Out of Eden: The Peopling of the World (54 page)

36.
Methods in Forster et al., op. cit.; Saillard, J. et al. (2000) ‘mtDNA variation among Greenland Eskimos: The edge of the Beringian expansion’
American Journal of Human Genetics
67
: 718–26.

37.
For the consensus nomenclature, see The Y Chromosome Consortium (2002) ‘A nomenclature system for the tree of human Y-chromosomal binary haplogroups’
Genome Research
12
: 339–48.

Chapter 1

1.
reporting a major advance
:
Newsweek
11 January 1988.
Rebecca Cann and colleagues
: Cann, R.L. et al. (1987) ‘Mitochondrial DNA and human evolution’
Nature
325
: 31–6.
clearly of African origin
: The Cann tree was better resolved in Vigilant, L. et al. (1991) ‘African populations and the evolution of human mitochondrial DNA’
Science
253
: 1503–7; and then again with further improvements on the African phylogeny, suggesting the single Out-of-Africa line, in Watson, E. et al. (1997) ‘Mitochondrial footprints of human expansions in Africa’
American Journal of Human Genetics
61
: 691–704.

2.
Watson et al., op. cit.; Richards, M. and Macaulay, V. (2001) ‘The mitochondrial gene tree comes of age’
American Journal of Human Genetics
68
: 1315–20.

3.
A number of trees for such sites including autosomal nuclear loci, each with their single branch coming out of Africa, have already been described: see e.g. Tishkoff, S.A. et al. (1996) ‘Global patterns of linkage disequilibrium at the CD4 locus and modern human origins’
Science
271
: 1380–97; Alonso, S. and Armour, J.A.L. (2001) ‘A highly variable segment of human subterminal 16p reveals a history of population growth for modern humans outside Africa’
Proceedings of the National Academy of Sciences USA
98
: 864–9. See also Wainscoat, J.S. et al. (1986) ‘Evolutionary relationships of human populations from an analysis of nuclear DNA polymorphisms’
Nature
319
: 491–3.

For the Y chromosome, one single mutation on the African tree (M168) defines all non-African lines. See Underhill, P.A. et al. (2000) ‘Y chromosome sequence variation and the history of human populations’,
Nature Genetics
26
: 358–61. This means that all non-African males inherit their Y chromosome from only one of the three extant African clans. The problem is that one of the three first-generation male clans descending from M168, haplogroup ‘III’ defined by YAP, is found both within and outside Africa, while the two others are both non-African. Peter Underhill regards YAP as having arisen in Africa, while Mike Hammer regards YAP as a re-entrant from Asia to Africa (rather like mtDNA subgroup M1 reentering Ethiopia). I agree with Hammer – see the discussion in
Chapters 3
and
4
.

4.
Thomas, M.G. et al. (2000). ‘Y chromosomes travelling south: The Cohen modal haplotype and the origins of the Lemba – the “Black Jews of Southern Africa” ’
American Journal of Human Genetics
66
: 674–86.

5.
geographic distributions of the branches and twigs
: Underhill et al., op. cit.; Richards, M. and Macaulay, V. (2000) ‘Genetic data and colonization of Europe: Genealogies and founders’ in C. Renfrew and K. Boyle (eds)
Archaeogenetics: DNA and the Population Prehistory of Europe
(MacDonald Institute for Archaeological Research, Cambridge) pp. 139–41.
A child’s skeleton in Portugal
: Duarte, C. et al. (1999) ‘The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia’
Proceedings of the National Academy of Sciences USA
96
: 7604–9.

6.
For a theoretical discussion see Wall, J.D. (2000) ‘Detecting ancient admixture in humans using sequence polymorphism data’
Genetics
154
: 1271–9. For a practical test with negative
results see Labuda, D. et al. (2000) ‘Archaic lineages in the history of modern humans’
Genetics
156
: 799–808.

7.
published in
Nature
in 1986
: Wainscoat et al., op. cit.
The technical objections
: Richards and Macaulay (2001) op. cit.

8.
Y chromosome
: Underhill et al., op. cit.
other genetic markers
: See note 3.

9.
Some of the geographic, climatic and mammalian perspectives in this paragraph are loosely drawn from Turner, A. (1999) ‘Assessing earliest human settlement of Eurasia: Late Pliocene dispersions from Africa’
Antiquity
73
: 363–70.
depended on the glacial cycle
: Geoclimatic changes are from Jonathan Adams’ website,
http://www.esd.ornl.gov/projects/qen/

10.
Dates reviewed in: McBrearty, S. and Brooks, A.S. (2000) ‘The revolution that wasn’t: A new interpretation of the origin of modern human behavior’
Journal of Human Evolution
39
: 453–563, e.g. p. 455.

11.
These dates depend on which approach to dating the first arrival of modern humans in Europe is used – fossil evidence or stone tools; see
Chapters 2
and
3
. On the former basis, some would put the first Cro-Magnons more recently.

12.
While present evidence points to a dead-end failure of this first exodus, there is another interpretation: while the date of the earliest colonization of Australia keeps moving back, there is always the remote theoretical possibility that the Israel colonization was contemporary with the movement to Australia, but still failed locally.

13.
Vermeersch, P.M. et al. (1998) ‘Middle Palaeolithic burial of a modern human at Taramsa Hill, Egypt’
Antiquity
72
: 475–84.

14.
Chicago anthropologist Richard G. Klein
: Klein, R.G. (1989)
The Human Career: Human Biological and Cultural Origins
(Chicago University Press); see the discussion of this and the 1999 edition in
Chapter 2
.
Jonathan Kingdon
and
first ‘failed’ northern exodus
: Kingdon, J. (1993)
Self-made Man – and His Undoing
(Simon & Schuster, London).
Stringer has taken the simplest approach
: Stringer, C. (2000) ‘Coasting out of Africa’
Nature
405
: 24–7; Stringer, C. and McKie, R. (1996)
The African Exodus
(Jonathan Cape, London), illustration (map) 48, p. 169; Vermeersch et al., op. cit.

15.
splitting the African continent into isolated human colonies
: Lahr, M.M. and Foley, R. (1998) ‘Towards a theory of modern human origins: Geography, demography, and diversity in recent human evolution’
Yearbook of Physical Anthropology
41
: 137–76.
this north-and-south viewpoint
: The multiple migration view reappears in a more recent article that Lahr and Foley co-authored with geneticists: Underhill, P.A. et al. (2001) ‘The phylogeography of Y chromosome binary haplotypes and the origins of modern human populations’,
Annals of Human Genetics
65
: 43–62.

16.
Kingdon op. cit.

17.
Turner op. cit.

18.
Richards, M. et al. (2000) ‘Tracing European founder lineages in the Near Eastern mtDNA pool’,
American Journal of Human Genetics
67
: 1251–76; Richards, M, and Macaulay, V. (2000) op. cit.; Kivisild, T. et al. (1999) ‘Deep common ancestry of Indian and western-Eurasian mitochondrial DNA lineages’,
Current Biology
9
: 1331–4. Most of the discussion below refers to these references (see also
Chapter 3
and notes 4–6 in this chapter).

19.
50,000 years old
: Richards et al. (2000) op. cit.
the ‘Out-of-Africa Eve’ twig, L3
: Richards and Macaulay (2000) op. cit.

20.
U6
. . .
North African lines
. . .
About one-eighth of maternal gene lines
. . .
This makes it extremely unlikely
: Rando, J.C. et al. (1998) ‘Mitochondrial DNA analysis of Northwest African populations reveals genetic exchanges with European, near-Eastern, and sub-Saharan populations’
Annals of Human Genetics
62
: 531–50.
Asian ‘M’ super-group
. . .
absent
. . .
from Europe, the Middle East and North Africa
: see e.g. Richards and Macaulay (2000) op. cit.

21.
If we look at the Y chromosome
: Underhill et al. (2000, 2001) op. cit.
Using markers passed down through both parents
: i.e. using nuclear autosomal markers, Tishkoff et al. op. cit.; Alonso and Armour op. cit.; see also
Chapters 3
and
4
. Note that the first geneticists to argue explicitly for an early southern route were Quintana-Murci, L. et al. (1999) ‘Genetic evidence for an early exit of
Homo sapiens sapiens
from Africa through eastern Africa’
Nature Genetics
23
: 437–41. Their analysis does not directly confront the European issue (which, by default, was regarded as a later northern dispersal) and mainly relates to Asian super-haplogroup M, which they regarded as originating in Ethiopia – as opposed to the Indian origin for M that I argue for.

22.
The age of the L3 cluster in Africa was originally estimated at 77,000 ± 2,400 years: Watson, E. et al. (1997) ‘Mitochondrial footprints of human expansions in Africa’
American Journal of Human Genetics
61
: 691–704. This estimate increases with improved resolution of the tree round the L3 node; I have calculated a more up-to-date estimate by using complete sequence data from Ingman et al. (2000) ‘Mitochondrial genome variation and the origin of modern humans’
Nature
408
: 708–13 as 83,000 years (unpublished work by the author SJO) which uses in principle, the same dating method with calculation of ‘rho’ by averaging new mutations in daughter types – for methods see Forster, P. et al. (1996) ‘Origin and evolution of Native American mtDNA variation: A reappraisal’
American Journal of Human Genetics
59
: 935–45; Saillard, J. et al. (2000) ‘mtDNA variation among Greenland Eskimos: The edge of the Beringian expansion’
American Journal of Human Genetics
67
: 718–26). This estimate also shows that both M and N and the African branches of L3 and L1c re-expanded around 70,000 years ago, presumably after the worldwide effects of the great Toba explosion. See also
Chapters 2
and
4
. The L3 age of 83,000 years has also been independently confirmed in Hill, C. (2003) et al. ‘Mitochondrial DNA variation in the Orang Asli of the Malay Peninsula’ (in press).

23.
Gabunia, L. et al. (2002) ‘Earliest Pleistocene hominid cranial remains from Dmanisi, Republic of Georgia: Taxonomy, geological setting, and age’
Science
288
: 1019–25.

24.
Rohling, E.J. et al. (1998) ‘Magnitudes of sea-level lowstands of the past 500,000 years’
Nature
394
: 162–5; Fenton, M. et al. (2000) ‘Aplanktonic zones in the Red Sea’
Marine Micropalaeontology
40
: 277–94.

25.
Stringer places late, large-brained, South and East Asian
Homo erectus
specimens such as Dali, Maba, Narmada, and Zuttiyeh in a group with
Homo helmei
, which would imply at least one additional exit by the southern route between those of
Homo erectus
and modern humans: see Stringer, C. B. (1996) ‘Current issues in modern human origins’ in W.E. Meikle et al. (eds)
Contemporary Issues in Human Evolution
(California Academy of Sciences, San Francisco) pp. 115–34. See also Foley, R and Lahr, M.M. (1997) ‘Mode 3 technologies and the evolution of modern humans’,
Cambridge Archaeological Journal
7
: (1)3–36, Fig 5. The appearance of both
Acheulian and Middle Palaeolithic technology in India successively over the same period would effectively have increased the number of exits to four.

26.
Homo georgicus
: Gabunia et al., op. cit.

27.
Foley and Lahr op. cit. Following my practice in the Prologue, I use the term
Homo helmei
loosely to distinguish Archaic
Homo sapiens
from modern humans. The term does not have general acceptance. See also next note.

28.
Stringer op. cit. The summary I have given here is oversimplified. The exact details of the cladistic relationships, names, and ages of these later large-brained humans living between 130,000 and 500,000 years ago are still argued over. For our discussion the important issue is that although they looked different from and were more robust than modern humans, they had similar-sized brains and resembled us more than they did previous humans. The subject is discussed further in McBrearty and Brooks op. cit., Foley and Lahr op. cit., and Lahr and Foley op. cit.