The Utopian- A rEvolutionary Blog

In the halls of academia researchers are often more concerned about protecting their intellectual property than publishing the truth. Blogging offers a way to respect previous research, mine the information glut, and quickly publish the results. This blog is an experiment in gathering, documenting, associating, and presenting important information about human evolution using only a browser, the internet, and copy/paste techniques. These are not "my" words. I am only the editor.

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I have a BS degree in Wildlife from O.S.U. but most of my education comes from self study. I don't watch much TV because I don't think subjecting myself to all the materialistic and social propaganda is healthy. You can't view the world clearly if you put blinders on. My conclusions about the literature I cite on this website will be confined to the comments section. Please read those comments if you want to see the insights I have gained from my personal study. An interesting thing happened when I began this experiment. I discovered that bolding the important points of the research I was citing produced a rough summary of the information I could scan quickly, and also provided a easily referenced outline I could use to associate data from different sources using multiple browser windows. This led to a number of personal insights. Learning how to use blogs to data mine effectively can contribute greatly to the spread of global knowledge, and reduce the "information glut" that has accumulated.

Saturday, February 12, 2005

Wading for Food: The Driving Force of the Evolution of Bipedalism?

"The recent discovery of sahelanthropus tchadensis has brought into focus once more questions about the factors which may have led some ape clades to begin to evolve those most distinguished human traits: large brain size and bipedality. This find, the oldest putative hominid yet, as well as recent nutritional studies have both strengthened the idea that human evolution occurred in water-side rather than arid, open savannah grassland habitats."

"Evidence is accumulating that suggests that the large human brain is most likely to have evolved in littoral and estuarine habitats rich in naturally occurring essential fatty acids. This paper adds further weight to this view, suggesting that another key human train, our bipedality, might also be best explained as an adaptation to a water-side niche."

"Evidence from apes in the wild show that though preferring to keep dry, they do go into water when driven to do so by hunger and tend to do so bipedally. A new empirical study of captive bonobos found them to exhibit 2% or less bipedality on the ground or in trees but over 90% when wading in water to collect food."

"The paleo-habitats of the earliest known bipeds, and all the evidence reviewed here (as is that of the newly discovered Sahelanthropus), is consistent with the hypothesis that wading contributed to the adaptive pressure towards bipedality."

"One tricky question remains: If a water-side habitat was the original driver both for a bipedal way of locomotion and for an increase in brain size, why did bipedality evolve so much earlier than large brains? The large brain capacity of Homo is a, relatively, recent phenomenon according to the fossil record and only really begins with Homo erectus and then accelerates more recently with Homo sapiens. If hominids have been living in water-side habitats all along, why did larger brains not evolve long ago?"

http://allserv.rug.ac.be/~mvaneech/Fil/Verhaegen_Language_
SpeculationsScienceTechnology.html

The aquatic ape theory (AAT) of Sir Alister Hardy (1) states that a few million years ago human ancestors spent a considerable part of their day swimming and diving in a river, lake or sea, and, at least partially, consumed aquatic food. The AAT is supported by the presence of our thick subcutaneous fat layers, by our lack of body hair and by several other features that are absent in non-human primates, but widespread among aquatic mammals (1-13).

The ability to speak is a uniquely human characteristic. Innumerable attempts to explain it have been made but the question of how language emerged is not yet solved. Recently, it has been suggested that the origin of speech was facilitated by our aquatic past (5,14). All aquatic mammals "voluntarily" control their breathing. When surfaced they open the airway passage whenever they want to inhale air, and they can hyperventilate and then close the airway passage when they intend to dive. The subtle "voluntary" control of breathing and airway closure in mammals in general is a pre-adaptation for speech (15,16).

Aquatic mammals can close the airway entrances much more completely than land mammals, thus avoiding being drowned by water entering the lungs, and they have a very refined voluntary control of mouth, nose and throat passages.

Modern man has a very special anatomy of the airway entrances that is not incompatible with a previous semi-aquatic lifestyle. He has a smaller mouth which can be closed more efficiently (24) and, presumably, the wet mucosa of our fleshy lips allows a better fit than the dry skin of the lips of non-human primates. In other primates, the tongue is generally flatter and somewhat less mobile than in humans (ref. 16, p.625). Our nasal cavity is elongated by an external nose (ref. 25, Figure 159) and narrowed by strongly developed inferior conchae, which often cause even complete obstruction in some humans (11,26,29). The nasal cavity can be disconnected from the throat by muscles that raise the velum (probably also in apes) (5).

Our primary motor projection cortex is much larger than that of apes, mostly due to the expansion of the areas for the musculature of mouth, throat and breathing, i.e. the latero-inferior section of Area 4 (see Figure 1). Just in front of that enlarged Area 4 lies Broca’s Area. It is a typically human structure indispensable for speech generation, and can be distinguished histologically from all other human cortical areas (ref. 30, pp.5-12).

In order to use the voluntary airway control for the vocal apparatus, our ancestor must have been able to register and interpret his own sound production (feedback, cf. motor theory of speech production) (31,32). This was certainly improved by the evolution of the arcuate fasciculus (see Figure 1), a typically human neural pathway between Broca’s Area and Wernicke’s Area (33).

Compared with a chimpanzee’s brain, our association areas are enormously large. These areas are found in the temporal, preoccipital, parietal and inferior frontal lobes (see Figure 1). The cortex of these areas can be distinguished histologically from the other cortical areas and even from Broca’s Area (ref. 30, pp.5-12). This suggests that Broca’s Area and the association areas evolved separately (respectively in Phases II and IV?). In my interpretation, most association areas evolved after the breathing and air-holding function of the enlarged Area 4 and Broca’s Area had been integrated with sound generation (Phase III). The new association areas amplified the possible applications of the sound-producing apparatus.

There are indications, I think, that our ancestors returned to a more terrestrial habitat not earlier than two million years ago (in a cooler and drier period of the Pleistocene? see ref. 11). In the hominid fossil record, the great expansion of the association areas seems to begin about two million years ago, with the genus Homo (34,35). The limited brain enlargement of Homo habilis could correspond broadly with the enlargement of Area 4, Broca’s area (34), the arcuate fasciculus and Wernicke’s Area; that of Homo erectus with a further association cortex enlargement.

The relatively small size of the brain of the australopithecines (possibly without a real Area of Broca (34)) could be explained by their dwelling or having dwelt in inland semi-aquatic habitats (e.g. gallery forests), and not in littoral habitats (11). If early Homo lived at the sea coasts, he had to dive deeper and longer than his freshwater cousins, so the voluntary control of this airway muscles became more important. Brain enlargement is a striking feature of many cetaceans. Conceivably, the support of the body (and brain) weight by the surrounding water allowed sea mammals to obtain large brains.

Concerning the relation of language and thought, I assume that a simpler (non-verbal) sort of thinking already existed in our pre-aquatic ancestors, but the great unfolding of human cognitive abilities became possible only after the acquisition of proper input/output organs for the brain. Hence, our great communicational capacities may not have evolved thanks to our large brain; rather the opposite seems true: large association areas only became usable with our voluntary sound production.

3 Comments:

Blogger Mr_Proteus said...

I like this theory and the reasoning behind it. My anthropology course in college (about six years ago) never mentioned this possibility, but it deserves some investigation.

It seems anthropologists are too narrow-minded at times. They neglect many factors in human behavior, such as climate, modern ape behavior, and simple human compulsion. Why couldn't proto-humans have waded in shallow water to find food? Or just to play, socialize or compete against each other?

I definitely have to visit here more often.

7:44 PM  
Blogger The Utopian said...

As a wildlife biologist I found the idea of humans evolving near water appealing, since it is common knowledge that many wildlife species take advantage of "the edge effect". Even today, the vast majority of humans live along coastal areas.

Consider also that some of the most successful species in the ocean, the whales and dolphins, are mammals like ourselves who spent some time on land and then migrated to the ocean. A very interesting reoccuring pattern of evolution is being revealed I think.

The question of why our brain size lagged behind bipedalism if the two evolved due to an aquatic influence is a very important question. It can be answered satisfactorily by the theory proposed by Marc J. M. Verhaegen however, and solve some puzzling questions about how human speech developed and why we are hairless at the same time. No other hypothesis answers so many questions about our human evolution as the Aquatic ape theory.

Bruce Lahn's genetic study demonstrated the huge amount of selection pressure required to account for our human evolution, so it should not be a surprize if our evolutionary history turns out to be very spectacular compared to other species. Multiple migrations out of coastal regions of Africa into the drier interior regions of multiple continents may have been exactly what was needed.

8:34 PM  
Blogger QrazyQat said...

Hi, my name is Jim Moore, and I've studied the evidence offered for the aquatic ape theory for over a decade, and I have a site critiquing it. I've found it to be chock full of errors of various sorts in all its various forms. My site can be found at http://www.aquaticape.org and has been used as a source by The Straight Dope, for an article in last October's Fortean Times, and by several college courses -- plus of course just plain folks interested in facts.

The aquatic ape idea in any of its various forms is very much a fringe idea at best, and it is argued for with phoney "facts" and misconceptions about evolution, as well as more than a touch of what seems to be outright dishonesty (it could be major ineptness instead, but that's small comfort). The proponents ignore contrary evidence, even when it's in the same sources they cite -- sometimes on the same page as things they cite! They also have a habit of misquoting people and altering quotes -- both are major no-nos of course.

On the 92% figure you quote from Algis' site, I notice you didn't see, or didn't report, that this was 92% of 37 seconds total for 9 ocassions over 3 days. This is a problem for several reasons, one of which is that he doesn't mention as prominently that those same bonobos were bipedal on land more than 4 times as much. Another of course is that 37 seconds for nine ocassions isn't much wading at any one time, yet he obviously considers this to be an example of a major selection pressure. Now it's not that 37 seconds itself isn't interesting and not worthy of reporting -- it's just that Algis has made rather too much of it, and also ignored several important questions he should've asked himself before he even got to the point of writing it up.

Most important is that when he looks at the amount of time in water that his subjects were bipedal he gets a number that's far greater than any other study; several times larger than the next largest percentage (which was about 24%; other studies have shown less than that). This cries out for examination as to why, but he doesn't do that. When you do a study where one of your measures is way off the graph, it doesn't necessarily mean that the measurement is bogus, but you have to ask why -- why is it so far out of line with everything else. There are several possibilities I can think of but these were apparently never examined; Algis didn't seem to ask himself this question. For instance, is it because the bonobos were getting food? we know that food-getting is a major factor in bipedality; in fact Algis is aware of this, or should be (in fact in one case he mentions the bonobo in question was bipedal on land just before entering the water -- he was begging for food). Is it due to some factor around the way the moat they waded in was constructed -- the slope of the sides or how slippery it was or anything like that? Was it something else? we don't know for sure and Algis apparently just didn't bother looking at that even though that is a question that should immediately spring forth when you measure something and get a number that's so wildly out of place compared to other studies.

BTW, the same is true of the number gotten for bipedality on land in Algis' study -- is it similar to what you'd expect in a wild population or is it under the value you might expect? For instance, Hunt's study shows a very large part of bipedality used in feeding, but in captivity the feeding is far different than in the wild, so we might well expect there to be far less bipedality used in feeding in captivity -- this would mean the amount of land-based bipedality could well be greatly underrepresented in a study like Algis'. This too he seems to have left unexamined.

This is typical of AAT research, in my experience; selective reporting of facts, ignoring unwanted data, and sometimes just making things up. BTW, Algis also has a critique of some of my site on his, and although I haven't tackled a detailed critique of that I have seen enough to know that most is similarly distorted -- check it out, and my site, for yourselves and see.

Here's a couple direct links as well; you may have seen the "AAT Leaflet" around the web which lists supposed aquatic characteristics; I have an annotated version which corrects the errors in it http://www.aquaticape.org/leaflist.html. My latest addition is a critique of the recent BBC Radio 4 show by David Attenborough (http://www.aquaticape.org/bbc4_notes.html).

12:26 PM  

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