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

Alternative Evolution Theories

Savannah Theory

Savannah hominids?The basic premise of the savannah theory, which ruled the human ancestral debate for most of the twentieth century, went something like this: 'the last common ancestor of chimpanzees and homo, for some reason or another, came down from the trees in the African jungle, and started to adapt to a life on the open grasslands - the savannah. For this reason, they stood up and began walking on two legs, lost their fur, developed speech and a larger brain. There's not really much point in going into the numerous individual reasons why none of these theories could really be supported as the theory has now been almost universally discredited by scientists. As Elaine Morgan said in her Foreword to Volume one of "Was Man More Aquatic in the Past? Fifty Years After Alister Hardy":

"In 2008, Don Johansen noted in his book, Lucy's legacy, that recent palaeo-environmental research “has sounded the death knell for the so-called savannah hypothesis that reigned supreme when I was a student.” As he explained: “These latest findings indicate that our primeval predecessors must have been bipedal in the forest. The concept of the woodland biped has now become, in its turn, the conventional wisdom, and the once ‘supreme’ savannah hypothesis has been so discreetly dismantled that some of today's students are unaware that it ever existed.”

For roughly half a century, it had been treated as proven by a solid consensus of the scientists specializing in the study of human origins. But towards the end of the 20th century doubts about the savannah scenario were accumulating, and were confirmed when new tools of research enabled scientists to analyse and identify fossilized pollen in the sites where hominid remains had been found. It meant that at least one of the salient hallmarks of mankind – bipedalism – must have evolved while our ancestors apparently occupied the same environment as the other apes.

Replacing the savannah scenario with a woodland one has been treated as a necessary but minor readjustment in the official story of human evolution. But this re-appraisal involves one major drawback. The strength of the savannah hypothesis lay in the fact that it offered possible explanations of unique human features such as bipedalism. The woodland hypothesis made this more difficult. We have a clear extant example of a ground-dwelling African ape: Adult gorillas walk on all fours in the forest, presumably because it has proved to be the most effective mode of locomotion in those conditions. Why then would a similar environment among the trees cause just one branch of the anthropoid apes to evolve along such different lines? The old question, "Why a naked biped?" - now seems further than ever from a solution in terms of the traditional scenario." [1]

Download Marc Verhaegen's power-point presentation which explains how the savannah theory falls apart.

Endurance Running / Persistence hunting

According to Wikipedia:

"The endurance running hypothesis is the hypothesis that the evolution of certain human characteristics can be explained as adaptations to long distance running. The hypothesis suggests that endurance running played an important role for early hominins in obtaining food. Researchers have proposed that endurance running began as an adaptation for scavenging and later for persistence hunting [2] ... a technique in which hunters use a combination of running, walking and tracking to pursue prey to the point of exhaustion. [3]

However, opponents of the theory point out that distance running animals are lightly built, with skeletons no heavier than necessary, whereas Homo erectus had thicker, heavier cranial and post-cranial bones skulls, twice as thick as a gorilla's and their bones were more dense. Furthermore, with a generally thicker cortex and narrower medullar cavity, the limb bones of Homo erectus were dense and heavy compared to Homo sapiens and other primates [4-9]. The extra weight created would have been an unnecessary burden for an endurance runner [10]. Long-distance human runners are lightly built compared to sprinters, and cursorial mammals such as dogs and horses do not have thick, heavy bones. Such heavy bones are very brittle (in other mammals & in human pathology). Most likely, if H. erectus had attempted to run long distance over open ground, he would have suffered fractures and exhaustion easily.

Kalahari bushman with GPS trackerEndurance running as an explanation of human evolution (why we lost our fur, started running on two legs, etc.) does not make much sense. Of course, a few people today run sometimes after kudus, but that doesn't mean that our ancestors would have done the same several million years ago. Whatever conventional "wisdom" tells us, long distance running is at best a very recent (Holocene, or perhaps late-Pleistocene) adaptation of some adult males (H.sapiens) a few isolated inland populations (E.Africa, Australia), with "modern" technology such as water containers, etc.

Another problem with the endurance running theory is that humans use eccrine glands for sweating, unlike almost all other terrestrial mammals, which pant or sweat from apocrine glands. Human sweating is profligate with both water and salt, meaning that we need to replace both if we engage in any strenuous activity or if we are exposed to hot temperatures. In fact, human beings need to drink more often than any other animal that lives on the savannah as we cannot consume much in one go and we waste so much. Therefore, running for hours or days across a hot arid landscape without ready access to water would in most cases be / have been fatal.

Homo sapiens also possesses a greater distribution of subcutaneous fat, a derived characteristic that would have been an extra burden of some ten kilograms for an animal reliant on endurance running; such adipose deposition is never seen in savannah predators. Compare, for example, the subcutaneous body fat levels in marathon runners vs. endurance swimmers. Furthermore, loss of sun-reflecting fur in an open, terrestrial environment would have increased the risk of overheating and sunburn since fur helps protect the skin from solar radiation [11].

Humans also have a shortened femoral neck, which could have been an adaptation to more efficient running, yet this feature first appears in Homo sapiens and is absent from earlier Homo species such as Homo erectus. This implies that erectus, with a relatively long and more horizontal femoral neck [12] was a less efficient runner than Homo sapiens. Also to be considered is that humans have a very small olfactory bulb [13] relative to apes [14], a significant flaw seeing as primary hunting predators or scavengers rely on their highly developed sense of smell. We also have a drastic and abrupt reduction of human masticatory muscles [15] unlike savannah carnivores such as dogs and hyenas that have well-developed masticatory muscles and use their excellent olfactory abilities to detect carcasses and prey.

Another important point as regards this theory: any evolutionary adaptation has to benefit all members of a species, regardless of gender. If our ancestors had evolved long legs for running after prey on the savannah, women carrying babies would have had to do it too, and in no extant persistence hunting human tribe does this happen - for obvious reasons. The only exception to this evolutionary preclusion would be epigamic (sexual selection) adaptations. If, as some endurance running proponents would have us believe, it was the males that went hunting while the females stayed at home with the babies, our species would have evolved differently as long-legged, bare-skinned, sweaty males and small, short-legged, furry females, but that is clearly not the case.

However we look at it, humans are poor runners capable of reaching speeds of only up to 20 km/hr over long distances, 36 km/hr over short distances. Some paleoanthropologists still believe that H.ergaster (Nariokotome Boy 1.6 Ma Kenya) had long legs for running over the savannah. The boy died in a swamp amid reeds, fish bones and hippo footprints, but since he had a tooth abscess, some paleoanthropologists speculated he might have had fever and gone into the swamp to cool off, where unfortunately he died. Long legs do not necessarily imply they evolved for running. Ostriches have relatively long legs, but flamingos have relatively longer legs. Our very long legs and bipedal stride are an indication for wading ancestors as with most birds and even probably dinosaurs.[16]

The walking / running theories of evolution have come about because certain features associated with human locomotion (pelvis, legs, spine etc.) are derived compared to apes, and because humans can run bipedally and apes can not, it may seem logical to assume these features must have come about as a result of humans running bipedally. However, humans can also tread water, swim and dive more efficiently than apes, and until these differences are also considered equally by researchers, any favouritism towards the above hypothesis must be considered incomplete.

As Elaine Morgan noted:

"In today's hunting-gathering tribes they don 't run after game but they might have done once. But they would have had to walk on two legs before they could run on them. Wading enforces walking on two legs. There is no other activity that regularly leads to bp walking in any ape. Running after game would be a consequence of being bipedal, not a cause of it. Running on four legs is faster." [17]


From: "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
C. Leigh Broadhurst1,*, Michael Crawford2 and Stephen Munro3

"The concept that early Homo populations may have hunted large mammals by running them to exhaustion has been criticized by Pickering and Bunn, who point to the fact that since large savannah mammals are considerably faster than humans, they would easily have been able to outrun any pursuing hominins, thus prey would soon be out of sight, meaning any successful pursuit would have required sophisticated tracking without utilizing visual contact. However, there is no evidence that early Homo populations had such tracking skills. Pickering and Bunn also note that the palaeo-ecology of early Homo sites would have been counter-conducive to successful tracking. Scavenging large mammals is another model, which has been discussed at length.

While undoubtedly a mechanism that was utilized, it is difficult to envision the entire human revolution based on this practice. African Plio-Pleistocene (5.33-2.59-0.012 Ma) savannahs were inhabited by numerous fast, efficient, well equipped predators and scavengers such as hyenas (e.g., Crocuta crocuta), felids (e.g., Panthera leo), hunting-dogs (Lycaon pictus) and vultures (e.g., Torgos tracheliotus), meaning there were no empty hunting or scavenging niches for early Homo populations. Early Homo could not have competed in terms of olfaction or running speed with hyenas, dogs and jackals; nor in visual identification and speed of arrival with vultures and marabou storks. Also no primate has the physiology or immune system of a carrion consumer, so relatively fresh kills would be obligatory for this model.

It is difficult imagining pregnant women, nursing mothers or children taking part in endurance running our scouting for fresh kills, so provisioning is an essential component of these models. Yet this implies that after consuming their share of the carcass, the scavenging or hunting party would then transport sufficient meat – including the nutrient rich but highly perishable organs – back to the pregnant women, nursing mothers and children. The most important item – the DHA-rich brain – would only last a day or two in the hot African sun.

Transporting fresh meat without pack animals or vehicles is costly in terms of extra weight, and greatly increases the risks of predator attack, and meat decay. Further, the rise in metabolism associated with increased protein digestion creates extra heat, and consumption of meat by the hunters would require increased water intake." [18]


REFERENCES:

1. Morgan, Elaine. Foreword to "Was Man More Aquatic in the Past? Fifty Years After Alister Hardy". Banthom ebooks.
2. https://en.wikipedia.org/wiki/Endurance_running_hypothesis
3. https://en.wikipedia.org/wiki/Persistence_hunting
4 Klein RG. The human career. Chicago: University of Chicago Press 1999.
5. Jacob T. Solo Man and Peking Man. In: Sigmon B, Cybulski J, Eds. Homo erectus: Papers in honor of Davidson Black. Toronto: University of Toronto Press 1981; pp. 87-104.
6. Mania D, Vlcek E. Homo erectus in middle Europe: The discovery from Bilzingsleben. In: Sigmon B, Cybulski J, Eds. Papers in honor of Davidson Black. Toronto: University of Toronto Press 1981; pp. 133-51.
7. Kennedy GE. Bone thickness in Homo erectus. J Hum Evol 1985;14: 699-708.
8. Rightmire G. The human cranium from Bodo, Ethiopia: Evidence for speciation in the middle Pleistocene? J Hum Evol 1996; 31: 21-39.
9. Wood B. The history of the genus Homo. Hum Evol 2000; 15: 39-49.
10. Verhaegen M, Munro S, Vaneechoutte M, Bender-Oser N, Bender R. The original econiche of the genus Homo: Open plain or waterside? In: Muñoz S, Ed. Ecology research progress. New York: Nova Publishers 2008; pp.155-86.
11. Schmidt-Nielsen K. Desert animals. New York: Dover 1979.
12. Ruff C. Biomechanics of the hip and birth in early Homo. Am J Phys Anthropol 1995; 98: 527-74.
13. Stephan H, Frahm H, Baron G. New and revised data on volumes of brain structures in insectivores and primates. Folia Primatol 1981; 35: 1-29.
14. Gilad Y, Man O, Pääbo S, Lancet D. Human specific loss of olfactory receptor genes. Proc Natl Acad Sci USA 2003; 100: 3324-7.
15. Stedman H, Kozyak B, Nelson A, et al. Myosin gene mutation correlates with anatomical changes in the human lineage. Nature 2004; 428: 415-8.
16. Marc Verhaegen, AAT group.
17. Elaine Morgan, AAT group discussions.
18. "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. C. Leigh Broadhurst1,*, Michael Crawford2 and Stephen Munro3


 
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