Let’s try to imagine biosphere more mature than one existing at our planet nowadays. What ways will evolution of species go? How it is possible to improve things that already seem perfect?
Text by Igor Kraj
(article is published here in authorial version with pictures sent by author himself; the magazine version can be seen here)
Evolution is more grounded in my experience than angels.
Describing planets rotating around far stars, sci-fi authors habitually take modern Earth, or one of past geological eras for a basis, having added original details at their own discretion to the general pattern. Having the textbook before eyes it is rather simple task to imagine the world of ferns and dinosaurs. But what if the alien world is elder than our one is? How would oceans, forests and animals look 100 million years in the future? What ways would evolution of species choose?
As it is known, those who pay the piper call the tune. On
the Earth plants pay for all, providing the live world with food and oxygen.
During the last 300 million years trunks of trees became stronger than, due
to what modern woods are three times higher than ancient thickets of tree ferns.
Branches have allowed increasing a crown, and roots have learned not only to
suck out water and mineral substances from ground, but also to keep it from
erosion and washing out by forming the root mat.
The deepest changes have affected the mechanisms of breeding and moving. Because if in the sea conditions are rather uniform and currents are able to transfer any spore from one ocean to the next, on the land the conditions are much more complicated. As a result gymnosperms had been replaced by angiosperms, and then by flowering plants. And trying to extrapolate this tendency to the future, it is not so difficult to imagine an ideal which the evolution of green kingdom points to via the trial and error method. The seed capable to active flight should find independently a site suitable to rooting with the necessary structure of ground, level of light exposure and humidity. Then it needs to exterminate weed vegetation on it, to find and to cut off another’s roots stretched in the ground. Then it is necessary to entrench itself, having first thing grown the chemical turret for prevention of re-colonization of the site by another seed.
Sending its spiny seeds to the journey on skins of animals,
burdock does not
consider necessary to offer compensation to its assistants.
From the evolutionary point of view such seed
– self-moving, self-targeting and self-exterminating the competitors – is quite
possible idea. But everything that can be made easier is done easier. And it
is easier for the tree – rather than to get wings, eyes, brain and acid turret
– to pay to anybody already it all. For tens of millions of years flowering
plants are pollinated with the help of the insects receiving the nectar as a
reward, and are settled by means of birds and mammals eating fruits and carrying
seeds in their stomachs.
Rather new invention of evolution is the appearing of myrmecophitic plants providing ants with ready nests – cavities in stalk – and also with food – nectar for imagoes and protein granules for their larvae. It appears cheaper than if the same ants will show up with their domesticated plant lice. And it is more favorable when the “trusted” family protects “its own” tree from pest insects.
But this is just the beginning. Because ants are capable of the greater tricks! In separate for now cases plants transform social insects into the instrument for conquering of vital space. In South America “devil’s gardens” – the forests formed only of trees Duroia hirsuta – expand quickly, exterminating all other vegetation by columns of six-legged symbionts. As early as in next some millions of years exception will inevitably become a rule. Any tree not being simultaneously also an ant hill will simply fail to exist. Former woods will disappear, and the planet will be covered by new “myrmecophitic” flora. Accordingly, ants and wasps closely related to them – even now in total weight inferior only to termites – will go through rough flourishing. The amount of insects eating live vegetation will decrease greatly.
Later – the process may take tens of millions of years – era of flowering plants and pollinator insects will become a thing of the past. Symbionts indissolubly connected their destinies with trees will fully shoulder the tasks like pollination and settling. The necessity for fruits and large weight of seeds will disappear. It will take place because each seed will be delivered with all precautions to the place carefully picked up, completely cleared away, fertilized and protected vigilantly. Because ant hills will not be constructed of vegetative dust anymore and anywhere. The family of social insects will come to plant and to cultivate its new house. It will demand lots of time, of course… But also some modern ant hills can exist for centuries.
Perhaps, new myrmecophitic forest will be not so pleasant place. Because an advantage in capture of place in the sun will be received by trees breeding within their trunks most furious and hard biting ants – capable to transform to the heap of dust even larger “green ant hill” if it closes light with its crone and takes away water with its roots. Such ants can drive away also the pest of size larger than a caterpillar! Accordingly, birds and small forest animals will feed entirely on ants. For fruits will become a thing of the past side by side with “flowering” epoch, and in any case for each leaf you will come to battle to insects protecting a tree.
Crustaceans are the ancient group of the arthropods
which have appeared, probably, even earlier, than trilobites. But while trilobites
had flourished, dominating in the seas more than 400 million years ago in Cambrian
and Silurian and have died out completely 300 million years ago, crustaceans
moved on to ucla for a long while and cautiously. In general they appeared in
fossil record somehow between the lines. But today they hold two important strategic
positions in the ocean. Small and the tiniest crustaceans form a basis of zooplankton
feeding on bacteria and unicellular algae – phytoplankton – and in turn become
a food to other aquatic inhabitants. Larger and more unhesitating species challenge
sea bottom resources with fishes and cephalopods.
And while the serious competition for not so honorable niche of plankton is absent, it is very strict for dominance at the sea bottom. But crustaceans are still hanging on for now. The Japanese spider crab – reaching 3.7 meters in leg span – is the largest of ever existing arthropods (though, the eurypterids extinct at the same time as trilobites had been heavier). “Escalation of arm races” inevitable in competition will most likely result in further appearing of even more effective forms.
In addition to web spiders receive in struggle for a place in
the sun a great help
from lungs allowing these primitive arthropods to reach rather great size. But if
eight-legged creepers will not buckle down and will not pass to a social way
of life, their future seems to be doubtful.
But there is one more interesting direction
of crustacean expansion – to the land. Because the coconut crab weighting 4
kilograms is the absolute champion in weight among the arthropods ever trampled
the sand. And it is already a serious attempt! It is not necessary to forget
also about wood lice, land-dwelling isopods. They are small and imperceptible,
but they are numerous. Hiding in holes and under stones, eating dead vegetation,
they are inferior in biomass only to termites and ants. But, as against to choosy
insects, isopods are tolerant to temperature and humidity, inhabiting both deserts
and cold, superfluously humid regions. At the moment they have developed the
care of posterity and colonial habit of life – and from it there is only one
step up to a superorganism. And as soon as this step will be made, insects will
lose their main advantage. Advanced decapods (common crayfishes, sea lobsters,
hermit crabs, shrimps and crabs belong to this group) are especially bound to
succeed in struggle for land. Of course, any of their attempts to intrude on
the niches occupied by vertebrates would be immediately terminated. But less
advanced atmospheric oxygen breathers will come to move.
Crustaceans do not fly. It is a minus which, however, spiders tolerate successfully for already 300 millions of years. In other respects crabs surpass the insects. At the equal sizes they are physically stronger – the muscles at crustaceans occupy considerably greater part of the body volume. External covers of crab are much stronger, rather than at beetle and can really be called as “armor”. And the main item is the following: terrestrial crustaceans have got lungs and are better adapted to air breathing compared to insects. As a consequence they presume to themselves to grow, not being afraid to choke or to fall effortlessly under their own body weight. And the size matters in nature. The larger is the creature, the lesser is a number of its natural enemies.
In holding their positions in struggle against much more progressive
fishes and cephalopods, crabs are helped by features of physical structure.
Movement on the bottom with the help of long legs demands smaller
expenses of energy compared to swimming. But the handfish adopts
this method rather successfully.
The forest in which each leaf fallen from the tree is immediately dragged off by social wood lice to their underground casemates, and along tree trunks crabs scurry – large enough to keep the armed neutrality even with mice and smaller birds – may look insufficiently original for the picture of the far future. But it will have some really spectacular details! For example, when the piece of bark, moss hummock or even small tree stub overgrown with mushrooms suddenly grows articulate legs, clicks its claws and runs away, it will be remembered for certain even to the person with healthy heart.
Decapods are well-known for the ability to use for their protection and masking everything their pincers will reach. Some crabs paste to their carapaces seaweed and sand grains. Others decorate themselves with beautiful, but dangerous sea anemones. Hermit crabs apply for protection mollusc shells. And whereas, say, sea anemones do not live on land, but the enterprising crab would necessarily use everything poisonous, burning and stabbing.
Some evolutionary tendencies are universal for all classes and phyla, allowing determining who is whose descendant literally at first sight. At each following step the number of extremities tends to reduction. For example, “live fossil” Nautilus had 90 tentacles. Cuttlefish still retaining shell rudiment has 10 ones. Octopus has 8, and squids, the youngest group in the evolutionary relation, actually have only two of them. The principle also works for arthropods. And even for vertebrates which typically have only four legs. The youngest group of amphibians in legless caecilians. The most succeeding group of reptiles is snakes. And remember about legless lizards, not becoming snakes yet, but aspiring to do it.
Isopods (including wood lice) have seven pairs of walking legs.
It is possible to trace this tendency also in primates. Primitive monkeys use tail, more advanced ones have two pairs of “hands”, and apes literally fly along branches, grasping them only by one pair of hands. The solution is simple: lesser the number of extremities, more attention can be given to operating of each of them. Decisions are accepted faster, the motor skills become more exact. In case of the reptiles compelled to compete to obviously more perfect warm-blooded animals, the complete refusal of the extremities releasing computing capacities of their brain for the solving of other tasks became the solution. At least, temporarily.
Formally mantis may be an example of a progressive four-legged
But actually it is not capable to break a rule of “three fulcrums” and is
compelled to move its legs one by one. When it is needed to move quickly,
mantis simply flies up.
Certainly, normally the number of extremities
is running not to zero, but to a reasonable minimum which value is determined
by the anatomy of the organism and problems it faces. So, for run four legs
represent an optimum variant. But only in case of vertebrates. To the arthropods
not having the advanced nervous system at least six legs are required – three
ones are used to keep stable equilibrium, and other three ones move. As a result
insects lost superfluous legs in due time run faster than spiders and crustaceans
walking using the out-of-date formula “four plus four”.
But evolution does not stand still. In the future it is expected the turning of walking on four legs at arthropods to the normal condition. The pair of extremities becoming superfluous will either atrophy, or will change its function, having turned to grasping pincers.
Already now the most perfect representative of arthropods –
the coconut crab – actually
has only “two and a half” pairs of walking extremities. Two front pairs of legs are perfectly
advanced and are used for run. The third pair is short, but is still used at tree climbing and
slow movement. And the fourth pair is rudimentary at all.
It is possible to estimate “promise” of an evolutionary branch by having compared the maximal sizes of its living and extinct representatives. If descendants are larger than ancestors, it means this phylum or class looks to the future optimistically. If huge forms existed any time ago, but have died out, it is quite probably that smaller ones will soon (in measures of geology) follow to their example. The matter is that the increase of the size is the most simple and effective way to move closer to the top of food pyramid, or, on the contrary, to protect itself against predators. And if even it does not help, or there is no opportunity to satisfy the appetite increased proportionally to weight, it means the design is hopelessly obsolete and has completely lost competitiveness.
Wolves can survive everywhere – from the Arctic deserts up to
subequatorial jungle. Creation
of more physically perfect average terrestrial predator seems to be an extremely nontrivial
problem. If solvable at all. “More cunning wolf” is more real.
The size criterion is rather reliable, giving
obvious failure only in case of mammals. From the formal point of view they
represent the most advanced class “on top”, because a blue whale possesses an
absolute record in weight among live organisms of all times. But in overland
standing the nonsense turns out. Indricotherium twice surpassing in weight the
African elephant has died out 20 million years ago. And during the last millions
of years everybody had started to become smaller: elephants, bears, wolves.
Even primates: Gigantopithecus had been larger than gorilla.
In rather near past rules of game had changed. Among directions of evolution unequivocally priority had expressed: the increase of intelligence. The complex behavior, ability to learning and communication produce the best results in the field of the adaptation, rather than the most refined physical specialization. Including the gigantism.
Cases when sea or river dolphins assisted fishermen by driving
fish into the net
had been described for many times. The curious detail is that dolphins instead
of people always appeared the initiators of interspecific cooperation.
It is possible to assume that after 20-30
million years forms of mammals inhabiting forests and deserts of our planet
will not differ appreciably from modern beasts. Unless, the differences may
include the enlarged skull and the increased propensity to gregarious way of
life. The design will become more modest and concise. Medium size is more preferable,
because it is more difficult to large creatures to keep together. Body proportions
will also become generalized. Too long canines are not required, if you know
the correct place to stick them. Sentinels warning of the appearing of the enemy,
or skills in arranging of ambushes relieve of necessity of quick run.
But after the next 50 million years the situation may change radically. Specialization will become fashionable again, having caused the appearance of small, huge, long-necked, powerfully armed and armored forms, and also of other outstanding physical features, including ones extremely burdensome and at first sight not too useful to their owner. The world will change once again, when developed up to the limit intraspecific cooperation will be added with interspecific one.
It is said the best of fictitious races is Zerg of StarCraft drawn from social insects. But it is primitive. Because it is too difficult to use the same DNA to create on its basis the universal set of monsters capable to solve every military task. It is easier to unite opportunities of different creatures … Because of it, despite of brain development, the most obvious and perspective direction of evolution is the creation of increasingly complex and efficacious symbiotic relationships between different species.
Today the mixed packs consisting of animals of two species are seen, but not frequently. Animals do not find common language in literal sense. Without information interchange fruitful cooperation is impossible, but each species has the unique set of signals fixed by instinct. As a result the conflict may arise easily from zero, for if at dogs tail waves represent an attribute of friendliness, at cats it is a sing of the contrary meaning! Nevertheless, a problem has a solution. Because when language becomes so complicated that it cannot be known from birth and is necessary to be learned like dolphins do it, nothing more would prevent adequate interpretation of another’s bark and howl.
Higher animals are capable to study languages of other species
if they spend a lot of time together.
But in a nature the conditions for this purpose are not present as a rule. Nevertheless, monkeys
and dogs can work together sometimes.
Failure may befall even well organized group, if no one of its members is able to climb trees easily or to dive. The pack uniting creatures with maximally diverse, mutually supplementing physical opportunities will get great advantage. It will grow as the species formed the symbiosis will specialize, adapting progressively better to carrying out the tasks facing to them.
Tale in which Shere Khan and Tabaqui act villainously together should become real sooner or later. Probably, jackals even will learn to flatter to tigers. But it will appear only at late stages of evolution – after not less than 100 million years. At first simply being less appreciable member of the pack Tabaqui will take care to investigation. It means, from the balanced and universal creature adapted to hunting, by means of natural selection, it will begin transforming to grotesque eared nose with the assimilative coloration… By the way, it Soviet cartoon film it even looks so. Is it a simple concurrence?
David Brin “The Uplift War”
Kir Bulychov “Intelligence for the tomcat” (in Russian)
Arthur C. Clarke “Dolphin Island”
Michael Crichton “The Andromeda Strain”
Ariadne Gromova “We be one blood, thou and I” (in Russian)
Harry Harrison “Deathworld”
Robert Heinlein “Tunnel in the Sky”
George R. R. Martin “Tuf Voyaging”
Jean Vercors “Les Animaux dénaturés”
Colin Wilson “Spider World. The Desert”