The reason why we have such great difficulty acknowledging that additionally formed organs are inseparable from our bodies goes beyond the physical distance between us and these units. Two further considerations play a role here: the mismatch in building materials and the entirely different genesis. Every organ in the human body – and in all other organisms – consists of variously differentiated cells or, as in the case of our fingernails, of products these cells secrete. Tools and machines, however, are made largely of metal, buildings typically of natural stone or concrete. Moreover, rather than being built by the organism itself, most of the additional organs of hypercell organisms are purchased from others. Perhaps these differences do in fact justify a principle distinction between additional organs and their cellular counterparts. In order to resolve this issue, it is again useful to take a look at the materials making up the organs of a broad range of organisms and to examine their genesis.
Even the lowly unicellular organisms have representatives that use both building blocks of their own manufacture and environmental material to form organs. The closely related species Amoeba euglypha and Amoeba difflugia are an instructive example. Both inhabit moist soils, often even in the same area (for example Sphagnum moss in moors). Most amoebas "flow around" the organic particles that make up their food and incorporate them into their bodies. A. euglypha and A. difflugia, however, which belong to the thecamoebas, form an urn-shaped case into which they can retract almost completely when they sense danger. They crawl around the bottom by stretching their thread-like "feet" or filopodia out from their case; they also use these projections to grasp food items, which they draw back into the case and incorporate into their bodies. Case formation in the two species, however, differs considerably. S. euglypha produces tiny silica platelets from metabolic products of digestion and transports these to its outer layer. Here, they are firmly cemented to one another by a sticky secretion termed pseudochitin. The result is a rigid case wall formed of relatively uniformly sized plates. A. difflugia, on the other hand, takes suitably sized sand grains up with its food; these are also shifted to the outside and glued together with pseudochitin to form a rigid case. Externally, these two very dissimilar protective structures closely resemble one another (Fig. 2A). Their rigidity is no doubt also comparable: the only difference is that one is composed of self-made platelets (A. euglypha), the other of freely available environmental material of approximately the same size (A. difflugia). Does this make the armor of A. difflugia any less an organ of this animal, merely because it isn’t composed of self-produced units?
Multicellular organisms provide the next few examples, specifically the larvae of caddis flies that abound in our streams. We have already examined one representative of this group, namely the species that uses filaments to construct funnel-shaped traps.
Fig. 2: Two examples of how fundamentally different material components of additional organs can be. A shows two amoeba species that produce protective cases into which they retract when threatened. Amoeba euglypha (a) uses silica platelets for its house: these are formed within its own body, transported to the outside, and firmly cemented together with a sticky secretion it produces itself. Amoeba difflugia (b) produces a very similar armor by using its pseudopodia to take up suitably sized sand particles with its food; it also transports these to its outer surface and then rigidly cements them together with a self-produced cement. The fact that both species often inhabit the same biotope is proof that both types of case are equally effective. Even at the level of unicellular organisms it is clearly inconsequential whether organs consist of the body’s own building blocks or of environmental materials.
B: Hermit crabs use empty snail shells as a protective organ
for the hind part of their body. Some species even transplant sea anemones
onto their shells for additional protection against sea stars. The snail
shell, which serves as a protective organ for the crab, was produced by
another animal; the sea anemones - as protective organs - are entirely
separate living organisms. Both examples clearly show that the material
and genesis of organs is irrelevant: the ability to fulfil necessary functions
is the key criterion.
Most caddis fly larvae, however, use their silk threads
to fabricate protective tubes into which they retreat when threatened,
much like the amoeba species retract into their cases. In order to strengthen
the delicate yet sturdy tubes that they carry about with them, they fortify
the silk network with sand grains, small stones, plant debris, tiny snail
shells, small twigs and other environmental materials. All of these elements
are attached to the tube with threads. Specialists who collect such tubes
can often assign them to a particular species based on their composition.
The larvae therefore demonstrate innate preferences in their tube-building
activity. Some species that use plant stems cut these into equally long
strips with their jaws; these strips fit more snugly up against the silk
tube and form a more tightly-knit protective sheath. This once more raises
the question: do these types of armor, which tightly enclose the body but
are not fused to it, represent organs of the animal or not? In snails,
which secrete calcium to form the protective shells into which they retreat,
no biologist has ever questioned this. The shell is an integral part of
the snail’s body and a very important organ indeed. The caddis fly’s tube,
however, is largely formed by adding layers of environmental material.
In many ways they already foreshadow the clothes that humans fashion of
natural materials.
The cell as a material component
At this point we need to discuss the inherent advantages and disadvantages of cells at the transition from uni- to multicellular organisms, when they relinquished their individual freedom as separate organisms and became building blocks of larger life forms. Bear in mind that when the cell assumed this new role, it already had a more than 2-billion-year-old history and had achieved an extraordinary level of efficiency and differentiation.
With only a single exception, which we will return to later, no building material other than the cell offers so many advantages and is capable of taking on such a wide range of tasks. We only need to recall that, in the multicellular body, practically the very same unit forms both the muscle and bone tissue, both nerves and kidneys, sensory organs and red blood cells. As white blood cells they still largely retain their independence, roaming through the body and disposing of wastes; after loading themselves up with toxins or pathogens that have breached the body’s defenses, they can even "commit suicide" for the good of the overall organisms by leaving the body as pus. Furthermore, building material, the cell is largely self-maintaining; in the event of damage, it even assumes a self-repairing function. When the need arises, cells can often re-differentiate themselves. This is the case when muscle cells transform themselves into bone cells or when connective tissue cells develop into cells that form blood vessels. A salamander can fully regenerate a limb lost due to injury. Even if all the bone has been lost, the remaining tissues give rise to new bony tissue through re-differentiation. Science has largely clarified the mechanisms that enable cells to transform themselves into such widely divergent structures and to take on such disparate roles. There is no need to delve into this matter here. We merely need to note that, as material components of larger living organisms, cells develop a diversity that borders on the miraculous.
These eminent advantages, however, are balanced by quite considerable disadvantages that have received much less attention in light of the cell’s stature as a living wonder. The first minus is that each cell – each individual building block – must be supplied with energy and substances, necessitating a highly intricate blood circulatory system. This requires countless, ever-branching tubular ducts along with one or more pumps to power circulation. A shot through the heart kills a human being almost instantaneously because this material component can no longer fulfil its task. At the same time, all the waste products formed during cell metabolism must be removed because they impair the cell’s abilities. In the human body, as in all higher vertebrates, this task is also largely left to the circulatory system; the process does, however, require further supporting organs such as the kidneys and the excretory ducts for the toxic substances. While the cell may be an exceptionally versatile building block, it very clearly does place considerable demands and entails commensurately high costs. This also means that cells cannot form organs that are not served by the circulatory system, and clearly none that are separate from the body either.
Organs whose function relies on not being permanently attached to the body – such as the spider’s web and most additional organs of humans – cannot be built of cells. This raises the inevitable question: is the process we refer to as "life" by definition tied to specific material components – even if other materials significantly boost capability? In my opinion this is an untenable position.
The cell as an efficient building material suffers from a further, no less grave disadvantage: this highly differentiated unit cannot tolerate higher temperatures. This helps explain why both uni- and multicellular organisms never developed organs or organ parts composed of metal, which would have required high smelting temperatures. On the other hand, additionally formed units that are separate from the body, like a forge or a blast furnace, do enable metals to be worked. This very process led to the development of those capable entities – human beings – that have so extraordinarily boosted the evolutionary process. The major industrial production and transportation systems are a case in point. None of these organs of hypercell organisms and their organizations could ever have developed via cell differentiation. We are once again confronted with the question of whether our definition of "life" need necessarily be restricted to cells and their products or whether perhaps less importance should be attached to this efficient building material.
In the case of crystals, growth is in fact dependent on the steady accretion of certain building blocks. Organisms, however, are physical structures that must exhibit certain capabilities in order to survive and reproduce. From this perspective it is difficult to understand why they should be conceptually bound to specific material components. Should other materials enable even greater capabilities, then natural selection, which can only evaluate results, will certainly not reject them.
These divergent strategies are already foreshadowed in
the two above-mentioned amoeba species and the caddis fly larvae. From
a functional standpoint, A. euglypha leads to all those organisms
whose material components are restricted to cells. The other path leads
via A. difflugia to all those organisms that also use foreign elements
to build their organs and that, ultimately, either form or otherwise procure
organs that are separate from the body. The list of weighty drawbacks that
cells have as building blocks for larger units will be extended later in
the book by a number of other examples. The two mentioned above suffice
for the time being.
The procurement of organs
During the course of my film activities in coral reefs, I often had the opportunity to observe the delicate longnose butterflyfish (Forciper longirostris). I followed this fish over great distances and used time-lapse techniques to show how they used their elongate, tube-like snout to probe the spaces between coral branches and pick at the small snails, crustaceans and other tiny invertebrates hidden there. This species, which is related to forms with short, pointed mouths, very clearly demonstrated to me the evolutionary pathway of this unusual feature. In foraging for food, one group had a decisive competitive advantage: those individuals who – through genetic variability due to mutation and recombination – had a longer and more pointed mouth. They were able to extract prey from cracks that were inaccessible to conspecifics and other competitors. Over millions of years, this selective advantage, as unspectacular as it may seem (and promoted by other changes in the genetic makeup) led to an increasingly elongated mouth. In the true Darwinian sense, a series of small steps yielded highly adapted forms. Thanks to this selective advantage they successfully reproduced and gradually gave rise to a new species. Similar trends can be observed in certain bird species. The very long, thin beak of the wall creeper (Trichodroma muraria) and sword-billed hummingbird (Ensifera ensifera), for example, helps them to extract small prey items hidden in rock cracks or to suck nectar from flower cups . This mode of feeding is difficult if not impossible for other species. On the other hand, these birds – much like the longnose butterflyfish – are at an advantage only when such special food niches actually exist. Were such highly adapted birds driven into the desert by winds, or such specialized fishes carried off to flat, sandy bottoms by currents, then their chances of survival would be limited. A further disadvantage is that the beaks of the former and the jaws of the latter are poorly suited defense organs against predators.
During his 5-year voyage on the research vessel "Beagle", Charles Darwin devoted particular attention to the finches of the Galapagos Islands. However, the eminent naturalist apparently failed to notice a particular trait of one of the finks he observed. This species developed an innate behavior pattern – no doubt through gradual changes in its genetic makeup – that enabled it to reach prey hidden in cracks in wood without any morphological change to its beak. After removing the bark with its beak, the bird breaks off long cactus needles and uses them to prod insects and other animals from their hiding places. Today, this woodpecker finch (Cactospiza pallida) serves as a classical example for tool use in the animal kingdom. One particular feature, however, usually receives no mention: the bird, which can also feed without using cactus needles, has gained an additional advantage due to its behavior. Cacti are abundant on these islands. The bird has no problem finding a suitable needle whenever it needs to extend its beak. After use, the needle is discarded and a new one found as the need arises. This bird’s feeding success would not be severely compromised if it were suddenly carried off to a region that lacked cactus needles: it is by no means dependent on the advantage that the needles afford. When these are unavailable, the bird is perfectly capable of capturing prey with its unmodified beak.
Fig. 3: Exploiting similar food niches in three bird species
A: The wall creeper (Tichodroma muraria) uses its particularly long, thin bill to extract insects from cracks in rocks. Its ancestors had shorter beaks, but mutants with longer beaks were able to reach prey that was inaccessible to the competition; this success led to the establishment of a new species.
B: The same evolutionary pathway enabled the great spotted woodpecker (Dendocopos major) to develop a long, powerful beak to hammer through the bark of rotting trees and reach insect larvae in their burrows. Mutations also led to an extremely long tongue with a sticky tip, with which the birds can probe even further into the burrows.
C: The woodpecker finch (Cactospiza pallida), a native of the
Galapagos Islands, gained an analogous advantage: here, in a series of
mutative steps, the bird developed an innate behavior pattern in which
it breaks off cactus needles and uses these to prod insects from their
hiding places. Based on its behavior, this bird belongs to a group of animals
that have increased their capability with additional organs that are not
fused to the body, organs whose advantage is that they can be put aside.
As opposed to the above two species, the woodpecker finch can use its powerful
beak to peck open seeds. If it needs a cactus needle to get into cracks,
then it breaks off a suitable needle, much like a human would grab a tool
to improve the capability of his/her hands.
Early man improved his hunting success by using suitable stones as projectiles. In areas where such stones were abundantly available, humans probably discarded these additional organs after each use. Later, when specially shaped hand axes were used as universal tools to dig, cut branches, and produce hunting spears, humans no doubt held on to them and protected them from theft. The great advantage of additional organs is evident both here and in the case of the woodpecker finch. Early man was also not necessarily dependent upon the advantages afforded by the hand axe and other additional organs. The material itself was of no consequence in either the projectile or the cactus needle: virtually unlimited supplies of both were available. From the standpoint of natural selection, both units represent additional organs even though they are not produced by the organism itself. The woodpecker finch’s needle is much like early man’s stone projectile and, subsequently, his hand axe, hatchet, hunting spear, noose, fall traps, and other artifacts: all serve to obtain food and therefore provide two decisive fundamental capabilities, namely energy gain and gain of vital substances. There is no reason why these artifacts should not be viewed as organs exactly like the extended mouth of the longnose butterflyfish or the beaks of the wall creeper and sword-billed hummingbird. The material making up the additional organs is irrelevant, as long as they function satisfactorily. Amoeba difflugia and Amoeba euglypha are a case in point. The same holds true for the great variety of mussels and clams as well as for the caddis fly larvae. The longnose butterflyfish and the woodpecker finch are further evidence. Many additional examples could be cited. I have restricted myself to these because I find them to be particularly illustrative.
One group that drives this point home is the hermit crabs. Numerous genera and species are widely distributed all over the world and provide convincing evidence for the selective advantage that their strategy offers against predators and other threats. The abdomen of most crabs is protected by a hard outer skeleton (exoskeleton), just like the remainder of the body. In hermit crabs the abdomen is soft. They use "prefabricated" units, i.e. the shells that snails leave behind when they die, to protect the hind part of their bodies. Originally, ancestors of these crabs may have merely improved the protective function of their armor by inserting their tails into empty snail shells. Over the course of time – in a series of many small evolutionary steps – they gradually reduced the armor of their tail, which had become a superfluous effort to produce. Today, hermit crabs can only live in areas that have a sufficient supply of snail shells. Marine snails are found worldwide and the shells they leave behind are very sturdy. This is the ideal prerequisite for the hermit crab’s success throughout the world’s oceans, particularly along tropical and subtropical coasts.
On the other hand, crabs (like all arthropods) must periodically shed their old exoskeleton and grow new, larger one as they become larger. During this phase they often retreat into cracks to hide from predators until the newly formed exoskeleton becomes hard enough. Even hermit crabs shed their exoskeleton from time to time. When the occupied snail shell becomes too small, the crab must seek and move into the next larger size. Hermit crabs have developed a series of further innate behaviors for this critical process, during which they are open to attack by predatory fishes. They manipulate and test potential new housings, checking each for appropriate size and fit. Once they have selected a suitable candidate, the actual change takes place very rapidly.
The evolution of hermit crabs is also characterized by morphological adaptations to the special situation of being able to acquire a vital organ rather than having to develop the organ itself. The unprotected abdomen of all modern hermit crabs is wound just like the whorls of the snail shell, yielding a perfect fit. This is accompanied by modified claw shape: when the crab is threatened it retracts its entire body into the shell along with all its walking legs. It then uses its claws – which snugly fit the shell opening – to hermetically seal its home like a safe door. This is reminiscent of technical constructions. The difference is that humans achieved this capability through intelligence, animals via the much longer evolutionary pathway involving advantageous changes in the genome.
The question we need to ask here is the following: is the acquired and functionally adapted snail shell an additional organ of the hermit crab or not? In the living snail, which produced the shell, we have no problem recognizing the shell as a bodily organ. When occupied by the crab, however, the very same shell is interpreted differently because it was produced by another organism. For natural selection, which decides which organism will survive and which won’t, this difference is inconsequential. The decisive criterion here is efficient protection – something that both animals require. Any number of different strategies can be used to achieve this end.
From the evolutionary perspective, I can see no adequate grounds, much less compelling arguments, for rejecting capability-enhancing units as true organs of an organism merely because they were produced by another organism. In fact, the adaptation of the hermit crab’s abdomen, which consists of cells, to the shape of the snail shell is strong evidence that the crab’s genome "recognizes" this unit (acquired from the environment) as an integral part of the organism.
This new, expanded organ definition therefore maintains that organs need by no means be composed of self-produced building elements. Most organs in animals and plants are, in fact, normally produced by the respective organism, making this the rule in evolutionary history. Nonetheless, other avenues of organ genesis exist. One method is to acquire freely available building material from the environment (such as in Amoeba difflugia and the ant lion) or to take up ready-made organs (as hermit crabs do). However, the full potential of this technique was first reached when humans consciously formed additional organs.
Some animals, for example, are also known to steal complex
cellular substructures termed organelles from their prey and convert them
into their own capability-enhancing structures. The most astounding example
is the purloining of stinging capsules (nematocysts) produced by coral
polyps. These capsules are exquisitely designed dartguns. Touching the
spine-like trigger of this organelle discharges a tiny, tethered dart into
a prey organism or enemy. In a fraction of a second, its tip folds out
into a ring of stiletto-like structures, which enlarges the wound. Then,
a tube is introduced and paralytic poison injected into the wound. Despite
this defense, certain sea slugs (Aeolidiacea) and a comb-jelly (Euchlora
rubra) feed on coral polyps – without triggering the polyps’ stinging
capsules. Instead these capsules are transported through the body into
special appendages, which thus become the new owner’s own protective organs.
One can hardly argue that such stolen organelles (cleptocnids),
whose origin has been known for some time, are organs while they are in
the epithelium of the coral polyps, but not in the epithelium of the sea
slugs. Whether they were produced by the snail or by a foreign genome,
they deliver the required capability in both one and the other. In animals
and plants such organ theft is an exceptional phenomenon. This situation
changes radically in hypercell organisms. While organs consisting of cellular
tissue can only rarely be transferred from one organ complex to another,
the additional organs of humans can very well be stolen and incorporated
into the capable entities of other hypercell organisms. Whether organs
are partially or entirely produced by the body’s own cellular activity
or obtained from other organisms is secondary, just as it was inconsequential
whether Homo proteus produced a necessary additional organ
him-/herself or stole, exchanged or purchased it from others. In the struggle
for existence (a phrase that Darwin frequently used), and particularly
when conflicts with competitors are involved, there is one and only one
set of criteria: the organism must have capability-providing units when
it needs them and it must integrate these units into its overall structural
complex (cellular plus additional organs), whereby each component must
support rather than hinder the function of the others.
Transforming other organisms into the body’s own organs
My studies in far-flung seas provided me with ample opportunity to observe the activities of many individual animals. I was able to witness how some marine organisms resolutely and ruthlessly converted others into integral components of their own capable entities. The wool crab (Dromia vulgaris) is a case in point. It uses sponges to more effectively camouflage itself. The crab selects a sponge, detaches it from the substrate, and uses its claws to cut and form the sponge so that it fits perfectly atop the crab’s carapace. Although one is tempted to interpret this meticulous procedure as a feat of intelligence, it remains an innate behavior program: like any morphological structure, it arose via a long succession of mutations and recombinations of the controlling genes, gradually becoming ever more improved. The crab turns the sponge from side to side, inspects it, and evaluates the work in progress until the sponge takes on the exact intended shape and fit. It then sets the sponge atop its arched carapace, holding it firmly in the back with the last pair of legs and anchoring it with hooks in the front. This camouflage renders the crab virtually invisible in its biotope, thereby considerably reducing its risk of being eaten by predators and – in the same measure – significantly improving its own feeding success. The sponge lives on despite its mutilation, and the association is in many ways reminiscent of people who "cut others down to size" and draft them into functional components of their own capable entities. As long as organisms, including humans and their material structures, are viewed solely from an external, material vantage point (as is the rule today), then every such comparison appears to be mere analogy. If, on the other hand, capability is the key to survival, and the underlying material structures and processes are treated as secondary, then the result is decisive, i.e. to what degree has capability been enhanced in one system and the other. If one human so successfully molds another that the latter ultimately subordinates his/her own will and goals to those of the former, then the originally independent organism will increasingly be reduced to an organ that serves to enhance the dominant entity’s power. Although individual freedom and individuality per se may not be transformed as dramatically or radically as the wool crab Dromia remodels its sponge, in both cases a particular behavior pattern can – under the appropriate circumstances – make independent organisms into completely dependent, subservient tools.
Symbiosis is an even more elegant example of how the capability of individuals can be enhanced by a mutually beneficial partnership. Hermit crabs, whose behavior I examined in detail, can again be cited as a well-known case of such ubiquitous and well-studied symbioses. Some species do more than merely transform the organ of one organism (i.e. the shell of a dead snail) into their own organ: they actually improve the effectiveness of the protective units they have acquired by making a further, living organism into an additional organ.
Sea stars are among the chief predators of hermit crabs. Although the crabs can retreat deep into the very sturdy shells when threatened, the sea stars can still get at their prey. They anchor themselves on the bottom with all five arms, attach their suckers to the crab’s claw, and pull the struggling victim out of the shell. Some crabs have developed additional behavioral programs that help them to thwart this predator. Using a complex sequence of stroking movements with their claws, they dislodge sea anemones that have firmly attached themselves to the rocky substrate. The hermit crab then transplants the anemone onto its shell, whereby the anemone actively attaches itself and accepts the shell as its new home. Its advantage is that it has transformed itself from a sessile to a mobile animal at virtually no cost. The anemone is carried about – a considerable advantage over the competition because of the vastly improved opportunity to always enjoy optimal living conditions. The hermit crab gains an additional defense mechanism in this exchange and therefore improves its own selective value; the anemone gains a locomotory organ that provides for all its needs. Each partner therefore makes another organism with an entirely different genome into its own additional organ.
This mechanism of gaining new organs is so important because it enables veritable leaps in capability. More closely examining the anemone’s situation in the hermit crab symbiosis reveals why. Anemones that are firmly attached to a rock substrate have only a very limited radius of activity. The symbiosis with the hermit crab, however, provides it with the services of well-developed legs that it could not have evolved itself even in hundreds of thousands of generations. Indeed, selection pressure to develop legs never existed because the food particles it needed floated right by its tentacles with the water currents. The fact remains that the anemone gained the advantage of these highly developed limbs with a moderate number of mutations and recombinations – a significant shift in the sense I introduced above. Its capability is enhanced by leaps and bounds, and in exchange for this, it provides one of its capabilities to the new partner. While the advantage of mobility may be modest to the anemone, it is clearly great enough to have given rise to this association with the crab. Under certain environmental conditions, however, such mobility may well provide a critical advantage. This underlines the evolutionary opportunities that symbioses have to offer: the partners gain new capabilities without themselves having to bear the development costs. This is the very principle that enables the universal mediator "money" to so dramatically boost the capability of hypercell organisms. Such shifts – in which organs with an entirely different developmental history are incorporated into an unrelated capable entity – are already evident in symbioses. And, in the course of evolution, each such shift can either prove to be only moderately significant or can lead to entirely new selective advantages. The latter was the case in Homo proteus, where the hand axe and hunting spear gradually gave rise to all manner of tools and to every industry founded by hypercell organisms.
The above strategy of acquiring and incorporating foreign organs into one’s own capable entity is already evident in animal and plant symbioses. It leads to a second evolutionary pathway that can briefly be introduced at this stage. Specifically, I am referring to the partnership arising from the presence of two sexes in more highly developed multicellular organisms: it is the most important mechanism for improvement as a fundamental capability. In brood-caring animal species in which the parents actively protect, feed or even "teach" their young, this type of interaction can be viewed as being functionally related to symbiosis. Although brood care involves an association of individuals of the same species, each partner becomes an additional organ of the other. This culminates in marriage, friendship and other forms of human partnership.
If we return to the hermit crab symbiosis, and if we accept that capabilities rather than bodily structures are the key feature in evolution, then we can legitimately ask whether this partnership does not in fact constitute an organism at a higher level of integration. This question is even amenable to experimental study. If the partners’ chances of survival as a team are generally greater than if each were to live alone, then we are dealing with a higher-level organism: a new, more complex living unit that must face natural selection. This can lead to an increasingly differentiated division of labor, such as in insect colonies. Using powers of intelligence, it can also lead to the governments founded by hypercell organisms (see Chapter 5).
Certain unicellular organisms already exhibit a remarkable transition from free-living individuals to temporary, cohesive units. After a period of independent life, thousands of individual slime molds (myxomycetes) aggregate to form a spore capsule; this grows from the substrate on a long stalk and serves the fundamental capabilities of reproduction and improvement. Here, the genome compels these unicellular organisms to aggregate and to undergo a cell differentiation rivaling that of multicellular organisms. On the other hand, the genome of each germ cell in multicellular organisms represents a cohesive unit; should cell division give rise to new individuals and members bearing this genome be dispersed in all directions, then it still retains the common organization that we define under the term "species".
In every cohesive organizational unit, as well as in all those whose components are not firmly connected, each organ is not merely an organ of a greater, common entity, but also serves as an additional organ for every other subunit. This is equally true in multicellular organisms and in the associations, business organizations and governments formed by hypercell organisms.
Termites demonstrate how insignificant the size-relationship between symbiotic partners is. These highly specialized organisms feed on the cellulose contained in wood, but are themselves unable to digest this material. This means they are unable to release and utilize the bond energy contained in the cellulose molecules for their own metabolism. A symbiosis with protozoans (flagellates of the order Polymastigina) than can break down cellulose has become the cornerstone of the termite’s existence. They live as "digestive helpers" in the termite’s gut, breaking down the consumed cellulose, covering both their own metabolic needs and passing the greater portion of the yield on to the thousand-fold larger termite. One advantage for the digestive helpers is the perfect protection afforded by the termite’s body. Also, they need expend no energy in looking for food: the termite provides them with a never-ending supply. If the gut of a termite is experimentally sterilized and the flagellates all killed, then the insect will starve regardless of how much wood it eats. Here, we are entirely justified in asking: can the endosymbionts be regarded as organs of the termite or not? According to current thinking the answer is no, they are not organs. First, because they are separate organisms with their own genetic makeup, and second because they do not originate from the termite’s genome: their production is not coded in the termite’s genetic makeup.
Termites are not the only organisms that rely on such digestive helpers. Many other insects and ultimately even cows would be unable to survive without such symbionts. In plant-sap sucking insects such as the jumping plant louse Psylla buxi, special organs (mycetomes) in the abdomen house the symbionts. This development reaches its epitome in other species, such as the weevil Cleonus piger, that have developed complex organs to spray their digestive helpers (in this case bacteria) onto their eggs. When the larvae emerge, they infect themselves with these bacteria or, from our perspective, procure the vital additional organs they need to survive. The symbiotic weevil also assumes a supporting role in enabling the fundamental capability of reproduction in the bacterial partner.
I reiterate the question: Is it justified to consider these extensive and complex multicellular mycetomes to be organs of the insect’s body, as has been taken for granted in the past, merely because they are produced by the body’s own genome, while at the same time denying this designation for those entities (bacteria) that actually enable the fundamental capability (energy gain)? After all, the entire role of the mycetomes is to support the bacteria. If the termites were in a position – via cell differentiation – to develop glands that secrete cellulose-splitting enzymes, then no one would hesitate to consider these glands as the body’s own organs. Such a cellular differentiation was apparently not possible through mutation and recombination, or perhaps the endosymbiosis provided a simpler means to the same end; this strategy was even supported by supplementary structures like the mycetomes, whose development was automatically promoted by natural selection. The decisive fundamental capability of energy gain was therefore achieved by an entirely different pathway. In my opinion, the termite’s digestive helpers are a prime example of how a different species can be transformed into an organ of one’ own capable entity. I discussed this condition in detail in an earlier work (1970).
Other endosymbionts enter into an even more intimate relationship with the cellular body of their much larger partners. The incredible reef structures that coral polyps build require the ability to extract the necessary building material (calcium carbonate) from seawater. This task consumes much more oxygen than is available in dissolved form in the water. Nonetheless, in this case symbiotic plants (unicellular algae) enable the process to go ahead. They live in the cell tissue of the polyps and can only be recognized under a microscope based on their different color. As plants, they produce oxygen, which the polyps can take up directly. Conversely, the algae in this partnership benefit from the fact that the polyp’s cells – like the cells of all animals – emit carbon dioxide. This is an important building block for the algae. Those who would maintain that the unicellular algae within the polyp’s tissue are not an integral component of the coral body (because they were not produced by differentiation of the coral’s own cells) will have to face the critique that they have long been misled by the uniform appearance of corals and by the false conclusions drawn from this. Again, a rigorous distinction between the true polyp and more "foreign" components can hardly be upheld. Natural selection is only concerned with capability, with success. More than one road leads to Rome.
In defining each unit that fulfills at least one task
in the organism’s division of labor as an organ, we are fully justified
in viewing symbionts as organs; this holds true even if they are
not produced by that organism’s genome and are therefore designated as
additional rather than natural organs.
Temporarily "renting" necessary organs
This section deals with another strategy of using additionally acquired organs to improve the selective value of the organism’s own capable entity. In the hypercell organisms formed by human beings, additional organs clearly do not need to become permanent fixtures of the capable entity. A visitor who needs a room for the night by no means needs to purchase that room; someone who flies to Rio de Janeiro rents a seat on the flight rather than buying the airplane. As indicated above, the situation is much the same when we hire the services of another hypercell organism, such as that of a secretary, a cook or a shipping agency. This is referred to as a short-term obligation rather than "renting", but functionally both are the same. In both cases, a required additional organ (which can either be an inorganic structure or another organism) is bound to a capable entity for some defined period rather than becoming a permanent fixture. The price is a charge or fee of some kind.
Early stages of such associations abound in organisms, particularly in the plant kingdom. The task facing plants, however, is radically different from that facing animals: their source of energy – the sunlight falling on the Earth – is anything but scarce. Scientists have calculated that plants can at best capture 1% of the solar radiation reaching the planet. On the other hand, in Earth’s early history when evolution was restricted to the underwater realm, plants had to develop structures that prevented them from sinking down into the dark depths. In the case of planktonic algae, fat or gas pockets provide buoyancy. Unicellular algae, much like unicellular animals, also have organs that allow active locomotion. The flagellate Euglena viridis, which is both plant and animal, uses its flagellum for both life strategies. If it behaves like an animal, the flagellum serves in seeking prey; if it behaves like a plant, the flagellum helps it to return to sunlit waters if it has sunk into darkness.
On land, the main problem became to obtain sufficient water for photosynthesis. Locomotory organs, on the other hand, became superfluous. Terrestrial plants are therefore bound to a particular site, while most animals need locomotory organs to reach their source of energy (other animals). Of the six fundamental capabilities that I believe all organisms must have, two became a particular problem for all land plants, namely reproduction and improvement.
When plants produce seeds, these can be distributed by currents in the water and by wind on land. Virtually all aquatic plants and, at least initially, all terrestrial plants took advantage of these favorable environmental factors. Later, some succeeded in turning other organisms into their additional organs by enclosing their seedlings in sugar-rich pulp, which animals enjoyed as food. The animals ate these auxiliary reproductive organs, which we term fruits. The seedlings passed undigested through their guts and were excreted at a new location along with the remaining feces. Clearly, this exploitative strategy can only function if the seedling is so well encased that it cannot be digested by the transporting animal. This is why seedlings hidden in fruit are enclosed in such sturdy protective casings (seeds). The return service that the transporting animal – usually a bird or mammal – receives for its unwitting role is, as mentioned above, the energy-rich, sugary fruit. A mutual exchange, about which both partners are "ignorant", takes place here. This holds true for all symbioses that have not been instigated by man. Again, natural selection is concerned only with the result. Whether this is achieved by conscious or unconscious strategies is irrelevant.
The second difficulty all land plants face is the sexual union of the gametes of different individuals – the most important evolution-promoting mechanism in multicellular organisms. Due to well-known reasons that need not be dealt with here, this mechanism functions optimally when gametes from widely separated regions cross; inbreeding – the crossing of closely related gametes – can involve considerable disadvantages. How can plants that are firmly anchored in the soil, however, arrange for their gametes to cross with those from individuals that are as remote as possible. Again, favorable environmental factors such as water currents or wind can play a supporting role. Higher plants, however, developed an even more effective solution: other organisms, in this case almost exclusively insects, were drafted as additional organs to fulfil this fundamental capability. The plants developed special organs, namely flowers, to promote this service. Flowers consist of units that secrete sugary nectar, additional units that attract the respective insects (conspicuous flower petals), and finally other units that help attach pollen that contains male gametes onto insects. These are then carried by insects to other flowers of the same species, where they fuse with the female gametes to form functional seedlings. The fruits and flowers are distinctively colored in order to draw the attention of and attract the desired symbiosis partner. In flowers, odor substances also play the same role.
Before proceeding further, we need to discuss a banality that turns out to be less banal than one would think. It revolves around the question why I have chosen to discuss the formation of fruit before going into that of the flowers. After all, everyone knows that fruits typically develop from flowers. Or, formulated more generally, why did I list the fundamental capability improvement as the last item after reproduction, although reproduction regularly follows mating in both plants and animals.
Foremost, all the fundamental capabilities I listed have no given natural sequence. The reason for putting energy gain first was merely because no other fundamental capabilities could have been realized without energy being available. On the other hand, energy gain would not be possible without most of the other fundamental capabilities and many supplementary capabilities. When I list reproduction in fifth position and place improvement last, it is because reproduction was the prerequisite for the evolution of organisms from the onset. Although mechanisms for structural improvement were equally important for evolution, they clearly only arose later. For billions of years, the most important mechanism was sexuality – the fusion of genomes of different individuals of the same species. During cell division, this enabled the random changes (mutations) in the genetic material to be recombined in a highly variable manner. The fact that this process can, if only rarely, lead to structural improvements is the functional basis for a mechanism that is both efficient yet very slow to yield progress. In my opinion, the so-called shifts that I introduced in this book are an additional mechanism behind major improvements. At this point, however, such shifts are merely a hypothesis I have forwarded and will not be treated in this section.
My putting reproduction before improvement (the sequence is actually reversed in both animals and plants) is simple to explain. Logically, mating after successful reproduction would be ineffective from several standpoints. According to Spencer, the reversed order is more suitable in every respect, and Darwin considers it to be more advantageous with regard to natural selection. The closer mating is to the reproductive process, the better the potential result. This also helps eliminate superfluous exertion and damaging influences. Even today, most people consider mating and reproduction as two acts in the same functional process. They fail to see that it in fact involves the inevitable linkage of two contrary functions. The task of reproduction is to achieve the most precise intraspecific replication, one that guarantees that no improvements made by the species are lost. Mating, on the other hand, also serves to yield altered and in this sense species-atypical progeny: without such individuals, no evolutionary development would ever have taken place at all.
To little, if any, emphasis has been placed on this functional conflict, which has played a key role in hindering and checking evolution. Put even more succinctly: on one hand, life could not have developed without reproduction (the error-free transfer of information to the offspring); the crucial aspect here was that once made, no progress should be lost. On the other hand, offspring that were mere mirror-images of each other would never have enabled new developments or improved capability. How could the one aspect become linked with the other? Up until Homo proteus, the direct coupling of mating and reproduction was the only solution. Mating had to immediately precede reproduction in order to ensure progeny of the same species, but also to improve the chances that some of these new variants developed traits that subsequently gave rise to better or new cellular organs or additional organs.
In numerous species of land plants, insects became the effective intermediaries in the first of these two such contrary processes, the fusion of male and female gametes. Flowers served as the requisite auxiliary structures. The insects innately recognize that energy-rich food is available here, and the flower’s shape enables it to attach pollen to the visiting insect. This pollen reaches the female flower quite naturally in the course of the insects’ activities. Some pollen grains invariably fall onto the stigma of the pistil; the male gametes contained therein reach the egg cells via the projecting pollen tube and the style. Later, the fertilized seeds that arise from this fusion are distributed by a second symbiosis, this one primarily involving birds and mammals. The auxiliary structures here are the conspicuous fruits. Their sugary, energy-rich pulp conceals the functional seeds. The latter are usually further enclosed in a hard shell to prevent them from being digested in the animal’s gut (in cherries, for example, this is the cherry seed). The seed itself is then transported over shorter or longer distances by the bird or mammal that ate the fruit; ultimately it is excreted along with the feces, which fertilize the seedling and therefore provide the plant with a good head start.
Note that both processes involve a temporary symbiosis in which the respective insect, bird, mammal or other animal temporarily becomes a component of the plant’s capable entity. They are "paid" for their services with energy and useful material, much like humans reimburse those whose services they contract. "Business" is conducted along the same principles in both cases. Plants were the first to take broad advantage of such temporary symbioses, i.e. "renting services" to obtain additional organs. In hypercell organisms, this strategy triggered an explosion of mutual capability enhancements.
In summary, the type of material used in organs and the production mechanisms are as irrelevant as whether the resulting organs are firmly attached to the cellular body or not. Cells are tremendously versatile, transformable and efficient material components, yet also very costly and burdened with serious deficiencies. They must be fed with energy and material and need to be hooked up to the appropriate supply lines, preventing them from forming organs outside the body. They cannot tolerate high temperatures and therefore cannot use metals as structural components. Additional organs, however, suffer no such limitations and can be made of virtually any material capable of delivering the required service. Organs of other organisms or even entire organisms themselves can be transformed into organs of one’s own capable entity, either forcibly or by exchange, either permanently or for a limited period of time.
In uni- and multicellular organisms, this method of acquiring
additional organs is limited, as is their ability to acquire foreign organs
or transform other organisms into their own organs. In the human-based
hypercell organisms, many of these limitations no longer apply. We built
or obtained an ever-larger number of additional organs, which needed upkeep
like their cellular counterparts. The difference was that the former could
be put aside and exchanged, freeing the capable entity to adapt to a broad
range of tasks. The introduction of money made it simple to rent additional
organs as needed; this was less costly than personal property. In the services
sector, we use the term "employment" to refer to the more long-term obligations
that hypercell organisms enter into. Additional commitments here, beyond
payment, might include lodging, paid vacations and social security. They
help bind the employee to the hypercell organism’s capable entity or to
the business enterprise. In short-term contracts, such additional obligations
are largely unnecessary, making the employer even more flexible and adaptable
in the face of competition.