THE SEX LIFE
OF DIMORPHIC FORAMINIFERA AND OTHER
FASCINATING FACETS OF EVOLUTION
by Les Cole
My apologies to Margaret St. Clair, but everything I find annoying about science fiction today may be summed up in a character from one of her stories. This character was called "Blixa," and she was the most glamorous, scintillating creature ever seen in the solar system-at least, until the next St. Clair story appeared. Blixa was Martian, and the reason she scintillated was because she was blue. Aside from this, she was as much a part of Homo sapiens as you or I. In fact, she was so much so that she and the hero, an Earthman, settled down and lived happily ever after.
What, you may ask, has this to do with dimorphic forams and evolution? Well, nothing directly to do with the forams, but any student of evolution and life, knowing the basic principles, could (and did!) immediately point out the large galomphing "errors" in this story.
To note just a few things, morphology-the form of an animal-is based on many factors, all in delicate equilibrium, chief among which are climate, food, and environment. In the geologic period just ended-the Tertiary-there were continuous changes in climate throughout; these changes were reflected by minor changes in the Pacific isotherms; but the changes in life forms, reflecting the changed climate, were sweeping. Or take, if you will, the changes which occurred in animals as a result of the recently ended glaciation.
Evolution proceeds, according to the geneticists, through four main agencies. Firstly, there is mixture. This occurs between individuals or populations and generally results in the introduction of new genes. It should be pointed out that the mere introduction of a new gene, regardless of dominance, does not imply an increase in frequency unless it's favored by some evolutionary agency. Next there is mutation, or a change in the composition of the gene. Selection, the third process, means that organisms possessing certain advantageous characteristics will survive while all others about them are losing their heads. Isolation, or random genetic drift, accounts for losses in genes in an isolated population.
While it is true that the "creative ability of the chromosome" forms the positive aspects of living phonomena, it is also true that among the ancient Aztecs, no form of sexual perversion was unknown, however, the negative aspects, selection and isolation are of great importance. In terms of geology, barriers are thrown up continuously which act against the spread of life forms. Mountains, large lakes, flooding of low-lying lands by seas, and glaciation all take a toll, and it becomes a question of "change or die!" Geographic isolation of land masses has occurred over and over again in the earth's history: indeed, today, we have two fine examples of this. Australia was cut off from the rest of Asia around the close of the Cretaceous. Australia's native mammalian population is of a low level, biologically. It's marsupial, a more or less intermediate stage. Africa was cut off in Pleistocene times, and on the whole Africa's population is only slightly-altered Pleistocene.
Selection is one of the negative aspects of organic evolution, for it creates nothing but permits living things to live provided they can survive in competition with life. This is the meaning of the phrase "survival of the fittest." It can be restated this way: those organisms best suited to survive within a given environment will survive.
Those are the general principles which push life along. To me they are interesting only as a means to an end, as an understanding of what caused the changes we are beginning to realize occurred.
It would be nice if I could tell you in pat phrases the difference between the two great kingdoms, the plant and animal. Like everything else in the earth sciences, there is no right definition because if you go far enough back along the path, you eventually come to a never-never land of plant-animal. Certain organisms exist about which you just can't say definitely into which group they fall. However, I just happen to have with me a few pat phrases which point up the essential differences between plant and animal, and if you'll accept them, we can go on discussing animals.
Most plants are capable of producing their own food from the soil and atmosphere, while most animals cannot. In animals organisms are developed in the embryo and growth consists of the maturation of these. In plants growth is unlimited and new organs and tissues are produced throughout their lives. Finally, locomotion is characteristic of most animals while plants are not able to move from place to place. I say this in spite of Mr. Hawks and his Thing and in spite of the obvious exceptions which spring to mind.
Animals may be classified into whole bunches of things and vertebrates, but don't get worried: I'm not going to reel off a series of names. You can get those from any basic biology or paleo text and be just as surely bored. However, among the dull invertebrates, there are certain groups which are important to us for economic reasons. We could get along without the culinary delicacies - the clams, shrimp, and ersters - but god help the oilmen if someone took away the forams!
Foraminifera are aquatic dwelling, an order within a class of the phylum Protozoa, the single-celled jobs. I won't go into the relationship of oil to forams, but I would like to tell you a little story about the bugs, as we oil men say. They are tenacious, hardy little fellows and have been in the life record since before the record got started some 500 million years ago. Today they are happy, healthy and begat themselves all over the place, but this was not always so.
You've all heard of asexual reproduction - budding, and what-have-you - and you've all heard of the Birds and Bees. So had the forams, and they were indulging in both these sports. But finally, some communist began to sow - and pardon the pun - to sow seeds of dissention. Political parties formed to the right and left, parading by torchlight, and screaming for adoption of one particular method over the other. Tension grew, and mutterings of "succession!" and "Foram rights!" were heard. Finally Henry Claystone, a foraminifera and great orator, suggested the Missouri Compromise of 1850 BC. This was grudgingly adopted, the communists were beaten, and today we have 3000 miles-and to a foram a mile is a long way-of undefended frontier. The compromise works as shown in Figure (1).
Some writers have claimed to see trimorphism in these critters, but I can't quite visualize it. Unless, of course, a half-man-half-woman foram meets another half-man-half-woman foram and the four of 'em go out together ...
I would like to break here for a moment and explain some things which just don't seem to fit anywhere else. The whole basis for present day biostratigraphy-or paleontology-may be found in three empirical laws formulated over a period of roughly 200 years. Without these laws we would still be blundering around looking for evidences of the flood. And essentially, the reason they are empirical is that workers in earth sciences have relatively little use of laboratories: you can't very easily drag a few trillion tons of earth into a lab, apply pressure, and say, "It'll fold that-a-way."
First to be discovered was the law of superposition which states that in a series of relatively undisturbed strata, the oldest will be on the bottom. Following this, and very similar to it is the law of stratigraphic succession of fossils: the same strata containing the same peculiar fossils are in the same order of superposition. The last, and possibly the most difficult to achieve in view of convention, is uniformitarianism: the same changes which are going on today went on in the past and at roughly the same rate. These three simple ideas were not easy to work out, and are not always as sharply defined in the field.
If you're an old Astounding reader, you've probably read de Camp's article on the Crossoptyrigian fish that was found in the Indian Ocean in 1939. This baby was supposed to have become extinct about 200 million years ago: at least, he disappeared from the fossil record then. His-or hers-isn't the only case of its kind. We have a "Fermat's Last Theorem" in paleontology: a few years ago a zoologist was working in Sidney harbor classifying molluscs that were being brought to the deck of a ship in nets. Up came a critter which was a specimen of Trigonia, a mollusc that was supposed to have died out in Jurrasic times. They lost it overboard again, but the crew confirmed the gentleman's claim, so Trigonia is also considered to be living. I'll bet they're still digging up Sidney harbor! There are many explanations to account for these biological sports, and unfortunately, none of 'em are very good, but at least they preserve the law of stratographic succession. I dunno, sometimes I think the Devil did put fossils in the rocks!
Early explanations of fossils generally tended toward two: either fossils were due to a supernatural agency-God, or the Devil-or, as in the case of the Greeks and Leonardo, the "correct" explanation. Somehow the former appeals to me: it's the sort of thing a geologist does when he carries a large rock for miles to an area where there are no other rocks like it, and carefully plants it, all the while muttering to some other geologist, 15 million years hence, "Now figure that one out, you low-born S.O.B.!" But I digress.
Sometime prior to 1/2 billion years ago, something happened. A collection of fairly complex molecules gathered itself together into a sub-cell, took a look around, saw what was obviously another sub-cell, whistled, and modern society was founded. How far back this occurred we don't know. It may have been as much as 1 1/2 billion years. In rocks older than the Cambrian, the first period wherein life was abundant, we find peculiar spotlets of carbon which we infer are the remains of cellular life. By the time the Cambrian actually rolled around, most of the invertibrate phyla were represented in a relatively advanced condition. Since the Cambrian is the beginning of life-history, this is a further validation of the inference that life started well back in the pre-cambrian.
Things went along fairly normally for a while: mountains were being formed, rains came along and wore 'em away, and in the oceans animals were eating each other with neatness and dispatch. About 100 million years after the Cambrian began-in the upper Silurian-some seaweed evidently got washed ashore after a storm. One turned to the other and said, "Some storm, huh? Who was that member of the laity I seen you washed up on the shore with?" And the second replied, "That was no laity, that was my wife!" Thus, the first joke was born, and with it-though they were unaware at the time - the first land plants.
From that humble beginning plants grew in stature. They were vitally necessary to the amphibians which followed soon after, and since that time plant changes have always preceded animal changes: in fact, it's a dictum that floral changes presage faunal changes.
About 40 million years after the plants emerged onto land, amphibians appeared. They held sway for 100 million years thereafter, but by the end of that time, the group as a whole was defeated. This occurred around the end of an era, the first in the history of life, and the reasons can be fairly easily set forth. Amphibians are tied to water. Their life cycle demands it, and no break can be made. You might really consider them as a special adaptation of fishes capable of walking on dry land. When a more efficient life form arose, it was found to become King Of The Mountain. That more efficient life form was the reptile.
Reptiles are more efficient than amphibians in a number of ways. The eggs they lay are better adapted to the land; the internal organs and tissues are better places and again, better adapted; they are independent of water as a habitat; and they have better means of locomotion: in amphibians the legs jut out at nearly right angles to the body plane of symmetry while in reptiles this angle comes much closer to zero.
The big joke here is that the mammal has the reptile beat all hollow. Even the primitive mammals, the marsupials, bring forth bigger, if fewer, young alive; and quality, not quantity, seems to be the watchword. Certainly, the most efficient animals, as far as control of environment is concerned, have sprung from the mammals. But before discussing Man, I'd like to break in again with some problems of time and space.
Some time back the idea grew that if a particular fossil-say a dinosaur-were found in a particular bed, then wherever that fossil occurred, the bed was of the same age. I use bed as synonomous with stratum. This was undoubtedly a result of the popularity of the stratographic succession of fossils. This was a great discovery, and people were making world wide correlations on the basis of these so-called "index fossils." Today, unfortunately, we know that this holds only in sensu stricto .
The reason for this is that environment is constantly shifting. Assume that a foram lives under a set of paticular conditions in a bay. Along comes the end of a geologic period and the bay shifts northward. The foram is forced to shift with it. This movement of the bay is the only reflection of the events which close the period.
Sometime later a paleontologist identifies the foram as an "index fossil" of Period X. He then finds, to the north, more of the same forams and thus identifies the rocks as belonging to Period X where as they really belong to Period Y. This is shown in Figure 2.
Population, or numbers of animals, is extremely important in the fossil record, especially among the vertebrates. They just don't breed as rapidly as the invertebrates, so that the chance of any one particular vertebrate being fossilized is fantastically low. The chance of an ancient man coming through is one in a trillion or a quadrillion. A quadrillion is a large number and more than all the spoken output of s-f fans of all time. The wonder is that any specimens became fossils.
The history of the horse is one of the better known histories, and yet it has been spliced together from bits and pieces: an old tooth here, broken femora there, and in relatively rare cases, a whole skeleton. However, it has been estimated that if all the horses from Hyracotherium, the "dawn horse," to Equus were to march past the Garden Library at 6 miles an hour, down Telegraph Avenue, the last one would go by in 365,400 years; and by that time, horses being what they are, and bored at the assembly area, there'd be more horses...
Or, if a photo were taken of each individual horse that ever was, on paper of book thickness, the resulting pile would be 10,000,000 miles high. Here, obviously, is the answer to Willy Ley's mass reaction problems.
McCown has tried to estimate the population of Palestine during the middle and upper Paleolithic times, about 25,000 years ago. This estimate, based on numbers of implements, comes out to be about 50,000 which is probably of the right order of magnitude.
Towards the end of the Pliocene epoch, Nature began experimenting again. Various forms of simians arose showing characteristics in common with the genus Homo. The Australopithecinae-a group of South African, dead-ended, extinct apes-had dentition similar to ours, a cranial capacity higher than apes today, and in one specimen-a 5 year old child-the brain cast was exceedingly like a human child's of equivalent age. This group may even have used fire.
Gigantopithecus, the biggest ape of 'em all, about the size of Mighty Joe Young, exhibited strikingly similar dentition to H. saps though he probably co-existed with Pithecanthropus. The Dryopithecinae, apes of SE Asia, were showing humanoid dentition as far back as the end of the Miocene.
Probably, man arose from several root stocks-as pointed out, many ape forms were converging that way-and this is known as the "polyphyletic origin" of man. In any event, in the early Pleistocene we have a beastie which regardless of name, must fall into the genus Homo. He, or rather, she is called Pithecanthropus. Though primitive, this organism knew the use of crude tools and fire, and that the best way to get at the most delicious food of all-the brains of any enemy-was through the hole in the back of the skull where it rests on the backbone. What more could you ask?
From this point on, the forms came with increasing rapidity: H. rhodesianensis with the bad teeth and mastoiditus; H. heidelburgensis with the thickest jaw in Europe and presumably the thickest skull; Eoanthropus dawsoni with the modern skull and completely primitive jaw; H. neanderthalensis; and finally, H. saps.
During the course of geological history certain life forms have risen to dominance. By "dominance" I mean, roughly, being widespread geographically, of numerous population, ability to reproduce relatively fast which is a reflection of adjustment within a given ecological niche, strength, protective coloration, etc. However, while the rise to a dominant position was taking place, destructive factors were at work, thus insuring the end of dominance and the furtherance of the evolutionary chain. The seeds of biological disaster are inherent in each new dominant species.
Back in the Cambrian, almost from the beginning, rose an animal called the Trilobite-pronounced Try -lo-bite-a distant relative of the crab (Figure 3). This was it . He was the master of all he surveyed. But by the next geological period, the Ordovician, the first vertebrate was hanging around the corner drugstore. The Ostracoderm (Figure 4) was a fish, and he probably lived on trilobites and by the end of the Ordovician the trilobites were rather minor.
The amphibians were on the land, and there wasn't anybody around to bother them. That is, until the Carboniferous period when they were at their height. Then was born a small creature, less than three feet in length, over which they shook their heads. Even now we're not sure whether Seymouria is an amphibian which is almost a reptile or a reptile which just stopped being an amphibian. Anyway, here was a reptiloid form millions of years in advance of the age of dinosaurs and smack in the middle of the strongest era of amphibians. Following the Carboniferous, came the Permian and with it arose Dimetrodon (Figure 5), the most aggressive meat-eater yet seen on earth. One of the interesting things about this animal was his close approach to the stem-mammal form.
Shortly after, about 15 million years, the dinosaurs were ascending. They didn't know it, but they were also in the process of descending. The mammals had already shown up even before the publicised and more spectacular dinosaurs came into being. Man took over from the mammals, generally. But if, and this is a big if, man is truly a dominant form, then the replacing form is probably already among us .
Specialization is a term used by life students to indicate odd growths in organisms. For instance, if a land animal develops fins and returns to the seas, it is specialized. An old maxim of paleontology is that when an animal specializes, the end is in sight. This is simply explained: specialization means living within an extremely limited environment. If the environment changes-Good night, Irene!
One of the more famous cases of specialization occurred with the Amonites. This was a marine group of invertebrates, closely related to the nautilus and octopus. By Cretaceous times, amonites were so specialized they were more or less like the snake which swallowed its own tail (Figure 6) Oddly enough, the ammonites became extinct at the same time the dinosaurs did.
Another case is Dimetrodon (Figure 5). That sail he carried on his back was a form of specialization: theories about it range from its use as protection to non-functional grounds as an unbalanced growth. Some wag has suggested that it would be used for sailing so that the beast could tack back and forth in a fashion approved in the best yachting circles. Anyway, Dimetrodon came to a quick, bad end.
The dinosaurs specialized towards the end. All sorts of weird forms evolved, and this specialization was probably as much a factor in the great dying as the mammals.
The point is: is man becoming specialized in a "mental" sense as well as physical?
I am put in mind of a poem composed by a friend of mine in presumably a black mood; it goes:
The sponge could not
Improve his lot.
And they died
The answer to this must be, from a paleontological point of view, a resounding "No!" Man's ability to control his environment holds out some hope, but not much. Probably, if environmental control is one of the criteria of advance in evolution from here on in, then the next form or the next will be the one to turn the trick. Man's future, according to the geneticists, looks about like this: He'll be brachycephalic in head form-like he is today-with slightly taller stature and growing taller. His eyes will be dark brown and his skin brownish in cast. His hair will be straight or possibly slightly wavy. And his extinction is more or less assured.
When? No one knows. Rates of evolution are extremely tricky and variable. The higher up on the volutionary scale an animal is, the faster it seems to evolve. During the Tertiary, hoofed mammals came and went at the rate of about one genus every 7 1/2 million years. So lets give Man something slightly less: Give him about 1-2 million years more.
If this depresses you, think of the saving grace inherent in all animals, from man right back down to Henry Claystone. "Life" is a completely pointless phenomenon, starting nowhere and ending nowhere.
Data entry and page scans provided by Judy Bemis
Data entry by Judy Bemis
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