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					BAHSHE                                              07-07-2003




           Blood unites us: genetics and the
         population history of the British Isles

                       David T. Croke
             Royal College of Surgeons in Ireland

                         dtcroke@rcsi.ie
                     History

Anthropology                       Archaeology




          Human origins & population
                   history



                               Genetics
     Linguistics
What is the true history
of the populations of
these islands ?



  Successive waves of
       invasion

        versus

Cultural exchange with
little or no movement of
           people
Themes


Genetic variation as a tool to ‘probe’ population history

Anatomically Modern Humans - a brief history

Palaeolithic & Neolithic Europe - the ‘Atlantic fringe’

More recent events in the population of these islands

Population admixture in Ulster

Genetics and ‘race’
Genetic variation as a tool to ‘probe’
    human population history
Harvard University Anthropological Survey of Ireland




        Aran Islands                  ‘Keltic’




         Waterford                    ‘Dinaric’
Mourant, 1954
Genetic ‘markers’ used in population studies


1. ‘Classical’ protein markers


2. Y-chromosome                  - paternally inherited


3. Mitochondrial DNA             - maternally inherited
      (mtDNA)

4. Recessive disease genes       - biparentally inherited
  Surveys within species reveal enormous genetic
          variation between individuals


On average, about 0.2% of our DNA differs between
             individual human beings


     Human and Chimpanzees differ by ≤ 2%



The amount & rate of accumulation of variation can
  be used to infer genetic relationship / ancestry
Tools

1. Availability of the human genome sequence and of
    genetic ‘markers’

2. Laboratory methods
   - Polymerase Chain Reaction [PCR]
   - DNA samples from modern populations
   - ‘Ancient DNA (aDNA)’

3. Population genetics theory

4. Mathematical & statistical tools
Anatomically Modern Humans

      - a brief history
Hominid
Evolution




Anatomically
Modern Humans
[AMH] emerged
some 150 kYBP
Neanderthals and AMH did not interbreed

                        Ancient & modern mtDNA; MDS analysis




                                             Krings et al., 1997
                                             Caramelli et al., 2003
Neanderthals and AMH did not interbreed

                        Ancient & modern mtDNA; MDS analysis




                                             Krings et al., 1997
                                             Caramelli et al., 2003
Neanderthals and AMH did not interbreed

                        Ancient & modern mtDNA; MDS analysis




                                             Krings et al., 1997
                                             Caramelli et al., 2003
‘Out of Africa’




      - a global palaeolithic population expansion
The ‘Neolithic Transition’ (Agricultural revolution)
Genetic traces of the neolithic expansion




                                            Cavalli-Sforza et al., 1994
The ‘Atlantic fringe’ of Europe


North-western Europe is different
Y-chromosome haplogroup 1.15




                               Hill et al., 2000
Y chromosome haplogroup diversity (a)




   Haplogroup 1.15 – the ‘Atlantic Modal Haplotype’


                                           Wilson et al., 2001
Y chromosome haplogroup diversity (b)




   A Y haplogroup spectrum shared with the Basques
              - a palaeolithic ‘remnant’
                                           Wilson et al., 2001
Y chromosome haplogroup diversity (c)




  Little similarity to the Near East  relatively little
   Neolithic influence on the ‘Atlantic’ populations

                                                 Wilson et al., 2001
Neolithic contribution in Europe [Y data]   Chikhi et al., 2002




               6%
                15%  67% 19%
                  21%     81%
          23%       91%
               41%     82%
       14%
    10%       0% 63% 100%
                      100%
Different male & female population histories [a]


                   Y DNA                           mt DNA




     Y chromosome --> male-mediated gene-flow

        mt-DNA --> female-mediated gene-flow
                                              Wilson et al., 2001
Different male & female population histories [b]


                   Y DNA                         mt DNA




 More female-mediated gene-flow (migration) between
  continental Europe and the Atlantic populations
              (excluding the Basques)
                                              Wilson et al., 2001
What about the Celts ?
6,000 – 4,000 YBP




Ireland & Britain were
part of a Megalithic
culture spread across
Western Europe




Palaeolithic & Neolithic
admixture of peoples
The Celts were much later !   1st millennium BC
Celticisation of
these islands ?

current model:

diffusion of elements
of celtic culture via
trading links

adoption of the celtic
‘cultural package’ by
local ruling elites


                   Cunliffe, 2001
Genetic evidence of more recent events
 in the population of these islands ?
Y chromosome census
 of the British Isles


   Samples:

   UK + Irl: 1,772

   Norway: 201

   Denmark }: 190
   N. Germany}


           Capelli et al., 2003
Reference populations




                        Capelli et al., 2003
Interpreting the data ?




                          Capelli et al., 2003
Overall, a degree of similarity   AMH+1 > 33%




                                     Capelli et al., 2003
Traces of Norwegian Viking admixture




                                       Capelli et al., 2003
N. German/Danish influences in England & Scotland




                                           Capelli et al., 2003
     Recessive disease mutations


Phenylketonuria (PKU) and the population
            history of Ulster
Phenylketonuria [PKU]

An inherited defect of amino-acid metabolism

Due to mutations in the Phenylalanine
Hydroxylase (PAH) gene [chromosome 12q]


29 different mutations have been identified in Ireland
                          Unidentified
                Others
                                                R408W
     IVS12nt1


    R243X
     F299C
       L348V             I65T                           O’Neill et al., 1995
                                         F39L
                                                        O’Donnell et al., 2002
Using PKU
mutations to
estimate Scottish
admixture in
Ulster
   Ireland            Scotland     Analysis based on
                                   frequency data for
                                   13 PKU mutations


                                   For Ulster as the
                                   hybrid population

                                   m = 0.46

             Ulster

Admixture proportion estimated as:
                m = (q2(rh-r2))/(q1r1-q2r2-rh(q1-q2))
                                           O’Donnell et al., 2002
Does ‘race’ have a biological basis ?
Global human genetic diversity

                             H. sapiens (100%)




                   Within regional                      Between regional
                    populations                           populations
                       (90%)                                (10%)




 Between local populations           Between individuals within
      Within regions                     local populations
           (5%)                                (85%)


 No biological basis for concepts of ‘race’ or ‘ethnicity’
                                                           After Relethford, 2003
   “…we must disavow entirely any mystical view of
 blood as a racial factor. Rather does a study of blood
 groups show a heterogeneity in the proudest nations
and support the view that the races of the present day
are but temporary integrations in the constant process
   of mutation, selection and mixing that marks the
           history of every living species…”



                        ‘The distribution of the human blood groups’
                        Arthur Mourant, Oxford, 1954
Suggested reading:

Steve Olson
‘Mapping human history: discovering the past through
our genes’
Bloomsbury Publishing Inc., 2002

Spencer Wells
‘The journey of man: a global genetic odyssey’
Penguin, 2002

John H. Relethford
‘Reflections of our past: how human history is revealed
in our genes’
Westview Press, 2003

				
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