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0:07 · [Music]
0:13 · the genetics of ireland [Music]
0:23 · the irish dna atlas is a powerful genetic tool that
0:28 · researchers led by the royal college of surgeons in ireland rcsi
0:34 · and the genealogical society of ireland gsi have built to untangle the origins of
0:42 · the peoples of modern ireland their collaborative study published in
0:48 · nature in 2017 as the irish dna atlas revealing fine scale
0:55 · population structure and history within ireland established the most comprehensive
1:01 · record we possess about who populated ireland when they arrived
1:07 · and how they interacted with the peoples already there a few months later in the journal
1:13 · plus genetics a group of researchers primarily from trinity college dublin published another
1:20 · study insular celtic population structure and genomic footprints of migration
1:28 · detailing an even wider scope of irish history and identity throughout the ages
1:34 · as they summarize in the open access article a recent genetic study of the uk
1:40 · expanded our understanding of population history of the islands using newly developed powerful
1:47 · techniques that harness the rich information embedded in chunks of genetic code
1:53 · called haplotypes these methods revealed subtle regional diversity across the uk
2:00 · and using genetic data alone timed key migration events into
2:07 · southeast england and orkney we have extended these methods to ireland identifying regional differences
2:14 · in genetics across the island that adhere to geography at a resolution
2:20 · not previously reported in the beginning
2:28 · the archaeological record of humans in ireland begins in castlepook cave county
2:34 · clare near the coastal city of cork on the south coast here
2:40 · a reindeer's femur has been discovered that radiocarbon dating has identified
2:45 · as 33 000 years old initially excavated over a hundred years
2:52 · ago by the naturalist richard usher from a place he called mammoth cave due to
2:58 · the abundance of mammoth bones found there between 1904 and 1912.
3:05 · the reindeer bone was recently re-examined with modern techniques and technology and found to possess clear
3:12 · signs of butchery it is the earliest specimen indicating human habitation in ireland
3:19 · but it doesn't prove continuous habitation sea levels have changed dramatically
3:26 · over the eons at times exposing land bridges to the british isles that early
3:31 · migrants may have crossed only seasonally others might have been able to access
3:37 · the irish shorelines in boats when the seas were far more shallow later immigrants almost certainly came
3:43 · in waves from the north and east and south adding layer upon layer to the societies
3:49 · and cultures that already existed there the earliest entries for human specimens
3:56 · in ireland currently listed at haplogroup.info are two dna samples
4:03 · one a mesolithic specimen from a cave in limerick whose u5 haplotype roughly
4:09 · corresponds to the gravettian culture and whose genetics indicate he may have
4:14 · had black skin brown hair and blue eyes
4:23 · and another gravitian-era sample that was found near galway a more ancient
4:28 · relative of cheddar man the famous specimen from somerset england from nine thousand years ago
4:42 · by 10500 bce another find from over a century ago a
4:48 · bare bone specimen from the alice and gwendolyn cave also in county clare
4:54 · shows clear knife marks on a freshly killed carcass
4:59 · this has generally become accepted as the first indisputable evidence of habitation in ireland
5:06 · but who were these people and from where had they come
5:14 · well no evidence exists of neanderthal communities in ireland even as they
5:19 · proliferated in britain and france and across the european continent
5:24 · as ice ages ended the climate shifted dramatically many times
5:30 · uprooting peoples and preventing them from settling finally around ten to twelve thousand
5:36 · years ago things more or less began to resemble the coastlines and climate that are
5:41 · familiar today the most likely land bridge connected
5:46 · southeast ireland and the coast of cornwall when ice ages reached their peak the
5:52 · seas receded and people advanced also kintyre in scotland is across a
5:59 · channel too deep to ever allow a land bridge but today it is less than 20 kilometers across and in earlier eras it
6:07 · was even narrower by 9000 bce those early migrants might
6:13 · have been maglimozian people who had migrated from denmark through england
6:19 · who conceivably visited irish shores but left little record of their stay
6:25 · or perhaps they were tarda nuasian from the west coast of france
6:30 · these were both modern human paleolithic cultures named after the locations of
6:35 · their most important finds they occupied woodlands and mud flats
6:41 · hunted with dogs and used flint and bone tools and weapons in different fashions
6:49 · a couple thousand years later the cardial or impressed where pottery peoples
6:54 · may have arrived to the south of ireland by boat known by the detailed pottery they
7:00 · impressed with heart-shaped cockle shells they dominated the southern european
7:05 · continent from 6400 to 5500 bce
7:11 · the eniolithic age is represented by two specimens from mesolithic-era caves
7:18 · one in litrim and another in limerick and from that point on a solid record of
7:24 · habitation and migration emerges
7:29 · the study the irish dna atlas is an ongoing
7:34 · genetic population study that has evolved into a biobank run by royal college of surgeons in ireland in
7:41 · collaboration with the genealogical society of ireland
7:46 · their website offers access to anyone studying the history and genealogy of
7:52 · ireland it states the landmark study provides the first
7:57 · fine-scale genetic map of the isle of ireland revealing patterns of genetic similarity
8:04 · so far in 10 distinct clusters roughly aligned with the ancient
8:09 · provinces as well as with major historical events including the invasions of the norse vikings and the
8:17 · ulster plantations the irish dna atlas project was
8:22 · co-designed by population geneticists and genealogists who came together to collect dna samples
8:29 · from 196 irish individuals with four generations of ancestry linked
8:36 · to specific areas across the island of ireland analyses of the dna
8:43 · and comparison with thousands of further samples from britain and europe are
8:48 · revealing geographic clusters within ireland so far seven of gaelic irish ancestry
8:57 · and three of shared british irish ancestry these findings add to the knowledge base
9:04 · required to improve the diagnosis of diseases where genes play a strong role
9:10 · particularly for populations of irish ancestry according to edmund gilbert rcsi
9:18 · first author on the paper our work informs on irish history
9:24 · we have demonstrated that the structure emerging from genetic similarity within ireland mirrors historical kingdoms of
9:31 · ireland and that ireland acts as a sink of celtic ancestry
9:37 · additionally we find evidence of a west norwegian-like ancestry that we believe
9:42 · is a signature of the norse vikings we also observe the impact of historical
9:48 · events such as the ulster plantations on the dna of the people of ireland
9:55 · michael merrigan gsi co-author on the paper stated for those interested in
10:00 · genealogy and irish history this study challenges many of our received narratives on the origins of the people
10:08 · of ireland we now get a clearer scientifically based map of the distribution and
10:14 · settlement of our ancestral groups across the island of ireland
10:20 · historians and students of medieval ireland have now a wonderful resource on
10:25 · the movements and interrelationships of our ancestor groups through their dna
10:30 · this opens up many new and very exciting research opportunities for many disciplines
10:36 · especially those researching the irish medieval genealogies and the history of
10:41 · irish clans slash septs professor giampiero cavallari who
10:47 · directed the research stated for our study designed to work it was vital for us to collaborate with the
10:53 · genealogical society of ireland they helped us reach the very specific
10:59 · cohort of people needed people who could demonstrate that all eight of their great grandparents had
11:05 · been born within 50 kilometers of each other this has allowed us to create a genetic
11:11 · map for the irish population with resolutions similar to that recently drawn for england
11:17 · whilst we are delighted by what the study to date has revealed this is a live study the more people who
11:23 · participate the greater resolution we can achieve
11:28 · key findings that prior to the mass movement of people in recent decades
11:35 · there were numerous distinct genetic clusters found in specific regions across
11:40 · ireland seven of those revealed so far are of gaelic irish ancestry and
11:46 · describe the borders of either irish provinces or historical kingdoms
11:52 · the remaining three are of shared irish british ancestry and are mostly found in
11:58 · the north of ireland and probably reflect the ulster plantations
12:03 · two of the gaelic clusters together align with the boundaries of the province of munster
12:09 · and individually are associated with the boundaries of the kingdoms of dal gays
12:14 · and the owenacht there are relatively high levels of northwest french-like probably celtic
12:22 · and evidence of west norwegian-like probably viking ancestry within ireland
12:29 · there is evidence of continual low-level migration between the north of ireland
12:34 · and the south and west of scotland and now for an even deeper look
12:41 · we turn to the introduction of the plus genetics article situated at the northwestern edge of
12:48 · europe ireland is the continent's third largest island with a modern-day population of
12:54 · approximately 6.4 million the island is politically partitioned
12:59 · into the republic of ireland and northern ireland with the latter forming part of the united kingdom alongside the
13:07 · neighboring island of britain alternative divisions separate ireland
13:12 · into four provinces reflecting early historical divisions ulster to the north including northern
13:19 · ireland leinster east munster south and connect west
13:26 · humans have continuously inhabited ireland for around 10 000 years though
13:31 · it is not until after the demographic upheavals of the early bronze age circa
13:36 · 2200 bce that strong genetic continuity between
13:42 · ancient and modern irish populations is observed linguistically the island's earliest
13:48 · attested language forms part of the insular celtic family specifically the
13:54 · gaelic branch whose historic range also extended to include many regions of scotland via
14:00 · maritime connections with ulster a second branch of insular celtic the
14:06 · britonic languages had been spoken across much of britain up until the introduction of anglo-saxon in the 5th
14:13 · and 6th centuries by which time they were diversifying into cornish welsh and
14:19 · cumbrick dialects since the establishment of written history
14:24 · numerous settlements and invasions of ireland from the neighboring island of britain and continental europe have been
14:31 · recorded this includes norse vikings 9th to 12th century especially in east lennster and
14:39 · anglo-normans 12th to 14th centuries who invaded through wexford in the southeast
14:45 · and established english rule mainly from an area later called the pale in
14:50 · northeast leinster there has also been continuous movement of people from britain in particular
14:56 · during the 16th to 17th century plantation periods during which gaelic
15:02 · and norman lands were systematically colonized by english and scottish settlers
15:08 · these events had a particularly enduring impact in ulster in comparison with other planted regions
15:15 · such as munster as with the previous norman invasion the less fertile west of the country connect
15:22 · remained largely untouched during this period the genetic contributions of these
15:29 · migratory events cannot be considered mutually independent given that they
15:34 · derive from either related germanic populations such as the vikings and their purported norman descendants or
15:41 · from other celtic populations inhabiting britain which had themselves been subjected to
15:47 · mass germanic influx from anglo-saxon migrations and later viking and norman
15:53 · invasions moreover each movement of people originated from northern europe a region
16:00 · which had witnessed a mass homogenizing of genetic variation during the migrations of the early bronze age
16:08 · possibly linked to indo-european language spread however
16:13 · each event had a geographic and temporal focal point on the island which may be
16:19 · detectable in local population structure previous genome-wide surveys have
16:26 · detected little to no structure in ireland concluding that the irish population is genetically homogeneous
16:33 · however runs of homozygosity alleles matching on compared chromosomes
16:39 · are relatively long and frequent in ireland and correlate negatively with population
16:45 · density and diversity of grand parental origins suggesting
16:50 · that low ancestral mobility may have preserved regional genetic legacies
16:55 · within ireland which may be detectable in modern genomes as local population
17:01 · structure embedded within haplotypes this is further supported by the
17:06 · restricted regional distributions of certain y-chromosome haplotypes
17:12 · haplotype-based methods were recently used to uncover hidden genetic structure among the people of modern britain
17:20 · these approaches exploit the rich information available within haplotypes usually statistically phased to identify
17:28 · clusters of genetically distinct individuals with a resolution that could not be attained using single marker
17:35 · methods in doing so the people of the british isles study was able to identify
17:42 · discrete genetic clusters of individuals that strongly segregate with
17:47 · geographical regions within britain though notably structure was undetectable across a large southeastern
17:54 · portion of the island however although this study sampled over 2000 individuals
18:01 · only 44 were from northern ireland with none from the remainder of the island
18:07 · ireland was also excluded from admixture and ancestry analyses due to the
18:12 · confounding effects of the island acting as a source and a sink for ancestry from
18:17 · the uk with this focus on a single island the people of the british isles study has an
18:25 · obvious limit despite its title here we have used the methods of their
18:30 · study to explore fine-grained irish population substructure
18:36 · we first investigate ireland on its own then we consider the genetic substructure observed on the island in
18:43 · the context of britain and continental europe using modern individuals from these two
18:49 · sources as surrogates for historical populations we apply a model to infer admixture
18:55 · events into ireland and we consider these in the context of historically recorded invasions and migrations
19:04 · our inclusion of irish data with previously published data from britain presents a more complete representation
19:12 · of genetic ancestry in the contemporary populations of the british isles
19:17 · providing a comprehensive population genetic perspective of the peopling of
19:23 · these islands at a high level both of the haplotype programs clustering loosely separated
19:30 · the historical provinces of ireland ulster leinster munster and connect
19:35 · suggesting that these socially constructed territories may have had an impact on genetic structure within
19:42 · ireland which is deeply embedded in time careful inspection revealed more nuanced
19:49 · relations between the provinces for example south lenster clusters share
19:55 · more haplotypes with those from north monster than with their central and north leinster counterparts
20:02 · the geographical distribution of this deep subdivision of leinster resembles
20:08 · pre-norman territorial boundaries which divided ireland into fifths
20:15 · with north leinster a kingdom of its own known as meth
20:20 · however interpreted the firm implication of the observed clustering is that despite its previously reported
20:27 · homogeneity the modern irish population exhibits genetic structure that is subtly but
20:33 · detectably affected by ancestral population structure conferred by geographical distance and possibly
20:41 · ancestral social structure the haplotype programs demonstrated high
20:46 · diversity among clusters from the west coast which may be attributed to long-standing residual ancient possibly
20:54 · celtic structure in regions largely unaffected by historical migration
21:00 · alternatively genetic clusters may also have diverged as a consequence of differential influence from outside
21:07 · populations as this diversity between western genetic clusters cannot be
21:13 · explained in terms of geographic distance alone south munster and cork clusters branch
21:19 · off first and show distinct separation from their neighboring north monster clusters
21:25 · indicating that south munster's haplotypic makeup is more distinct from its neighboring regions and the
21:32 · remaining regions than any other cluster analysis supports this observation with
21:38 · the cork cluster in particular showing strong differentiation from other clusters
21:44 · this may reflect the persistent isolating effects of the mountain ranges surrounding the south munster counties
21:51 · of cork and cary restricting gene flow with the rest of ireland and preserving
21:56 · older structure in contrast to the west of ireland eastern individuals exhibited relative
22:03 · homogeneity a similar pattern was observed in the people of the british isles study in
22:10 · which all samples in a large region in southeast england formed a single
22:15 · indivisible cluster of genetically similar individuals comprising almost half the data set
22:22 · however while east coast clusters in ireland are the largest and demonstrate strong cluster integrity
22:29 · the largest of these central leinster comprises roughly a fifth of our data
22:34 · set suggesting by extension that deeper structure persists in
22:40 · eastern ireland than in southeast england the overall pattern of western diversity
22:46 · and eastern homogeneity in ireland may be explained by increased gene flow
22:52 · and migration into and across the east coast of ireland from geographically proximal regions the closest of which is
22:59 · the neighboring island of britain to explore this we estimated the extent
23:05 · of admixture per individual in the irish dataset from britain along with 18 ancient british
23:12 · individuals from the iron age roman and anglo-saxon periods in
23:17 · northeast and southeast england we call this the british component
23:23 · which was among the lowest for individuals falling in irish west coast clusters including the south munster and
23:30 · cork cluster groups supporting the interpretation that these regions differ
23:36 · in terms of restricted haplotypic contribution from britain
23:41 · our analysis also captures an east-to-west anglo-celtic cline in irish
23:47 · ancestry this may explain the relative eastern homogeneity observed in ireland which
23:53 · could be a result of the greater english influence in leinster and the pale during the period of british rule in
24:00 · ireland following the norman invasion or simply geographic proximity of the irish east
24:07 · coast to britain notably the ulster cluster group harbored an exceptionally large
24:13 · proportion of the british component undoubtedly reflecting the strong influence of the ulster plantations in
24:20 · the 17th century and its residual effect on the ethnically british population
24:26 · that has remained the principle split in the combined irish and british data defined two
24:34 · genetic islands that discerns their north-south and west east genetic
24:39 · structure and places orkney and north-south wales as independent entities
24:46 · from the bulk of the british data north to south variation in ireland and
24:52 · britain are therefore not independent reflecting major gene flow between the
24:57 · north of ireland and scotland which resonates with three layers of
25:02 · historical contacts first the presence of individuals with strong
25:08 · irish affinity among the third generation scottish sample can be plausibly attributed to major economic
25:14 · migration from ireland in the 19th and 20th centuries second the large proportion of northern
25:22 · irish who retain genomes indistinguishable from those sampled in scotland accords with the major
25:29 · settlements including the ulster plantation of mainly scottish farmers
25:34 · following the 16th century elizabethan conquest of ireland which led to these
25:40 · forming the majority of the ulster population third
25:45 · the suspected irish colonization of scotland through the dol rieta maritime
25:51 · kingdom which expanded across ulster and the west coast of scotland in the 6th
25:57 · and 7th centuries linked to the introduction and spread of gaelic languages
26:04 · such a migratory event could work to homogenize older layers of scottish population structure
26:10 · in a similar manner as noted on the east coasts of britain and ireland
26:16 · earlier communications and movements across the irish sea are also likely which as we already know
26:23 · at its narrowest point separates ireland from scotland by approximately 20 kilometers
26:36 · genomic footprints of migration into ireland
26:41 · using modern surrogate populations represented by 4514 europeans and 1973
26:50 · individuals from the people of the british isles dataset excluding individuals sampled from
26:56 · northern ireland of all the european populations considered ancestral influence in irish
27:03 · genomes was best represented by modern scandinavians and northern europeans
27:09 · with a significant single date one source admixture event
27:14 · overlapping the historical period of the norse viking settlements in ireland this
27:20 · was recapitulated to varying degrees in specific genetically and geographically
27:25 · defined groups within ireland with the strongest signals in south and
27:30 · central leinster the largest recorded viking settlement in ireland was dublin in present-day
27:37 · dublin followed by connect and north lannister ulster this suggests a contribution of
27:44 · historical viking settlement to the contemporary irish genome and contrasts with previous estimates of
27:51 · viking ancestry in ireland based on y chromosome haplotypes which have been
27:56 · very low the modern day paucity of norse viking
28:01 · y-chromosome haplotypes may be a consequence of drift with the small patrilineal effective
28:08 · population size or could have social origins with norse males having less
28:14 · influence after their military defeat and demise as an identifiable community
28:19 · in the 11th century with persistence of the autosomal signal through recombination
28:26 · regarding this single date one source admixture event let's look a bit more into dublin's
28:33 · recorded past although initially founded as a small settlement by the gaels on the banks of
28:39 · the river liffey it rose to prominence as the norse kingdom of dublin in the 9th century ce
28:46 · the first reference to the vikings comes from the annals of ulster and the first entry for 841 a.d reads
28:54 · pagans still on loch knee it is from this date onward that historians get
29:01 · references to ship fortresses or long forts being established in ireland
29:07 · it may be safe to assume that the vikings first overwintered in 840-841
29:14 · the actual location of the long fort of dublin is still a hotly debated issue
29:20 · norse rulers of dublin were often co-kings and occasionally also kings of
29:25 · jorvik in what is now yorkshire under their rule dublin became the biggest slave port in western europe
29:34 · over time the settlers in dublin became increasingly gala sized they began to
29:40 · exhibit a great deal of gaelic and norse cultural syncretism and are often referred to as norse gales
29:50 · back to plus genetics european admixture date estimates in northwest ulster did not overlap the
29:57 · viking age but did include the norman period and the plantations
30:03 · this may indicate limited viking activity in ulster or that due to the
30:08 · similarity in sources for the viking and anglo-norman invasions and the plantations our models cannot
30:15 · disentangle the earlier events from the later this is not unexpected given the extent
30:22 · of the plantations in ulster the relative timings of the invasions and
30:27 · the degree of viking involvement in britain and europe yet the overall influence of british
30:33 · admixture in ireland and vice versa has involved extensive and constant gene
30:40 · flow before during and after the major population movements
30:45 · with particular swells of peopling during the ulster plantations
30:50 · the genetic legacies of the populations of ireland and britain are therefore extensively intertwined
30:58 · and unlike admixture from northern europe too complex to model
31:06 · their conclusions our results show that population structure is detectable on the island of
31:14 · ireland and is consistent with a combination of the homogenizing effect of geographically punctuated admixture
31:22 · and diversification among celtic sub-populations the inclusion of irish data with british
31:29 · samples from the people of the british isle study provides an anchor for celtic ancestry
31:36 · in the british isles filling out the genetic landscape of the islands
31:46 · it is also clear that historical migrations into ireland have left a greater genomic footprint
31:52 · than previously anticipated our methods have allowed us to detect a much greater viking influence than
31:58 · previously estimated with y chromosome data although the genetic imprint of the
32:04 · british plantations is much harder to delineate the inter-island exchange and clustering
32:11 · observed between present day individuals from northern ireland and scotland
32:17 · signals the enduring impact of these historical movements of people
32:23 · as these studies survey increasingly rare genetic variants in larger
32:28 · populations the geospatial segregation of rare haplotypes and variants will become
32:35 · increasingly important especially when environmental effects and interactions
32:41 · play a role our observation that these haplotypes are intricately tied to geography in
32:48 · ireland and britain highlights the importance of considering fine-grained population structure in
32:55 · future studies in an interview with the irish mirror geneticist dr ross byrne of trinity
33:02 · college dublin said this subtle genetic structure within such a small country has implications
33:10 · for medical genetic association studies as it stands current corrections for
33:15 · population structure in study designs may not adequately account for this
33:21 · within country variation which may potentially lead to false positive results emerging
33:28 · we feel this will be particularly important in the analysis of rare variants as these are expected to be
33:34 · less uniformly distributed throughout a country we intend to explore this further and
33:41 · identify if this structure should be accounted for in corrections
33:47 · the medical community can use this data to address genetic and hereditable
33:53 · diseases such as cystic fibrosis celiac disease
33:58 · and galactosemia a serious metabolic disorder that prevents the breakdown of
34:04 · sugars in dairy legumes and organ meats that occur in irish populations at a
34:10 · higher rate than in other european countries this study also reveals that the chance
34:16 · to contract multiple sclerosis increases in both the uk and ireland the further
34:22 · north one lives in the same interview co-author professor russell mclaughlin added
34:30 · the long and complex history of population dynamics in ireland has left
34:35 · an indelible mark on the genomes of modern inhabitants of the island
34:40 · we have shown that using only genetic data we can accurately reconstruct elements
34:46 · of this past and demonstrate a striking correlation between geographical providence
34:53 · and genetic affinity understanding this fine-grained population structure
35:00 · is crucially important for ongoing and future studies of rare genetic variation in health
35:07 · and disease [Music]
35:39 · you