Forbidden Archeology: The Hidden History of the Human Race

What does this have to do with human evolution? The standard idea is that the fossil record reveals a basic history, true in outline even though not known in every detail. But this might not at all be the case. Can we really say with complete certainty that humans of the modern type did not exist in distant bygone ages? Consider Van Andel’s point that out of 6 million years, only 100,000 may be represented by surviving strata. In the unrecorded 5.9 million years there is time for even advanced civilizations to have come and gone leaving hardly a trace.

Darwin’s appeal to the incompleteness of the fossil record served to explain the absence of evidence supporting his theory. It was, nevertheless, basically a weak argument. Admittedly, many key events in the history of life probably have gone unrecorded in the surviving strata of the earth. But although these unrecorded events might support the theory of human evolution, they might radically contradict it.

Today, however, almost without exception, modern paleoanthropologists believe that they have fulfilled the expectations of Darwin, Huxley, and Haeckel by positive discoveries of fossil human ancestors in Africa, Asia, and elsewhere. We will now give a brief summary of these discoveries, placing them within the framework of the history of life on the earth as reconstructed by paleontologists. In this summary, we shall introduce the standard system of geological dates and time divisions that we will use throughout the book.

1.7 The Geological Timetable

The story of life on earth now accepted by paleontologists can be outlined as follows. About 4.6 billion years ago the earth came into being as part of the formation of the solar system. The earliest evidences of life are fossils reputed to be of single-celled organisms. These date to 3.5 billion years ago. It is said that only single-celled organisms inhabited the earth until about 630 million years ago, when simple multicellular creatures first make their appearance in the fossil record.

Then, some 590 million years ago, there was an explosive proliferation of invertebrate marine life forms, such as trilobites. This marks the beginning of the Paleozoic era and its first subdivision, the Cambrian period. The first fish are often said to have appeared in the Ordovician period, beginning 505 million years ago, but Cambrian fish have now been reported. In the Silurian period, beginning some 438 million years ago, the first land plants entered the fossil record. We note, however, that spores and pollen from such plants have been reported from Cambrian and even Precambrian marine strata (Jacob et al. 1953, stain forth 1966, McDougall et al. 1963, Snelling 1963). In the Devonian period, which began 408 million years ago, the first amphibians came on the scene, followed by early reptiles in the carboniferous period, the beginning of which is set at about 360 million years ago. Next is the Permian period, which began some 286 million years ago and marks the end of the Paleozoic era.

The next period is the Triassic, which began some 248 million years ago and is marked by the appearance of the first mammals. In the succeeding Jurassic period, which extends from 213 million years to 144 million years ago, paleontologists note the appearance of the first birds. The Jurassic and Triassic periods, along with the following cretaceous period, are famous as the Age of the dinosaurs and are known collectively as the Mesozoic era. At the end of the cretaceous period, some 65 million years ago, the dinosaurs mysteriously died out.

Then comes the Cenozoic era. The name Cenozoic is made of two Greek words meaning “recent” and “life.” The Cenozoic is divided into seven periods: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and finally the Holocene or most recent period, dating back 10,000–12,000 years. The dates for these periods, and the periods comprising the Paleozoic and Mesozoic eras, are given in Table 1.1. These dates are taken from A Geologic Time Scale, a recent text on radiometric dating (Harland et al. 1982).

The geological time divisions were largely formulated in the nineteenth century, on the basis of stratigraphic considerations. Initially, there was no way to assign quantitative dates to these divisions, and thus geologists referred to them qualitatively—a particular period was simply said to be earlier or later than another. In the twentieth century, scientists began to assign quantitative dates by means of radiometric methods, and they have continued to revise these dates periodically up to the present time. Thus today many roughly equivalent systems of dates are used by different geologists and paleontologists.