Fossil Evidence

Where is the evidence?

If the Aquatic Ape Theory (AAT, or waterside, littoral or underwater foraging model) were true, why do we only find early Homo fossils in savannas and not on the coast?

One of the main objections people have to the AAT is that hominin fossils are found in savannas, and not on the coast. This perception is clouded somewhat because most people assume (following the orthodox view), that the australopithecines are human ancestors, whereas it is more likely that most australopithecines are more closely related to the ancestors of chimps or gorillas than to human ancestors. Regardless, australopiths do not have any adaptations we would associate with slow underwater foraging (large brain, external nose, large streamlined bodies with heavy bones, femora displaying platymeria etc.), and therefore the location of their fossils, though interesting, has little to say about the evolution of humans (virtually all australopithecine fossils are found in wetland habitats, nevertheless).

When we begin to see Homo species with the above features in the fossil record (about 2 million years ago), they are indeed in some cases associated with savanna habitats (although one of the earliest – Mojokerto, in Indonesia at 1.8Ma – is coastal). Savannas, however, are no problem for the waterside or underwater foraging model of human evolution; indeed, savanna wetlands are a very likely place for Homo populations to have inhabited.

One of the problems with people’s perceptions of the habitats of species such as Homo erectus, is that most discussions of human evolution tend to focus on the extent of forests, grasslands and woodlands, with very little discussion of water. This means that when paleoanthropologists publish papers on new fossil sites, they tend to focus on animals that reveal something about whether the habitats were forested, wooded or open grasslands. Aquatic species are not generally discussed, because the assumption is that these have little to do with human evolution. This imbalance in reporting and discussion leads to the impression that the only fauna discovered with early human fossil and archaeological sites are terrestrial. This is simply not the case.

So it is certainly true that some early Homo fossils in Africa, for example, have been discovered in savanna biomes, but it needs to be remembered that water bodies such as rivers, swamps and lakes are important elements of savanna habitats, which is why we find hippos, crocodiles, fish, frogs, water birds, aquatic gastropods and bivalves in savannas.

In fact, Homo fossils in the Pleistocene are virtually always found in the presence of aquatic animals such as hippos, crocodiles, fish, water birds, aquatic gastropods and bivalves. Of course, when this is pointed out to opponents of the AAT, they counter that due to taphonomic processes this evidence has little meaning. It is important to remember, however, that that the AAT (or waterside, littoral or underwater foraging models) are not based in the first place on the palaeoecological data (though they are not contradicted by it either), but on the comparative biological and physiological data. Hardy’s initial thesis was based on comparative data, Elaine Morgan’s was also, and Verhaegen and others place a heavy focus on comparative data. In other words, the AAT is based on the fact that the combination of the various comparative data suggest that the best explanation for the combination of human nakedness, subcutaneous fat, external nose, small mouth, reduced olfactory abilities, linear build, high need for water, sodium, iodine, DHA (for brain growth), as well as enhanced breath control (a pre-requisite for spoken language), tool use (for opening hard shelled bivalves), etc., is that human ancestors went through a phase in their evolutionary past where they spent part of their time foraging in relatively shallow waters close to land for slow moving foods such as shellfish.

This is not contradicted by any early Homo fossil or archaeological sites. In other words, there are no sites at which early Homo fossils or tools have been found which have not also provided evidence of a permanent water body in which foods such as shellfish could have been gathered, and these sites are virtually all basins or river systems connected to the coast. None of this precludes savanna habitation or terrestrial hunting, gathering or scavenging, and therefore evidence for carcass butchering (always near permanent water), is completely consistent with waterside, littoral or underwater foraging models.

But what about coasts? Surely if they evolved and dispersed around coasts, we would expect to find more fossils and tools in coastal locations. In fact there are a number of sites associated with Homo erectus that include coastal elements, but coasts are not always great places for fossils to preserve (due to high energy wave action), and sea levels rises through the Pleistocene (when the genus Homo emerged) mean that most Pleistocene coastlines are today submerged under water. Despite this we have Pleistocene coastal sites in Java, England, Africa and the Mediterranean.

In conclusion, the idea that human ancestors once may have spent more time foraging in water for food than other apes is based primarily on the comparative data: the combination of nakedness, subcutaneous fat, large brain, small mouth, breath hold control, external nose etc. However, the palaeoecological data are completely consistent with this model; Pleistocene human remains are virtually always found alongside water dependent animals such as hippos, fish, crocodiles, ducks, mussels, aquatic snails etc.

Dr. Stephen Munro (National Museum of Australia)

Map showing the location of Homo fossil sites in Africa and beyond. When seen within the context of earlier environmental conditions, it can be noted that most fossils were found either in rainforest, open woodland (mosaic) forest, coastal regions or by inland lakes and rivers.

Indeed, Homo fossils, as opposed to australopiths, are typically found near shell fish (e.g., Chiwondo, Chemeron, Nariokotome, Trinil, Boxgrove, Terra Amata, Gesher Benot Ya’aqov, Rabat, Hopefield, Gibraltar). Although tides, waves and changing sea levels have erased most fossil and archaeological hominid remains at seashores, H. erectus has been discovered amid molluscs, barnacles and corals – from the Mojokerto skull at Java ~ 1.8 Ma to the Acheulean tools of Eritrea ~ 0.1 Ma. Stone tools discovered on Flores suggest that H. erectus-like people had crossed the 19-km-wide water barrier known as Wallace’s Line more than 1 Ma. Since a littoral diet including shell fish still best meets the human dietary requirements, their diaspora between Java, England and the Cape likely occurred along the seashores, from where side-branches apparently migrated up rivers into the interiors of Eurasia and Africa including the Rift Valley, at first possibly temporarily (especially during Interglacials?) and seasonally (especially during Summers?).

Marc Verhaegen1,*, Stephen Munro2, Pierre-François Puech3 and Mario Vaneechoutte4
Fifty Years after Alister Hardy Waterside Hypotheses of Human Evolution Verhaegen et al., 2011 Bentham Science Publishers, CHAPTER 4 Early Hominoids: Orthograde Aquarboreals in Flooded Forests? p.78

Clear evidence for shell fish consumption as far back as 125,000 years ago (125 ka) by early H. sapiens is found along the South-African and Red Sea coast. Large shell middens of edible species, with some shells blackened from cooking, provide incontrovertible evidence that shell fish were a subsistence base. Remains of not only shell fish, but also Cape penguins, turtles, tortoises, fur seals, various flighted shore birds, ostrich eggs, fish and numerous terrestrial mammals are found in the South-African coastal caves, indicating that these anatomically modern humans ate a wide age of foodstuffs. Interestingly, both Marean et al. and Klein et al. recovered whale barnacles, indicating that the cave occupants scavenged beached whales. Note that the amount of LC-PUFA (long chain polyunsaturated fatty acids) that could be attained by the consumption of whale meat and blubber is in the hundreds of kilos – far greater than any other source known, either hunted, fished or scavenged.

Littoral populations could have easily learned to hunt by using sharpened sticks to spear or club fish, crabs, turtles and flightless sea birds and these hunting skills could have been expanded to include a range of terrestrial animals. Eventually, some Homo populations became so well adapted to terrestrial living they were able to move further from the water’s edge, and to begin a tradition of organized hunting.

C. Leigh Broadhurst1,*, Michael Crawford2 and Stephen Munro3
"Was Man More Aquatic in the Past? Fifty years after Alister Hardy. Chapter 2: Littoral Man and Waterside Woman: The Crucial Role of Marine and Lacustrine Foods and Environmental Resources in the Origin, Migration and Dominance of Homo sapiens, p. 22-23

ARCHAEOLOGICAL AND FOSSIL EVIDENCE FOR A LITTORAL SUBSISTENCE BASE

It is often assumed that the fossil and archaeological records of early Homo offer support for an open, semi-arid savannah model as opposed to a waterside model, but the data do not support this. Homo fossil and archaeological sites located within the East-African Rift Valley, as well as other parts of the world, are consistently associated with evidence for water.

Although cautious interpretation of actual foodstuffs is required due to the taphonomic aspects of ancient lake bed environments, most early Homo fossil and archaeological sites are consistently and unarguably waterside contexts replete with potential aquatic food resources. In the Rift Valley, freshwater fish and shell fish provide a major link in the food chain. They are consumed by birds, small mammals, reptiles, amphibians etc., all of which in turn could have been consumed by hominins. Since plankton and algae are the ultimate source of DHA, both herbivorous and carnivorous fish and shell fish contain LC-PUFA, though the amounts and ratios of the lipids vary from species to species.

Detailed surveys of Homo fossil and archaeological sites associated with freshwater and marine resources are given in Cunnane and Stewart [1] and Chapter 5 of this book*, and we urge the reader to consult these important sources and the many references therein. In all cases, although there is evidence for open and arid habitats at many sites, the sites are always associated with what were at the time probably permanent water bodies, and therefore these data offer little support for traditional savannah models.

As discussed below, clear evidence for consumption of shell fish, Cape penguins, turtles, tortoises, fur seals, various flighted shore birds, fish and whales is found on the South-African and Red Sea coasts. Some evidence for the actual consumption of food is limited within the archaeological and fossil record, but cut marks on bones can be taken as a good indication that the animal in question was most probably used for food. The bones of large animals are more likely to preserve cut marks than the bones of small animals such as fish, frogs and rodents. Despite this bias, however, the
types of large animals identified as having cut marks are informative. In a number of sites the taxon represented by a bone with cut marks is unidentifiable beyond family (i.e., bovid, equid, giraffid), but sometimes the species or genus is identified, and some of the more common taxa within the archaeological record include the genera Hippopotamus and Kobus. These genera are both associated with waterside environments, and their lifestyles and habitats suggest that there would have been no need for long-distance walking or running for their exploitation.

Although stone tools are well known from sites through out the world, there is also evidence of shell tool use in early Pleistocene deposits from Java about 1.5 Ma, and some butchered remains in Africa that have no stone tools associated may have resulted from shell tool use.

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[1] Cunnane SC, Stewart KM. 2010. Human brain evolution: The influence of freshwater and marine resources. Hoboken: John Wiley & Sons 2010.

C. Leigh Broadhurst1,*, Michael Crawford2 and Stephen Munro3
*"Was Man More Aquatic in the Past: Fifty Years after Alister Hardy. Chapter two: Littoral Man and Waterside Woman: The Crucial Role of Marine and Lacustrine Foods and Environmental Resources in the Origin, Migration and Dominance of Homo sapiens, p.26 - 27

Fossil evidence is scarce and this has been the main reason why critics have been reluctant to consider the theory. It is unlikely that an ancestor fossil will ever be found that conclusively identifies an aquatic lifestyle because the skeleton would not necessarily reflect the aquatic adaptations. Fossilisation is easiest in stagnant or slowly moving water, but waves (including tides, tsunamis, sea-level changes) prevent or at least hinder fossilisation. However, it can't be denied that the majority of hominid fossils have so far been discovered at the sites of prehistoric lakes, rivers or coasts and often surrounded by evidence of a semi-aquatic lifestyle, such as shellfish, fish and turtle fossils, harpoon or fishing tools, seaweeds, weeds or swamp plants. [1]

Close to all key hominin fossils known, about a thousand specimens, are dug up from what would have been at the time, waterside silts. The Taung child was catalogued along with fossilized turtle eggs; Lucy with crab claws and the like. The Danakil depression in East Africa, which has revealed so many key Homo fossils, around 2.5 million years ago, right when Homo erectus started to sprout in its brain capacity, which is argued linked to foraging on saline seafood containing DHA (a key Omega-3 fatty acid) and especially Iodine, until Homo erectus surpassed a full litre of brain, then that exact region was flooded with sea water from the Red Sea and the Indian Ocean; then it was a tropical archipelago "paradise." These then marine sediments is exactly where we find our first big-brained ancestors.

Website: F. Mansfield, 2015

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