The How and Why Library/Life/Animals-Section IV
IV. The Web of Life: Mother Nature at Her Loom
Big boys and girls, when they finish high-school, have to write graduation essays. One of the subjects they often choose to write about is "The Web of Life is Strangely Woven." They like to tell how life is made up of different things, all woven together: Joy and sorrow, health and sickness, work and play are woven in and out into one web. They see the poetry and the prose of living, loving, working, enjoying.
The writer of this had been out of school a long, long time before he learned that his own body was just such a wonderful web. A living body, of a plant or an animal, is a web. It is made up of single cells, multiplied and woven together. Mother Nature uses the same kind of cells, put together in different ways, to make leaf, stem, bark, flower and fruit, in the tree. So she makes skin-tissue, bone-tissue, muscle-tissue, nerve-tissue in the animal.
It took Mother Nature ages and ages, sitting at her loom, experimenting, to learn to make these different tissues out of one material. In the amoeba she had only a very thin skin and a jelly-like muscle. In the sponge she made a horny bone. In the earthworm she made the first ring muscle.
If you get up very close to Mother Nature, as she sits at her loom, you can watch how she works. Her shuttle has a back and forth movement, through the long web of lives. First, she made a plant cell that couldn't move, then an animal that could. Then she made the sponge, an animal that was fastened to a rock, like a deep-sea lichen; then a sea-anemone that could let go of the rock. The amoeba hasn't any bones, the sponge has, the jelly-fish hasn't, the star-fish has. Now bones are very important. Why, when Mother Nature learned to make them for sponges, did she drop the idea, and then come back to it afterwards?
Let us see if we can find out. We will also see Mother Nature weaving lower forms of life into the higher. What looks more different than Johnny with his fishing pole, and the earthworm he uses for bait? Yet there are many things about that earthworm that are just like things in Johnny. The earthworm's body is made up of ring muscles. Those are the very first hints of the ring-joints in Johnny's backbone. Those ring muscles are what makes it possiblefor the earthworm to turn and twist and move forward and to shrink.
Yet, in making those ring muscles for the earthworm, Mother Nature's shuttle shot back across the web. She dropped the bones she made for the sponge and star-fish. One thing at a time, she says. I'll go back for those bones, when I get ready to put the earthworm into a shell. The crawfish is only a worm in a shell. The spider, the ant, the bee and the fly are all ring-jointed, but have no shell. When she got up to insects, Mother Nature dropped the bone or shell idea, to make better brains and senses. The bee, the ant, and the spider have such large brains, in proportion to their bodies, that they are a wonder to men.
Having made brains and sensitive nerves, Mother Nature began to use bones again. But when she made ring bones along the back of the fish, she dropped behind in brain power. A fish isn't nearly as bright as an insect. A reptile is a little brighter than a fish, a bird—you know how "smart" a crow is? By and by, Mother Nature made little boys and girls who can read, and understand this story of life.
It is very important to have a backbone, something to stand up with. You saw that in the great world of plants, when the simple yeast cell was slowly changed into the noble forest trees. All animals with a backbone are put into one class, called vertebrates. Those without backbones are called invertebrates.
Man is the most wonderful of all the animals, but even he isn't as clever in everything as are many of his humble relatives. He cannot swim like the fish, nor fly like the bird. That is he cannot do these things at first. But he has brains to "think out" things. Then he can build ships and flying machines.
When he first comes into the world, man is the most helpless of all animals, and he remains helpless the longest. But that is an improvement. It was a great thing in the history of life when animals began to think about their babies, and about taking care of them. Little insects born as creeping larva, are able to take care of themselves as soon as they come out of the cocoon. But they never get very far, and they soon die. It is only when animals begin to spend a part of their lives learning things of their mamas—as spiders and ants and bees and birds do—that they amount to much.
The children of savage men—such as Indians—live longer with their parents and depend upon them more than do the animals, and so they learn still more. White children spend still more of theirtime at home, and at a great place called school, which gives all of its time to carrying on the work that is begun in the home.
In both home and school the greatest thing of all that a boy or girl learns, is to love and to help other people. So far as his body is concerned, a boy doesn't differ so very much from animals lower than himself. He differs most of all in his power to reason, and to think and to care for the happiness of others. He has a sense of right and wrong, of honor, of justice, of unselfishness, of fair play, of pity. These are the social and moral powers that, alone, make human beings far above all the other animals.
But these fine feelings, too, began far back with the first animals that cared for their babies. Long before Mother Nature got up to human beings, she made ants and bees live and work in colonies, and birds care tenderly for their nestlings.
What, do you suppose, was the very first animal that carried her helpless babies about with her, and fed them in some strange way?