Out of Eden: The Peopling of the World (53 page)

Prologue

1.
Some have suggested
: Senuta, B. et al. (2001) ‘First hominid from the Miocene (Lukeino Formation, Kenya)’
Earth and Planetary Sciences
332
: 137–44. This paper controversially argues that a newly discovered hominid,
Orrorin tugenensis
, is at 6 million years ancestral to the
Homo
genus, displacing the current contender
Ardipithecus/Australopithecus ramidus
(at 4–5 million years: White, T.D. et al. ‘
Australopithecus ramidus
, a new species of early hominid from Aramis, Ethiopia’
Nature
(1994)
371
: 306–12) onto the
Pan
(chimpanzee) branch. The
implication is that the
Pan
/pre-
Homo
split is put back to 8 million years.
first clear evidence for bipedalism
: see the fine pictures of a hominid knee joint on pp. 44–5 in Leakey, M. (1995) ‘The farthest horizon’
National Geographic
188
(Sept.): 38–51.

2.
Wheeler, P.E. (1993) ‘Human ancestors walked tall, stayed cool’
Natural History
102
(2): 65–7.

3.
Elton, S. et al. (2001) ‘Comparative context of Plio-Pleistocene hominid brain evolution’
Journal of Human Evolution
41
: 1–27; see p. 19 for
Paranthropus
and stone tools and p. 21 for
Paranthropus
and meat. For additional original data for hominid brain size comparisons used in this chapter, see Ruff, C.B. et al. (1997) ‘Body mass and encephalization in Pleistocene
Homo
’
Nature
387
: 173–6.

4.
Elton et al., op. cit.

5.
even into the modern size range
: Saldanha 1 and Kabwe (Broken Hill 1) had brain volumes of 1,225 and 1,280 cm
³
respectively, and were both
Homo rhodesiense
. Their dates have recently been re-assessed stratigraphically to 1.07–1.3 million years – see 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 pp. 461, 468, 482.

6.
Aiello, L.C. and Wheeler, P. (1995) ‘The expensive tissue hypothesis: The brain and the digestive system in human and primate evolution’
Current Anthropology
36
: 199–221.

7.
Elton et al., op. cit. p. 23.

8.
Elton et al., op. cit.

9.
1.07–1.3 million years ago
: McBrearty and Brooks op. cit. p. 482.

10.
Elton et al., op. cit. pp. 19, 21.

11.
Foley, R. and Lahr, M.M. (1997) ‘Mode 3 technologies and the evolution of modern humans’
Cambridge Archaeological Journal
7
(1): 3–36; see also 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.

12.
another terrible series of ice ages
: This was during Oxygen Isotope Stages (OISs) 35–32, see Rossignol-Strick, M. et al. (1998) ‘An unusual mid-Pleistocene monsoon period over Africa and Asia’
Nature
392
: 269–72, Fig. 1b.
Homo rhodesiensis
: very similar to European
Homo heidelbergensis
; the terms are sometimes used synonymously (for more clarification, see McBrearty and Brooks op. cit. p. 480).
a brain volume of as much as 1,250 cm
³
: Ruff, C.B. et al. (1997) ‘Body mass and encephalization in Pleistocene
Homo
’
Nature
387
: 173–76. op. cit.
about half a million years ago, and carried the Acheulian technology with them
: Foley, R. and Lahr, M.M. (1997) op. cit., Fig. 5.

13.
another severe ice age struck
: OIS 10, see Lahr and Foley (1998) op. cit.
archaic
Homo sapiens
: on strict cladistic grounds,
Homo sapiens sensu lato
.
To avoid confusion
: This is a contentious area; my summary is an oversimplification of the discussions in McBrearty and Brooks op. cit. p. 458; and Foley and Lahr (1997) op. cit.
the Middle Palaeolithic
: ibid.

14.
given rise to
Homo neanderthalensis
: Opinion is divided as to whether
Homo neanderthalensis
evolved in Europe and the Middle East out of this quite recent dispersal, or from an earlier out-of-Africa
Homo heidelbergensis
movement: see the discussion in Lahr and Foley (1998) op. cit. (but see also discussion in McBrearty and Brooks op. cit. pp. 480–81). Sequencing of Neanderthal mtDNA has suggested a molecular coalescent with modern humans of about 500,000 years ago. (Krings, M. et al. (1999) ‘DNA sequences of the
mitochondrial hypervariable region II from the Neanderthal type specimen’
Proceedings of the National Academy of Sciences USA
96
: 5581–5.) The coalescent for a particular molecular locus is not necessarily the same as the species (or population) split. The coalescents for other loci, e.g. some of the nuclear polymorphisms within modern humans, go back much further. Even if
Homo neanderthalensis
and
Homo sapiens
are regarded as drifted races of Archaic
Homo sapiens
(
sensu lato
) (or
Homo helmei
), their mtDNA coalescent may well go back half a million years (i.e. much earlier than the type specimen for Archaic
Homo sapiens
) irrespective of precisely when the ancestor of Neanderthals left Africa.
and had several possible relatives in India and China
: Stringer regards
Homo heidelbergensis
as the ancestor of modern humans and Neanderthals and tends to place Asian specimens such as Dali, Maba, Narmada, and Zuttiyeh in this group. See Stringer, C. (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.

15.
OIS 6; note that ‘
Homo sapiens
’ with no other qualifier means anatomically modern
Homo sapiens
(
sensu stricto
). For the population fall to 10,000, see Takahata, N. et al. (1995) ‘Divergence time and population size in the lineage leading to modern humans’
Theoretical Population Biology
48
: 198–221.

16.
Ruff et al. op. cit.

17.
For a discussion of Baldwinian coevolution, see Deacon, T. (1997)
The Symbolic Species
(Penguin, London) pp. 322–34.

18.
For evolution of cultural traits, or ‘memes’, see Blackmore, S. (1999)
The Meme Machine
(Oxford University Press). See also; F. John Odling-Smee et al. (2003)
Niche Construction: The Neglected Process in Evolution
(Princeton University Press).

19.
Deacon op. cit. pp. 214–16.

20.
Ibid. Chapters 8 and 9.

21.
Ibid. pp. 248–50.

22.
the greatest theoretical ‘social capacity’
: Cetaceans have similar brain volumes to humans but have much larger bodies. As an aside, I gather that dogs, with much smaller brains, have a pretty good memory for personal smells.
a group size of over 300
: See Table 2.10 in Gamble, C. (1999)
The Palaeolithic Societies of Europe
, Cambridge World Archaeology (Cambridge University Press) p. 54.
exchanging material goods
: ibid.
Chapter 2
.

23.
See discussion in ibid. p. 53–55.

24.
See the discussion and interpretation of Köhler’s work in Englefield, R. (1977)
Language: Its Origin and Relation to Thought
, eds G.S. Wells and D.R. Oppenheimer (Elek Pemberton, London)
Chapter 1
; and also an update in Wells, G. (1999)
The Origin of Language
(Rationalist Press Association, London).

25.
The greatest star of this story is Kanzi
: Savage-Rumbaugh, E.S. and Lewin, R. (1994)
Kanzi: The Ape at the Brink of the Human Mind
(John Wiley, New York).
Chimps have also been shown to demonstrate
: Deacon op. cit., esp. pp. 413–14.

26.
The Condillac view
: Englefield op. cit.; Wells op. cit.
The full theory sees gesture language
: For a lucid, referenced, non-technical, historical review of the evolutionary versus ‘big bang’ theories of language, see ibid.

27.
genetically hard-wired into our brains
: Chomsky, N. (1968)
Language and Mind
(Harcourt, Brace & World, New York).
concept originated with Plato
: see the discussion in
Englefield op. cit. p. 131. Jakob Grimm: Grimm J. (1851)
Über den Urschprung der Sprache
in L. Spiedel (ed.) (1911)
Aus den kleineren Schriften von Jacob Grimm
(Berlin) p. 268.
Max Müller, ‘Language is our Rubicon . . .’
: Müller, F.M. (1891)
The Science of Language
Vol. I (Longmans, London) p. 490;
‘without speech, no reason . . .’
: ibid. Vol. II p. 79.

28.
Clottes, J. et al. (1995) ‘Radiocarbon dates for the Chauvet-Pont-d’Arc cave’
International Newsletter on Rock Art (INORA)
11
: 1–2.

29.
a lopsided brain
: Steele, J. (1998) ‘Cerebral asymmetry, cognitive laterality, and human evolution’
Current Psychology of Cognition
17
: 1202–14. For a less ‘biologically determinist’ view of cranial asymmetry, see Deacon op. cit. pp. 309–15.
Homo habilis
is thought by some
: The argument for Broca’s area in
Homo habilis
is less convincing since it relies too much on the concept of Broca’s area as a speech organ.

30.
two important speciation events
;
mutations might be associated with cerebral asymmetry
: Crow, T.J. (2000a) ‘Did
Homo Sapiens
speciate on the Y chromosome?’
Psycoloquy
11
(001) (also at
http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?11.001
); Crow, T.J. (2000b) ‘Schizophrenia as the price that
Homo sapiens
pays for language: A resolution of the central paradox in the origin of the species’
Brain Research Reviews
31
: 118–29. Crow, T.J. (2002) ‘Sexual Selection, Timing and an X-Y Homologous gene: did
Homo sapiens
Speciate on the Y Chromosome’
Proceedings of the British Academy
106
: 197–216.

31.
imprinted at an early stage
: Human language ability, which includes lexical, syntax, symbolic, and syntactic inference and phoneme analysis (as opposed to learning new languages), can be acquired only during a critical period in early childhood when detailed rote learning skills are still rather poor. After this window period, normal acquisition of a first language is severely impaired.
a particular part or parts of the brain
: In any case, Broca’s and Wernicke’s classical speech centres evolve their critical nature during human development, i.e. they are plastic at first and their function can be taken over to a certain extent by other areas if they are damaged at a very early stage; see Deacon op. cit. pp. 282–8, 307.

32.
Crow (2000a) op. cit.; Klein, R.G. (1995) ‘Anatomy, behavior, and modern human origins’
Journal of World Prehistory
9
: 167–98.

33.
humans and chimps were even more closely related
: see Table 3 of Sarich, V. (1971) ‘A molecular approach to the question of human origins’ in P. Dolhinow and V. Sarich (eds)
Background for Man
(Little Brown, Boston) p. 73.
split not much more than 5 million years ago
: Now estimated as 6.5 million years – see Goodman, M. et al. (1998) ‘Toward a phylogenetic classification of primates based on DNA evidence complemented by fossil evidence’
Molecular Phylogenetics and Evolution
9
: 585–98. 6.5 million years is also the age of the chimp–human split obtained by the author (see
Figure 0.3
) by extrapolating from another calibration approach and using complete mtDNA sequence data (unpublished analysis SJO).

34.
For a personal account see Watson, J.D. (1968)
The Double Helix
(New York, Atheneum).

35.
This mutation rate applies if one takes the HVS 2 segment of the mtDNA control region normally studied – see methods in Forster, P. et al. (1996) ‘Origin and evolution of Native American mtDNA variation: A reappraisal’
American Journal of Human Genetics
59
: 935–45.