6. The Heritages of the Chordate Phylum

6.2 Biological intelligence and survival

Some organisms endowed with a low degree of consciousness succeeded in living during millions of years without change. For example the species of horseshoe crab that lives on the Florida Gulf coast (see fig. 5.14) is 500 million years old. The species of sharks and mussels we observe today appeared 300 million years ago and the cockroach is 280 million years old. The turtles and crocodiles, which are more sophisticated species, have existed for the last 200 million years and the opossum for the last 60 million years. This stability is, however, much more the exception than the rule. In general, rapid change of an animal species is more common.

If transience of most individual species is well documented, it is also observed that, within each genus, the level of encephalization of the succeeding species composing the genus remains fundamentally the same for the time enclosed within a defined geological epoch or period. Brain size increase, indicating an increase in biological intelligence, often occurs in a discontinuous way and brain size remains thereafter stable for very long periods. Brain size increase and biological intelligence are not crucial for the survival of a species.

6.2.1 Biological intelligence

Animals which frequently move from one place to the other have to solve a major problem, that of orientation. Wherever they are, they must be able to reach their target. This applies to migratory birds, to insects such as bees which leave their beehive for several kilometers, to birds which go out to catch insects, to fishes which travel several thousand kilometers to spawn, to turtles which do the same, and is found in rare cases among domestic animals (cats, dogs) that have been abandoned several kilometers from their home.

For short distances, keeping a memory of the travel accomplished from the starting point solves the problem. Bees do so. In general, they remember their environment. Yet, for longer distances, they rely on the position of the sun, correcting the course automatically for the influence of wind and apparent displacement of the sun towards the West. In overcast weather, bees rely on polarized light. Nocturnal birds rely on the polar star or on the earth’ s magnetic field and also possess an internal clock and detect polarized light. Doves rely on the sun to find their way back and have an internal clock that makes them take in account the movement of the sun in the course of the day. Doves also possess a compass: they can measure the intensity of the magnetic terrestrial field and also can detect polarized light and ultraviolet-light. Doves might be able to measure the Coriolis forces. At the equator, the earth revolves at 1,700 km/ hour upon itself, while at the poles its revolving speed is negligible. This differential movement from poles to equator is detected in the direction taken by the whirling movement of water flowing out of a bathtub. In the Northern Hemisphere, the whirling moves counter clockwise and, in the Southern Hemisphere, like hurricanes, the move is in the same direction as the fingers of a clock. Finally and lastly, doves are credited by certain scholars with an incredibly sensitive olfactory system.

Loggerhead sea turtles migrate around the North Atlantic, encountering different magnetic fields en route. The turtles detect these fields, like boundaries, and use them to stay on course, wherewith they may travel over thousands of miles with remarkable precision. By recognizing and responding to regional magnetic fields, hatchlings with no prior experience make their way to the sea, avoid fatally cold water and make their way across oceans. The small turtles of Uzbekistan, which room over 20 hectares, for males, and 40 hectares, for females, know perfectly their territory, which is recognized solely by smell.

Zambian mole rats dig underground tunnels that stretch 200 meters or more and build a nest at the end. They consistently position the nests in a southerly direction, changing the location of the nests in accordance with a shifting magnetic field. Birds, fish, crustaceans and other animals appear to use regional variations in the magnetic field, to navigate. Other animal species emit and detect ultrasounds (dolphins, bats). Seals follow their prey in muddy water by the vibration of their whiskers. Various animal species perceive their surroundings in other ways than humans do, by means that are totally alien to us.

The world, as Humans perceive it, is different for other animal species. This is also true for human beings pertaining to different human cultures and civilizations, who interpret a reality in different ways. The world is a creation of our nervous system.

We perceive the external world through the intermediary of various sensory organs. In Humans, information is received mainly through the eyes and ears. Other animal species have a different eye system and get different information about the external world. Still other species rely mainly on the perception of chemical substances. They construct a world different from our own and we in turn miss something since we are unable to smell but in a rudimentary way and fail to appreciate the significance of subtly different odors. The brain works from the stimuli it receives, to create a model of a possible world.

Biological intelligence is a measure of the quality of the particular world created by a particular animal species. Biological intelligence is the capacity to construct a perceptual world in which sensory information from various modalities is integrated in the brain as information about objects in space and time. This intelligence is most elaborately developed in the primates, which are characterized by an enlargement of the brain superior to that of any other mammal, except the cetaceans, and the development of learned behavior mechanisms that culminated in man with the capacity for imagery, language and culture.

Animals deprived of a nervous system or endowed with only a rudimentary system may subsist without any creation of a world. These animals respond without pliancy or flexibility to external stimuli. Their behavior is bound to specific stimuli by fixed action patterns of responses. The majority of the animal species on this earth responds to stimuli in such a fashion. Within the chordate phylum itself, this response is the preferred type even among the most intelligent species of the evolved bird class. Only among mammals has biological intelligence reached its highest level and been transformed into a unique human intelligence. Until this highest level is reached, biological intelligence will remain only one of several dimensions of behavior and will not be the most important for survival.

6.2.2 Brain size and species survival

The hominids are only one evolving line amongst several that evolved towards a superior organizational level. Among the mollusks, we have the squid; among the arthropods, we have bees; among the birds, we have the parrot, the canary and the myna bird; among cetaceans we have the killer whale (Orcas) and the dolphin, etc. This trend towards a refinement of the nervous system was however not “per se” an assurance of survival until it had been refined to the point that it may serve an entirely new purpose. Biological intelligence and survival are not necessarily linked. The survival potential of the genus “horse”.

Figure 6.4. depicts the fate of the genus “horse”.


Figure 6.4. Genealogy tree of the genus “horse”. In this figure, an attempt was made to depict the fate of the genus on three continents. The bulk of the evolution took place in North America. At least 24 evolutive lines were pursued. The size of the brain of some members of the genus has been schematically represented.

Eohyppus, the ancestor of the horse, is a small animal about 30 cm high at the shoulder. It was found 58 million years ago during the Eocene period in Europe as well as North America. This indicates that the two continents were linked at that time. This animal had 4 fingers on its forefeet and 3 fingers on the hind feet. It was decidedly a forest dweller. Three evolutive series appeared thereafter in Eurasia. They were all three doomed, the most successful disappearing during the Oligocene period, 40 million years ago. In North America the genus developed during the same Oligocene period into Mesohyppus that was slightly smaller than a lamb. Mesohyppus had three fingers on all feet and was still a forest dweller.

During the Miocene period, 29 million years ago, we witness an explosion of new forms. One series (Anchiterium) developed in the Old World and disappeared immediately at the end of the Miocene period. All the other forms developed in the New World, the majority of them continuing well within the Pliocene. These forms left the forest for the plain.

Only five series continued within the Pleistocene period, a million years ago. The three South American groups and the Old World offspring disappeared, while Pliohyppus, now changed into the modern horse, populated the North American continent and invaded South America and Eurasia through Beringia. In the New World, the form died out during the Holocene period, less than 10,000 years ago. The disappearance of Beringia prevented its return there. In 1519, Cortes took with him 16 horses to Mexico and the species so reintroduced in the North American plains found again favorable conditions to thrive and multiply.

Five times in 58 million years has the genus “horse” invaded the Old World. The four first times, it failed to adapt and survive. If the Bering straits had not been crossable during the Pleistocene period or if the horse had not been at that time willing or able to cross them, we would nowadays be without horses. This genus is presently represented by 6 species3. During the 60 million years that this genus was in existence, it pursued 24 evolutive lines on three continents. Only one was fortunate enough to survive until today.

The brain of the first true horse, Eohyppus, was very primitive. The next representative of the series – Mesohyppus – has a brain of a remarkably greater size. From then on in the course of time, the brains increase in size in a rather orderly and logical fashion. Thus, whereas Eohyppus has a brain similar to that of the most primitive marsupials, it develops extraordinarily later on.

Eohyppus, the first true horse, definitively without a big brain, was as able as his descendant living 57 million years later to migrate to another continent. With its small brain, Eohyppus managed to survive a longer time than its most recent offspring, i.e. about 10 million years instead of three. Eohyppus was on the North American continent at the origin of a long series of new evolving species of which the modern horse appeared to be a dead issue since this modern horse disappeared totally from that North American continent within 2 million years. It was rescued from doom only because a bridge appeared between Alaska and Siberia that allowed a timely passage towards Asia.

The increase in brain size of the phylum took place most spectacularly at the moment the genus left the forest for the plain. It was thus presumably developed in order to provide better coordination of locomotion and was in the meantime a consequence of the development of the genus into a “runner”. The phylum had at its disposition an organ, the brain, that might potentially help it to adapt snugly to its new environment, the plain, and the genus used it. The development of the brain in this case was thus a predisposition to “fit in” better into the environment. When the environment changed at the end of the Pleistocene period, the species was virtually wiped out and was maintained only by the grace of Holocenean geography. It is thus apparent that evolution may produce animal species endowed with increasing levels of conscience without however granting them a more secure life expectancy. This is observable within the human species also: brains are not the most important for survival, nor are they in high demand. In primitive cultures, all that is asked from various members of a community is a reasonable level of consciousness. The accent in education is then put on character (see the Roman and Spartiate educative systems), not intelligence. In contemporary cultures, the most intelligent men are rarely the most successful. They are usually found in Universities (Einstein, Oppenheimer, the vast majority of Nobel Price winners), where their disruptive way of thinking is supposed to be harmless. The survival potential of the hominoids

It can be argued that the increase in consciousness – every time there appears one – is not of such a magnitude that it would grant its possessor a definitive advantage in its struggle for life among its rivals. If one analyzes the fate of those mammals whose evolution was mainly directed at an increase in the size of the brains, namely the hominoids, the record is not much improved. The survival edge they should have over other animals due to their unquestionably superior intelligence does not exist. Disregarding the monkeys whose intelligence level is still low, we have presently living as great apes, our hominid cousins the gorilla, the bonobo and the chimpanzee in Africa. The orangutan, in the island of Borneo, is not so amenable to learn. Less intelligent still is the African gibbon. That is all, and of these, only a few thousand subsist. All the other hominids, presumably endowed with higher levels of consciousness than the gibbon (the Man from Makapan, Swartkrans, Java, Peking, Olduvai, Neanderthal) disappeared between 2 million years and one thousand years ago. Biological intelligence is thus not the most important parameter for the survival of a species.


3. The horse, the donkey, the Equus hemionius, which is an Asian donkey, and the zebra, itself composed of three species.

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