By: Francis Hitching
The Fossil Record
The number of intermediate varieties, which have formerly existed on the earth, must be truly enormous. Why then is not every geological formation and every stratum full of such intermediate links? Geology assuredly does not reveal any such finely graduated organic chain; and this, perhaps, is the most obvious and gravest objection, which can be urged against my theory.
- Charles Darwin, The Origin of Species, 1859
Stroll around a zoo and look at the giraffes and elephants; wander through a natural history museum and gaze at the reconstructed dinosaurs; pick up a piece of limestone and crack it open to reveal the ancient fossil shell inside; swim in the sea and enjoy, even as you avoid it, the translucent membrane of a floating jellyfish, unchanged in form for 550 million years.
Evolution is about how these wonders happened. How do we come to have lions and jellyfish and things? What is it that has brought about life on Earth in all its astounding diversity?
More than a century ago, Charles Darwin believed he had the answer. It was a beguilingly simple one. If you went back through the fossil record, he said, you would find that today's perfectly adapted life forms had emerged as victors over previous less perfect forms. The predecessors of giraffes or elephants were slightly different animals, perhaps less strong or less large. At any rate, they were feebler compared with those around them, and they had been wiped out by what he called natural selection.
Throughout nature, and throughout Earth's history, he saw that creatures and plants living on its surface had been involved in a constant struggle for survival. In each generation, only the fittest made it. These fit varieties were marginally more successful than their parents - they had better eyesight, maybe, or longer legs to let them run faster, or leaves that enabled them to withstand a sudden extreme of cold. Gradually almost imperceptibly, these novel features accumulated until a quite new sort of animal or plant emerged - a life form unrecognizable from its distant ancestors millions of years before.
This, said Darwin, solved the greatest puzzle of evolution: the origin of new species (a species is usually defined as a living thing that can only reproduce with its own kind). ‘From the war of nature, from famine and death, the production of higher animals directly follows.’
The idea seemed so blindingly obvious, and so satisfyingly complete, that it quickly replaced the Biblical account of creation, and became a new way of looking at the living world. With a few hiccups, it had held its place ever since. Darwin’s friend Thomas Henry Huxley, who trounced Bishop Wilber-force in an historic debate on the subject at the British Association in Oxford in 1860, is said to have remarked after reading The Origin of Species, 'How stupid of me not to have thought of that.'
Yet for all its acceptance in the scientific world as the great unifying principle of biology, Darwinism, after a century and a quarter, is in a surprising amount of trouble.
Evolution and Darwinism are often taken to mean the same thing. But they don't. Evolution of life over a very long period of time is a fact, if we are to believe evidence gathered during the last two centuries from geology, paleontology (the study of fossils), molecular biology and many other scientific disciplines, Despite the many believers in Divine creation who dispute this (including about half the adult population of the United States, according to some opinion polls), the probability that evolution has occurred approaches certainty in scientific terms.
We can be as sure about this as we are sure that ancient civilizations once existed on Earth but no longer function. The archaeological record tells us about these relatively recent times, and the fossil record about earlier ones. If you walk along the trails leading down to the depths of a great fissure such as the Grand Canyon, you can see some of the stages of evolution illustrated by the fossils in front of your eyes.
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SRA |
SYSTEM AND PERIOD |
SERIES AND EPOCH |
DISTINCTIVE FEATURES |
YEARS AGO |
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|
 |
QUATERNARY |
RECENT PLEISTOCENE |
Modern man Early man. Northern glaciations |
11 thousand ˝ to 3 million 13 million 25 million 36 million 58 million 63 million |
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TERTIARY |
PLIOCENE MIOCENE OLIGOCENE EOCENE PALEOCENE |
Large carnivores First abundant grazing mammals Large running mammals Many modern types of mammals First placental mammals |
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|
CRETACEOUS |
First flowering plants, climax of dinosaurs and ammonites Followed by extinction |
135 million
180 million
230 million
280 million
310 million
345 million
405 million
425 million
500 million
600 million |
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|
JURASSIC |
First birds, first mammals Dinsaurs and ammonites abundant |
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|
TRIASSIC |
First dinosaurs Abundant cycads and conifers |
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|
 |
PERMIAN |
Extinction of many kinds of marine animals including trilobites Glaciation at low altitudes |
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UPPER CARBONIFEROUS |
Great coal forests, conifers First reptiles |
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LOWER CARBONIFEROUS |
Sharks and amphibian abundant Large and numerous scale trees and seed ferns |
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DEVONIAN |
First amphibians and ammonites fishes abundant |
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SILURIAN |
First terrestrial plants and animals |
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ORDOVICIAN |
First fishes; invertebrates dominant |
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CAMBRIAN |
First abundant record of marine life trilobites dominant, followed by extinction of about two-thirds of trilobite families |
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PRE-CAMBRIAN |
Fossils extremely rate, consisting of primitive aquatic plants. Evidence of glaciation. Oldest dated algae, over 2.600 million years |
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The evolution of life on Earth, according to the fossil record.
The Earth is old, belongs to an even older universe, and life forms have been upon it for about three quarters of its existence.
On the other hand Darwinism (or neo-Darwinism, its modern version) is a theory that seeks to explain evolution. It has not, contrary to general belief, and despite very great efforts been proved.
This is not so surprising as it may at first seem. The process of evolution is so slow (some 580-600 million years from the earliest sea creatures until now, according to the latest estimate) that we can scarcely hope to see it happening within our own lifetime, except at a trivial level. We can breed dogs or horses or vegetables and see that great variations of size and appearance can be achieved. In the wild, we can watch dark-winged moths gradually replace light-winged moths on soot-blackened tree trunks, because their camouflage is better and birds don't eat so many of them. In the laboratory, we can bombard fruit flies with x-rays and produce mutants with two sets of wings, deformed bodies, and other unpleasantness Darwin's theory is in fact quite good at explaining minor changes of this sort.
But after that, we can do no more than Darwin did, and extrapolate: that is, to infer that over millions of years, these variations and mutations 'must have' gradually added up to the evolution of giraffes and jellyfish and things.
