16 From Natural Fibers to Man-Made Plastics 16.1.History and Classifications Fibers Natural fibers were utilized by mankind considerably earlier than metals,alloys,and ceramics.Indeed,it can be reasonably as- sumed that fibers were applied by humans long before recorded history.Moreover,even some animals use fibers,for example, when building nests (birds,mammals),webs (spiders),for pro- tection during pupation(caterpillars,silkworms),or for retriev- ing insects out of narrow holes (chimpanzees).In short,some animals produce fibers for their needs,whereas others collect them.The history of the utilization of fibers is,however,much harder to trace than that of metals and ceramics because fibers often deteriorate through rot,mildew,and bacterial action.In other words,only a few specimens of early fibers have been found so far. The first raw material that man turned into fabrics was prob- ably wool.Scholars assume that this might have occurred as early as during the Paleolithic period,that is,during the Old Stone Age, about 2 million years ago(see Chapter 1).Fabric from wool may have been produced by felting,a process that yields a nonwoven mat upon the application of heat,moisture,and mechanical ac- tion to some animal fibers,as will be explained in Section 16.2. That there was trade in wool can be inferred from documents and seals dating back to 4200 B.C.which have been found in Tall al- Asmar (Iraq).Breeding and raising wool-producing sheep appar- ently commenced in Central Asia and spread from there to other areas of the world.This was possible by the fact that sheep adapt easily to different climates.For example,it is reported that the Phoenicians brought the ancestors of the Merino sheep from Asia16 Natural fibers were utilized by mankind considerably earlier than metals, alloys, and ceramics. Indeed, it can be reasonably as￾sumed that fibers were applied by humans long before recorded history. Moreover, even some animals use fibers, for example, when building nests (birds, mammals), webs (spiders), for pro￾tection during pupation (caterpillars, silkworms), or for retriev￾ing insects out of narrow holes (chimpanzees). In short, some animals produce fibers for their needs, whereas others collect them. The history of the utilization of fibers is, however, much harder to trace than that of metals and ceramics because fibers often deteriorate through rot, mildew, and bacterial action. In other words, only a few specimens of early fibers have been found so far. The first raw material that man turned into fabrics was prob￾ably wool. Scholars assume that this might have occurred as early as during the Paleolithic period, that is, during the Old Stone Age, about 2 million years ago (see Chapter 1). Fabric from wool may have been produced by felting, a process that yields a nonwoven mat upon the application of heat, moisture, and mechanical ac￾tion to some animal fibers, as will be explained in Section 16.2. That there was trade in wool can be inferred from documents and seals dating back to 4200 B.C. which have been found in Tall al￾Asmar (Iraq). Breeding and raising wool-producing sheep appar￾ently commenced in Central Asia and spread from there to other areas of the world. This was possible by the fact that sheep adapt easily to different climates. For example, it is reported that the Phoenicians brought the ancestors of the Merino sheep from Asia Fibers From Natural Fibers to Man-Made Plastics 16.1 • History and Classifications