The Seven Mysteries of Life

by Guy Murchie

  From the viewpoint of each microscopic grain of pollen of course, it makes an extremely hazardous journey, as scarcely one in a million can hope to alight precisely upon a waiting stigma (female organ) of exactly the right kind of plant to spunk it into a seed. Yet while the vast hordes are drying up, drowning or merely withering in frustration, the lucky few will each touch a bit of stigma, usually sticky and sweet with just the chemical complement needed to germinate it.

  Germination is expressed by the pollen's sprouting a kind of phallic root that in a few hours elongates to worm its way down the surface of a papilla (hair) of the stigma, which is significantly coated with a potent chemical aphrodisiac. Once it penetrates the papilla's base, it draws further strength from the very nutritious tissue now around it, which also enfolds it snugly like a vagina, seeming to seduce it deeper and deeper until at last it bursts triumphantly into the cavity of the ovary and seizes one of the ovules, pouring its contents into her until their two substances fuse into one and she is fertilized. This is the key genetic act in vegetable reproduction, the union of male and female germ cells that conceives a new plant.

  BIRTH

  The mammalian equivalent of seed germination or egg hatching we know as birth. I will not dwell long on it, for it is comparatively easily understood as a critical step in reproduction. But I must mention that it varies about as much as any other function in life, the ease of delivery among mammals alone ranging from that of the opossum baby, who weighs one twenty-fifth of an ounce or one ten-thousandth as much as his little mother and may be born only eight days after intercourse but already able to climb hand over hand up into her pouch, to that of the newborn blue whale who may tip the beam at fifteen tons or over one tenth the weight and two fifths the length of his huge mother. Although a fetus is a relatively easy burden when the uterus around it is supported in the sea, the very real risks in whale birth are shown by the many known cases of mothers who did not survive it. The uterus nevertheless has proven a remarkably adaptable organ on land as well as sea, having been measured in some pregnant mammals to stretch to 400 times its original size, a flexibility obviously important in bringing forth a youngster big enough to get along independently his first day out as is true of the agouti, a rodent born with a hairy coat and open eyes.

  You might think the porcupine mother would be in for trouble in giving birth to a prickly baby, especially in cases of breech presentation, but actually it is easy, for the infant (as with so many animals) comes wrapped in a smooth membranous sac. On the other hand one would not expect mice, who beget as many as seventeen litters a year, to have any of the whale's trouble delivering them, but, surprisingly, at least one European species of mouse called Acornys caharinus with relatively large offspring has been observed to need "midwives" and uses them in two thirds of all births, the experienced female mice helping with difficult confinements, biting off the umbilical cord and cleaning the little ones as they appear. Some degree of midwifery is practiced, incidentally, by a good many other animals, from male frogs to female elephants.

  A more unusual kind of birth assistance was evolved over 200 million years ago among the first land mammals to return to the sea. I am thinking of Stenopterygius, a kind of pre-porpoise of the Triassic age whose young always emerged very slowly tail first, taking weeks to be born, during which time the baby-to-be learned to swim at first just with its tail, then gradually worked its body and flippers into the act until, when at last its head came free, it was well able to rise to the surface for air. Modern porpoises, using a newer, presumably safer, system, are born 400 times faster, but afterward usually find themselves "tied" to their mother's "apron strings" for several days as the tough umbilical cord remains intact while they are led around getting used to breathing, swimming and nursing. More primitive animals such as fish, some of whom produce live young, can afford more carefree birth, as witness the great manta ray, who is born in midair while his mother (sometimes 20 feet in wingspread) leaps clear of the waves. A few kinds of fish in a reverse amphibian tactic crawl out of the water to give birth on dry land. And there are curiously handed "births" like those of the starfish and sea urchin, who develop in the left-hand side of their larval "mothers." However, since they almost totally consume her body before emerging, this sort of debut might more properly be considered a metamorphosis.

  It is in the human sphere that some of the strangest births have been recorded, revealing the extremes of which nature is capable. The size of surviving human babies ranges all the way from a ten-ounce girl born unattended in England in 1938 to a 24-pounder in southern Turkey in 1961, and a few unconfirmed reports of ones up to 33 pounds. The numbers of babies that can share a birth have an interesting frequency schedule, human twins occurring statistically about every 86th confinement (when no ovulation-stimulating hormone, such as gonadotropin, has been used), triplets roughly once in 10,000, quadruplets once in a million, while about every year one mother somewhere on Earth produces quintuplets, about every four years sextuplets, more than once every decade septuplets, and approximately every three decades octuplets, the two octuplet cases thus far this century having been reported in Tampico, Mexico, in 1921 and in Kwoom Yam Sha, China, in 1934.

  As significant as multiple births in a single delivery, I should think, are multiples of deliveries and the total numbers of offspring per mother, so it is interesting to read of the unconfirmed report of a Brazilian woman who begat 44 children in her life, all single births, to achieve which she could hardly have missed any chances in averaging a baby every eleven months from puberty to menopause. Then there is the authenticated case of Madame Feodor Vassiliev of Russia, who bore 69 children, with sixteen pairs of twins, seven sets of triplets and four sets of quadruplets. Her peasant husband deserves mention too, I'd say, for, after her well-earned demise, his second wife bore him eighteen more children in six pairs of twins and two of triplets, making him the father of 87 children, from only two wives and with no single birth in the lot!

  EGGS AND INCUBATION

  The ovulation and gestation rates of terrestrial animals are quite unmistakably influenced by the earth and her motion in relation to the sun or, in the case of tidal creatures like oysters, by the moon as well. Indeed large wild mammals generally bring forth their young only in spring, thereby alloting them three quarters of a year in which to get ready for their first winter. Even eggs are seasonally regimented so the young have the maximum chance to survive. Starting as a germ in every female before she is born, the egg remains a single cell for a long time, but, on being fertilized in the mating season, it suddenly starts growing in distinct layers. A typical bird's egg yolk (food for the embryo) has twelve layers created in six days, as in the first chapter of Genesis, strictly at the command of the sun: a yellow layer each day and evening followed by a thin white layer each night. Next the egg's albumen appears, its white layers accompanied by the watery fluid that supports and protects the central yolk. Then come two tough membranes plus four final layers of chalky shell that harden in less than a day. The outer one of these is patterned and colored in the exact design evolved by that particular species of bird.

  Eggs vary almost as much as seeds, their shapes ranging from the nearly round ones of fish and turtles to the long pointed ones of the cliff-dwelling murre which, if disturbed, have the life-saving tendency to roll in tight circles. Some are laid like beads on a string or stuck together in jelly, in pods, biscuits, cups, spiral coils or vermicelli threads. Some flying fish and also the ocean's only insect (the waterstriding Halobates) anchor their eggs to drifting feathers shed by sea birds. Certain moth eggs are cuboid and laid in courses like bricks. Shark eggs have horns. Wasp eggs may be injected into living animals, who will serve as food after they hatch. Others won't hatch until they have been chewed, swallowed and partly digested. And some ant parasites lay polyembryonic eggs which, like MRV missiles, separate into many. The eggs of insects are probably the most diverse of all,

  as the illustration suggests. But e
ven birds' eggs range in bulk all the way from the pill of the hummingbird to the bigger-than-football ovoid of the extinct "roc" of Madagascar, and in color from robin's-egg blue and egret green to the emu's black and the blood red of a newly laid ptarmigan's egg.

  Some birds with few enemies, such as the albatross or the petrel, lay only one egg a year and, even if it is. lost, will refuse to lay another. Some, known as "determinate layers," in effect count and remember their eggs and stop laying at four or some other definite number whether or not any eggs have been removed. Others, called "indeterminate layers," will keep on if someone takes their eggs, a case in point being the flicker whose newest egg was experimentally removed daily until she had laid 71 of them in 73 days. Champion in this category, however, must be the domestic duck who laid 363 eggs in 365 days! And perhaps equally impressive is the performance of a wild ruddy duck weighing one pound who in about two weeks laid a single clutch of fifteen eggs weighing over three pounds or three times her own weight.

  Most birds incubate their eggs by sitting on them, but a few have devised rather intriguing alternative means. I'm thinking of the turkey-like megapode, who lays hers on a huge pile of fermenting, steaming compost, then covers them with just enough sand to keep them at 92°F., or the maleo of Celebes, who specializes in hot springs and fumaroles, sometimes literally incubating her eggs by volcano! Meanwhile inside the shell during this critical period (which, depending on the species, can last anywhere from 11 to 90 days) the homogeneous yolk with its microscopic ovum miraculously turns into a hatched bird. In the first two or three days the ovum duplicates and reduplicates itself into a visible embryo with rootlike blood vessels reaching thirstily outward into the nourishing yolk. After two fifths of the incubation time has passed, the embryo has separated itself from the shrinking yolk except for a kind of umbilical blood stalk that feeds it. Halfway, most of its organs are visible, particularly the dark, shining eyes. At the three-quarter mark, the chick is fully formed, yet has still to absorb the final third of the yolk via its cord. In the last day or two before hatching, it starts to breathe from the expanding air chamber at the large end of the egg which is replenished through the shell's pores, the shell steadily thinning as its lime flows into the growing bones. And associated with the breathing it makes faint peeping sounds, by means of which, scientists have discovered, adjacent eggs can talk to each other and their mother and coordinate their hatching, ensuring that all the chicks of a clutch start pecking their shells to get out at the same time. This is important for giving them all an equal chance to survive, especially in the case of such helpless and naked hatchlings as baby songbirds who seem geared to grow at a furious rate. In some cases such youngsters have been known to multiply their weight by 50 in three weeks from eating mostly proteins conscientiously brought to them every minute or two all day long. A pair of great tit parents in England indeed were recorded in one test as making more than 900 feeding trips to their brood in a single day.

  Mammal incubation, on the other hand, while it occurs mostly in the womb instead of an eggshell, works in the same basic way except that the mother's body directly supplies the young mammal with food for a much longer period, including serving it milk after birth. Evidently it was for this important purpose that the great mammalian invention of the nursing breast was evolved with its own wide range of models. Did you know that the familiar pair- or multiple-pair-breasted physiognomy of man, dogs, cats, mice, etc., is only one of many designs and that the number of breasts or nipples can vary widely even in the same species. I guess the official maximum is the 22 teats in two rows on the tenrec of Madagascar, who has litters up to 36, but there are all sorts of odd cases, like the opossum with 13 teats (sometimes more) close together inside her pouch where the tiny young clamp on for more than five weeks, with quick starvation the hard lot of the late-born, who commonly find all stations already occupied. Baby bats have a better chance and perhaps a merrier time hanging to their mother's teats while she zigzags intricately through the night sky, grazing on insects every couple of seconds. The platypus mother, believe it or not, serves her milk from no teats at all, and the young, after hatching from eggs, must lick it off her fur. The whale mother also eschews teats in favor of slits, which are more streamlined, and has them way back on her tail so she can lift them clear of the water while her air-breathing calf is getting his nourishment pumped into him with special milk muscles. The dolphin's mammary glands are often colored like targets, so the bumbling baby, even while tied to her "apron strings," can't miss them. And target-like also, come to think of it, is many a human breast with its dark red disk signaling the way to the nipple.

  And this brings to mind the further fact that the variability of breasts in number and location applies to humans almost as much as to animals, for medical anomalies include practically every abnormality one can think of from amazia (complete absence of breasts) and cases of only one breast to all sorts of supernumerary ones in odd places from under the arm to the back, even the thigh, sometimes turning a figure into a panorama. Handily enough, most of these function too. Anne Boleyn is reputed to have had three breasts and there is a famous painting in the Louvre by Rubens showing a woman with four. That this anomaly is more prevalent than most people realize is suggested by one researcher's report of finding 60 instances out of 3956 persons examined, which is 1.56 percent - the men, surprisingly, sprouting extra nipples about twice as often as the women.

  Of course nursing is only one side of mothering, which is quite general on Earth, even among such animals as turtles and alligators - and by no means excludes the vegetable kingdom (page 66). Centipedes and scorpions are particularly maternal toward both their eggs and young, and the Surinam toad mother carries her eggs on her back until they hatch as fully formed toadlets. I could go on, but there seems no point in further belaboring this large and well-accepted subject.

  ORIGINS OF SEX

  We have by now looked at many aspects of sex from its abstract relativity to its concrete workability. Yet I cannot conclude without saying something about sex's origins in life and evolution, its reason for being.

  So let us take a glance backward into the older, simpler, littler, lower world, where procreation is more and more a matter of chemistry and more orderly - where, beneath the large-scale, emotional drama of love, there unfolds the basic need that makes it happen. We find ourselves then back in the habitat of cells and molecules, the microcosm where reproduction and sex began. Obviously we must sift and sort some elementary facts. What in essence is sex? And is it the same thing as reproduction? No. These phenomena are not only not the same (witness the dandelion's prolific reproduction without sex) but, in a basic way, they are opposites. I mean, if the main requirement of reproduction is to multiply the numbers of individuals, turning the singular into the plural, then sexual activity or the uniting of two or more individuals is contrary to it in reducing multiflesh into one flesh or, to use biological terms, conjugating the separate sperm and ovum into a single embryo.

  To clarify our thinking on this not-so-familiar aspect of the subject, let's first consider reproduction, which of course is more fundamental than sex. Reproduction is basically a kind of growth - and it is a growth that almost always leads to separation into new units, as when a bit of the parent body splits off and grows into a new parent body, which in time splits again. All life somehow must reproduce itself (whether or not via sex) if it is to continue beyond its individual organisms, which obviously cannot go on forever just as they are. And the cell, generally regarded as the unit of life, has evolved three principal ways of reproducing, only the newest and most complicated of which makes use of sex.

  The first and simplest method of cell reproduction, already described in some detail (page 105), is division of the cell into halves or, in a few cases, smaller fractions. Second is the budding or sprouting upon the cell of a small, specialized sporelike appendage, which soon breaks loose and grows into a new complete cell. Yeast propagates itself this way. Thi
rd is the specialization of the cell into two or more genetic strains, which, when they attain enough differentiation, become unable to split and reproduce themselves until they can get together and exchange genetic material. This most ancient form of copulation is the exception, not the rule, in single cells, which generally reproduce by simple division (one into two), but it nevertheless seems to have become important in the long run for maintaining genetic vigor, and is known to be practiced at rare intervals by both bacteria (vegetables) and protozoans (animals), usually starting when they are under stress, say from drought, famine or temperature change. It also occurs among viruses, which are hardly more than minerals and where the strains (genders) are labeled only plus and minus or (at the molecular level) right and left. It may even, as the illustration suggests, have begun between identical crystals that are indisputably minerals!

  The interesting thing about this primordial version of sex is that it has little to do with reproduction and not only was imposed upon it but, in fact, actively opposes it. Its function seems rather to be to reinvigorate the species as with a shot in the arm after a long, hard siege of redundant stagnation - and, in the case of paramecia, this genetic swap definitely slows down reproduction by consuming over an hour's time, enough for three generations of ordinary division, which division obviously must be postponed the while. Thus 2 protozoans making "love" of a morning (sexually so to speak) will end their session as 2 protozoa instead of 16, which otherwise would have been the number of their great-grandchildren procreated (by simple division) in the same period. So don't assume sex necessarily promotes a family.

  Yet sex has its usefulness, for it increases variableness and adaptability by its exchange of genes (significant details of which we will take up in the next chapter). In essence sexual conjugation is a randomizing process, a shuffling of the genetic "cards" that, in the hundreds of millions of years it has been going on, has been largely responsible for the extraordinary variableness and proliferation of nature. It is also a liberalizing process as compared with the conservatism of plain reproduction. It keeps trying out new combinations of genes, partly by chance meetings (as between boy and girl), partly by selection (as when a girl with many suitors decides whom to say "yes" to), the results, if any, appearing in subsequent offspring.