Download 1. What did recursion recurse?

1. What did recursion recurse?
In their recent overview of current language-evolution research, Hauser,
Chomsky and Fitch (2002) suggest that researchers should begin by seeking
for some type of recursive ability (perhaps developed for navigation, number
quantification or social relationships) among other species. They admit that
the discovery of such an ability would merely “open the door to another suite
of puzzles”, but regard as plausible the suggestion that a previously
impenetrable module–for navigation, say–“may have become penetrable and
domain-general” as a result of either “particular selective pressures” or as a
“by-product” of “neural reorganization” (Hauser et al. 2002, 1578), thereby
giving rise to language.
Although Hauser et. al. do not use these terms, what they hypothesize could
only be some form of what has been variously termed “pre-adaptation”,
“exaptation”, or “change of function”, with a Gouldian twist in the second,
“by-product” possibility (Gould and Lewontin 1979). Accordingly, we have to
take into account the nature of such processes. Although these are quite
widely attested–buoyancy chambers into lungs, cooling panels into wings, and
so on–they normally involve new functions being found for old body parts,
rather than for old computational mechanisms. I know of no case where an
abstract computational mechanism devoted to one function has been exapted
to serve some other function (granted, this may be merely my ignorance–in
which case I hope for speedy enlightenment–or because no-one so far has
looked for such developments). However, if we assume that this is possible,
the circumstances attending such exaptation must necessarily differ from those
where a physical organ is involved. In the latter case, that organ merely needs
to modify its existing form for the new function to take hold. But any abstract
capacity requires a separate and distinct domain over which it can range. For
example, recursion would have to have something to recurse with.
Recursion could not have applied to the units of any animal communication
system (ACS) that preceded language, because ACS units are complete and
self-contained. Two units in sequence mean simply the sum of the unit’s two
meanings: a food call followed by an alarm call, for instance, simply means
“There’s food here” plus “There’s a predator coming.” Essential to any
recursive process is the capacity to embed one unit within another (for
instance, to convert–as some early generative grammars did lierally–“A dog
bit me” and “The dog ran away” into “The dog that bit me ran away”). Thus
for recursion to have been able to operate at all, there must first of all have
existed particulate units–units standing for smaller chunks of meaning than
ACS units–that could be arranged and re-arranged in a variety of ways: in
other words, words (or perhaps manual signs–the distinction is of no
importance here).
The approaches both of Hauser and his colleagues (Hauser et al., 2002; Fitch,
Hauser and Chomsky 2005) and of their critics (Pinker and Jackendoff 2005)
take a similar perspective. To both, language evolution is viewed as an
abstract problem, not a dynamic process that occurred at a specific time or
times, in a specific location or locations, as merely a part (albeit arguably the
most significant part) of the overall evolution of the human species. Their
focus is on what attributes of language are unique to humans and what are
shared with other species. No attempt is made to determine the chronological
sequence in which attributes developed, nor the manner in which, whether
unique to humans or shared with other species, they were integrated with one
another to form the well-articulated whole we now know as language..
While an approach of this type has obvious advantages, it needs to be
supplemented by one that looks more closely at the dynamics and pragmatics
of the evolutionary process. By no means all aspects of this process depend
on our correctly interpreting sketchy and often equivocal archaeological
evidence. Some can be determined by simple logic. The temporal precedence
of particulate symbols over recursion (regardless of whether or not this was
exapted from some prior function) is just one of such aspects. Logical
considerations enable us to determine much more than this about the materials
to which recursion would eventually apply.
2. Symbolism, predication and displacement.
For there to exist units to which recursive operations might apply, two other
novel properties–properties not found in ACSs, with a tiny handful of
exceptions that I shall deal with shortly–would have had to emerge:
symbolization and predication.
Why , precisely, can ACS units not be concatenated? Not, for sure, because
serial juxtaposition lies beyond the powers of non-humans. Animals that have
been taught quasi-linguistic systems have without exception concatenated the
units of those systems to form crude propositions, apparently with little if any
formal instruction in proposition-making. Basic to such proposition-making is
predication: a process that links two or more systemic units in a relationship
where one (or more) of such units tells us something about another unit.
Without some such semantic linkage, what would be the point of
concatenating two or more items, and what could they possibly mean if you
did concatenate them? A sequence like “Here’s some food of type X”, could
not, of its very nature, tell us anything about “Look out, there’s a leopard!”–or
vice versa. Thus not merely particulate units, but the predicative use of such
units, must have preceded the exaptation of recursion.
Such particulate units must also have been symbolic. ACS units are, almost
without exception, indexical: they point to an existing state of affairs (“I am
angry”, “I want to mate with you”, “Get out of my territory!” or whatever) or
an object located within the sensory field (“Here’s food of type X”, ‘A
predator’s coming”, or whatever). There is no way in which these could have
been used to describe past or future states of affairs, or objects accessible only
through the memory store. But once you have particulate units describing
objects or events (or, to be more precise, describing concepts of such objects
and events), in isolation from one another and from any particular
instantiation of those objects and events, it becomes possible to achieve
displacement: the capacity to refer to any object or event, irrespective of when
or where it occurred or is/was/will be located. It is, perhaps, possible to
imagine that recursion preceded symbolism, but much harder to imagine what
value recursion would have had if it hadd been hobbled within the here-andnow.
Note, further, other characteristics of language that become available once
symbolization and predication are in place. To the extent that ACSs are
referential, their reference is indissolubly linked with their indexicality.
If a leopard is present, a vervet monkey’s leopard alarm call can be referential,
but if no leopard is present, it is merely a mistake or a tactical deception
Unlike words, ACS units cannot be questioned (“Is that a leopard?” or simply
“leopard?”) or negated (“No leopards here!”). Recursion is not a pre-
requisite for such utterances: simple predication, which does not necessarily
involve more than two units casually concatenated, suffices to produce them.
And since, as suggested above, predication preceded recursion, we may
conclude that questions and negations, essential ingredients of language as we
know it, also preceded the emergence of recursion.
Symbolization, predication and displacement thus form the foundation on
which the complex structure of language subsequently arose. If these factors
necessarily preceded recursion in the evolution of language, they might seem
worthy of more attention than they have hitherto received (see Table 1).
(Insert Table 1 about here)
Their appearance must, at the very least, indicate the boundary line between
ACSs and a communicative system (call it protolanguage, or whatever) as
unique to human ancestors as language itself. Indeed, if they constitute a
necessary as well as a sufficient condition for the emergence of true language,
they may represent a more significant Rubicon between humans and nonhumans than recursion itself, unique to our species though that be. Such would
be even more clearly the case if recursion turned out to be, rather than a preexisting, exapted faculty, an entirely new and emergent property for which the
emergence of symbolism and predication formed an important selective
pressure. However, such issues lie far beyond the scope of the present paper,
which limits itself to possible origins for symbolization and predication.
3. Among the hymenoptera
If we seek out precursors of predication and symbolization by the means
Hauser at al. suggest–comparative studies–our search takes us in an
unexpected direction. The only species where such possible precursors occur
are found among the hymenoptera: ants and bees.
It has long been claimed that bees have a “dance language” that is symbolic in
that it can convey information about pollen and nectar that is at some distance
from, and beyond the sensory range of, both the communicating and receiving
bees (von Frisch 1967; Gould 1976; Dyer and Gould 1983; but see
Wenner 2002 for a contradictory view of bee communication). Less
well publicized, but perhaps even more impressive, are the
communication systems of ants (Wilson 1962; Hangartner 1969;
Moglich and Holldobler 1975; Holldobler 1978), which feature not only
symbolization of non-present objects but even a precursor of
predication.
Why should this be the case? Why should these relatively primitive
organisms have access to capacities that even the great apes lack?
The answer can only be that, for bees and ants, the standard symbolless, predication-less ACS must be inadequate. Other species do not
develop symbolization and predication under natural conditions
because they can live their lives perfectly well without such things. The
fact that at least some species can acquire symbolization and
predication under training shows that motivation, rather than the
necessary neural infrastructure, is what is lacking here. Under the
appropriate motivation, it may be that an extremely wide range of
species might develop at least rudimentary forms of the functions in
question.
Why would a standard ACS be inadequate for bees or ants? Both are
extractive foragers. Both operate from a central point, foraging
individually or in small groups. In the case of ants, a variety of different
food sources are utilized, some involving objects too large for a single
ant to deal with. Both for ants and bees, the food source may be
transient and require numbers for its efficient exploitation. These
factors make recruitment a necessary strategy.
It is necessary to make very clear what is meant here by recruitment. It
means inducing conspecifics to exploit food sources of otherwise
unpredictable location that neither the sender of the signal nor its
receiver can directly perceive by any sensory means. It does NOT
mean inducing conspecifics to exploit a food source that the sender
can directly perceive at the moment of signaling. For that, a simple
food call or rallying cry would suffice. Recruitment in the sense
intended here demands at least some type of symbolization, if not
predication.
Recruitment among ants takes several forms: tandem running, where a
single ant presents a food sample to another ant and then leads it
towards the food; light trail laying plus a waggle display, used to recruit
groups; and the establishment of a semi-permanent chemical trail,
sometimes varying in strength according to the quality of the food
source, where the source is large and mass recruitment is required
(Sudd & Franks 1987). Tandem running would seem to be the closest
of these strategies to predication. “When a forager finds a plentiful
food source it returns to the nest and regurgitates food to its
nestmates. Then it raises its gaster and extrudes its sting bearing a
droplet of liquid. This attracts nestmates to it in the nest. As soon as
the first of these nestmates reaches the caller, the caller runs out of the
nest and leads the nestmate to the food source” (Sudd & Franks 1987,
p. 112, based on the description of Leptothorax species, Moglich et al.
1974). It may not seem overly fanciful to paraphrase this as, “Come, X
food [is] this way”–a subject with a comment about it, in other words an
act of predication.
Obviously, a communication system composed of such elements falls
far short of the simplest system that we would recognize as a
language. First, the elements it can symbolize are sharply limited;
second, messages in such a system can involve only the limited
domain of foraging; third, since the meaningful behaviors involved are
innately programmed, the system cannot freely add additional units, as
any language can freely add words. However, such systems are
capable of transferring factual information of a type that other ACSs
cannot transfer, just as human language is.
4. Factors favoring recruitment
The need for recruitment arises from the particular niches developed
by ants and bees respectively: niches that have some obvious
differences (bees forage aerially, ants terrestrially, for example) but
have many more similarities than differences. By examining these
similarities we can specify the characteristics of both species and niche
that would select for an ACS with the essential feature of displacement,
a central component of symbolism: that is, the conveying of objective
information about things that are not physically present.
With regard to the species, recruitment can only arise in a species that
is social. In addition, it requires that such a species be co-operative.
Species can, of course, be social without being co-operative; primates
notoriously will go to some lengths to keep prized portions of food to
themselves. There must, therefore, be some specific reason for cooperation to arise in a social species. One such reason is eusociality; if
all the members of a group are
siblings, inclusive fitness ensures that the good of all will be the good
of each. But eusociality, if perhaps a sufficient cause of co-operation,
may not be a necessary one. Another may be vulnerability to
predation; a social species is more likely to be co-operative if it has
come under heavy pressure from predators and co-operation between
members can reduce this threat.
Characteristics of niches that select for recruitment are as follows.
Basic is that the means of subsistence should be extractive foraging.
Carnivory and herbivory do not require recruitment. Carnivores can’t
recruit for a food source because that source is mobile and by the time
any recruit gets back to where it was, it probably won’t be there.
Herbivores don’t need to recruit for a food source because (except in
occasional severe droughts) there is usually enough in plain view to
render communication unnecessary. Food sources may be widely
scattered; if food is clumped and contiguous, there is correspondingly
little need for information about it to be exchanged. Sources should
also be unpredictable; if groups know where and when a particular food
source will be present, the need to communicate about it is again
weakened. If in addition to being scattered and unpredictable, sources
are also transient, communication is still more strongly encouraged,
while an intake of food that is diversified puts an adaptive premium on
information about type and quality. Another factor favoring recruitment
applies if the food is sizeable; if potential food is several sizes larger than
the forager, recruitment becomes almost inescapable. Other necessary
niche characteristics involve the means by which extractive foraging is
carried out. The groups engaged in it should have a fission-fusion
structure. Clearly, if a group forages as a unit, there is no need for
members to communicate their finds to one another. The pattern of
foraging is likelier to encourage recruitment if the foragers operate from
a central place where information can be exchanged; central-place
foraging is in turn made likelier if the species concerned habitually
engages in provisioning relatively immobile young.
Ants and bees both meet a substantial subset of the relevant criteria.
Both are eusocial (hence co-operation is inbuilt, so to speak) and both
engage in extractive foraging. Though food sources for bees are not
diverse and the food items themselves not sizeable, the flowers that
furnish them with nectar and pollen are widely scattered (often at
considerable distances from the hive), transient (many blooms open
only at certain hours, others last less than a day), and largely
unpredictable (or at least, too numerous and irregular in their
appearance for any organism with a bee-sized brain to keep track of all
of them in memory, although single persistent patches may be returned
to by bees even after overwintering, Winston 1987, p. 176). Ants eat a
wide diversity of foods: “even those species which count as specialists
for meat or vegetable food are not always consistent in this” (Dumpert
1978, p. 236). To the extent that they function as predators and
scavengers (rather than fungus growers or aphid dairymen), their food
sources are transient, unpredictable and scattered. They are also often
sizeable; ants often capture larger animals which would be impossible
for individuals to manage (Wilson 1958). Both ants and bees employ a
fission-fusion strategy in foraging, except for some species such as
army ants, which are dramatically unselective in their choice of diet.. All
honey bees, and most ants (some are nomadic) forage from a central
place (the nest or hive) to which they return with their booty to provision
their larval young.
It follows that for both ants and bees, recruitment plays a vital role in
subsistence. It is possible that they could survive without it. It is certain
that, if there were insect colonies that practiced recruitment and insect
colonies that did not, those that practiced it would prosper at the
expense of the others. Accordingly, recruitment strategies have proven
highly adaptive and have been adopted by the majority of bee and ant
species.
As with predications, and in striking contrast to the signals in other
ACSs, recruitment signals in ants can be shown to require
concatenation. Holldobler (1971) demonstrated this experimentally in
Camponotus socius, an ant that first uses shaking behavior to draw
recruits and then follows a chemical trail of its own making to the food
source. However, removal of this lead ant causes the recruits to
abandon the trail. By mixing contents of the ant’s bladder and poison
gland and ejecting this mixture, Holldobler caused leaderless ants to
persist in following the trail, thus indicating that both the directional trail
and continuing signals from the leader were required to insure
recruitment.
5. Niche construction.
If natural selection by the environment, acting on variation within the gene
pool of a species, was the sole force driving evolution, it would be hard to
explain why humans are so different from the other great apes. The genetic
difference involved here–less than 2% in some cases–is of an order that might
be expected to produce differences in behavior no more radical than those
between horses and donkeys, or lions and tigers. Recently, however, it has
been suggested that there is another force driving evolution: the active
construction by species of unique niches, which in turn impose novel selection
pressures on that species, leading to a feedback process (Laland et al. 2000;
Odling-Smee et al. 2003).
Hitherto, evolution has been generally perceived as a one-way process
in which a variable but largely autonomous environment selected from
genetic variation in populations of living organisms. The role of those
organisms was thus essentially a passive one. The environment,
however, is itself to a large extent the creation of the organisms that
inhabit it. Without photosynthesizing organisms there would be
insufficient oxygen to support multicellular life; without earthworms and
similar creatures there would be insufficient soil to support the majority
of plant forms on which all mobile organisms ultimately subsist; without
beavers, many wetlands that support a variety of fish, birds, amphibians
and other life forms would not exist. In other words, evolution is a two-
way not a one-way street. Environmental factors may select for genetic
traits, but those factors themselves may result from prior activity by the
species concerned; for instance, the physical shapes of beavers’ lips,
teeth, oil-glands, eyelids, tails and feet were influenced if not wholly
determined by the consequences of their initial “decision” to create an
environment in which their lodges would not be threatened by the
periodic shrinkages and dangerous overflows characteristic of running
streams. On this view, organisms play a role in their own destinies that
goes far beyond anything envisioned by the neo-Darwinian consensus.
One significant advantage of niche construction theory is that, in
contrast to previous biological theories, it does not merely account for
human-ape differences, but directly predicts them. Other apes all
inhabit roughly the same kind of niches and have remained in those
niches, as far as we know, throughout the last seven million years.
Human ancestors, in contrast, have inhabited at least four distinct
niches. First came a foraging niche, characteristic of at least some
species of australopithecines, in which tubers furnished a significant
portion of the food supply. Then came a scavenging niche, in which a
substantial percentage of nutrition was derived from the carcases of
animals, including megafauna. There followed a hunting niche, in
which scavenging and foraging were supplemented by the communal
pursuit of living animals. Finally and quite recently we entered a
farming niche based on agriculture and the domestication of animals.
Since the niche forms the organism just as much as the organism forms
the niche, differences in primate niches are the obvious places to look if
we are trying to understand differences in primate adaptations–in
particular, those adaptations that gave rise to language,
6. Homo in the scavenging niche.
Around 2mya, world climates became cooler and drier, and savannas
largely replaced the mosaic woodlands that had been the previous
habitats of human ancestors (Reed 1997). Hominid patterns of
behavior changed; day-ranges probably increased considerably
(McHenry 1994). Scavenging already provided part of hominid diet, but
it was probably low-end scavenging, conducted after other predators
and scavengers had taken their share, and involving mostly harvesting
of foods inaccessible to other species (Binford 1985). Bone marrow, for
instance, could be obtained if primitive stone tools were used to crack
open bones, but little meat would have been left by the time earlier and
more powerful scavengers had done with the carcass. However, in a
mosaic woodland habitat other food sources would have been readily
available, including fruit and nuts and small animals such as red
colobus monkeys, which chimpanzees catch readily without weapons
(Stanford 1998). Although such a niche might have required ranges
larger than those of contemporary apes, it would not necessarily have
placed a premium on recruitment.
However, when woodlands were replaced by grasslands, food sources
other than meat (except for tubers, O’Connell et al. 1999) became
much more rare. At this point, hominids engaged in counteractive niche
construction (Odling-Smee et al., 2003: 46): a process in which a
species counteracts an environmental change by relocating to a new
environment or changing some aspect of its behavior. The new niche
was a logical move for organisms that had already used stones to break
open bones and (probably) digging sticks to excavate tubers. All they
needed were the flakes struck off in the production of Oldowan tools.
At least by the Plio-Pleistocene boundary hominids had moved their
focus from brain and bone-marrow to active scavenging and butchery
(Bunn & Kroll 1987 Blumenschine 1987). The efficacy of Oldowan tools
was practically demonstrated by Kathy Schick and Ray Dezzani, who
used them to butcher an elephant that had died of natural causes
(Schick and Toth 1993, pp. 166ff). They “were amazed as a small lava
flake sliced through the steel gray skin, about one inch thick, exposing
enormous quantities of rich, red elephant meat.” Since “modern
scavengers normally do not eat a dead elephant until it has
decomposed for several days”–they can’t, their teeth cannot penetrate
the skin until decay and the expansion of internal gases has split it
open–“such carcasses may have provided occasional bonanzas for
Early Stone Age hominids” (see also Blumenschine et al, 1994). In
fact, the bonanzas may not have been so occasional. While it is true
that bones of animals larger than 2000 kg are rarely found at catchment
sites, by or soon after 2mya hominids had moved to territory
scavenging rather than catchment scavenging (Larick and Ciochon
1996), making it likelier that large carcases would have been exploited
in situ, and would accordingly remain widely scattered and rarely
unearthed by researchers. It seems plausible that under prevailing
conditions there were quite large numbers of elephants, rhinoceroses
and hippopotami, as well as other megafauna now extinct. Such
animals would have presented a formidable challenge to most
predators; besides, why would a predator kill something knowing it
would have to wait days for it to be ready to eat? For this reason, a
high percentage of megafauna must have died natural deaths.
This enables us to explain the phenomena of tooth-marks
superimposed on cut-marks, which suggest that hominids were
sometimes accessing carcases before carnivores (Monahan 1996).
Some researchers who, based on good evidence that meat formed a
substantial part of early diets, are reviving the “early-hunting”
hypothesis (e.g. Dominguez-Rodrigues 2002) often write as if all
animal deaths represented kills, and therefore that the cut-before-bite
evidence must result from either hunting or confrontational scavenging
(in which hominids are seen as driving competitors away from a kill
before any of them have had time to dismember it). While it is likely
that relatively few deer-sized or smaller animals survive to die natural
deaths, the same cannot be true for megafauna. Moreover, optimal
foraging theory (Stephens & Krebs 1986), supported by a variety of field
and/or experimental studies on organisms as diverse as gulls (Irons et
al. 1986), stream insects (Velasco& Millan 1998) and white-tailed deer
(Schmitz 1992), indicates that, other things being equal, any species
will select the food that yields the highest calorific intake relative to the
energy expended in obtaining it. Since for hominids this goal would be
best represented by untouched megafauna carcases, optimal foraging
theory suggests that they may have gone to some trouble to locate and
exploit dead megafauna, even in preference to more widespread, more
easily obtainable, but less nutritious alternatives (although they
doubtless continued to exploit the more readily available brains and
bone-marrow from stripped carcases, as well as vegetable foods,
whenever fresh megafauna were unavailable).
7. Homo and recruitment conditions.
The niche described in the preceding section was one that fulfilled most
of the conditions favoring recruitment strategies described in Section
4.1 above. The hominids involved (probably h. erectus or h. ergaster, if
indeed these are distinct species) were a social species whose niche
would surely have made them co-operate more than most primates. A
major factor would have been the risk of predation by savanna-dwelling
carnivores. Forest apes, though not immune from predation, seem very
seldom to serve as prey (except to humans), witness the contrast
between the specialized alarm calls of vervets and the complete
absence even of a generalized alarm call among chimpanzees or
bonobos. Relatively few predators inhabit forested areas or climb trees,
and apes can climb faster than leopards. In contrast, predators of
several species, some now extinct, ranged the savannas and impacted
heavily on hominds (Lewis 1997); even today, in areas where major
predators are found, modern humans frequently fall victim to them
(Treves & Naughton-Treves 1999).
Two consequences follow from this state of affairs. The need for trust
and co-operation, to be sure that there would always be somebody
watching your back, must have been considerably raised among
hominids. The tendency towards Machiavellian strategies, intrigues
and one-upmanship must have been correspondingly lowered.
Moreover, larger day ranges and the need to be constantly on the lookout for predators would between them have substantially lowered both
the available time and the sense of security necessary for prolonged
and intensive socializing.
Next, consider foraging patterns. These are uncertain, due in part to
ongoing controversy over whether home bases existed in the PlioPleistocene (Isaacs 1978; Binford 1981; Rose and Marshall 1996;
Cavallo 1997). If there were home bases then by definition there was
central-place foraging (there may also have been provisioning of the
young, but, as with home bases, it cannot be determined at what stage
of hominid evolution this began). But is the converse necessarily true?
To determine this we should look at the behavior of other grounddwelling primates, such as hamadryas baboons (Kummer 1968).
These have no fixed base; however, they alternate between several
“safe places” (usually rocks or cliffs near a river bed) where they
overnight, shifting periodically from one to another. The net result,
however, is not significantly different from central-place foraging,
Typically they start from one such place and return to it, either
remaining there for the following night or traveling in a group to the next
safe place. Given the risk of nocturnal predation, their inability to climb
as quickly as other primates, and the extreme scarcity of trees to climb,
it seems almost certain that h. habilis (and probably also early h. erectus)
employed a similar strategy.
That they also employed, in their foraging, a fission-fusion strategy also
seems more than a reasonable conjecture. This strategy, in some form
or other, is common to advanced primates generally, whether bonobos
or baboons. We can ignore, for present purposes, the kind of fissionfusion that relates to longer time periods, in which overall group
membership changes as some members drift off by themselves or to
other groups while members of other groups wander in. What concerns
us here is fission-fusion within the day-range as a strategy to maximize
resource extraction. If a range has a high density of resources, such
maximization requires only a minimal separation of subgroups;
subgroups seldom need to travel outside eye- or earshot of one
another, so that the need for communication between subgroups (and a
fortiori the need for recruitment to exploit resources) is minimal.
However, if a range has a low density of resources (as was probably
true, in a majority of cases, around 2 mya and later) it becomes
inefficient for subgroups to remain in close contact, since foraging on a
narrow front would result in no-one getting enough to eat. If, however,
the main group split into four subgroups, and if each selected a different
quadrant with reference to the central place, four times the area could
be covered, and (assuming a uniform resource distribution in all
quadrants) each individual would get four times as much to eat.
The foregoing is not a consideration for baboons, whose diet consists
almost entirely of leaves (96% at the end of the dry season) or seeds
and flowers (87% in the long rains; data from Kummer 1968, Table
XIV), and who accordingly do not need to cover a wide area for even
groups of a hundred or more to be adequately fed. However, to some
extent for australopithecines and perhaps early h. habilis in a mosaic
woodland setting, and to a much greater extent for later homo in a
grassland setting, the foraging logic would have become inescapable.
On the one hand, the scarcity of good night refuges plus the need for
numbers to protect against a mass attack by nocturnal predators of the
hyena class would have pushed towards large nighttime group sizes.
On the other, the thin and dispersed state of food sources would have
pushed towards small daytime group sizes. The optimal solution would
have been for nighttime groups of, say, ~50 to split into several smaller
groups for daytime foraging, then regroup at the original point of
dispersal.
Finally, consider to what extent properties of the food supply satisfied
conditions for recruitment. The diet as a whole was necessarily
diversified. Setting aside leaves and grass (save in dire emergencies),
hominids probably ate whatever they could get. We need not, for the
moment at least, consider bones, which though scattered and
unpredictable in their locations would have remained in place for long
periods. The same is true of roots and tubers, which were not even
unpredictable, given that hominids should have had good cognitive
season-by-season maps of all the vegetable resources within their
home range. We should focus, therefore, on the most nutritious and
highly-prized food-source, the intact carcasses of large dead animals.
These fulfilled all the conditions requiring recruitment. They were
scattered, indeed relatively rare. Their location was unpredictable,
except perhaps that in drought seasons they were somewhat likelier to
be found around dried-up waterholes. They were highly transient, in
that they offered a very narrow window of opportunity between the
moment of death and the first rupture of skin. Post-rupture, they would
have been highly dangerous, surrounded by hungry and impatient
animals in considerable numbers. Indeed, prospective scavengers may
have start arriving well ahead of the first rupture, so that the sooner
hominids located the carcasses, the better. One thing going in their
favor was that predators and scavengers alike are good cost-benefit
analyzers. No animal is going to risk being lamed by a well-aimed
stone when the feast is a prospect still several hours away (when the
carcass is open and ready and you either grab your piece or go hungry,
it’s a different story). But the most crucial condition was that the
carcasses were sizeable–many times larger than any hominid.
This was a situation no other primate ever had to contend with. The
paradigm case for all other primates is that of an animal confronted by a
rare and delicious fruit, probably not more than a pound or so in weight,
whose possession of it is in no way threatened by any other species–
only by other members of its own group. Under such circumstances,
selfishness pays off, and the animal will employ any stratagem that
allows it to eat undisturbed. Now consider an animal confronted by a
rare and delicious carcass, weighing in excess of a ton, whose
possession of it is threatened by a variety of very ferocious species.
Selfishness is futile here, co-operation is the only way to go; animals
that do not co-operate get nothing.
Suppose a small sub-group of hominids, alerted by vultures or just
lucky, stumbles on a huge carcass, still unruptured. Possibly other
animals are already stalking around. The group could, of course, take
its chance and start cutting. But to start cutting would have the same
effect as a rupture, it would immediately trigger a feeding frenzy in the
other scavengers, and the smells of blood and meat might draw more of
them. The whole sub-group could be overrun in minutes and end up as
dinner too. Besides, how could they, even if they drove off all other
scavengers, eat all that meat by themselves? Some might have close
relatives in other sub-groups; inclusive fitness would then also come
into play. In other words, almost every factor in the situation would
cause them to seek additional helpers..
We are now in a position to compare the niches of ants, bees, apes and
early Homo with respect to the conditions favoring recruitment that
obtain in all four niches, as shown in Table 2.
(Insert Table 2 about here)
The homo scavenging niche is much closer to the niches occupied by
ants and bees than it is to the niches occupied by closely-related
primate species. Similar niches yield similar pressures. If the selective
pressures in the hominid niche favored recruitment, how exactly could
recruitment be undertaken in a species many times larger and with
vastly more brain power than the hymenoptera?
6.0 How language began.
Having a brain the size of a coconut rather than the size of a pinhead
has disadvantages as well as advantages. One disadvantage, in this
context, is that you are then an individual rather than a cog in a
machine; you have your own agenda, your own preferences, and
definitely a will of your own. Your subgroup may have found some
tempting source of food, but another subgroup might have made finds
of its own (piles of bones, bees’ nests, termite mounds...). The state of
mind might often have been: why should I go to your find, why don’t you
come to mine? Optimal foraging required some means by which the
finds of different sub-groups could be compared and evaluated.
Recruitment, therefore, couldn’t happen unless the nature of the find
could somehow be indicated. One of the advantages of the coconutsize brain is that it holds primary representations (Bickerton 1990) of a
very broad range of organisms and entities, including all the species
with which the individual habitually interacts. To express these, all that
is needed is a layer of secondary representation: some unique labels
that will signify the objects concerned and trigger associations with
those objects in the minds of others.
Much ink has been spent on whether the original form of language was
signed or spoken: often it seems to be assumed that these are mutually
exclusive options (Hewes 1973; MacNeilage 1998). But this is not
necessarily the case. Ant “language” contains visual, chemical and
tactile elements. It could well have been the case that the original form
of language was equally mixed, involving sounds, manual signs, facial
expressions, mimesis (Donald 1991) or pantomime (Arbib 2004):
whatever worked best communicatively. Its original units need not all
have been symbols: some of them, like those of ants and bees, could
have been indexical or iconic. Symbolism would enter through the use
of such units in the context of fission-fusion foraging, where it would be
clear, precisely from this context, that objects not physically present
were being referred to, In other words, displacement would have
formed the wedge that introduced symbolism into the human
communication system.
Thus a group that had located the carcass of an elephant, rhinoceros,
hippopotamus or other large mammal could transmit this imitation by
imitating the sound made by the animal or by mimicking some aspect of
its behavior, following this with arm-waving and a pointing gesture–a
sequence that would roughly correspond to the ant’s “Come, X food [is]
this way” (see example in Section 4) and that is, of course, a
predication. Once this type of communication had become functional, it
could be expanded to include other information relevant to deciding
which food sources to pursue. An optimal decision would have to take
into account not merely the energy budget that helps determine all
animal food choices–is the input going to be worth the effort?–but also
the choice between high gain/high risk and low gain/low risk. Should
the group take a chance of losing some of its members for a highprotein food that would last days, or content itself with the patch of
tubers that some of its members were already engaged in harvesting?
A number of factors might influence the choice: distance to carcass,
hours of light available, length of time the carcass had been “on the
market”, number and species of scavengers already at the site (if any),
patch size of the tubers, and so on. To be able to transmit any of this
information would make for a better choice.
Once the breakthrough had been made, units would progress from
iconicity to true symbolism by a process well attested for both spoken
and signed languages. Units of the former suffer constant phonological
attritions and mutations: “laboratory” goes to “labratry”, “forehead” to
“forred”, while changes such as that in the first syllable of “breakfast”
sever the word from its original meaning of “breaking a fast”. Thus
even the auditory imitation of an elephant’s trumpeting would in time
become shortened and stylized into a stereotypic form that might give
the illusion of arbitrariness. Similar process apply in signed languages.
Klima and Bellugi (1979, pp. 67-83) give a telling example: the
American Sign Language sign for “sweetheart” originated as the
pressure of both hands on the region of the heart, but changed
gradually over time into an abstract gesture in open space before the
center of the body.
According to some writers (e.g. Mithen 1997; Jackendoff 2002) initial
attempts at language would have been limited to some narrow
function–if language developed to aid foraging, it would have been
restricted to foraging contexts. Granted that ape and bee “languages”
are limited in this way, but we are now talking about organisms with
brains several orders of magnitude larger than hymenopteran brains,
and I see no possible justification for supposing that those brains would
be subject to similar restrictions. The brains of possibly all organisms
above a particular brain/body ratio contain a wide range of primary
representations. (Herrnstein 1979; Bickerton 1990). Once it has been
discovered how to voluntarily label just one of these, it becomes
potentially possible to voluntarily label all: there are no privileged lines
of access between those areas of the brain that store concepts and the
various motor areas, and no internal barriers that would block access to
other conceptual representations. If what we are talking about is
something with (at least some of) the defining properties of language,
rather than those of a PCS, the units (equivalent to words or signs in a
modern language) would not have been innate and genetically
determined, but added voluntarily, invented on the fly and used until
they were generally understood or replaced by some equivalent that
was better understood. A number of different attempts to express the
concept “elephant” might have had to be made before one of them, or
some amalgam of more than one, got selected as the elephant. And
since such a unit (as distinct from an alarm call) would be expected in
the absence rather than the presence of its referent, the progress
towards true symbolism (hence use of the term in a variety of contexts)
might have been slow, but could hardly have been avoided in the long
run..
The foregoing scenario would work well in a context of central-place,
fission-fusion foraging. But it does not crucially depend on such a
scenario. A paper that argues against both the central-place model and
the centrality of meat-eating (O’Connell et al. 1999) contains a striking
vignette of recruitment along similar lines: “Neither would transport of
parts to ‘central places’ be indicated...; individuals or groups may simply
have called attention to any carcass they encountered or acquired, just as
do modern hunters...If the carcass had not yet been taken, the crowd so
drawn could have done so, then consumed it on or near the spot, again
just as modern hunters sometimes do” (O’Connell et al. 1999, p. 478,
emphasis added). In order to “call attention” to such a carcass, and
recruit “the crowd ” that was needed to exploit the situation, some
means of going beyond the prior ACS into the realm of displacement
had to be found. Once found, that means could be, and was, exploited
in a potentially infinite number of ways.
A test of the approach proposed here would be to examine the niches of
other species in order to determine whetherthey need to practice
recruitment, and if so, how they set about it. The prediction is that, given
a sufficient subset of the conditions for recruitment described above, any
species should develop some precursors of predication and symbolism.
Unfortunately, surprisingly few species seem to require recruitment inj
the sense used here. Animals that forage co-operatively may signal the
presence of food to conspecifics, but only when the source lies within
their sensory field, and a standardized call, in isolation, is adequate for
this purpose. The only case known to me, outside those discussed
above, is that of ravens (Heinrich 1989).
Young ravens who have not yet mated or staked out a territory compete
for prey carcasses with well-established pairs. To do so their must
recruit other birds, and this seems to take place in the nightly roosting
areas. However, the means by which this is done remain unclear, and
the time-lag between discovery of and access to prey is much longer (a
minimum of a whole night) than in the case of bee or ant recruitment,
and probably longer than in the case of human ancestors. More
research is needed here. But the hypothesis is clear enough: if and only
if recruitment is required will a species move beyond the limitations of a
standard ACS. If this is so, then recruitment for scanvenging
megafauna carcasses represents the only way in which human
ancestors could have broken through into language.
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19
68
47
symbolization
0
0
0
predication
0
0
0
displacement
0
0
0
Table 1
Frequencies of mention for four significant categories
in three recent papers on language evolution
Chimpanzees/ Homo
Bonobos
Predation risk Low
High
Central place No
??*
foraging
Fission-fusion Yes
Yes
social structure
Provisioning No
??*
Food sources:
widely
scattered
No
Yes
transient
Not often
Often
diversified
Often
Yes
unpredictable Often
Often
sizeable
No
Sometimes
Ants
Bees
High
Yes
High
Yes
Yes
Yes
Yes
Yes
Usually
Often
Yes
Yes
Sometimes
Yes
Usually
No
Yes
No
Table 2
Comparison of recruitment-favoring factors in the niches
of primates and hymenoptera
*Dates of origin of these functions are still unknown,