<<

. 33
( 43 .)



>>

Mode 1, the earliest technology that was employed by the early forms of
Homo (attributed to ergaster, erectus, antecessor), was an economical and lo-
cal technology. There was no requirement to cover large distances to obtain
particular raw materials. Tools were made in situ and discarded once used.
In the particular circumstances of early Pleistocene Africa, a relatively stable
climate but more unstable than previously, this tool kit was advantageous in per-
mitting greater options of resource exploitation. The hominids that practised
this technology thrived and Mode 1 spread, permitting the bearers to breach the
tropical barrier for the ¬rst time. The process of spread was slow. By the time
Mode 1 reached Eurasia it was in an evolved form (Carbonell et al., 1999a).
The next technological mode to appear was Mode 2, associated with the
production of bifacial tools and with early (ergaster) and evolved (heidelber-
gensis) forms. Mode 2 had no clear advantage over Mode 1 as the two survived
in parallel for 1 Myr. We have no knowledge of whether groups of hominids
alternated between these two technological modes depending on ecological cir-
cumstances. Because Mode 2 required particular types of raw materials, which
Survival of the weakest 197

required speci¬c searches that had not been needed for Mode 1 and because
there were costs involved in manufacture, we have to assume that this was a
more costly technology than Mode 1. In the type of conditions in which Mode
1 evolved, the more costly Mode 2 would have been at a disadvantage which is
probably why it took some time for it to become widespread and why Mode 1
was often used instead when the two options were available. How would Mode
2 have originated? In my view Mode 2 would have arisen in peripheral tropical
African populations that were more stressed than core populations using Mode
1. As Mode 1 populations expanded it would have been the peripheral popu-
lations, in sub-optimal habitats, that would have had to increase their scale of
operation to reduce risk of extinction. Living in increasingly patchy landscapes
in terms of their preferred resources these populations would have become
wider ranging. A portable kit, like Mode 2, though more costly would have
been increasingly advantageous. It would have been the product of increased
innovation under increasing stress. Why did Mode 2 not evolve, then, among
the Eurasian populations that would have been under even greater stress? These
Eurasian Mode 1 populations would have been at much lower densities so it
is unlikely that they would have reached the densities that created the kinds
of demographic pressure that affected the African populations. The low den-
sity would have statistically reduced the chances of innovations appearing and
spreading. So, in Eurasia, we would expect thinly spread populations continuing
with Mode 1.
As the world became increasingly unstable and all populations adopted a
more highly mobile form of living, Mode 1 became extinct and Mode 2 survived.
The rapid spread of Mode 2 in Europe in an evolved form, after a signi¬cant
delay in arrival, is perhaps the ¬rst example of the ecological release followed
by rapid spread that, as we have seen, characterised later human populations.
The delay in arrival in Europe, in spite of the greater mobility and dispersal
capacity of these populations may re¬‚ect worsening environmental conditions
that slowed down the rate of spread. We can thus envisage a situation, starting
with the bearers of Mode 1, in which dispersal out from Africa is achieved
under relatively benign conditions by slow dispersing hominids. Increasingly
harsh conditions would have slowed the rate of dispersal of later populations
but this would have been counteracted by increased dispersal capacities and
more versatile technology. The result is that hominids kept dispersing out from
Africa. A further prediction of this model is that, as dispersal ability and tech-
nological versatility improved, populations dispersing from Africa should have
been increasingly able to expand the range further than previous dispersing
populations, turning former barriers into corridors. This prediction would ap-
pear to be met. Bearers of Mode 1 dispersed across tropical and sub-tropical
regions of Eurasia including the Mediterranean. Bearers of Mode 2 reached
198 Neanderthals and Modern Humans

areas of temperate western Europe. Bearers of Mode 3 expanded further into
areas of Eurasia. Bearers of Mode 4 were the ¬rst to colonise the Eurasian Plain
and reach North America. I am not making any distinction as to the biological
identity of the bearers of these technologies nor indeed whether the different
modes dispersed with populations or simply spread through cultural transmis-
sion. The net effect is the same “ bearers of Mode 4 colonised the largest areas
of the planet and bearers of Mode 1 the smallest.
The sobering conclusion that I derive is that it has been the peripheral popula-
tions, those in some way weaker and displaced by density-dependent processes,
that have adapted to situations of increased risk. As the world has become an in-
creasingly risky place so these populations have been at an advantage and have
spread while the less versatile core populations have lost out. This need not be
the result of competitive processes. It is far more likely that less versatile popu-
lations were reduced and eliminated by instability and others, better able to deal
with instability, moved in then to become core populations in their own right,
with a slowed rate of change. New peripheral populations then went through
a process of increasing adaptive versatility and the process was repeated all
over again. The last cases would have included the extinction of the so-called
˜archaic™ populations (including the Neanderthals), starting as on all previous
occasions with those in tropical Africa, and the ¬lling of the empty space left
by them by the peripheral Moderns.
Most discussions of the relationship between Moderns and the Neanderthals
end with the Neanderthal extinction that is put at around 30“28 kyr in the last
sites (Chapter 7). Clearly Neanderthals must have survived somewhat later as
these dates are for sites in which the Neanderthal population density must have
been high enough for the archaeological record to detect it. It is na¨ve to think of
±
these as the latest dates of Neanderthal survival. Even so, we can agree that the
last Neanderthal populations probably became extinct before the onset of the
LGM, at some point towards the end of OIS 3. So, at the onset of the LGM we
have a world that is apparently, in Eurasia at least, inhabited only by Moderns.
So what happened to these Moderns?


The last glacial maximum

I will focus this discussion on the European and Middle Eastern picture as it is the
best documented. With the onset of the LGM and the advance of the ice sheets
(Chapter 6) much of Europe was inhospitable to humans (Housley et al., 1997;
Bocquet-Appel & Demars, 2000a). We observe a pattern of human dispersion
that is not dissimilar to that of earlier cold events, except that on this occasion
it is Moderns and not Neanderthals that are involved. The heightening of the
Survival of the weakest 199

LGM sees the intrusion of temperate environments well into the Mediterranean
refugia, most so in the continental peninsulas of the Balkans and Italy, and
also across much of the central Iberian tablelands. Steppe dominates these
plains and montane vegetation descends even in the thermo-Mediterranean
coastal belt. Steppic species reach far south, with mammoth reaching the latitude
of Granada in Spain (37—¦ N) and woolly rhinoceros, reindeer and wolverine
reaching well into central Iberia (Garcia & Arsuaga, 2003). The worsening
of conditions at the end of OIS 3 saw the corresponding expansion of plains
adapted humans across the Eurasian Plain (Chapter 7), ¬rst with Aurignacian
technology and then with Gravettian technology. Towards the start of the LGM
these populations became highly dispersed and fragmented in the Eurasian
Plains and many local populations would have become extinct. Instead there is
a population demographic explosion in the southern refugia, at least within the
Iberian Peninsula and parts of south-western France. This increase is related to
people carrying a new technology (the Solutrean) that appears adapted to the
exploitation of open vegetation plains fauna with long-range weapons (Straus
et al., 2000). The increase corresponds to the expansion of steppic environments
in Iberia. Some authors have connected this population increase with the decline
in the Eurasian Plain, suggesting southward displacement of these populations.
Although there may have been an element of southward dispersal as populations
retreated, I think that it is more likely that these populations simply were unable
to adapt fast enough to the change and went extinct. At the same time those that
had penetrated Iberia were adapted to steppe and their populations expanded.
This scenario is not dissimilar to those that Neanderthals would have faced
in previous glaciations with one exception. For the ¬rst time we have steppe-
adapted populations of humans within the refugia able to capitalise on the
spread of these habitats. But we saw in Chapter 5 that one difference between
Moderns and Neanderthals was that the former could also exploit heterogeneous
environments. So the people of the Solutrean were also able to survive along
the coastal mountains of Cantabria and the Mediterranean coast of Iberia.


The last deglaciation

The deglaciation was marked by a demographic explosion (Demars, 1996;
Bocquet-Appel & Demars, 2000a) and by the expansion of humans from
southern and eastern refugia into the Eurasian Plains as the ice sheets receded
(Aldhouse-Green & Pettitt, 1998; Torroni et al., 1998, 2001; Street & Terberger,
1999; Blockley et al., 2000; Semino et al., 2000). The size of Iberia meant that
it probably held the largest population of humans in Europe, so it is not sur-
prising to see the extent of their subsequent genetic in¬‚uence as they spread
200 Neanderthals and Modern Humans

northwards (Torroni et al., 1998, 2001; Semino et al., 2000). The Cantabrian
populations of Moderns expanded further and colonised upland areas as these
opened up with global warming (Straus et al., 2000). This is not surprising
as these populations were experiencing similar Euro-Siberian vegetation and
faunal conditions to those further north. The Mediterranean ones were, in-
stead, on the decline (Figure 7.8; Straus et al., 2000). My view is that as the
Mediterranean forests expanded many previously suitable areas of steppe or
heterogeneous landscapes became unavailable. Forests were challenging on
account of the dispersed nature of prey species, that would also have been less
visible, and the dif¬culty of penetration into their depths. So the southern popu-
lations were restricted to the coastal areas where many, perhaps resembling the
response of earlier populations of Neanderthals under similar circumstances,
became heavily dependent on marine resources. This dispersion pattern within
Iberia continued into the early Holocene, Epi-Palaeolithic populations being
largely distributed coastally in the Mediterranean (Oliver & Juan-Cabanilles,
2000) and in Portugal and extending into high mountains in the north (Straus
et al., 2000).
In the Eurasian Plain we see the cultural and technological explosion that
we relate to the Magdalenian. Following from my earlier point about the de-
velopment of innovations in times of stress, we observe the beginnings of this
diversi¬cation in the Solutrean, which corresponds to the period of greatest
population stress. The Magdalenian is the ¬rst great cultural and technologi-
cal diversi¬cation of the Modern Humans, breaking away from dependence on
mammalian herbivore meat towards the exploitation of a diversity of resources
(Chapter 5; Holliday, 1998). These changes were themselves induced by envi-
ronmental stresses as the mammalian herbivore fauna of the Eurasian Plain, on
which humans had become dependent since the Aurignacian, became depleted.
Some authors consider this depletion to have been induced by the Palaeolithic
hunters themselves but others prefer to regard the late Pleistocene megaherbi-
vore extinction to have been induced by climate driven habitat change. Either
way, Modern Humans had to, for the ¬rst time, develop lifestyles that were not
heavily dependent on the hunting of large mammalian herbivores. The large
packages of protein (Chapter 2) that had characterised the landscapes in which
humans evolved were signi¬cantly reduced.
The deglaciation and the Holocene were not the ¬rst period of global warming
that humans experienced in Europe and western Asia. Neanderthals recovered
from earlier glacials as we saw in Chapter 7. However, they did not diversify
anywhere near to the extent that the Magdalenian Moderns did. The reason
may simply be due to the cumulative effects that I have alluded to that led
to the progressive increase in technological complexity that we observe in the
archaeological record. This does not mean that the Neanderthals could not have
Survival of the weakest 201

diversi¬ed in the way that the Magdalenians did. It simply means that the starting
template of the Neanderthals and that of the Magdalenians was different, largely
due to reasons of contingency. Additionally, the faunal pattern would have been
very different in the two cases. The Neanderthals would have lived in a world that
remained rich in mammalian herbivores, whereas the Magdalenians, as we have
seen, lived in a world of progressive impoverishment of mammalian herbivore
diversity and biomass. Nevertheless, we have tantalising glimpses that suggest
that Neanderthals may have responded in a similar way to Magdalenians with
regard to resource exploitation. During OIS 5, at Vanguard Cave, Gibraltar,
Neanderthals were exploiting marine resources including seals and dolphins
(Balter, 2001; Chapter 5). It suggests the possibility that, as forests covered
Iberia and the continental shelf was submerged as a result of global warming,
the southern Iberian Neanderthals at least were diversifying their resource base.
We cannot be certain of this and must await further evidence of Neanderthal
behavioural ecology during the last interglacial.


Systems of food production

Why did the Neanderthals not evolve food production during the last inter-
glacial? Why did the early Moderns not do so either? Indeed, some societies “
such as the aboriginal Australians “ never acquired food production at all
(Diamond, 1997). These may seem pedantic questions but attempting to an-
swer them may help us understand the conditions in which food production
might be expected to arise. We have seen that Neanderthals differed from Mod-
erns in the way in which they exploited the landscape, frequently moving within
a relatively small annual home range. We have no evidence that Neanderthals
cached resources and it appears unlikely that they remained for long periods at
any particular location. I have also suggested that there was little, if any, divi-
sion of labour in these Neanderthal groups that were, in all probability, small.
A highly mobile strategy largely based on the exploitation by encounter of re-
sources that were highly dispersed would not seem suited for the conditions
required for agriculture (semi-permanent or sedentary existence, within-group
division of labour) to evolve. We therefore do not need to seek cognitive ca-
pacity explanations (e.g. Diamond, 2002) to explain why food production only
evolved in Moderns. The early Moderns were evolving a type of mobility pat-
tern that might have provided suitable conditions for such a development to
take place during the last interglacial, but it never happened. It seems that these
early Moderns were simply not in the right place at the right time. During the
last interglacial they were still con¬ned to tropical Africa. This gives us another
insight “ the geographical component in the evolution of agriculture.
202 Neanderthals and Modern Humans

Agriculture has originated independently on several occasions. The geo-
graphical pattern shows that agriculture has never originated in areas of the
Eurasian Plain. The reason for this is a combination of absence of the plants
suitable for domestication, the seasonality related to latitude and the harshness
of the winters. Indeed, reindeer herding has been the only form of food pro-
duction that has evolved in the Eurasian Arctic (Diamond, 1997). Agriculture
has rarely originated in the tropics either, although there are examples in, for
example, Mesoamerica, the Andes and Amazonia (Diamond, 1997). The rea-
son for this may be harder to explain. There are suitable plants, for example
maize, beans and squash in Mesoamerica and potato and manioc in the Andes
and Amazonia, which were widely domesticated. It is also hard to ¬nd satisfac-
tory climatic explanations. The reason may lie in the people themselves. Most
humans living in the tropics did not experience the same level of shortages
of mammalian herbivores that those in the temperate regions did. In addition,
tropical regions provided a wider range of food resources that could be gathered
or hunted than temperate areas. So it seems that the pressures to develop food
production were simply not present.
The signi¬cant early Holocene developments in agriculture have taken place
in areas across the Eurasian mid-latitude belt “ the fertile crescent, and China
in particular (Diamond, 1997; Lev-Yadun, 2000). From these nuclei agricul-
ture spread to adjacent areas with similar climatic characteristics. These areas
held a range of plant species that were suitable for domestication (Diamond,
1997). Climatic conditions were such that mammalian herbivores, after the
late Pleistocene extinctions, were scarcer than in tropical areas though they
were not wholly unavailable. The diversity of alternative food resources would
have been lower than in the tropics. Yet climate was suf¬ciently benign to permit
the sustainable development of agriculture. Even so, foraging lifestyles contin-
ued in areas of, for example, the Iberian Peninsula where the rich resources of
estuaries allowed this even after the arrival of Neolithic food production sys-
tems (Straus et al., 2000) brought by maritime pioneers around 7.5 kyr (Zilhao,
2001). The rich marine resources of the Strait of Gibraltar also permitted a sub-
sistence based on the harvesting of marine resources in the Neolithic (Finlayson
et al., 1999). In Japan, hunting“¬shing“gathering societies persisted until 300
bc when the transition to rice cultivation took place (Akazawa, 1996b). Ex-
ploitation of marine mammals off the Californian coast from 7040 bc to ad
1400 indicates continued use of widely available wild resources (Porcasi et al.,

<<

. 33
( 43 .)



>>