British Isles when the glaciers began to retreat around 15,000 years ago. In the UK, the modern Welsh appear to bear most genetic similarity to these earliest settlers.
3. After the original post-Ice-Age hunters settled in Britain, substantial migration continued across the English Channel for thousands of years. DNA from these later migrants spread across England and Scotland, but had little impact in Wales. The majority of the ancestors of British people today were these Palaeolithic and Mesolithic hunters who settled in Britain from 14,000 – 7,000 years ago.
4. In the west of Ireland, the people of Connaught (the westernmost point of Europe) have been most isolated genetically from the movements of people that shaped the genetic makeup of the rest of the British Isles. In the east of Ireland there has been a greater influx of genes from across the Irish Sea; most of the genetic variation in Ireland accumulated over the past 4,200 years following rapid population growth in the Early Bronze Age.
5. There is no single ‘Celtic’ genetic group. In fact the ‘Celtic’ parts of the UK (Scotland, Ireland, Wales and Cornwall) are among the most different from each other genetically.
6. The majority of eastern, central and southern England is largely made up of a single genetic group with a significant DNA contribution (20 – 40% of total ancestry) from Anglo-Saxon migrations from 450-600 AD after the collapse of the Roman Empire. This shows that the Anglo-Saxons intermarried with, rather than replaced, indigenous British populations.
7. Many of today’s genetic clusters in Britain correspond geographically to the tribal groupings and kingdoms as they were around end of the 6th century AD, after the settlement of the Anglo-Saxons. This suggests that these tribes and kingdoms may have maintained a regional identity for many centuries.
Population: 35.5 million. Ethnicity: Canadian 32% (mainly British or French origins but no-longer self identify with their ethnic ancestry), English 21%, French 16%, Scottish 15%, Irish 14%, German 10%, Native American 2.6%, Métis 1.4% (mixed-race descendants of Native American women and European men as well as men of African descent), Inuit 0.2%.
8. Of the small number of individuals who migrated from the Beringian land bridge into North America around 16,000 years ago, only 70 of them left their genetic print in modern Native Americans throughout the continent.
9. Modern-day Inuits arose from later migrations across the Bering Strait from Siberia. A single founding population of Paleo-Eskimos migrated around 6,000 years ago and endured the harsh environmental conditions of the Canadian Arctic for almost 5,000 years. A separate migration of Inuit ancestors emerged from western Alaska around 1000 AD and eventually displaced the Paleo-Eskimos.
10. French Canadians descend from a founding population of around 10,000 French settlers who came to Canada in the 17th and 18th centuries. Less than 20 generations of high population growth and genetic isolation is reflected in the much lower levels of French-Canadian genetic diversity compared to that of French people still living in France.
11. The earliest French settlers on the first wave of colonization in the frontier regions, where land was more available, contributed more to the current French Canadian gene pool than later French migrants to settled regions, where land was more scarce.
United States of America
Population: 321 million. Ethnicity: White European 64% (non Hispanic, mainly British, Irish and German), Hispanic or Latino 17% (Latin America and Spain), Black or African American 12%, Asian 5%, Native American 0.7%.
12. Native Americans experienced a significant contraction in population size around 500 years ago, reflected in a mitochondrial DNA study which found that the female population size reduced by around 50%. This depopulation was not localized but widespread. The sudden drop appeared to occur immediately after the arrival of Europeans, but before settlement began, suggesting it was a result of disease sweeping through native communities, rather than warfare or mass slaughter. The population gradually rebounded as those Native Americans surviving the initial wave of disease passed on their genes to the next generation.
13. The average African American genome is 73.2% African, 24% European, and 0.8% Native American.
14. Ancestors of current-day Yoruba people from West Africa provided the largest contribution of genes from Africa to all present day American populations. The highest levels of African ancestry among African Americans are found in southern states, especially South Carolina and Georgia. The most common European genetic source in African Americans comes from the British Isles.
15. More than 14% of African Americans from Oklahoma carry at least 2% Native American ancestry. This likely reflects the Trail of Tears migration in the 1830s when thousands of Native Americans were forcibly relocated to Oklahoma, home to a significant number of black slaves.
16. The average Latino American genome is 65.1% European (mostly from the Iberian Peninsula), 18% Native American and 6.2% African.
17. Latinos from Louisiana have the highest proportion of African ancestry (around 20%). Latinos in Tennessee and Kentucky, tend to have high proportions of European ancestry. Latinos in states bordering Mexico tend to have higher proportions of Native American ancestry.
18. An average of 3.5% of European Americans have 1% or more African ancestry; many may be unaware of their African ancestry since the African ancestor may be 5 to 10 generations in the past. European Americans with African ancestry are found at much higher frequencies in southern states – in South Carolina and Louisiana about 12% of European Americans have at least 1% African ancestry. In Louisiana too, about 8% of European Americans carry at least 1% Native American ancestry.
19. In all American populations, the European element of their ancestry tends to be male, while the African and Native American element of their ancestry tends to be female. This pattern began almost immediately after the first European settlers and African slaves arrived in North America.
Australia & New Zealand
Australia – Population: 23.8 million. Ethnicity: White European 83% (mainly English, Irish, Scottish, and Welsh), Asian 12% (mainly Chinese, Vietnamese, Filipino and Indian), Indigenous Australian 3% (including people of mixed descent), Black 2% (total or partial recent ancestry from Sub-Saharan Africa) .
20. Australian Aborigines are direct descendants of the first modern humans to migrate out of Africa over 60,000 years ago and may have the oldest continuous culture on the planet. Their ancestors migrated into South Asia, before reaching Australia around 50,000 years ago.
21. Some Aborigine populations in the Northern Territories can trace as much as 11% of their genomes to more recent migrants from India who reached Australia around 4,000 years ago. This genetic mingling coincided with the arrival in Australia of the dingo, which most closely resembles Indian dogs.
22. The British colonization of Australia from 1788 and subsequent intermarriage with Aborigines is reflected in the genome of a modern Aboriginal population in New South Wales, which carries an average of 36% European ancestry. This population’s Aboriginal ancestry was on average 37.5% male and 97.5% female.
New Zealand – Population: 4.4 million. Ethnicity: European 65% (mainly British and Irish), Māori 15%, Asian 12%, Pacific Islanders 7%, Other 1%.
23. New Zealand was the last major landmass to be permanently settled by humans. The ancestors of today’s Maori originally set out from Taiwan on mainland south-east Asia 6,000 years ago and, hopping from island to island, arrived in New Zealand 800 to 1,000 years ago. During the island-hopping phase, men from Melanesian communities joined the boats, perhaps as guides, changing the genetic mix of the Maori population today. Mitochondrial DNA in women confirms their ancient Asian origin, while Y-chromosome DNA in men shows Melanesian ancestry.
24. Maori Mitochondrial DNA experienced a severe genetic bottleneck when the population first settled in New Zealand. It has been estimated that just 56 women created the diversity of today’s population. The is consistent with Maori legend, which says that a fleet of 7 great waka (canoes) brought the Maoris to New Zealand. If 20 people travelled in a canoe the size of a waka, then founding population may have been around 140 people.
25. The first Europeans to reach New Zealand were the crew of Dutch explorer Abel Tasman in 1642, but it was after British naval captain James Cook visited the islands in 1769 that European contact with the Maoris became more firmly established – mainly to trade European goods for Māori food, water and sex. European settlement of New Zealand began from the early 19th century. As a result of the genetic mixing over the last 200 years, virtually all, if not all, Māoris today have some European ancestry.
1. Nature – UK mapped out by genetic ancestry
2. American Journal of Human Genetics – The Genetic Ancestry of African Americans, Latinos, and European Americans across the United States
3. Proceedings of the National Academy of Sciences – Native Americans experienced a strong population bottleneck coincident with European contact
4. American Journal of Human Genetics – Whole-Genome Genetic Diversity in a Sample of Australians with Deep Aboriginal Ancestry
5. Nature – Genomes link aboriginal Australians to Indians
6. ABC Science Online – Maori men and women from different homelands