No one knows exactly when humans first became interested in fossils, but some Neanderthal graves have been found with fossils, perhaps used for decorative or religious purposes. In some early civilizations, fossils were used as jewelry and regarded as curiosities, but generally not well understood. Although a few early Greek and Roman philosophers correctly recognized fossils as the remains of past life forms, this was the exception rather than the rule. The philosopher Aristotle (384-322 BC) believed living things could arise spontaneously from rocks or mud, or from "seeds of life" therein, and that fossils were the incomplete examples or failures of this process.

Similar misconceptions persisted for many centuries. During the Middle Ages (about 500-1450) fossils were variously regarded as works of the devil, direct creations in rock by God, the results of vis plastica or "molding forces" in rocks, or simply "sports of nature." In Europe, fossil bones were widely believed to be the remains of animals and humans that had perished during Noah's Flood. In China, fossil bones and teeth were often collected as "dragon bones" and used as medicinal cure-alls. In some areas of China they are still sold as such today.

One of the first scholars to express a relatively modern view of fossils was the famous engineer and artist Leonardo da Vinci (1452-1519). He understood that marine fossils were remains of ancient life forms, and that they provided evidence that ancient seas once covered areas that are now dry land.

In 1664 the science of geology took a step forward when Danish scholar Nicolaus Steno developed the concept of superposition, which holds that the lowest strata (rock layers) in any one place were deposited first, and therefore were the oldest. Meanwhile, a growing number of naturalists, such as Britain's John Ray (1627-1705), began to recognize fossils as the remains of once-living things, and to study them more closely. However, the great age of fossils and the earth itself was not widely appreciated, and many people (including many scholars) still believed that most fossils were remains of Noah's Flood or other catastrophe's that took place only a few thousand years ago (such concepts, known as Flood geology or catastrophism, are still held by many "young-earth" creationists).

During the 1700's, also known as the "Age of Enlightenment," fossil collecting became popular among professionals and laymen alike. Georges Cuvier (the "father of paleontology") and William Smith (the "father of English geology") described and mapped a number of European rock formations, and showed that rock strata in different areas could be recognized and correlated on the basis of fossil content. Other scientists began to classify and describe fossils in a detailed and consistent manner.

During the late 1700's and early 1800's forms of Flood geology and catastrophism, were still common, being promoted even by some major figures such as Georges Cuvier. However, a growing number of naturalists began to maintain that fossils were part of a longer and more complicated geologic past.1 James Hutton and other geologists developed the concepts of actualism and uniformitarianism, which held that present-day processes acting over long periods can explain most geologic features, and that rock layers were primarily the products of long periods of deposition and erosion, rather than one or a few recent catastrophes. These and other geologic concepts were subsequently synthesized by Charles Lyell in a landmark work entitled Principles of Geology, published in three volumes between 1830 and 1833.

Lyell's writings had a major influence on other scientists of his day, including Charles Darwin. One of the principles Lyell emphasized (which was noticed by others as well) was that there was a definite change in fossils through time--that is, a sequence or succession of fossil forms in the geologic record. Darwin combined this fact with his own extensive observations of the natural world to formulate his theory of evolution, which he described in his famous 1859 book On the Origin of Species. Unlike earlier theories of evolution, Darwin's model included a plausible mechanism of evolutionary change known as natural selection.

This concept held that naturally occurring variants of plants and animals having advantageous traits survived and reproduced in greater numbers than their "less fit" competitors, thus changing the characteristics of the species in succeeding generations.

Darwin's theory was strongly opposed by some (including a number of prominent scientists in his day), but his basic model of biologic change was increasingly accepted among scientists. By 1890 biologists had rediscovered the neglected work of Austrian monk Gregor Mendel on garden peas (first published in 1866), which showed how traits are passed from parent to offspring. Subsequent genetic work, including the recognition of mutations (spontaneous changes in genes that can be passed on to offspring), provided a source of "natural variations" which Darwin's theory required.

Meanwhile, spectacular new fossil discoveries in America and Europe from the mid 1800's onward further confirmed that many prehistoric creatures were very different from those living today, and appeared in consistent sequences in the geologic record. The new finds included bones and footprints of fantastic reptiles first called dinosaurs or "terrible lizards" by Richard Owens in 1841, as well as flying reptiles called pterosaurs and large aquatic reptiles such as plesiosaurs, mosasaurs, and ichthyosaurs. During the late 1800's Americans were treated to a soap-opera like rivalry between two prolific and colorful dinosaur bone hunters: Othniel C. Marsh and Edward Drinker Cope. From Germany came what is often called the world's most famous fossil: Archaeopteryx. This unusual creature had wings like a bird but also a number of reptilian features (including teeth)--prompting many to hail it as an intermediate form between reptiles and birds.

By the late 1800's an essentially modern geologic time scale had been worked out, at least in relative terms. The composition and order of major geologic units were well known in Europe and parts of America, and most geologists recognized that the earth was much older than previously thought (perhaps many millions of years older). However, as yet no widely accepted method of assigning a specific or actual age to the earth or the major geologic periods was known.

This situation changed after the discovery of radioactivity in 1896, which led to the development of radiometric dating methods in the early and mid-1900's. These new dating techniques (discussed later) allowed actual or absolute dates to be assigned to rock layers and geologic periods with much greater confidence and reliability than ever before, confirming the great antiquity of the earth and the fossils in it. Although dates obtained with these methods are still subject to margins of error, they are widely regarded as reasonably accurate from a geologic perspective.

The early and mid 1900's featured a continued proliferation of fossil excavation and study, and the building and expansion of major museums of natural history. Today there are literally thousands of paleontologists and fossil collectors throughout the world, and fossils are widely appreciated as objects of beauty and scientific importance. New fossil discoveries and interpretations are being made faster than ever before, aided by similarly rapid developments in the complementary fields of geology, chemistry, biology, and genetics. While still inspiring much wonder and mystery, fossils today are routinely used to identify and correlate rock units; to study the history, form, function, and ecology of ancient plants and animals; to understand ancient environments; and to help locate gas and oil deposits (which are themselves derived from fossils).

Moreover, concepts which just a few decades ago might have seemed very radical and reminiscent of catastrophism, such as giant meteorites smashing into the earth and contributing to mass extinctions, are now being seriously studied by many geologists and paleontologists. According to one recent author, "Today's earth scientists claim Lyell's Principles of Geology their founding document, but in reality, the modern view is a mixed deck of catastrophic and uniformitarian elements."3

Modern paleontologists can study the tiniest details of a fossil with an electron microscope, explore the internal structures of fossils with X-rays and CAT scanners, analyze complex data with computers, and prepare and reconstruct fossils with a wide range of modern tools, techniques, and materials. Some workers are now extracting bits of genetic material from prehistoric bones and tissues in order to unravel complex ancestral relationships. The most optimistic speculate that someday it may even be possible (though perhaps unlikely) to bring back to life long-extinct species through genetic engineering, as depicted in the popular film Jurassic Park.

However, many aspects of paleontology do not require elaborate or expensive equipment. Many relatively simple, "tried and true" methods are still in use by amateurs and professionals alike. Many non-professionals, armed with a few simple tools and a natural curiosity, can enjoy collecting and studying fossils, as well as make important contributions to paleontology.

1. Cuvier thought the earth was perhaps hundreds of thousands of years old, but believed in a form of "progressive creationism"-that new creatures were created after each of several catastrophes.

2. Darwin's contemporary, Alfred Russel Wallace, independently developed a similar theory of evolution.

3. Milner, Richard. 1990. The Encyclopedia of Evolution. Facts on File, New York and Oxford, pg. 445.