Common misconceptions and unproven assumptions about the aquatic ape theory
A Guest Post by Marc Verhaegen
It is often assumed that Alister Hardy’s and Elaine Morgan’s aquatic ape theory (AAT) suggests that more than 5 Ma (million years ago) there was a semi-aquatic phase in our past (explaining e.g. human fur loss, fatness and upright bipedalism), which was followed by a savanna phase on the African plains. In 2011, AAT proponents published an eBook, Was Man more aquatic in the past?, which showed a rather different picture of AAT. Here I very briefly describe my view of ape and human evolution (for details and references, see my publications at the end of this article).
The Homo-Pan last common ancestor (LCA)
My 1994 paper concluded:
… insofar as the fragmentary fossil material and the incomplete comparisons with extant apes allow, ontogenetic and morphological evidence tends to favour the hypothesis that the LCA of Homo and Pan 8–4 Ma was a partially bipedal, gracile australopith with chiefly a mosaic of human and chimpanzee (especially bonobo) features: low sexual dimorphism, minimal prognathism, slightly enlarged canines, non-protruding nasal skeleton, smooth ectocranium without crests, “small” brain with ape-like sulcal pattern, relatively non-flexed basicranium, intermediate position of foramen magnum, “short” forelimbs without knuckle-walking features, low ilia, (very) long femoral necks, “short” legs, (very) valgus knees, full plantigrady, longer and not very abductable halluces …
This conclusion is still correct (except that I would now replace ‘partially bipedal’ by ‘vertical’ or ‘orthograde’). Most paleo-anthropologists now agree that the LCA differed from both humans and chimps today: both lineages acquired evolutionary innovations. Chimps got longer and stronger arms and fingers, much longer iliac blades, a narrower pelvis and shorter femoral necks, more grasping big toes, knuckle-walking etc. Humans got an external nose, a much larger brain, longer and straighter legs etc.
Mio-Pliocene hominoids: aquarboreal?
During the Miocene (23–5.3 Ma) and Pliocene (5.3–2.6 Ma), the early ‘apes’ were quite diverse, but their fossils (e.g. Helio-, Gripho-, Dryo-, Oreopithecus, Lufengpithecus, Sahelanthropus, Orrorin, Ardi-, Australopithecus) were typically found in coastal, flooded or gallery forests, lagoons or wetlands, where they – like lowland gorillas who feed on floating vegetation in the swamp or bai today, but much more frequently – could have eaten aquatic herbs, sedges or papyrus, eggs, crabs, snails and bivalves between reeds or mangroves etc. Such lifestyles – climbing and hanging vertically, grasping branches above the water, wading on two legs, floating vertically collecting floating vegetation etc. – help explain hominoid (ape and human) body enlargement, tail loss, vertical spine, dorsal shoulder blades, and wide thorax and pelvis.
All great apes in the wild are regularly or occasionally seen in the water, but possibly the Pleistocene coolings (Ice Ages 2.6–0.01 Ma) caused the ape ancestors to spend less time in the water, the different ape species to different degrees. Apparently, gibbons kept the vertical body but became smaller arm-swingers in the higher canopy, orangutans elaborated a suspensory lifestyle lower in the canopy, and chimp and gorilla ancestors in parallel reduced their vertical postures to knuckle-walk quadrupedally on the drier forest floor.
In my view, the Homo-Pan LCA ~5 Ma, like all or most fossil hominoids (including the australopiths), was still what Marcel Williams called aquarboreal (aqua=water, arbor=tree). In australopiths, aquarborealism can explain the remarkable combination of curved hand phalanges (branch-hanging), a vertical spine, and flat feet and footprints (wading, swimming): Pliocene australopiths were typically found in swamp and gallery forests, and Pleistocene robust australopiths in more open wetlands, papyrus swamps or lagoons (how the different habilis fossils lived is less clear, some ex-aquarboreal, others ex-littoral?).
Archaic Homo: littoral diving?
If the Homo-Pan LCA lived in African littoral forests along the Indian Ocean or the Red Sea, this could explain the archaic Homo finds ~1.8 Ma as far as Java (Mojokerto, amid barnacles and shells), Georgia (Dmanisi, amid ‘rich lacustrine resources’ near the Black-Capsian Sea connection then), Algeria (Aïn-Hanech floodplain) and the African Rift (erectus appeared at Lake Turkana together with stingrays, suggesting a marine connection then).
Sea-levels repeatedly dropped more than 100 m during Glacials, and on the continental shelves, vast territories – presumably tree-poor and shellfish-rich – became available for intelligent, dextrous, tool-using, coastal forest-dwelling hominoids, who could open mangrove oysters (like capuchin monkeys do) and coconuts (containing fresh water) and beach-comb for turtles and their eggs, mussels and crabs. An extensive overview of the literature by Stephen Munro showed that virtually all known archaic Homo sites (including those in ‘savanna’) were associated with permanent water and edible shellfish, and we can expect that these handy beach-combers on their diapsora to different continents and islands learnt to dip and later dive, gradually deeper, for bivalves, abalone and perhaps seaweeds.
In fact, only regular diving can explain archaic Homo’s pachy-osteo-sclerosis (POS), the extreme thickness and density of cranial and postcranial bones of most erectus-like fossils. In modern humans, such hyper-mineralisation causes brittleness and multiple fractures (osteopetrosis), and POS is only seen in slow littoral divers, e.g. dugong and manatee, walrus, Kolponomos, pakicetids, Odobenocetops, and Thalassocnus spp. Marine biologists agree POS has a hydrostatical function (ballast) – Homo erectus was no exception!
Littoral diving most parsimoniously explains many other features seen in Homo – fossil (e.g. ear exostoses, protruding nasals and mid-face, platycephaly, flattened femora, brain size) and living (e.g. fur loss, SC fat, head–spine–legs in one line, in human newborns vernix caseosa and reniculi). The abundant brain-specific nutrients in aquatic foods (e.g. DHA, iodine) facilitated fast brain growth (sapiens’ poorer post-aquatic diet required a longer youth to grow the same brain size).
From the coasts and estuaries, different Homo populations gradually – at first seasonally, later also permanently – ventured inland along rivers. Neandertals generally have less POS than erectus, their fossils often lay just above those of beavers, and some of their tools bear traces of cattails, so perhaps they hunted or scavenged ungulates amid reeds, but at the coast they still collected shellfish and butchered whales and seals (e.g. Gibraltar).
Homo sapiens: from wading to walking?
Gracile skulls (i.e. loss of POS) of H. sapiens appeared at Omo and Herto in East Africa less than 0.2 Ma, and humans got straighter legs and longer tibias, shorter and more vertical femoral necks, a narrower pelvis, and very long and more vertical spinous processes of the mid-thoracal vertebrae (strengthening the spine in an upright stance?), which suggests our ancestors ~0.2 Ma abandoned regular diving, but often waded vertically on two legs, possibly to better see fishes swimming and spear them from above. They might have slept in reed houses above the water (safer from predators), used reed boats, dugouts, and nets, and spent more and more time outside the water. Maps of human population densities show that, although we have become fully terrestrial today, we are still a waterside species, and almost half of human dietary calories still come from the water (e.g. rice, aquaculture, fish, shell- and crayfish).
The nowadays popular endurance running ideas (e.g. ‘dogged pursuit of swifter animals’, ‘born to run’, ‘le singe coureur’, ‘Savannahstan’) are no doubt among the worst hypotheses ever proposed. In 1987, in Nature, I wrote:
… it is highly unlikely that hominid ancestors ever lived in the savannas. Man is the opposite of a savanna inhabitant. Humans lack sun-reflecting fur, but have thermo-insulative subcutaneous fat layers, which are never seen in savanna mammals. We have a water- and sodium-wasting cooling system of abundant sweat glands, totally unfit for a dry environment. Our maximal urine concentration is much too low for a savanna-dwelling mammal. We need much more water than other primates, and have to drink more often than savanna inhabitants, yet we cannot drink large quantities at a time …
Apparently we evolved running – only lately, and only about half as fast as horses or dogs – in spite of our plantigrade feet, broad build, profuse sweating, and our large fat tissues (~10 % of body weight in lean persons, ~10 times more than in chimps). Of course, there exist a few inland populations in East Africa today where adult men running after ungulates sometimes provide a limited part of the calories, but this dogged pursuit is probably very recent and derived, and it requires a considerable technology (e.g. water bags, weapons, poisons). Quadrupedal chimps can hunt colobus monkeys and even eat them raw, but archaic Homo with their heavy bones (POS), very broad pelvis, shorter legs and flat feet were much too slow on land. In fact, our small mouth, spatulated canines and closed tooth-row, short tongue and smoothly vaulted palate are ill-designed for meat eating, but ideal for consumption of slippery foods.
Unproven assumptions about AAT
My scenario makes clear that, in my opinion, AAT is
- less about becoming aquatically adapted by gradually wading deeper and deeper, than about aquarboreal hominids in densely vegetated swamp or mangrove forests descending into the water below the trees,
not about why Homo and Pan split, but about what happened after the split, not about ‘aquatic apes’ or even australopiths, but about archaic Homo (erectus more than Neandertals), and not about what happened 10 or 5 Ma, but rather about what happened less than 2 Ma, during the Ice Ages, when Homo populations spread along the coasts to England, the Cape and Flores,
less about how modern humans behave in water than about erectus’ differences with us (in my 1996 paper, the data show that erectus differed from sapiens almost as much as it did from A. africanus),
less about bipedalism or even bipedal wading (except <200 ka) than about slow and shallow diving, and not about surface-swimming (as in most Mio-Pliocene hominoids?), but about bottom-diving (where Homo’s food was),
less about what happened in Africa or even the Rift Valley than about what happened on the Indian Ocean or Mediterranean shores, and less about out of or into Africa or Asia scenarios than about coastal diaspora (e.g. on both the African and the Asian side of the Red Sea),
less about a riverine evolution in fresh-water than about a coastal (and perhaps later also riverine) life,
not in the first place about an isolated evolution on Danakil or another island, but about a littoral and estuarine life on African and Eurasian coasts (presumably including islands) during most of the Pleistocene,
not about anthropocentric views, including just-so explanations for ‘unique’ human features (e.g. bipedalism ‘for’ wading, SC fat ‘for’ surface swimming), but about a comparative analysis of our features (e.g. the combination bipedalism + vertical spine is only seen in humans and penguins on land),
not about sudden mutations, saltations or evolutionary jumps from ape- to human-like, but about a gradual mosaic-like evolution in small steps (horizontal arboreal > above-branch aquarboreal > below-branch vertical aquarboreal > littoral > vertical wading > bipedal walking),
and even less about the hominid fossil record than about our embryological, anatomical and physiological ‘scars of evolution’ (Elaine Morgan): ‘the remnants of the past that don’t make sense in present terms – the useless, the odd, the peculiar, the incongruous – are the signs of history’ (Stephen Gould).
In brief, instead of the ‘old’ AAT, I propose:
(1) an aquarboreal theory of Mio-Pliocene hominoids, including australopiths,
(2) a littoral theory of Pleistocene Homo.
Publications on ape and human evolution
- The aquatic ape theory: evidence and a possible scenario. 1985 Med Hypoth 16:17–32
- The aquatic ape theory and some common diseases. 1987 Med Hypoth 24:293–9
- Origin of hominid bipedalism. 1987 Nature 325:305–6
- Aquatic ape theory and speech origins: a hypothesis. 1988 Specul Sci Technol 11:165–171
- African ape ancestry. 1990 Hum Evol 5:295–7
- Aquatic ape theory and fossil hominids. 1991 Med Hypoth 35:108–114
- Aquatic features in fossil hominids? 1991 in Roede ed.:75–112
- Human regulation of body temperature and water balance. 1991 id.:182–192
- Did robust australopithecines partly feed on hard parts of Gramineae? 1992 Hum Evol 7:63–64
- Aquatic versus savanna: comparative and paleo-environmental evidence. 1993 Nutr Health 9:165–191
- Australopithecines: ancestors of the African apes? 1994 Hum Evol 9:121–139
- Aquatic ape theory, the brain cortex, and language origins. 1995 ReVision 18:34–38
- Morphological distance between australopithecine, human and ape skulls. 1996 Hum Evol 11:35–41
- Sweaty humans. 1997 New Scientist 2091:53
- In den Beginne was het Water – Nieuwste Inzichten in de Evolutie van de Mens. 1997 Hadewijch Antwerp
- Oi, big nose!. 2010 New Scientist 2782:69
With Stephen Munro, Pierre-François Puech and/or Mario Vaneechoutte:
- Bipeds, tools and speech. 1999 Mother Tongue 5:161–8
- Hominid lifestyle and diet reconsidered: paleo-environmental and comparative data. 2000 Hum Evol 15:175–186
- The continental shelf hypothesis. 2002 Nutr Health 16:25–27
- Aquarboreal ancestors? 2002 TREE – Trends Ecol Evol 17:212–7
- Possible preadaptations to speech – a preliminary comparative approach. 2004 Hum Evol 19:53–70
- New directions in palaeoanthropology. 2007 in Muñoz ed.:1–4
- The original econiche of the genus Homo: open plain or waterside? 2007 id.:155–186
- Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods. 2011 HOMO – J compar hum Biol 62:237–247
- Early Hominoids: orthograde aquarboreals in flooded forests? 2011 in Vaneechoutte ed.: 67–81
- Pachyosteosclerosis in archaic Homo: heavy skulls for diving, heavy legs for wading? 2011 id.:82–105
- Seafood, diving, song and speech. 2011 id.:181–9
- Reply to John Langdon’s review of the eBook: Was Man more aquatic in the past? 2012 HOMO – J compar hum Biol 63:496–503
M Roede, J Wind, J Patrick & V Reynolds eds 1991 Souvenir London. Aquatic Ape: Fact Or Fiction?
SI Muñoz ed 2007 Nova NY. Ecology Research Progress.
M Vaneechoutte, A Kuliukas & M Verhaegen eds 2011 eBook Bentham Sci Publ. Was Man More Aquatic in the Past? Fifty Years after Alister Hardy.
Images in post provided by Marc Verhaegen. Feature image (added by Laden) credit: marygiordano via Compfight cc
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:-) Thanks Marc and Greg!
Thank you for this excellent analysis. The picture is becoming much clearer for me, thanks to your detailed explanation. Arboreal, aquatic, coastal, and only recently increasingly terrestrial.
I suppose people most likely moved down the west coast of the Americas, too?
Hi Jim, AFAIK it was only during the latest phase (< 20 ka, much later than our Pleistocene littoral past in the strict sense ("AAT")) that some sapiens populations (Amerindians) followed the American west coasts south (somebody called this the "kelp route" IIRC). --marc
Marc is right in "misconceptions".
In our swimming, diving, bathing, physiology, skin, organs, brains, appreciation of "fruits de mer" everywhere, need of daily water and a bit of NaCl (sea salt)Semi are a heritage of our semisaquatic ancestors. May be even gesticulating, yelling, singing and killing...
Sad feeling Dirk Meijers missing Elaine Morgan.
"man is the opposite of a savanna inhabitant."
("Man"? That's misogynistic)
Well, people living in the savannas as resistance hunters apparently haven't been informed of that.
Cynical Skeptical, you better be cynical & skeptical of the savanna ideas. There are only a few remote inland populations in E.Africa & perhaps Australia who recently (Holocene IMO, with the help of weapons, waterbags, poisons etc.) "resitance-run": 99 % of humans still simply live near coasts & rivers (or bathrooms).
For a recent summary of the "coastal dispersal model" (term of Stephen Munro, the discoverer of the Javanese shell engravings, see Joodens cs 2014 Nature) + a disproof of the old outdated or ill-informed "open plain" ideas, please read "The aquatic ape evolves: common misconceptions and unproven assumptions about the so-called Aquatic Ape Hypothesis" Hum.Evol.28:237-266, 2013, which is partly based on the above guest post, google researchGate marc verhaegen, or independent. academia. edu/
The vast majority of humans have lived inland from the seas until fairly recently.
The majority of australopith fossils are found in an area that never had more than a stream anywhere nearby, probably close to rainforest habitats (but not like any existing rainforest, more seasonal, less rain) and not very "savanna" like.
The "savanna" hypothesis is held mostly by people who don't know much about the fossil record or paleo climate (evolutionary psychologists and such, who like to use the record without the trouble of learning about the record). But the "aquatic ape hypothesis" does not explain much.
Having said that there is strong evidence that water based adaptations have been very important to humans at key points in human prehistory. But the idea that the vast majority of hominids were "aquatic" in some ways or relied on aquatic resources for most of time is not borne out by the evidence at all.
1) Glacial sea-coasts were c 100 m under today's sea-level. The more coasts are explored underwater the more evidence is found of human (Homo! not australopiths!) occupation. All archaic Homo fossils were found in association with coasts (from Pakefield to the Cape to Mojokerto) or large bodies of water: oxbow lakes, large rivers, beaver ponds (2 spp of beaver), lime caves... From what we know, early-Pleistocene Homo followed the coasts intercontinentally (1.8 Ma from Aïn-Hanech to Mojokerto), later they went more & more inland along big rivers (at first seasonally?), still later some populations (e.g. (pre)neandertals?) probably lived more inland at big rivers that at the coasts (but traces of cattails on neandertal tools, traces of waterlily roots in their dental plaque: these people were not the big-game hunters they're still often believed to have been, but no doubt (often?) butchered ungulates they found in reeds or mud, and I'd think once a year went to the coast, e.g. marine mammals & shellfish consumption in Gibraltar (Stringer cs PNAS).
2) Australopiths (no relevance to Homo's semi-aquatic evolution) are typically found in wetlands, papyrus swamps & forest swamps, e.g. Lucy lay amid crab claws & crocodile eggs, for a survey see my Hum.Evol.papers.
3) Nobody speaks of the "vast majority of hominids" (whatever that means = Gorilla? Pan? Orrorin? australopiths? archaic Homo? sapiens?). Our papers are about the undeniable "coastal dispersal" (term of S.Munro) of archaic Homo: pachy-osteo-sclerosis (erectus), ear exostoses, long low flat skulls, very broad bodies, large thorax, projecting nostrils (neandertals), brain expansion (DHA), "sudden" intercontinental dispersal, typically found in association with edible shellfish etc.etc.: all these features are typical of littoral animals. There's no doubt that our ancestors at some time (probably early-Pleistocene) were littoral. Archaic Homo spp were not unlike other animals (we've seen more than enough anthropocentrism in anthropology: fur loss to run over savannas etc. :-D), they were no exception. The evidence is clear for any not-prejudiced biologist, see e.g. my 2011 paper with Stephen Munro "Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods" HOMO J.compar.hum.Biol.62:237-247. Why have PAs never studied the malacological evidence? Because they "knew" that our ancestors ran after antelopes on the African plains! Just see the recent paper of Joordens & Munro in Nature (shell engravings), or Stephen's PhD thesis "Molluscs as Ecological Indicators in Palaeoanthropological Contexts" (Austr.Nat.Univ Canberra 2010). When you look at the evidence without the old PA prejudices, it's clear (e.g. José Joordens' papers) that Pleistocene Homo simply followed the African & Eurasian coasts & rivers instead of running over African savannas.
Google "researchGater marc verhaegen" or so.
Early Homo at the Transvaal caves are not near the coast or associated with any large bodies of water.
We've discussed this before, but for those just tuning in the AAT was once all about australopiths, until that idea was falsified too many times, and now it has moved to Homo.
"Australopiths (no relevance to Homo’s semi-aquatic evolution) are typically found in wetlands, papyrus swamps & forest swamps, e.g. Lucy lay amid crab claws & crocodile eggs, for a survey see my Hum.Evol.papers."
Only if you ignore the majority of the fossils, which are found in various South African localities that are not near large bodies of water.
First you said "Cynical Skeptical, you better be cynical & skeptical of the savanna ideas. There are only a few remote inland populations in E.Africa & perhaps Australia who recently (Holocene IMO, with the help of weapons, waterbags, poisons etc.) “resitance-run”: 99 % of humans still simply live near coasts & rivers (or bathrooms)."
Then you said "Nobody speaks of the “vast majority of hominids” "
Laden claims without arguments: "the “aquatic ape hypothesis” does not explain much".
The term "aquatic ape" is often misunderstood by outdated or ill-informed PAs: it's not about apes, but about Pleistocene Homo, and "littoral" is IMO a better biological term than "aquatic".
In fact, our Pleistocene littoral dispersal (diving for seafood, followed by bipedal wading etc.) explains most of what discerns us from chimps: our fur loss, brain expansion, voluntary breathing, speech preadaptations, poor olfaction, small mouth, hyoidal descent, tool use, head-spine-legs in 1 line, SC fat, sweating water+salt, external nose, etc.
OTOH, traditional paleo-anthropology hasn't explained anything so far. University courses & textbooks still repeat the old ideas about how our ancestors lived in African savannas: butchering carcasses or even running after antelopes. There's no evidence for these suppositions. In fact, there's even no scientific critique on AAT apart from 2 papers of John Langdon, which we have disproved, e.g. A.Kuliukas 2011 p.213-226 in M.Vaneechoutte cs eds "Was Man more aquatic in the past?" eBook Bentham Scient.Publ, and M.Vaneechoutte, S.Munro & M.Verhaegen 2012 "Reply to John Langdon’s review of the eBook: Was Man more aquatic in the past?" HOMO J.compar.hum.Biol.63:496-503.
Laden, your last post, please don't accuse me of ignoring evidence.
- Sarmiento & Wrangham 2012: S.African australopiths = wetlands = large bodies of water (as is the case for the E.African australopiths).
- But AAT is not about australopiths but about Pleistocene Homo dispersing along African & Eurasian coasts & then rivers.
Please discern between
- australopiths in wetlands & swamp forests cf lowland gorillas wading for sedges & floating vegetation in bais,
- human unique evolution: (Plio?-)Pleistocene Homo's coastal intercontinental dispersal.
FYI, a summary of our view:
We proposed (Med.Hypoth., New Scient., Nature, Hum.Evol., Nutr.Health, TREE, HOMO, ebook, book etc.) 3 hypotheses on ape & human evolution, mostly based on comparative biology of extant & fossil apes & humans:
1) Aqu-arboreal Hypothesis (<20 Ma):
Mio-Pliocene hominoids (incl.australopithecines) often dwelt in swamp forests & wetlands, parttime feeding on floating herbs, papyrus sedges etc. cf. extant lowland gorillas in forest bais (note fossilisation is less likely in coastal forests & mangroves).
2) Coastal Dispersal Hypothesis (<2.5 Ma):
Pleistocene archaic Homo followed African & Eurasian coasts & rivers (1.8 Ma e.g. Dmanisi, Mojokerto, Turkana, Aïn-Hanech), beach-combing, diving & wading bipedally for littoral, shallow aquatic & waterside foods.
3) Wading-Walking Hypothesis (<0.5 Ma):
Late-Pleistocene H.sapiens waded & later walked upright with complex tools (e.g. distance weapons, nets) for shallow-aquatic & terrestrial foods.
On speech origins, see e.g. our 2011 paper
"Seafood, diving, song and speech":
1) Miocene hominoids evolved gibbon-like duets of loud & varied songs.
2) Much later, seafood consumption pre-adapted Pleistocene Homo to
- breathing control at free will (breath-hold diving),
- labial-dental-palatal-velar... consonants (seafood suction & smacking),
- brain growth (brain-specific nutrients in aquatic foods, e.g. DHA).
3) Late-Pleistocene, upright wading "freed" not only the hands (complex tools), but also the airways (voluntary sounds), which got more & more involved in spoken language.
Wrangham is actually wrong about that. We've discussed it. The South African case is wetter, but not extensive, just streams and such, where the fossils are found. The Delta Hypothesis is a different story, there I think we are on to something, but that is not based on any fossil evidence in the region. Plus, you were for a while there ruling out australopiths, now you are using them, so you may need to make up your mind.
Wrangham's delta hypothesis is based on our work (TREE), and Sarmiento usu.knows very well what he's talking about, we've also discussed it, but whatever, apparently, you still don't get what we're saying, I don't "use" australopiths, we simply have to look at them in their own way, instead of confusing them withou our ancestors, it's not difficult at all, but you have to get rid of your preconceptions:
- Plio-Pleistocene australopiths lived in swamp forests & wetlands (this has nothing to do with Homo, e.g. please read Yohn cs 2005 PLoS: our direct ancestors might have been absent from Africa between at least 4 & 3 Ma, possibly they lived then in S.Asian coastal forests),
- Pleistocene Homo dispersed along coasts & rivers.
For a summary of my view, see "The aquatic ape evolves: common misconceptions and unproven assumptions about the so-called Aquatic Ape Hypothesis" Hum.Evol.28:237-266, 2013, google researchGate marc verhaegen.
This whole article seems like a "watering down" and rehash of the basic AAH findings proposed as something new. The specifics are speculative in either case, but the aquatic component is key.
Frank, my article "The aquatic ape evolves: common misconceptions and unproven assumptions about the so-called Aquatic Ape Hypothesis" (Hum.Evol.28:237-266, 2013) doesn't propose the "basic AAH findings as something new", on the contrary: it argues that many pro-AAH as well as anti-AAH students have a lot of unproven preassumptions & misconceptions on what they believe "AAH" is. In fact, the littoral theory (or "coastal dispersal model", S.Munro 2010) is not about something that happened >6 Ma as Elaine Morgan thought (her "AAH"), it's not about apes (aquatic or not), nor about australopiths, but about early-Pleistocene Homo following African & Eurasian coasts.
The conventional paleo-anthropological view is that human ancestors became bipedal by moving from the forests to the plains (schematically: ape=>human = forest=>plain = 4-legged=>bipedal). This is biologically & physiologically unlikely, e.g. primates that move from forest to plain become more quadrupedal, not less ("the baboon paradox"); sweating requires salt & water (both scarce in arid grasslands); etc.
An account of human evolution which discusses "bipedality" in arboreal & terrestrial but not shallow-aquatic settings is incomplete. In fact, comparative, paleo-environmental & other data show:
(1) Plio-Pleistocene australopithecines (fossil hominids (vs pongids), i.e. relatives of Pan-Homo-Gorilla) were typically swamp forest & wetland species (e.g. K.Reed 1997 JHE). The combination of water + trees parsimoniously explains the remarkable combination of bipedality (e.g. for wading) + curved hand-bones (for vertical climbing) in australopiths (google "aquarboreal"). Human fetuses never have hand-like feet, but prenatal African apes have more humanlike feet (e.g. with longer & adducted big toes) which later become more hand-like (e.g. C.Coon 1954). This suggests Pan & Gorilla had more bipedal ancestors (e.g. parttime wading for papyrus, frogbit, waterlilies etc.), google e.g. "bonobo wading" or "gorilla bai".
(2) Our Pleistocene ancestors (archaic Homo spp) did not disperse intercontinentally walking or running over the open grasslands, but simply followed African & Eurasian coasts & rivers ("coastal dispersal model", S.Munro 2010), walking & wading bipedally & parttime diving for waterside, littoral & shallow-aquatic foods (which are richest in brain-specific nutrients such as DHA, e.g. S.Cunnane 2005 "Survival of the fattest"), even colonizing islands overseas (no need to suppose boats or rafts): Flores, Crete, Cyprus etc.
Homo's diet included animal (e.g. shellfish opened with hard tools, waterside carcasses of herbivores & marine mammals, salmon & other fish) as well as plant foods (e.g. traces of waterlily roots in neanderthal dental calculus & of cattails on their tools).
Homo's brain enlargement (e.g. DHA) & parttime shallow diving (which requires breathing control) were preadaptive to human spoken language.
Hi Marc and Greg. Have you seen this?
It's a merciless attack on the same old straw men.
Hi Jim, yes, I've seen this. :-( Prof.Roberts apparently hasn't even listened to the radio programmes, which provided several recent arguments (vernix caseosa, squalene, shell engravings, etc.) that our ancestors were at least waterside (in fact, H.erectus' pachyostosis, ear exostoses, external nose, brain expansion etc. show they were littoral: frequently *diving* in shallow water). Roberts' comments are irrelevant & outdated, and her savanna ideas are just-so anthropocentrisms: "The nowadays popular ideas about Pleistocene human ancestors running in open plains (‘endurance running’, ‘dogged pursuit of swifter animals’, ‘born to run’, ‘le singe coureur’, ‘Savannahstan’) are among the worst scientific hypotheses ever proposed. The surprising frequency and diversity of foot problems (e.g. hammertoes, hallux valgus and bunions, ingrown nails, heelspurs, athlete’s feet, corns and calluses - some of these due to wearing shoes) and the need to protect our feet with shoes prove that human feet are not made in the first place for running. Moreover, humans are physiologically ill-adapted to dry open milieus: “We have a water- and sodium-wasting cooling system of abundant sweat glands, totally unfit for a dry environment. Our maximal urine concentration is much too low for a savanna-dwelling mammal. We need much more water than other primates, and have to drink more often than savanna inhabitants, yet we cannot drink large quantities at a time” (Verhaegen 1987). This does not imply to say that human ancestors or relatives never lived on savannas, only that if they did, it was at the wetlands and rivers there. Apparently we evolved running - only lately, and only about half as fast as equids, bovids, felids or canids, and even slower than arboreal primates - *in spite of* our broad build, short toes and plantigrade feet, profuse sweating, and large subcutaneous fat tissues (a burden of >10 kg in most people). Of course, healthy adult men can sometimes outrun ungulates (the usual ‘argument’ of conventional paleo-anthropologists) and provide a limited part of the calories for the group, but this dogged pursuit is largely confined to a few inland populations in East Africa today, is derived and probably very recent (less than a few thousands of years): it requires a rather specialized technology with water bags, weapons and poisons." (Hum.Evol.28:237-266, 2013).
I saw that.
And you agree, of course, like every sensible scientist...
The mistake of traditional paleo-anthropology begins with believing that that the australopithecines are closer relatives of us than of the African apes because they were "bipedal". Statistically, however, it's impossible that of the 5 or 6 extant hominid species (sensu African hominoids), 1 species (H.sapiens) has 1000s of fossil ancestors or relatives, and the other 4 or 5 species (common chimps, bonobo, lowland & highland gorilla) have virtually no fossil relatives, as traditionally assumed. This can't be due to fossilisation bias, since the Asian great apes (orangutans) do have a lot of fossil relatives, e.g. Sivapithecus, Lufengpithecus, Gigantopithecus. Most likely, Pan & Gorilla also had more bipedal ancestors, e.g. their fetuses still have humanlike feet (flat feet with long & adducted big-toes): "The embryo of a chimpanzee at one stage has a foot resembling that of man in that its great toe points forward ... Only as it approaches its birth size does its foot acquire the appearance of a hand. At no stage of its development does the human foot resemble that of an adult ape" (C.S.Coon), IOW, the human flat foot is probably more primitive than adult chimp & gorilla feet. Running animals invariably have very long & strong middle toes, the opposite of australopiths, humans & prenatal African apes, who have flat feet with rel.long first last digital rays, which are typically seen in animals that swim or wade a lot. Australopiths fossilised in well-wooded & well-watered regions (K.Reed 1997 JHE), very likely they often waded bipedally or even swam for sedges, papyrus, frogbit, waterlilies & other wetland foods, like bonobos & lowland gorillas still do but much more frequently (google e.g. "bonobo wading", see illustrations). In a series of papers in Human Evolution in the 1990s, I showed that cranio-dentally, A.afarensis & A.boisei (from E.Africa) resembled Gorilla more than Pan or Homo, and that A.africanus & A.robustus (from S.Africa) resembled Pan more than Gorilla or Homo, see e.g. 1994 "Australopithecines: Ancestors of the African Apes?" Hum.Evol.9:121-139. I have no doubt that if proteins will be extracted from australopith teeth or bones, A.boisei will show to be a closer relative of Gorilla than of Pan of Homo, and A.robustus of Pan than of Gorilla or Homo.
What is the relevance of this for the AAH (= Pleistocene littoral dispersal of archaic Homo)? First that "bipedalism" is no argument pro or contra AAH (the early hominoids e-were probably already "upright" - gibbons & humans still are). That AAH has to be situated, not before the australopiths (& even Sahelanthropus c 7 Ma), but much later, in Homo, probably when all possibly-littoral features appear in the fossil record (after c 2 Ma): pachy-osteo-sclerosis, much larger brain, auditory exostoses, external nose, platycephaly long low flat brain-skull), platymeria (dorso-ventrally flatrtened thigh bones), fast intercontinental dispersal, colonisation of islands far overseas, etc.
Something went wrong with my previous post. Here's the rest: Conclusion: traditional paleo-anthropology (not the facts but the interpretations) is pre-darwinian anthropocentrism, wrong in almost every idea. (1) Australopiths are no human ancestors, but more likely fossil relatives of Pan or Gorilla, (2) the traditional views of fossil hominid lifestyles are very wrong: (a) australopiths were no bipedal runners, but wetland dwellers (vertical aquarboreals), who fed (at least seasonally) on wetland plants & other foods, (b) H.erectus were no "endurance runners", but typical littoral creatures, who soon dispersed intercontinentally along African & Eurasian coasts, feeding on shellfish etc., (c) neandertals were no tundra dwellers, but probably wetland dwellers, who seasonally followed the river to the coast, and who ate all possibly edible waterside foods: drowned carcasses of ungulates, stranded whales, cattails, salmon, waterlily roots etc. (d) early H.sapiens were no savanna runners, but long-legged wetland dwellers, who also used complex distance weapons (spears, nets etc.) e.g. to hunt fish, fowl etc.