Aquatic Ape Human Ancestor Theory

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. 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

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Ear exostosis (surfer's ear)

Ear exosostisAural exostoses (surfer’s ear) provide vital fossil evidence of an aquatic phase in Man’s early evolution.

PH Rhys Evans1, M Cameron2
1Lister Hospital, London, UK
2East Sussex Healthcare NHS Trust, UK

ABSTRACT
For over a century, otolaryngologists have recognised the condition of aural exostoses, but their significance and aetiology remains obscure, although they tend to be associated with frequent swimming and cold water immersion of the auditory canal. The fact that this condition is usually bilateral is predictable since both ears are immersed in water. However, why do exostoses only grow in swimmers and why do they grow in the deep bony meatus at two or three constant sites? Furthermore, from an evolutionary point of view, what is or was the purpose and function of these rather incongruous protrusions?

In recent decades, paleoanthropological evidence has challenged ideas about early hominid evolution. In 1992 the senior author suggested that aural exostoses were evolved in early hominid Man for protection of the delicate tympanic membrane during swimming and diving by narrowing the ear canal in a similar fashion to other semiaquatic species. We now provide evidence for this theory and propose an aetiological explanation for the formation of exostoses.[1]

The relationship between auditory exostoses and cold water: A latitudinal analysis

GE Kennedy 1986 doi 10.1002/ajpa.1330710403 Am J phys Anthrop 71:401-415

The frequency of auditory exostoses was examined by latitude. It was found that discrete bony lesions of the external auditory canal were, with very few exceptions, either absent or in very low frequency (< 3.0 %) in 0–30° N and S latitudes and above 45°N. The highest frequencies of auditory exostoses were found in the middle latitudes (30–45° N and S) among populations who exploit either marine or fresh water resources. Clinical and experimental data are discussed, and these data are found to support strongly the hypothesis that there is a causative relationship between the formation of auditory exostoses and exploitation of resources in cold water, particularly through diving. It is therefore suggested that since auditory exostoses are behavioral rather than genetic in etiology, they should not be included in estimates of population distance based on nonmetric variables. [2]

Exostoses of the external auditory canal

JR DiBartolomeo 1979
Ann Otol Rhinol Laryngol 88 Suppl.61:2-20

Abstract:
Exostosis of the external ear canal is a disease unique to man. It has been identified in prehistoric man, affecting the aborigines of the North American continent. Aural exostoses are typically firm, sessile, multinodular bony masses which arise from the tympanic ring of the bony portion of the external auditory canal. These growths develop subsequent to prolonged irritation of the canal. The large, primitive jaw of prehistoric man placed great mechanical stress on the tympanic ring. Chronic aural suppuration seen in the preantibiotic era was soon followed by exostoses. Today, prolonged contact of the external ear canal with cold sea water is the most prevalent cause (aquatic theory). As a result the disease is now essentially limited to coastal regions. In this way we have seen exostoses appear in different stages of the evolution of man as a result of mechanical, chemical and now thermal irritation. The author is an otolaryngologist in a coastal region. In examining 11,000 patients during a ten-year period, 70 cases of symptomatic exostoses of the external auditory canal were identified. The incidence of exostoses was found to be 6.36 per 1,000 patients examined for otolaryngologic disease. It is a predominantly male disease. The development of these "irritation nodules" is painless until the tenth year of aquatic exposure to irritation, when symptoms of obstruction occur. The hearing loss associated with exostoses is usually a conductive type, secondary to occlusion of the canal by impacted cerumen or acute external otitis. The results of studying the thermal characteristics of the body of water used for such aquatic activities is presented. [3]

Ancient human genome from southern Africa throws light on our origins ― Garvan Institute of Medical Research

What can DNA from the skeleton of a man who lived 2,330 years ago in the southern-most tip of Africa tell us about ourselves as humans?
eafood diet: The complete 1.5-metre tall skeleton was examined by Alan Morris (biol.anthrop. Univ.Cape Town). Morris showed that the man was a "marine forager". A bony growth in his ear canal (surfer's ear) suggested that he spent some time diving for food in the cold coastal waters, while shells carbon-dated to the same period, and found near his grave, confirmed his seafood diet. Osteoarthritis & tooth wear placed him in his fifties.[4]

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Comment by Marc Verhaegen (AAT discussion group 30.9.14):
Thanks a lot, this confirms that still recently a lot of humans dived regularly for seafood. It doesn't mean that our aquatic adaptations ("AAT") were late-Pleistocene: AFAWK typically littoral features in Homo are apparently early-Pleistocene: coastal sites + marine shells, almost world-wide coastal dispersal, drastic brain enlargement, pachy-osteo-sclerosis, external nose, platycephaly (long & flat skull-caps), platymeria (dorso-ventrally flattened femora) etc. Many male neandertals had extensive & bilateral ear exostoses. This is sometimes used as an anti-AAT argument: "If they had been regular divers, they hadn't had these 'diseases'", but it only suggests they regularly dived in colder waters.


External auditory exostoses in the Xuchang and Xujiayao human remains:

Patterns and implications among eastern Eurasian Middle and Late Pleistocene crania Xujiayao 15 left temporal bone.A: lateral; B: inferior. Only the zygomatic process, the medial petrous tip, and small chips along the squamous suture are absent; a sutural bone was likely present anterosuperiorly. Scale bar: 5 cm.
Erik Trinkaus & Xiu-Jie Wu 2017 PLoS
Published: December 12, 2017
https://doi.org/10.1371/journal.pone.0189390

Abstract:

In the context of Mid- & Late-Pleistocene E-Eurasian human crania, the EAEs of the late archaic Xuchang 1 & 2 & the Xujiayao 15 early Late-Pleistocene human temporal bones are described.
- Xujiayao 15 has small EAEs (Grade 1),
- Xuchang 1 presents bilateral medium EAEs (Grade 2),
- Xuchang 2 exhibits bilaterally large EAE (Grade 3), especially on the right side.
These cranial remains join the other E-Eurasian later Pleistocene humans in providing frequencies of
- 61 % for 18 archaic human &
- 58 % for 12 early modern human samples.
These values are near the upper limits of recent human frequencies, they imply frequent aquatic exposure among these Pleistocene humans.
The medial extents of the Xuchang 1 & 2 EAEs would have impinged on their tympanic membranes, the large EAEs of Xuchang 2 would have resulted in cerumen impaction. Both effects would have produced conductive hearing loss, a serious impairment in a Pleistocene foraging context.

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Comment by Marc Verhaegen (AAT discussion group, posted 16.12.17):

Thanks for this very interesting article. It has become clear that human ancestors were no endurance-runners on hot and dry plains as still often
popularly assumed (google e.g. "original econiche Homo"), but that they always have been waterside (some references below), and that Pleistocene
Homo dispersed intercontinentally following African and Eurasian coasts and rivers, as proposed by the "Coastal Dispersal Model" (S. Munro) of
early-Pleistocene Homo: no wonder that part of their food came from the water (aquatic foods are extremely rich in brain-specific nutrients) and
that so many Pleistocene Homo skulls displayed external auditory exostoses (EAEs). Less expected in my opinion is that EAEs were still very frequent
in early Homo sapiens skulls about 100,000 years old, as shown in this article. This suggests that the genus Homo, until not very long ago, still
often relied on aquatic foods. Note that the possible complications of EAEs, such as cerumen impaction and hearing loss through air conduction,
were not disadvantageous in shallow diving (where hearing occurs though bone conduction), but could have protected the eardrum (tympanum) against barotraumata.

1. Goren-Inbar N. et al. 2014 "Beneath still waters - multistage aquatic exploitation of Euryale ferox (Salisb.) during the Acheulian" Internet
Archaeol. doi 10.11141/ia.37.1.
2. Joordens J. et al. 2009 "Relevance of aquatic environments for hominins: a case study from Trinil (Java, Indonesia)" J.hum.Evol.57:656-671.
3. Munro S. 2010 "Molluscs as ecological indicators in palaeoanthropological contexts" PhD thesis Austr.Natl.Univ.Canberra.
4. Stewart K. 2010 "The case for exploitation of wetlands environments and foods by pre-sapiens hominins" pp.137-173 in Cunnane S. & Stewart K. eds"Human brain evolution: the influence of freshwater and marine food resources" John Wiley, New Jersey.
5. Verhaegen M. & Munro S. 2011 "Pachyosteosclerosis suggests archaic Homo frequently collected sessile littoral foods" J.compar.hum.Biol.62:237-247.


 
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