Marc Verhaegen

The Aquatic Ape Theory: Evidence and a possible scenario

Much more than other primates, man has several features that are seen more often in aquatic than terrestrial mammals: nakedness, thick subcutaneous fat-layer, stretched hindlimbs, voluntary respiration, dilute urine etc. The Aquatic Ape Theory states that our ancestors once spent a significant part of their life in water. Presumably, early apes were plant and fruit eaters in tropical forests. Early hominids also ate aquatic food; at first mainly weeds and tubers, later sea shore animals, especially shellfish. With the Pleistocene cooling, our ancestors returned to land and became bipedal omnivores and scavengers and later hunters of coastal and riverside animals.

Hominid lifestyle and diet reconsidered: paleo-environmental and comparative data

AbstractIt is traditionally believed that human ancestors evolved in a warm and dry environment. The available evidence, however, favours the vision that it happened in a warm and wet environment.The paleo-environmental data suggest that the early australopithecinesAustralopithecus anamensis, afarensis andafricanus lived in warm, moist, and wooded landscapes such as gallery forests. In the Pleistocene, the robust australopithecinesA. robustus andboisei seem to have dwelt in more open, possibly cooler and generally dryer places, in the vicinity of shallow and relatively stagnant waters of lakesides, lagoons, marshes and riverbanks. Dental and microwear studies suggest that the australopithecines, more than Western lowland gorillas, regularly fed on aquatic herbaceous vegetation (AHV). Homo fossils, on the other hand, as suggested by the paleo-environmental data, are more frequently discovered near lakes, seas and rivers where molluscs were abundant. Shellfish could provide a dietary supplement for their omnivorous diet. This is how early hominines might have learned to use stones to crack bivalves. This subsequently could have led to stone tool use for other purposes.

Australopithecines: Ancestors of the African Apes?

Since australopithecines display humanlike traits such as short ilia, relatively small front teeth and thick molar enamel, they are usually assumed to be related toHomo rather than toPan orGorilla. However, this assumption is not supported by many other of their features.This paper briefly surveys the literature concerning craniodental comparisons of australopith species with those of bonobos, common chimps, humans and gorillas, adult and immature. It will be argued, albeit on fragmentary data, that the large australopiths of East Africa were in many instances anatomically and therefore possibly also evolutionarily nearer toGorilla than toPan orHomo, and the South African australopiths nearer toPan andHomo than toGorilla. An example of a possible evolutionary tree is provided. It is suggested that the evidence concerning the relation of the different australopithecines with humans, chimpanzees and gorillas should be re-evaluated.

Aquatic versus Savanna: comparative and paleo-environmental evidence.

This paper begins by comparing anatomical and physiological features of humans and other groups of mammals (apes and arboreal mammals, open-country dwellers, fully aquatic mammals, and semi-aquatics), in order to establish the nature of the environment where Homo originated. It concludes that the evidence completely invalidates the savanna theory and strongly favours the semi-aquatic hypothesis. The second part points out that nothing in the fossil record disproves this conclusion, and quotes paleo-environmental evidence concerning the milieu where the ancient hominids fossilised.

African ape ancestry

It is commonly believed that the australopithecines are more closely related to humans than to African apes. This view is hardly compatible with the biomolecular data which place theHomo/Pan split at the beginning of the australopithecine period. Nothing in the fossil hominid morphology precludes the possibility that some australopithecines were ancestral to gorillas or chimpanzees and others to humans.

Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods

Fossil skeletons of Homo erectus and related specimens typically had heavy cranial and postcranial bones, and it has been hypothesised that these represent adaptations, or are responses, to various physical activities such as endurance running, heavy exertion, and/or aggressive behavior. According to the comparative biological data, however, skeletons that show a combination of disproportionally large diameters, extremely compact bone cortex, and very narrow medullary canals are associated with aquatic or semi-aquatic tetrapods that wade, and/or dive for sessile foods such as hard-shelled invertebrates in shallow waters. These so-called pachyosteosclerotic bones are less supple and more brittle than non-pachyosteosclerotic bones, and marine biologists agree that they function as hydrostatic ballast for buoyancy control. This paper discusses the possibility that heavy skeletons in archaic Homo might be associated with part-time collection of sessile foods in shallow waters.

Possible preadaptations to speech. A preliminary comparative

Human language is a unique phenomenon and its evolutionary origins are uncertain. In this paper we attempt to explore some of the preadaptations that might have contributed to the origin of human speech.The comparative approach we use is based on the assumption that all features of a species are functional, and that all features can be compared with those of other animals and correlated with certain lifestyles. Using this method we attempt to reconstruct the different evolutionary pathways of humans and chimpanzees after they split from a common ancestor. Previous results from comparative studies suggest human ancestors may not have evolved on the open African savannas as was once believed, but more probably were coastal omnivores feeding on plant matter and easy to catch invertebrates such as shellfish from beaches and shallow waters. Fossil and archaeological data suggest this coastal phase occurred at the beginning of the Pleistocene, whenHomo ergaster-erectus dispersed between East-Africa, North-Africa, South-Asia and Indonesia.This paper presents comparative data suggesting the various human speech skills may have had their origins at different times and may originally have had different functions. Possible preadaptations to speech include, for instance, musical skills present in a variety of primate species (sound production); airway closure and breath-hold diving for collecting seafood (voluntary breath control); and suction feeding adaptations for the consumption of fruit juice or certain seafoods (fine control of oropharyngeal movements). The different evolutionary pathways of chimpanzees and humans might explain why chimpanzees lack language skills and why human language is a relatively recent phenomenon.

Morphological distance between australopithecine, human and ape skulls

This paper attempts to quantify the morphological difference between fossil and living species of hominoids. The comparison is based upon a balanced list of craniodental characters corrected for size (Wood & Chamberlain, 1986). The conclusions are: craniodentally the australopithecine species are a unique and rather uniform group, much nearer to the great apes than to humans; overall, their skull and dentition do not resemble the human more than the chimpanzee’s do.

Reply to John Langdon's review of the eBook: Was man more aquatic in the past? Fifty years after

We welcome the opportunity, offered by the editors of HOMO Journal of Comparative Human Biology, to respond to John Langdon’s review (Langdon, 2012) of our recently published eBook, Was Man More Aquatic in the Past? (Vaneechoutte et al., 2011). Langdon’s review, however, is not so much about the eBook itself – as he hardly discusses any of the rich data and hypotheses forwarded by the eBook – but rather represents his critical attitude towards the aquatic hypothesis (AH). His criticisms are largely rhetorical, focusing on philosophical questions about science, rather than substance, and as such they can be applied equally to science in general. Our comments address these reflections, and also highlight the fact that some of Langdon’s statements are based on misinterpretations and misrepresentations, not only of the content of the eBook and of the AH, but also of some of the palaeo-anthropological and comparative biological data.

Reply to John Langdon's review of the eBook: Was Man more aquatic in the past? Fifty years after Alister Hardy, Mario Vaneechoutte, Algis Kuliukas, Marc Verhaegen (Eds.), in: Waterside Hypotheses of Human Evolution. Bentham eBooks (2011), 244 pp., eISBN: 9781608052448

We welcome the opportunity, offered by the editors of HOMO Journal of Comparative Human Biology, to respond to John Langdon’s review (Langdon, 2012) of our recently published eBook, Was Man More Aquatic in the Past? (Vaneechoutte et al., 2011). Langdon’s review, however, is not so much about the eBook itself – as he hardly discusses any of the rich data and hypotheses forwarded by the eBook – but rather represents his critical attitude towards the aquatic hypothesis (AH). His criticisms are largely rhetorical, focusing on philosophical questions about science, rather than substance, and as such they can be applied equally to science in general. Our comments address these reflections, and also highlight the fact that some of Langdon’s statements are based on misinterpretations and misrepresentations, not only of the content of the eBook and of the AH, but also of some of the palaeo-anthropological and comparative biological data.