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4.0 Introduction

There is no discussion about the reality of the evolutive process but no theory explains the totality of the accumulated observations adding up to this process. The emergence of bacteria from viruses, the appearance of eukaryotic cells from bacteria, the … Continue reading

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4.1 The Mechanisms of Speciation

4.1.1 Darwin: natural selection The Greeks and Romans seriously studied fossil remains and were fascinated with the remains of giant creatures (mastodons, mammoths, rhinoceroses, giant bears). They had museums where the bones were displayed and they examined the fossils with … Continue reading

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4.2 Gene Determinism: an Erroneous Paradigm of Life

Modern biology has been dominated by three revolutions. The first was initiated by Mendel, who founded modern genetics, the second by Darwin, who investigated the mechanism of evolution and the last by Watson-Crick. The Watson-Crick era began as a paradigm … Continue reading

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4.3 Molecular Strategies in Biological Evolution

Most of the basic concepts in evolutionary theory predate 1953 when virtually nothing was known about DNA12. As early as 1930, it became clear that evolving organisms had to maintain old functions as they gained new ones. One way to … Continue reading

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4.4 The Challenges of the Environment

A light granitic crust that is about 40 km thick underlies the continents. A dense basaltic crust about 7 km thick underlies the oceans (fig. 4.2). These continental and oceanic crusts are in turn both underlain themselves by a mantle … Continue reading

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4.5 Environmental Challenges and Species Survival

4.5.1 Ammonoids The ammonoids are a sub-class that forms, with the sub-class of the nautiloids and that of the colloids, the cephalopod class. Squids are cephalopods. The ammonoids were sea dwelling animals that formed successive shells made of calcium carbonate. … Continue reading

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5.0 Introduction

The evolutive direction taken by the metazoa was improvements of energy utilization and refined perception of the internal as well as external world by the endocrine and nervous systems. The development of a nervous system with the accumulation of a … Continue reading

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5.1 The Phyletic Lines

  Figure 5.1. Geologic time chart. Ice Ages occurred 600 million years ago, 280 million years ago and 1 to 2 million years ago. They define the 3 geological great eras. Each era is subdivided in periods, themselves divided in … Continue reading

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5.2 Land Invasion by Chordates

The appearance of representatives of the chordate phylum has long been assumed to occur about 475 million years ago, during the Ordovician period, i.e. late in evolutive times. Finds in China (1999) show that at least two species of 2 … Continue reading

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5.3 The Amphibians

A period of severe drought prevailed during the Devonian period. This was precisely the time when the crossopterygian fishes were around, and their ability to use atmospheric air favored them. The lung was probably developed by bony fishes because they … Continue reading

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