The social trackways theory (for full introduction see my previous article on the topic in Biological Theory) is centered on the remarkable 3.66 mya Laetoli Fossilized Trackways, for they incontrovertibly reveal our ancestors were already obligate bipeds with very human-like feet, and were intentionally stepping in other band members’ footprints to maintain safe footing. Trackways are unique among natural sign systems in possessing a depictive narratively generative structure, somewhat like the symbolic sign systems of gestural languages. Therefore, due to daily embodied reiteration of their own and other band member’s old footprints, both for bipedal safety and as recognizable wayfinding markers for socio-ecological navigation, incrementally our Mid-Pliocene ancestors began to acquire a cognitive capacity for episodic personal memories and episodic future simulations. They began mentally representing themselves (and others) as intentional agents continuously travelling from the past into the future. This spatially and temporally self-projecting awareness manifested itself as extra theory of mind and mental space-and-time-travel capacities, which increasingly enabled intentional or conscious, top-down executive adjustment of past behaviors for the sake of achieving better ways of doing things in the future. Future-directed behavioral and cultural adaptations began to increase fitness in all domains, thus creating powerful selective feedback for further entrenchment. Here we focus on overtly or consciously intentional exploratory wayfinding and transmission of elsewhere-and-when information, using pragmatic, discursive modes of communication, which enabled far more cooperative and efficient foraging practices. Selection for better communication thus led to intentional trail marking and the earliest emergence of more conventional/symbolic depictive and gestural “protolanguages.”
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Alternatively, some theorists like Richard Moore (2016) claim no cognitive shift past the ape mind-set was needed, so an incipient gestural protolanguage (or another cultural shift like more complex toolmaking and/or foraging skill) does the selective triggering, backed by some environmental change. I am extremely skeptical, and only partly because the question of why no other great ape lineages (all of which make simple tools and can communicate with flexibly used gestures) attained language readiness remains unanswered by all these models. My other reasons are empirically based, and presented herein.
I use this term deliberately, rather than just “mental time travel,” because it is of course perfectly possible to imagine one’s self in a different space in the here-and-now; for example, we do this continually when we are orienteering, as will be explained later in this paper.
This autobiographical/narrative self-reflective awareness or consciousness was called “autonoesis” many years ago by Edmund Tulving, who more recently stated (2005) it was the key to all “higher” human cognitive capacities for creating cumulative culture. It is based on mental time travel, incorporating “nested scenarios” of who-what-where-when episodic memories and episodic future simulations or prospections in the “theatre of the mind” (Suddendorf and Corballis 2007).
Canines were highly reduced in both sexes, but like their big flat molars with hyper-thick enamel, this was an adaptation allowing grinding motions of their powerful jaws when masticating tough sedge rhizomes.
Recently reviewed evidence consisting of an australopithecine-type portion of jaw and molars discovered in East Africa in the 1970s has confirmed a date of 5.9–5.5 mya (Kissel and Hawks 2015), and large apes with similarly megadont characteristics were present in East Africa (Chororapithecus) around 10 mya and in Southeast Europe (Ouranopithecus/Graecopithecus) between 9.6 and 7.1 mya.
Sahelanthropus tchadensis (7.2–6.8 mya); Orrorin tugensis (6.0–5.7 mya); Ardipithecus kadabba (6.4–5.5 mya); and Ardipithecus ramidus (4.4 mya): they were habitually bipedal, with progressively reducing canines and more sexually monomorphic body size, and possessed omnivorous Homo-like molars.
Support for the “Waterside Ape” theory is now becoming a tidal wave of paradigmatic change, in the opinion of Sir David Attenborough (BBC Radio 4, September 2016, “The Waterside Ape”: two-part audio series).
Large crocodiles would always be a worry in more extensive waterways, but they hunt mostly at night, and like all reptiles do not need to eat very often, compared to warm-blooded mammalian predators.
In fact, Orrorin tugensis possessed the most human-like hominin thumb ever found.
Recent work indicates bonobos are less derived than chimpanzees from the 8 mya Pan/Homo LCA (last common ancestor) (Diogo et al. 2017). This explains why they are more socially tolerant, and lends support to my alloparenting LCA theory.
And their tails are much longer; those species that have remained less derived, more terrestrial omnivorous foragers in more open environments around upland watersheds (Tibetan and stump-tailed macaques) remain relatively tailless and have retained their alloparenting sociality.
Towards the end of the rainy season hordes of catfish move onto seasonal floodplains to spawn; as the dry season commences they become trapped in small ponds and shrinking river-pools. Like salmon in Western North America, they provide essential saturated (Omega 3) fats and protein for all carnivores and omnivores.
Their post-cranial elements also look very early, perhaps even earlier than habilis (Peter Hiscock, personal communication, June 2017).
Many SET theorists have claimed they do not, thus maintaining their “afarensis was our direct ancestor” narrative.
Extreme polar glaciation has often been triggered by massive volcanic events, and of course has much delayed but far more long-lasting climactic consequences.
There are several ethnographic reports of trackers’ comments on how easy it is to recognize human bipedal trackways (e.g., Silberbauer 1981). Recently a few paces worth of footprints was found to be recognizable by computers to 99.8% accuracy, so the way we walk is as unique to us as our fingerprints (Pataky et al. 2012).
It is important to remember here that stone-flake technology remained extremely simple for a million years after its first appearance, with the only difference being that in the beginning they were made using other stones as anvils, rather than through free-handed knapping. After Acheulian hand-axe technology kicked in around 1.7 mya, there was a further hiatus of a million years. It was more co-operative foraging, better reading of signs and routine behaviors of prey animals, more efficient communication, and increasing encephalization for neural storage of this knowledge that made erectus the most successful, eusocial predators on the planet.
Here I use consciously rather than overtly because the orienteering cognitive process is usually introspective—of course when two or more people are travelling together, they may speak out loud, that is, their cooperative orienteering becomes overtly intentional, or ostensive.
African locals still do this to attract catfish and eels within spearing range.
There are many ethnographic examples of using highly informative whistled communication, and/or the use of mimetic bird calls, for coordinating individual activities during cooperative hunting excursions.
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Earlier drafts of this article were written while I was fully supported by a PhD Research Scholarship from the Australian National University. Many thanks to my present and earlier supervisors Kim Sterelny, Peter Hiscock, Ben Jeffares, Brett Calcott, and Russell Gray; my past and present fellow students, especially Adrian Currie and Anton Killin; my walking/sounding-board friend Antek Skotnicki, and my computer-guru friend John Mills in Lyneham, Canberra; my oldest/longest-suffering nonacademic friends—and, of course, my family—for, let’s face it, their extreme patience, combined with discerning yet always encouraging critiques and/or pragmatic/emotional support. I am also very grateful to friends Ben Frazer and Kirsty Douglas for harboring my old camper van on their property whenever I am not using it as temporary accommodation in Canberra.
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Shaw-Williams, K. The Social Trackways Theory of the Evolution of Language. Biol Theory 12, 195–210 (2017). https://doi.org/10.1007/s13752-017-0278-2
- Agential self
- Evolution of language
- Extra theory of mind
- Mental space and time travel
- Observational self
- Pragmatic discourse