Word Count: 7,842

Making Friends, Making Tools and Making Symbols

By Matt J. Rossano

What kind of mind immediately preceded the human mind? In decades past, it was assumed that the step from the nonhuman mind to the human mind was a qualitative one. The defining characteristics of the human mind such as language, episodic memory, recursion, mentalizing (theory of mind) were, by their very nature, dichotomous (Chomsky 1966: 78;

Povinelli 2000; Suddendorf and Corballis 1997). In other words, these mental traits were either present or absent with no intermediate states possible. Recent research, however, has questioned this assumption

(e.g. Clayton, Bussey, and Dickson 2003; Slocombe and Zuberbuhler

2006; Tomasello, Carpenter, Call, Behne, and Moll 2005).

Symbolic thinking has typically been grouped into this same category as another uniquely human and strictly dichotomous mental attribute. Studies with nonhuman primates, however, suggest that a rudimentary symbolic faculty may be present in them as well (Pollick and de Waal 2007; Slocombe and Zuberbuhler 2006). It seems reasonable to assume that our hominin ancestors built upon this rudimentary capacity, incrementally approaching the full-blown symbolism of Homo sapiens.

The current paper argues that symbolic thinking can be broken down into a series of progressive stages using the framework proposed by philosopher Charles Peirce. Evidence for the presence of these stages is observable in the archeological record. It is further proposed that the cognitive requirements for increasingly sophisticated tool-manufacture

1 and social cooperation were the key selective forces behind the evolution of symbolic thinking.

Incrementally Approaching Symbolism

In their book In Search of the Neanderthals, Stringer and Gamble

(1993:203) express a strictly dichotomous view of symbolism: “… arranging behaviour according to symbolic codes is an all or nothing situation. The onset of symbolic behaviour can be compared to the flick of a switch…” Symbolism is either there or not, no in-between. This attitude stands in contrast to those expressed recently by two other archeologists.

Bar-Yosef (2000:14) has characterized Late Mousterian hominins as possessing a ‘low level of symbolic behavior,’ while Wadley (2001:208) has suggested that image-making varies in its ‘symbolic complexity.’ The conflict between Stringer and Gamble’s view on the one hand, and Bar-Yosef and Wadley’s on the other, may be more apparent than real. It all turns critically on how one defines ‘symbolism.’

One of the most thorough examinations of semiotics (the study of signs and symbols) comes from American philosopher C. S. Peirce

(Peirce 1932[1960]; or see Hawkes 1932 for a good discussion). Peirce defined three levels of reference: iconic, indexical, and symbolic. Iconic referents are ones that bear a perceptual or physical resemblance to the things they signify, such as using a round pebble to represent a soccer ball. Indexical referents are ones that indicate (as the name implies) the presence of what they signify based on a temporal or spatial association.

For example, a weather vane indicates the wind (when the wind blows, the vane moves), tears indicate sadness, smoke indicates fire, etc. While both iconic and indexical referents can be thought of as ‘symbolic’ in the

2 sense that one thing is standing for another, Peirce reserves the term

‘symbol’ for only those occasions where the relationship between the signifier and the signified is purely arbitrary. For example, the ‘$’ is truly symbolic because its relationship to money is based solely on convention.

The $ does not resemble real currency (and therefore is not connected iconicly to its referent) and only rarely occurs in temporal or spatial proximity to currency (and therefore is not connected indexically to its referent). While these levels of reference are distinguishable, they are not necessarily mutually exclusive. A sign can sometimes overlap levels of reference. A smiley face looks like a smiling face, but can also indicate happiness or the intention of conveying a joke (as is the case with electronic messages).

The purely arbitrary nature of symbolic associations make them especially taxing to acquire. Deacon (1997:75-92) provides a detailed discussion of the hierarchical relationships among the different levels of reference. He shows how indexical referents are ‘built up’ from iconic ones and symbolic referents are ‘built up’ from indexical ones with each level placing increasing cognitive demands on the organism. Acquired symbolic reference is acutely memory-intensive:

To learn the first symbolic relationship requires holding a lot of

associations in mind at once while at the same time mentally

sampling the potential combinatorial patterns hidden in their

higher-order relationships. Even with a very small set of symbols

the number of possible combinations is immense, and so sorting

out which combinations work and which don’t requires sampling

3 and remembering a large number of possibilities (Deacon

1997:93).

Neuroscience studies confirm the notion that extensive ‘brain power’ is required for symbolic function. A broad network of neocortical structures is necessary for the acquisition of the purely arbitrary associations required when learning symbols (Asaad, Rainer, and Miller

1998; Chee, Sriram, Soon, and Lee 2000; Dimitrov et al. 1999; Eacott and Gaffan 1992; Murray, Bussey and Wise 2000; Savage et al. 2000).

These structures include the inferior temporal cortex, the dorsolateral prefrontal cortex, and the uncinate fascicles connecting the two.

Therefore, while we would expect icons and indices to precede symbols, we would not necessarily expect the move from one to the other to be inevitable, especially when going from indices to symbols.

Thus, if by ‘symbolism’ we mean strictly Peircian symbols

(arbitrary referents based on cultural convention) then Stringer and

Gamble may indeed be correct – this is something that either exists or doesn’t. Peircian symbols, however, do not emerge ex nihlio. Iconic and indexical referents provide the basis for their construction. Bar-Yosef’s

‘low level’ of symbolism and Wadley’s varying degrees of ‘symbolic complexity’ may reflect the presence of iconic and indexical reference systems in the archeological record. All of this raises the possibility that the human mind, with its full-blown capacity for (Peircian) symbolism, was preceded by hominin minds capable of lesser forms of referential thinking

(iconic and indexical). There is reason to suspect that this might be the case. Studies of both ape language learning and language development in humans show that they progress from an initial indexical phase to one

4 of symbolic understanding (see discussion in Deacon

1997:85-92,135-142). Thus, we might expect that the emergence of fully symbolic artifacts in the archeological record would be preceded by iconic and indexical ones, providing evidence for the existence of these pre- symbolic hominin minds.

Iconic Artifacts

Evidence of red ochre and other mineral pigments dates as far back as

300,000 years before present (ybp) in the hominin archeological record

(Barham 2002; Clark and Brown 2001; de Lumley 1969; Roebroeks

1986). Barham (2000; 2002), for example, has unearthed over 300 pieces of variously colored mineral pigments dated anywhere from 270,000 –

170,000 ybp from the Twin Rivers site in . The pigments appear to have been intentionally transported to the site from remote locations and show evidence deliberate modification. Though red ochre and other mineral pigments can have utilitarian uses (Bahn and Vertut 1988; Keeley

1978; 1980), evidence from many of these finds suggests ritual rather than practical use (Knight, Power, and Watts 1995; Watts 2002). Barham

(2002:187) notes that the wide variety of different pigments found at the

Twin Rivers site argues against purely practical use.

If mineral pigments had ritual meaning, then what was the most likely form that meaning took? Our hominin ancestors’ earliest use of pigments, according to Kuhn and Stiner (2007:46), was probably to enhance or alter physical appearance making the wearer more dramatic, impressive or intimidating – as is not uncommon in contemporary traditional societies. Using archeological and anthropological data, Knight,

Power, and Watts (1995) have proposed a somewhat different function

5 for early pigments, especially red ochre. In their view, red ochre would have signified menstrual blood and the fertility associated with it.

Common to both Kuhn and Stiner’s view and that of Knight et al., is that the pigment’s meaning would have been closely tied to perceptual appearance – either the appearance of the pigment itself (as blood) or the appearance of what it enhances (facial expressions, bodily contours, etc.). All of this suggests that where ritual use of mineral pigments appears likely from the archeological record, its reference value was iconic in nature. In other words, it stood for things by virtue of perceptual cuing. Given that iconic referents are the most basic, it is also not surprising that this is the first form of reference emerging in the archeological record.

Mineral pigment use may not be the only example of early iconicity in the archeological record. Though fraught with speculation and controversy, two of the earliest examples of what some researchers have called ‘art’ may also represent iconic referents. A three-million-year-old jasper cobble roughly resembling a human face was uncovered from a site near , . The nearest source for this item was ten kilometers from the recovery site, leaving open the possibility that it was intentionally transported presumably by a hominin who was intrigue by its anthropomorphic quality (Bednarik 1993; Dart 1974). A similar type artifact was found at Berekhat Ram in the Golan Heights. This was a

233,000 year old human-figure-shaped stone that showed evidence of intentional modification – possibly to enhance its anthropomorphic shape

(d'Errico and Nowell 2000; Marshak 1997). The singularity of these finds

6 warrants caution in their interpretation; however, if there is any meaning to them at all it would likely be iconic.

More recent examples of this can be found in the Neanderthal

‘mask’ found at La Roche-Cotard, and the bear head figure from

Tolbaga, Siberia, both dated to 35,000 ybp (Abramova 1995; Marquet and Lorblanchet 2003). The La Roche-Cotard ‘mask’ is a trapezoidal shaped piece of flint with a natural perforation that gives it a roughly human-face appearance. It shows evidence of having been modified to enhance its face-like qualities. The bear-head is a piece of woolly rhino vertebra whose natural qualities appear to have been intentionally modified creating a more detailed mouth and nose.

Finally, what appears to be a ritually-modified snake-rock was recently found in a in the Hills of (Minkel 2006).

Dated to around 70,000 ybp, the six-meter long rock seems to have been intentionally modified so that the ‘head’ and exterior surface make a more dramatically snake-like impression presumably for ritual activities within the cave. The ritualistic use of the artifact suggests that its meaning may have extended beyond its iconicity into something more purely symbolic.

That notwithstanding, it appears that an early phase of hominin image- making involved an attraction to and deliberate enhancement of naturally- occurring iconic objects.

Indexical Artifacts

Temporal or spatial association links indexical representations to what they signify. Beads and body adornments may fit the criterion as indexical referents. Until recently, the first evidence of body adornments were the

13 ostrich egg shell beads from Enkapune Ya Muto in dated to

7 about 40,000 ybp (Ambrose 1998). Recent finds, however, have pushed this date back considerably. Intentionally perforated shell beads dated to over 75,000 ybp were recently uncovered from in South

Africa (Henshilwood, et al. 2004), and even older shell beads

(100,000-135,000 ybp) were found among artifacts uncovered from the

Skhul site in and Oued Djebbana in (Vanhaeren, et al.

2006). Among contemporary !Kung hunter-gatherers, shell beads such as these are often used as gifts reinforcing reciprocal relations among different bands, called hxaro (Wiessner 1982). The fact that the Skhul and

Oued Djebbana sites are remote from the sea-shore origin of these shells supports the notion that they were transported there, possible by trade networks.

What made the shells valuable, however, was what they represented when worn. The beads from Blombos show evidence of having been strung together in a necklace or bracelet. Traces of red ochre were also found on the beads suggesting that they were either intentionally colored or that they picked up pigment from the wearer. In either case, it seems clear that the beads were intended as body decoration and that their meaningfulness came from their presence on the body. According to archeologist Clive Gamble, the emergence of art in prehistory was all about identity. “It [solved] the problem of who belonged where, and what roles a person had to fulfill in order to ensure groups and tribes could survive a tight, hard way of life” (quoted in

Stringer and McKie 1996:214). Wynn (1996:279), Wadley (2001:215), and Kuhn and Stiner (2007:46) have all commented similarly, contending that such things as lithic style and jewelry served as ‘indices’ of social

8 identity, family connections, and resource holdings. Recent studies of grave goods at Paleolithic and Mesolithic sites have offered empirical support for this view. Vanhaeren and d’Errico (see d’Errico et al 2003:52) found consistent differences in both the source materials and manufacturing style between roughly contemporaneous grave sites associated with different human groups. They interpret these differences as representing cultural markers differentiating one group from another.

It appears reasonable to assume that beads and other body ornaments indicated something about group membership or status (i.e. they were indexical referents). Certain beads might have identified one’s clan or tribe. Others might have indicated status within the tribe. In the context of hxaro (!Kung gift-giving alliances), an abundance of beads signals a rich network of friends and allies beholden to the wearer – a cautionary note to potential rivals. The fact that indexical referents are based on learned associations and not just perceptual resemblance means that they are more difficult to acquire compared to iconic referents.

Thus, it is not surprising that evidence of indexical referents (in the form of beads and other potential body adornments) emerges later in the archeological record compared to the first evidence iconic referents.

From Icon to Index: Reading Distant Signs

Levels of reference can at times overlap, and higher levels can be built upon lower ones. This provides a natural mechanism for the evolution of increasingly sophisticated systems of reference, such as when indexical referents are constructed from iconic ones. So while red ochre gains its referential value from its iconic relationship to blood and other naturally

9 occurring “rednesses”, its potential ambiguity provides a context for the construction of indexical referents (Humphrey 1984:152). The red of rage may be threatening, but the red of lips is attractive.

Disambiguating red’s message may have provided an early context where iconic referents were used to create indexical ones.

Imagine a ritual where red is displayed during the course of hunting actions (throwing, chasing, stabbing motions) versus during the course of a sensuous female dance. Or in a more naturalistic setting, consider the red drops of blood or red-stained tracks that would have provided welcome indicators of injured prey. Curiously, while nonhuman primates can utilize some indexical signs (e.g. facial expressions as indicating emotion/intent), they do not typically respond to tracks or other traces left by potential prey or predators as either positive or threatening indicators

(Cheney and Seyfarth 1991; Stanford 2007:99). It may be that that indicators such as tracks on the forest floor, unlike facial expressions, are simply too remote from their referent to allow for an easy connection.

Over time, our hominin ancestors were connecting perceptual cues with increasingly remote spatial and temporal events creating ever-more sophisticated indexical referents. The increasing complexities of hominin social life and tool manufacture very likely provided the selective context for moving the hominin mind from iconic thinking to unprecedented levels of indexical thinking.

Social Selection Pressures for Indexical Thinking

The earliest selection pressures for increasingly sophisticated indexical thinking were probably social. Nowell (this volume) discusses how life history factors changed dramatically among later H. erectus as infants

10 were born in an increasingly altricial state and childhoods were extended.

The necessity of some degree of male provisioning seems irresistible in this species. Deacon (1997:387-393), however, cautions that male provisioning in the mixed-sex, multiple-breeding social context of H. erectus is highly precarious.

Male provisioning is evolutionarily difficult to sustain in group-living contexts where offspring paternity is uncertain (Deacon 1997:387-393).

Among nonhuman primates, male provisioning or protection is found among pair-bonded species such as gibbons or owl monkeys, or in harem species such as gorillas. However, isolated pairs or single male harems seem highly unlikely among H. erectus. Instead, this species was most likely a multi-male, multi-female group-living species comparable to chimpanzees or bonobos (Foley and Lee 1989; Nowell, this volume).

Males among these species are largely indifferent to infants and juveniles. Even among social carnivores such as wolves a strict breeding hierarchy provides males some certainty that the offspring they are provisioning are, in fact, genetically related to them.

So how then could paternity be assured in a mixed-sex, multiple- breeding context such that offspring provisioning might be selectively advantageous to H. erectus males? Deacon’s (1997:393-401) solution to this is a novel one, and not without controversy: pair-bonding rituals that unambiguously and publically signaled who was mating with whom.

Whether H. erectus invented marriage ceremonies or not is debatable, however, it does not seem unreasonable to propose that this species was under strong selection pressure to read more remotely displaced signs related to mate value. For males, these would have been signs of future

11 sexual fidelity (e.g. an avoidance of males, blushing, a disinterest in matters sexual). For females, these would have been signs of resource acquisition ability (e.g. tool-making skill, hunting prowess, a generalized industriousness) and a willingness to share (e.g. generosity, good with kids). Note well how all these signs would have been in reference to behaviors far displaced into the future.

Tool Making and Indexical Thinking

If the social pressures cited above became especially acute among later erectus (say about 1mybp—.5mybp), then they would have only slightly preceded convergent pressures associated with tool-making. As both

Wadley (this volume) and Ambrose (2001; this volume) have pointed out, composite tool manufacture – which may extend as far back as 300,000 ybp (Ambrose 2001; McBrearty and Tryon 2006) – makes special demands on the cognitive system. Composite tools are those requiring multiple components (such as a point, hafted to a handle or shaft using some binding material or adhesive), which are assembled using a multi- stage process sometimes extending over hours or days (see Wadley this volume). The assembly process requires planning a sequence of motor actions and monitoring the progress of each stage (Ambrose 2001; Haidle this volume; Wadley this volume). A distinct advantage would have gone to those tool-makers who could read signs emerging during the course of the assembly process indicating the future viability of the tool. The viscosity of the adhesive, the feel of the point’s fit to the shaft, or the sturdiness of the binding material may all have provided key indicators of the progress of the ongoing tool-construction process. If properly understood, these signs may have allowed for critical adjustments in the

12 process leading to a better tool. Once again, note how all these signs would have been in reference to a distant event – the future state of the tool.

Though more controversial, handaxe manufacture may also have contributed importantly to the evolution of indexical thinking. Some late

Acheulean handaxes (around 500,000 ybp) show a degree of symmetry and attention to form that may represent an important cognitive advance

(Donald 1999; Mithen 2006:188; Suddendorf 1999; Wynn 1981). There are also some recent studies suggesting that the late Acheulean handaxe was not an easy tool to make, requiring a high degree of skill, motor control, brute strength and bravery (Bril, Roux, and Dietrich 2005;

Edwards 2001; Roux and David 2005; Shick and Toth 1993:237; Stout

2005; Winton 2005). This claim is not without challenge, however, as other studies have indicated that the final form of the handaxe may be fully and more parsimoniously explained as the result of resource availability and multiple resharpenings over the course of the tool’s history

(Jones 1979; McPherron 2000). That claim notwithstanding, Kohn and

Mithen (1999) have argued that handaxes may have served an important function in mate selection as an indicator of planning ability, motor skill, resourcefulness, aesthetic appreciation, and over-all good genes. The handaxe may have been one of a number of display signals that late erectus females used in judging male mate quality as pair-bonding and offspring resourcing pressures were intensifying.

This line of argument leads to the hypothesis that social factors and increasingly demanding tool construction served as important mechanisms for moving the hominin mind from iconic to indexical

13 reference. Since these factors would have been present prior to the emergence of anatomically modern humans, this hypothesis predicts that evidence of indexical reference should be present in Neanderthals and other archaic species. The degree of continuity in the archeological remains for the Levantine Middle and Upper Paleolithic (see Belfer-Cohen and Hovers this volume) supports the presence of a common indexical reference ability across archaic and modern hominins. Furthermore, evidence of beads and other body ornaments that could be considered indexical have been found among Neanderthals (d’Errico, et al 1998;

Zilhao and d’Errico 1999). However, the rarity of this evidence relative to that for anatomically modern humans suggests that there were unique selection pressures on this species that pushed indexical thinking further in them compared to others, laying the foundation for symbol use. As will be seen shortly, I will suggest that these unique pressures were located in the increasing complexities of Homo sapiens’ social life, such as expanded trade networks and the social rituals used to establish inter- group alliances and maintain intra-group stability.

The Emergence of Symbolism

The elaborate burials, spectacular cave art, and highly imaginative figurines from the Upper Paleolithic stand as singular achievements of modern Homo sapiens. While Upper Paleolithic art contains iconic and indexical elements, some of it also appears to be purely culturally defined

(i.e. symbolic). Such items as the sorcerer image of Les Trois-Freres cave, the lion-headed man from Holenstein-Stadel, the circles, spirals, and other geometric forms found in Australian , and the numerous mythic and therianthropic images of European cave art appear to possess

14 arbitrary elements that may only be completely understandable from within the cultural context of their creation.

The move from index to symbol, however, is exceptionally difficult placing enormous demands on memory capacity. Unlike iconic and indexical signs, whose meanings are cued by appearance or spatial/temporal associations, symbols are entirely arbitrary with little or no cuing support. Deacon (1997:264) comments directly on this point when he says that symbol acquisition “requires a predisposition for working with difficult conditional associative relationships, maintaining items in working memory under highly distractive conditions.” An important part of these “distractive conditions” is that the symbol’s perceptual appearance and temporal/spatial associations not only do not support its meaning, but often interfere with it. Again, consider the $ sign, which neither looks like nor typically appears with real currency.

Building on the ideas of Richard Klein (Klein 1995; Klein and

Edgar 2002), Coolidge and Wynn (2005; Wynn and Coolidge 2004) have argued that distinctively human cognition resulted from a fortuitous genetic mutation that enhanced working memory capacity. This enhancement made anatomically modern humans more capable of sustaining attention on an ongoing task in the face of competing external or internal signals. Given the memory demands of symbolic reference this hypothesis seems not only reasonable but quite likely necessary in explaining the move from index to symbol. However, random ‘good fortune’ may not be the sole origin of this mutation. Positive selection pressures for working-memory-enhancement may have been present in the unique demands of Homo sapiens’ social life.

15 Trade Networks and Social Cognition

That social pressure might be critical in brain and cognitive evolution is becoming an increasingly prominent theme among those who study human evolution (Alexander 1989; Byrne and Whiten 1997; Dunbar 1996;

Geary 2005). Those of our ancestors who were best able to track social relationships, build strategic alliances, and make critical judgments about intentions and trustworthiness, very likely gained a fitness advantage.

These social demands undoubtedly strained cognitive resources. A recent study directly linking social engagement with enhanced cognitive performance and working memory capacity supports this contention

(Ybarra, et al 2008). This study found that survey measures of social interaction served as reliable positive predictors of cognitive performance.

Furthermore, ten minutes of social interaction (discussion of a controversial social issue) was as effective as engaging in non-relational intellectual activity (e.g reading for comprehension, mental rotation tasks, crossword puzzle solving) in boosting performance on both speed of processing and working memory tasks. This suggests that social engagement alone activates cognitive systems associated with working memory producing performance enhancements. These cognitive systems came under increasing pressure as the Homo sapiens’ social world expanded and complexified.

Archeological evidence from southern and eastern Africa indicates the emergence of expanded trade networks around 70,000 ybp among our Homo sapiens ancestors. The ‘precocious’ Howiesons Poort and Mumba industries which emerge around this time feature fine- grained, non-local, microlithic artifacts. The non-local origin of these

16 artifacts suggests more extensive trade among local populations

(Ambrose 2002; this volume). Ecological degradation, possibly associated with the massive Toba eruption (around 73,000 ypb) may have compelled human groups to established more far-reaching trade networks in an effort to more effectively utilize dwindling, more highly scattered resources.

While the evidence of fine-grained, non-local microliths declines over the ensuing millennia, in certain regions evidence of ostrich eggshell beads emerges. In some locales then, trade networks did not wither but instead adopted a new medium of exchange. Evidence of similarly extensive trade networks can be found among Upper Paleolithic humans, but significantly, is lacking among archaic hominins (Feblot-Augustins

1999; Gamble 1999; Soffer 1985). A recent comparison of Cro-Magnon and Neanderthal hunting strategies in Eastern Europe has reinforced this point, finding that while hunting tactics did not substantially differ, Cro-

Magnons often enjoyed greater access to resources due to more extensive social networks (Adler et al. 2006).

Unlike their archaic counterparts, our ancestors expanded their social realm to include less familiar but strategically important trading partners and alliance members. This taxed their mental resources in a number of important ways. First, it increased the frequency of novel, less predictable social/cognitive engagements. Recent neuroscience evidence indicates that novel, unpredictable cognitive tasks produce increased activity in brain areas associated with working memory (regions of the prefrontal and parietal lobe) resulting in increases in working memory capacity (Olesen, Westerberg, and Klingberg 2004).

17 Second, it forced them to understand levels of ‘value’ beyond just the utilitarian or practical. Cementing reciprocal trade alliances with gifts require that one understand the value of such gifts. Fine grained microliths made from ‘exotic’ materials must be understood to be ‘special’ tools carrying value by virtue of their look, shape, and composition – otherwise they will likely fail as a vehicle of social bonding. Having no utilitarian function at all, ornamental beads as gifts require even greater mental abstraction. One must understand that a functionless gift is actually more valuable than a functional one because the functionless gift expresses affection for who one is rather than what one does (Ambrose

2002:20).

Third, expanded trade networks place increasing cognitive demands on communicative skills. Ambrose (this volume) argues that direct, declarative speech forms (e.g. commands) may work well within a hierarchically arranged group. However, this form of communication does not foster trust or facilitated alliance-building between groups. Instead, inter-group suspicions are far better allayed using a more nuanced, indirect form of speech – diplomatic speech. Those groups and group leaders best able to couch their communicative efforts in terms most likely to build trust and persuade neighbors would have had an advantage over their more direct, plain-spoken competitors.

Finally, and most importantly, the increasingly complex social world of Homo sapiens put pressure on ritual behavior. While trust- building diplomatic communication probably did involve changes in spoken language, it was by no means restricted to this. Across the animal kingdom, where careful communication is a necessity, ritualized behavior

18 is typically the solution (de Waal 1990; Guthrie 2005:68; Silk 2001). Thus, there is good reason to suspect that ritual behavior was under strong selection pressure during this period as well, both as a mechanism for establishing inter-group alliances and in maintaining intra-group solidarity.

Ritual Healing and Enhanced Working Memory

The Homo sapiens who survived the degraded ecological conditions affecting Africa about 70,000 ybp, did so by advancing their social sophistication. As their social worlds complexified, ritual behavior became increasingly critical as a mechanism for establishing between-group trading alliances as well as maintaining within-group stability. Ritualized, rhythmically coordinated actions such as marching, dancing and chanting together can be effective social bonding mechanisms (Donald 1991;

Frecska and Kulcsar 1989; McNeill 1995). Under the stress of resource scarcity, those groups with the most effective intra- and inter-group rituals of social bonding were very likely selectively favored over less-ritually capable groups. Ritual behavior, though, goes even deeper than this when comes to potential selective advantage.

Along with social boding effects, group-coordinated ritual actions can have equally powerful healing effects (e.g. Mithen 2006:95-101,151,

235-236). Group rituals involving repetitive rhythmic activities can induce a health-enhancing altered state of consciousness, an essential element of traditional healing practices (Katz 1982). These healing practices have been found to be especially effective for a range of maladies where psychological factors are involved such as chronic pain, burns, bleeding, headaches, skin disorders, gastrointestinal disorders, and the discomforts and complications of childbirth (McClenon 2002).

19 McClenon (2002) and Rossano (2007) have argued that ritual healing was an important selective force in our evolutionary past. Those of ancestors whose minds were most capable of focusing attention so as to induce a health-enhancing altered state of consciousness may very well have had a selective advantage in overcoming injury, disease, and the rigors of childbirth. Furthermore, those parts of the brain important for working memory (e.g. dorosolateral prefrontal cortex and anterior cingulate cortex) are also the ones activated during ritual healing practices. Recent findings indicate that common meditative practices such as focusing attention on breathing and non-reactive awareness of external signals can actually expand attentional control capacities

(Slagter, et al. 2007). This finding suggests that working memory and cognitive control capacities are not just activated by ritual/meditative practices, but enhanced as well.

Those of our ancestors with the most ritually-capable brains were very likely the ones who reaped the greatest health benefits from community healing rituals. Thus, ritual behavior itself may have been a critical aspect of the environment that selected for enhanced working memory capacity. This means that Baldwinian mechanisms may have been at work in human cognitive evolution. The Baldwin effect – where somatic adaptation provides a pathway for genetic adaptation – may have heightened the probability of a memory-enhancing mutation in human populations that regularly practiced forms of ritual healing. If community- based rituals of social bonding and personal healing were more characteristic of anatomically modern human groups compared to archaic

20 hominins, it might explain why this mutation arose in Homo sapiens sapiens and not in other species.

A Hypothesis About Timing: The Gregarious Inherit the Earth

Recent studies offer a potential hypothesis regarding the time frame when unique social pressures involving trading networks and community rituals emerged as significant forces in human evolution. Sometime after

100,000 ybp, increasingly cold conditions and advancing Neanderthals chased anatomically modern humans from the Levant. Not long after this

(around 70,000 ybp), there is evidence of both a population bottleneck associated with ecological degradation and a dramatic (relative) population expansion among certain anatomically modern populations in

Africa (Mellars 2006). These populations expanded precipitously across

Africa replacing or absorbing other resident groups, prior to embarking on a global expansion. Ecological degradation forced anatomically modern humans to expand their social networks in order to more effectively utilize scarce and scattered resources. Most human groups failed this test

(hence the bottleneck), but the most socially adroit did not, and their numbers expanded sharply (hence the relative population expansion).

Thus, after their initial retreat from the Levant, a more socially sophisticated strain of Homo sapiens sapiens emerged from Africa and marched across the world. Based on the evidence reviewed in this paper,

I would offer the hypothesis that it was during this critical ‘interim’ period in Africa that trading networks and ritual behavior created the social conditions for the spread of the enhanced-working-memory mutation in the population.

Summary

21 Perhaps as far back as three million years ago, but certainly by 300,000 ybp, hominins were especially intrigued by natural minerals and objects whose perceptual qualities reminded them of particularly significant aspects of their environment such as blood and faces. Their efforts to enhance and reproduce these naturally occurring objects resulted in the creation of the first iconic reference systems. Over time, they elaborated the meanings of these iconic referents by tying them temporally and/or spatially to other important actions or events, creating simple indexical referents. The increasing complexities of social life and tool manufacture created the conditions for ever-more sophisticated indexical systems whose referents were displaced broadly in time and space. While the move from icon to index placed additional demands on the hominin cognitive system, associative cuing helped support the transition. The move from index to symbol, however, had no such cuing support and more than likely required an enhancement of working memory capacity.

This enhancement was probably facilitated by the unique social conditions of Homo sapiens sapiens after 100,000 ybp.

Creating effective long-range trading networks, often by using inter- and intra-group rituals of social bonding put powerful selection pressures on hominin cognitive and working memory capacity. Moreover, these rituals provided a selective health advantage to those with greater working memory and attentional abilities. The enhancement of working memory necessary for symbolism emerged out of this social context where greater brain power produced a fitness advantage through better groups, more trade, and better health. The critical time period for this

22 process was probably some time after 100,000 ybp and before 60,000 ybp.

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