Aquatic Ape Human Ancestor Theory

Aquatic Ape Theory - What is it?

A Brief Summary of AAT - key arguments

A Brief History and Key Proponents of AAT

Current Aquatic Evolution Theories

Timeline

Alternative theories of human evolution

Wikipedia and the scientific community

. Anatomical Evidence
... Bipedalism
... Birth and babies
... Brain
... Breath control
... Fat
... Fingers, toes and feet
... Furlessness
... Hair and baldness
... Kidneys
... Menopause
... Nose
... Olfactory sense
... Pachyostosis
... Paranasal Sinuses
... Platycephaly
... Sexual features
... Surfer's ear
... Sweating
... Tears
... Underwater vision

. Diet
. Language & Song
. Sleep (USWS)
. Waterside environments
. Sea Gypsies

. Homo erectus - shallow diver

. Fossil evidence
. Paleoecological evidence

A call to scientists...

Recent News and Updates

Books and publications

Videos links

Links

Contact

Current 'Aquatic Ape' Theories

The LCA divergence Model

Alister Hardy and Elaine Morgan were both supporters of the idea that, some time relatively soon after chimpanzees and early human ancestors diverged from the Last Common Ancestor (LCA) approximately 4-6 million years ago, water played a key role in shaping the line that led to Homo.

As Hardy said in his New Scientist Article in 1960:

human evolution"My thesis is that a branch of this primitive ape-stock was forced by competition from life in the trees to feed on the sea-shores and to hunt for food, shell fish, sea-urchins, etc., in the shallow waters off the coast. I suppose that they were forced in to the water just as we have seen happen in so many other groups of terrestrial animals.I am imagining this happening in the warmer parts of the world, in the tropical seas where Man could stand being in the water for relatively long periods,that is, several hours at a stretch. I imagine him wading, at first perhaps still crouching, almost on all fours, groping about in the water, digging for shellfish, but becoming gradually more adept at swimming.Then, in time, I see him becoming more and more of an aquatic animal going farther out from the shore; I see him diving for shellfish, prising out worms, burrowing crabs and bivalves from the sands at the bottom of shallow seas, and breaking open sea-urchins, and then,with increasing skill, capturing fish with his hands." [1]

However, opponents of this theory, such as Marc Verhaegen, suggest that the majority of differences between chimps (Pan) and Homo, came about much later, 2 My and after, and that bipedalism is not, in fact, evidence of an aquatic interlude, but rather the result of an orthograde spine inherent in all apes and attributed to aborealism (living in trees) and spending time in water part of the time to find food. As Algis Kuliukas states on his website:

"Some AAH proponents, including Morgan and myself, were very sceptical of this idea initially. It seemed to complicate matters. The beauty of the AAH for us was that it seemed to explain the differences between humans and apes, and here was Marc muddying the waters with the idea that, actually all apes were already partly aquatic. For me, the turning point came in December 2000 with the discovery of Orrorin tugenensis, a putative biped and an even more putative hominid. It seemed to me that here was a possible bipedal ape dated (at 6Ma) at around the time, or even before, the widely accepted molecular dates for the last common ancestor, at around 5.5Ma. Having just listened to a paleoanthropology lecture by Mark Collard at UCL, extolling the accuracy of the molecular clock, I was rather surprised when, just a few days later, that the same guy made an announcement to the weekly departmental meeting suggesting that this fossil discovery was no big deal. Well it was a big deal to me and I wrote to Marc immediately congratulating him on his idea and voicing my support from that point on. It is probably true that most AAH-proponents today now support a model of human evolution that is based on an early wading-climbing phase for all apes and a more coastal-littoral phase for the genus Homo." [2]

Wading and The River Apes Model

Algis Kuliukas has probably done the most research on how wading may have played a role in helping our ancestors to become bipedal. Bonobo wadingHe did a Masters degree at UCL in Human Evolution so that he could research this question further. According to Algis (following Morgan and Hardy) wading in shallow water is the simplest and most predictable way of getting an ape to move bipedally. In waist deep water any chimp, gorilla, orang-utan will move on two legs while in deep water. If he tried to enter the water quadrupedally, he would either have to swim, or drown. He states:

"Precious little work had been done studying extant ape behaviour in water as they have always been considered to be rather hydrophobic. However, recent observations of western lowland gorillas at the swamps of Mbeli Bai have started to change this image. In fact, digging around the literature reveals that all four species have been observed to go into water when the need arises and, when they do, it is usually bipedally. I carried out a new empirical study of captive bonobos’ bipedal time at the wildlife park at Planckendael near Brussels in different substrates. I found that whilst they were bipedal only 2% of the time on land, the figure rose to over 90% when in water." [3]

Opponents of the wading theory tend to point out that the LCA of Pan/Homo/Gorilla was already somewhat bipedal, and that once again, bipedalism is not evidence of an aquatic interlude, but rather the result of an orthograde spine inherent in all apes and attributed to aborealism (living in trees). Also, they claim that many early hominids, such as 'Lucy' and 'Ardi' were most likely bipedal most of the time, but they were not conclusively Homo ancestors.

The Aquarboreal Model

Marc Verhaegen, Stephen Munro, et al, suggest that most early apes probably lived in gallery forests, lagoons or mangrove-like swamps, and it was the combination of their orthograde spines, long arms and curved phalanges that enabled them to climb out of the water and to enter the water from the lower branches to search for food. There is more and more evidence to show that many apes will enter water to eat floating vegetation, etc. Verhaegen states:

"During the Miocene (23–5.3 Mya) and Pliocene (5.3–2.6 Mya), 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 Orangutan fishingshoulder blades, and wide thorax and pelvis."

He goes on to suggest that it was this 'aquarborealism' (living partly in the trees and partly in the water) that most likely led to a partial bipedal gait in early hominids such as Australopithecus (although they were probably no direct ancestors of Homo).

"In my view, the Homo-Pan LCA ~5 Mya, 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." [4]

However, the Aquarboreal model talks only about the earlier stages (+/- Mio-Pliocene) of hominoid evolution. It doesn't explain how or why the majority of human 'aquatic features' came into existence. For that one needs to consider a littoral theory of Pleistocene Homo.

The Coastal Migration Model/ The Littoral Theory of Pleistocene Homo.

Homo erectusAccording to Marc Verhaegen and Stephen Munro, the essence of the Aquatic Ape Theory begins with Pleistocene Homo, who may have trekked along coasts to different continents and inland along rivers. They state that our most aquatic phase is not something that happened 6 million years ago because all the distinguishing features of Homo appear in the fossil record from 2.6 - 0.01 Ma, eg: larger brain, external nose, pachyostosis (heavy skeleton), platycephaly, platymeria (flattened thigh bones), ear exostoses, fossils among shellfish, dispersal to islands, etc. This would suggest that our most aquatic ancestor lived in the early Pleistocene, (i.e. less than 2.5 million years ago). They argue that the majority of 'human' characteristics and evidence of frequent diving appear only after 1.8 million years ago, although that could be due to the absense of Homo fossils.

Verhaegen believes that Homo erectus (or close relatives) probably lived along coasts and, at least part of the time, dived for seafood. Some populations may have trekked inland along rivers, seasonally or during interglacial periods. He says that if the most aquatic phase had ended before 3 million years ago, we would have lost most aquatic features and would certainly not suffer so much from a variety of common ailments and problems, eg: obesity, asthma, acne, cretinism, seborrhea, male pattern alopecia, vernix caseosa, vasomotor rhinitis, sinusitis, sleep apnea, Cheyne-Stokes, varicosis etc.

Verhaegen notes that during the Pleistocene, turn-over of species was several times higher than before and there's no reason why hominids would have been an exception. During that time, sea levels dropped by 100 metres during glacials, leaving vast regions available on the continental shelves during glacials. These areas would likely have had scarce trees and may have been rich in shell and crayfish.

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The Mixed Theories Model

Hardy asked the question: "Was man more aquatic in the past?" Evidence seems to suggest that our hominid ancestors have been at the very least littoral (coastal, shore or lake dwellers), for much of their existence. If it started as long ago as the LCA split, as Hardy and Morgan believed, a possible scenario may well be as follows: the first descendants of our last common ancestor lived in or near swamps or mangrove forest, much as Bonobos do today, and from there, our affinity with water began. This would explain why later descendants - Australapithecus, Ardi, Naledi, etc. - were most-likely tree-climbing bipeds who spent much of their time in the water, as well as in the trees. Later descendants, such as H. erectus, then began to spread out along the coasts and inland waterways, travelling northwards / eastwards and out of Africa as far as Dmanisi in Georgia and Java and Flores in Indonesia. H. erectus was possibly the most aquatic of all our relatives, becoming at one time so dependent on aquatic resources that he became a proficient diver and could remain underwater for longer periods than we can today. His bones, similar to those of many bottom feeding mammals such as manatees and walruses, were so much heavier than ours that he would have had difficulty running across the plains or spending large amounts of time far from water. Later Homo sapiens was then well equipped to leave the coasts as the climate cooled and head inland, making their way across the Bering straits into North America. Some of them also found their way down to Australasia.


 
Website: F. Mansfield, 2015

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