Symposium Water and Human Evolution April 30th 1999 University Gent Flanders Belgium Proceedings Australopiths wading Homo diving http allserv rug ac be mvaneech Symposium html http www flash net hydra9 marcaat html Marc Verhaegen Stephen Munro 23 July 1999 Abstract Asian pongids orangutans and African hominids gorillas chimpanzees and humans split 14 10 million years ago possibly in the Middle East or elsewhere in Eurasia where the great ape fossils of 12 8 million years ago display pongid and or hominid features In any case it is likely that the ancestors of the African apes australopithecines and humans lived on the Arabian African continent 8 6 million years ago when they split into gorillas and humans chimpanzees They could have frequently waded bipedally like mangrove proboscis monkeys in the mangrove forests between Eurasia and Africa and partly fed on hard shelled fruits and oysters like mangrove capuchin monkeys thick enamel plus stone tool use is typically seen in capuchins hominids and sea otters The australopithecines might have entered the African inland along rivers and lakes Their dentition suggests they ate mostly fruits hard grass like plants and aquatic herbaceous vegetation AHV The fossil data indicates that the early australopithecines of 4 3 million years ago lived in waterside forests or woodlands and their larger robust relatives of 2 1 million years ago in generally more open milieus near marshes and reedbeds where they could have waded bipedally Some anthropologists believe the present day African apes evolved from australopithecine like ancestors which would imply that knuckle walking gorillas and chimpanzees evolved in parallel from wadingclimbing aquarborealists After the human chimp split some 6 4 million years ago our ancestors could have stayed at or returned to the Indian Ocean shores where they elaborated their shellfish eating tool using beach combing and wading diving skills From here the different Homo species could have colonized Africa and Eurasia by following the rivers as bipedal omnivores Homo erectus crossed Wallace s Line and reached Flores before 0 8 million years ago and the earliest erectus fossils are found in beaches and swamps from Java to Georgia and Kenya 1 8 1 6 million years ago Voluntary breath holding an essential requirement for diving probably facilitated the evolution of human speech Symposium Water and Human Evolution April 30th 1999 University Gent Flanders Belgium Proceedings Key words Hominid evolution bipedalism speech origins dryopithecines Australopithecus Homo erectus aquatic herbaceous vegetation enamel microwear stone tools Introduction There is a strong belief within certain sections of the anthropological community that australopithecines were ancestral to humans and that the ancestors of chimpanzees and gorillas are not represented in the African fossil record Evidence suggesting that australopithecenes were bipedal such as fossilized footprints and skeletal remains is often used to support this hypothesis Of course this hypothesis is based partly on the assumption that chimpanzees and humans descended from ancestors that were not yet bipedal and that bipedalism only emerged after the ancestral lines leading to chimpanzees and humans had separated A popular theory once held that bipedalism emerged when human ancestors moved out of the forests into a more open and arid environment We believe however that an alternative hypothesis may be more accurate namely that the australopithecines were no closer to the ancestral line leading to humans than they were to the ancestral lines leading to the African apes Further we believe the common ancestor of humans chimpanzees and gorillas was already at least partly bipedal regularly wading in flooded forests such as coastal mangrove forests Gorillas and chimpanzees according to this hypothesis evolved knuckle walking features independently in parallel after moving from the coast to the African interior via rivers and gallery forests Humans on the other hand descended from a hominid population that remained nearer the coast and which gave rise to efficient waders and divers and eventually to the various species of the Homo genus some of which later returned to a more terrestrial lifestyle This hypothesis in our opinion helps explain many unique human adaptations including the development of human tool manufacturing skills and the origins of speech Hominid fossils and scenarios Symposium Water and Human Evolution April 30th 1999 University Gent Flanders Belgium Proceedings The evolutionary history of all animals including our ancestors has been influenced by a number of environmental factors Thus we believe many evolutionary insights can be gained by comparing the parallel and convergent adaptations of different animals in similar environments In fact we believe evidence gained from comparative anatomy and physiology of living species is as important to evolutionary studies as fossil evidence The fossil record displays well known shortcomings It is biased and incomplete For instance it could be possible that hominids living in certain environments were less likely to leave fossilized remains than hominids living in other milieus More specifically geologists note that fossilization is extremely difficult in mangrove areas because tidal water movements spread the bones over a vast area and the high acidity of the water dissolves the bony remains Moreover in mangrove areas the sea floor is flat so there is almost no chance that a landslide would ever cover remains Because of the scantiness of the fossil record paleontologists now generally accept the late Colin Patterson s view that the direct ancestors of living species are unlikely to be found within it Nelson 1998 As a result it is probable that most if not all fossil hominid species found to date are simply extinct side branches of the lines leading to the present living hominids In part it was this likelihood that led us to be extremely cautious about using the fossil record as the sole basis for attempting to develop a viable hominid family tree Instead we adopted the practice of assembling and considering all the credible available evidence in a comparative and systematic methodology While the totality of the evidence remains incomplete the multiple cross checking process does produce a cautious confidence in the tentative scenarios it suggests Primate locomotion Most primates are four legged tree dwellers with very
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