Evolution of Plants

It is instructive to look at the various kinds of cabbages, such as cauliflower and Brussels sprouts, kale and curly greens, and remember that they are all scions of the not very promising wild cabbage found on our shores. And are not all the aristocrat apple-trees of our orchards descended from the plebeian crab-apple of the roadside? We know far too little about the precise origin of our cultivated plants, but there is no doubt that after man got a hold of them he took advantage of their variability to establish race after race, say, of rose and chrysanthemum, of potato and cereal. The evolution of cultivated plants is continuing before our eyes, and the creations of Mr. Luther Burbank, such as the stoneless plum and the primus berry, the spineless cactus and the Shasta daisy, are merely striking instances of what is always going on.

There is reason to believe that the domestic dog has risen three times, from three distinct ancestors—a wolf, a jackal, and a coyote. So a multiple pedigree must be allowed for in the case of the dog, and the same is true in regard to some other domesticated animals. But the big fact is the great variety of breeds that man has been able to fix, after he once got started with a domesticated type. There are over 200 well-marked breeds of domestic pigeons, and there is very strong evidence that all are descended from the wild rock-dove, just as the numerous kinds of poultry are descended from the jungle-fowl of some parts of India and the Malay Islands. Even more familiar is the way in which man has, so to speak, unpacked the complex fur of the wild rabbit, and established all the numerous colour-varieties which we see among domestic rabbits. And apart from colour-varieties there are long-haired Angoras and quaint lop-eared forms, and many more besides. All this points to evolution going on.

The Romance of the Wheat

It is well-known that Neolithic man grew wheat, and some authorities have put the date of the first wheat harvest at between fifteen thousand and ten thousand years ago. The ancient civilisations of Babylonia, Egypt, Crete, Greece, and Rome were largely based on wheat, and it is highly probable that the first great wheatfields were in the fertile land between the Tigris and the Euphrates. The oldest Egyptian tombs that contain wheat, which, by the way, never germinates after its millennia of rest, belong to the First Dynasty, and are about six thousand years old. But there must have been a long history of wheat before that.

Now it is a very interesting fact that the almost certain ancestor of the cultivated wheat is at present living on the arid and rocky slopes of Mount Hermon. It is called Triticum hermonis, and it is varying notably to-day, as it did long ago when it gave rise to the emmer, which was cultivated in the Neolithic Age and is the ancestor of all our ordinary wheats. We must think of Neolithic man noticing the big seeds of this Hermon grass, gathering some of the heads, breaking the brittle spikelet-bearing axis in his fingers, knocking off the rough awns or bruising the spikelets in his hand till the glumes or chaff separated off and could be blown away, chewing a mouthful of the seeds—and resolving to sow and sow again.

That was the beginning of a long story, in the course of which man took advantage of the numerous variations that cropped up in this sporting stock and established one successful race after another on his fields. Virgil refers in the "Georgics" to the gathering of the largest and fullest ears of wheat in order to get good seed for another sowing, but it was not till the first quarter of the nineteenth century that the great step was taken, by men like Patrick Sheriff of Haddington, of deliberately selecting individual ears of great excellence and segregating their progeny from mingling with mediocre stock. This is the method which has been followed with remarkable success in modern times.

One of the factors that assisted the Allies in overcoming the food crisis in the darkest period of the war was the virtue of Marquis Wheat, a very prolific, early ripening, hard red spring wheat with excellent milling and baking qualities. It is now the dominant spring wheat in Canada and the United States, and it has enormously increased the real wealth of the world in the last ten years (1921). Now our point is simply that this Marquis Wheat is a fine example of evolution going on. In 1917 upwards of 250,000,000 bushels of this wheat were raised in North America, and in 1918 upwards of 300,000,000 bushels; yet the whole originated from a single grain planted in an experimental plot at Ottawa by Dr. Charles E. Saunders so recently as the spring of 1903.

THE WALKING-FISH OR MUD-SKIPPER (PERIOPHTHALMUS), COMMON AT THE MOUTHS OF RIVERS IN TROPICAL AFRICA, ASIA, AND NORTH-WEST AUSTRALIA

It skips about by means of its strong pectoral fins on the mud-flats; it jumps from stone to stone hunting small shore-animals; it climbs up the roots of the mangrove-trees. The close-set eyes protrude greatly and are very mobile. The tail seems to help in respiration.

Photo: "The Times."

THE AUSTRALIAN MORE-PORK OR PODARGUS

A bird with a frog-like mouth, allied to the British Nightjar. Now in the London Zoological Gardens.

The capacious mouth is well suited for engulfing large insects such as locusts and mantises, which are mostly caught on the trees. During the day the More-pork or Frog-mouth sleeps upright on a branch, and its mottled brown plumage makes it almost invisible.

PELICAN'S BILL, ADAPTED FOR CATCHING AND STORING FISHES

There is an enormous dilatable sac beneath the lower jaw.

SPOONBILL'S BILL, ADAPTED FOR SIFTING THE MUD AND CATCHING THE SMALL ANIMALS, E.G. FISHES, CRUSTACEANS, INSECT LARVÆ, WHICH LIVE THERE

AVOCET'S BILL, ADAPTED FOR A CURIOUS SIDEWAYS SCOOPING IN THE SHORE-POOLS AND CATCHING SMALL ANIMALS

HORNBILL'S BILL, ADAPTED FOR EXCAVATING A NEST IN A TREE, AND ALSO FOR SEIZING AND BREAKING DIVERSE FORMS OF FOOD, FROM MAMMALS TO TORTOISES, FROM ROOTS TO FRUITS

The use of the helmet or casque is obscure.

FALCON'S BILL, ADAPTED FOR SEIZING, KILLING, AND TEARING SMALL MAMMALS AND BIRDS.

PUFFIN'S BILL, ADAPTED FOR CATCHING SMALL FISHES NEAR THE SURFACE OF THE SEA, AND FOR HOLDING THEM WHEN CAUGHT AND CARRYING THEM TO THE NEST

The scaly covering is moulted in the autumn.

We must not dwell too long on this particular instance of evolution, though it has meant much to our race. We wish, however, following Professor Buller's Essays on Wheat (1919), to explain the method by which this good seed was discovered. From one we may learn all. The parent of Marquis Wheat on the male side was the mid-Europe Red Fife—a first-class cereal. The parent on the female side was less promising, a rather nondescript, not pure-bred wheat, called Red Calcutta, which was imported from India into Canada about thirty years ago. The father was part of a cargo that came from the Baltic to Glasgow, and was happily included in a sample sent on to David Fife in Ontario about 1842. From one kernel of this sample David Fife started his stock of Red Fife, which was crossed by Dr. Saunders with Hard Red Calcutta. The result of the cross was a medley of types, nearly a hundred varieties altogether, and it was in scrutinising these that Dr. Saunders hit upon Marquis. He worked steadily through the material, studying head after head of what resulted from sowing, and selecting out those that gave most promise. Each of the heads selected was propagated; most of the results were rejected; the elect were sifted again and yet again, and finally Marquis Wheat emerged, rich in constructive possibilities, probably the most valuable food-plant in the world. It is like a romance to read that "the first crop of the wheat that was destined within a dozen years to overtax the mightiest elevators in the land was stored away in the winter of 1904-5 in a paper packet no larger than an envelope."

Thus from the Wild Wheat of Mount Hermon there evolved one of the most important food-plants of the world. This surely is Evolution going on.