A Chronology of the Stone Age

A Chronology of the Stone Age The Stone Age in human prehistory also referred to as the Paleolithic Period, is the period between about 2.7 million and 10,000 years ago. Youll see different dates for the starting and ending dates of the Paleolithic periods, in part because were still learning about these ancient occurrences. The Paleolithic is the time when our species Homo sapiens,  developed into the human beings of today. The people who study the past of humans are called archaeologists. Archaeologists study the recent past of our planet and the evolution of physical human beings and their behaviors. Those archaeologists who study the very earliest human beings specialize in the Paleolithic; scientists who study the periods prior to the Paleolithic are paleontologists. The Paleolithic period begins in Africa with the earliest human-like behaviors of crude stone tool manufacture about 2.7 million years ago  and ends with the development of fully modern human hunting and gathering societies. Domestication of plants and animals marks the beginning of modern human society. Leaving Africa After decades of debate, the majority of scientists are now convinced that our earliest human ancestors evolved in Africa. In Europe, where humans finally arrived after about a million years in Africa, the Paleolithic was marked by a cycle of glacial and interglacial periods, during which time glaciers grew and shrank, covering massive portions of land and forcing a cycle of human depopulation and recolonization. Today scholars divide the Paleolithic into three categories, called Lower Paleolithic, Middle Paleolithic, and Upper Paleolithic in Europe and Asia; and Early Stone Age, Middle Stone Age and Later Stone Age in Africa. Lower Paleolithic (or Early Stone Age) about 2.7 million-300,000 years ago In Africa, where the earliest humans arose, the Early Stone Age begins some 2.7 million years ago, with the earliest stone tools recognized to date in the Olduvai Gorge of East Africa. These tools were simple fist-sized cores and whole flakes created by two ancient hominids (human ancestors), Paranthropus boisei and Homo habilis. The earliest hominids left Africa about 1.7 million years ago, arriving at sites such as Dmanisi in Georgia, where hominids (probably Homo erectus)  made stone tools suggestive of those from Africa. Human ancestors, as a group, are called  hominids. The species that evolved in the Lower Paleolithic include  Australopithecus,   Homo habilis,   Homo erectus,   and  Homo ergaster, among others.   Middle Paleolithic/Middle Stone Age (about 300,000-45,000 Years Ago) The Middle Paleolithic period (ca 300,000 to 45,000 years ago) witnessed the evolution of Neanderthals and the first anatomically and eventually behaviorally modern Homo sapiens. All of the living members of our species, Homo sapiens, are descended from a single population in Africa. During the Middle Paleolithic, H. sapiens first left from northern Africa to colonize the Levant between about 100,000-90,000 years ago, but those colonies failed. The earliest successful and permanent Homo sapiens occupations outside of Africa date to about 60,000 years ago. Achieving what scholars call behavioral modernity was a long, slow process, but some of the first glimmers arose in the Middle Paleolithic, such as the development of sophisticated stone tools, caring for the elderly, hunting and gathering, and some amount of symbolic or ritual behavior. Upper Paleolithic (Late Stone Age) 45,000-10,000 Years Ago By the Upper Paleolithic (45,000-10,000 years ago), the Neanderthals were in decline, and by 30,000 years ago, they were gone. Modern humans spread all over the planet, reaching the Sahul (Australia) about 50,000 years ago, mainland Asia about 28,000 years ago, and finally the Americas, about 16,000 years ago. The Upper Paleolithic is characterized by fully modern behaviors such as cave art, hunting a range of techniques including bows and arrows, and making a wide range of tools in stone, bone, ivory, and antler. Sources: Bar-Yosef O. 2008. ASIA, WEST - Palaeolithic Cultures. In: Pearsall DM, editor. Encyclopedia of Archaeology. New York: Academic Press. p 865-875. Close AE, and Minichillo T. 2007. ARCHAEOLOGICAL RECORDS - Global Expansion 300,000-8000 years ago, Africa. In: Elias SA, editor. Encyclopedia of Quaternary Science. Oxford: Elsevier. p 99-107. Harris JWK, Braun DR, and Pante M. 2007. ARCHAEOLOGICAL RECORDS - 2.7 MYR-300,000 years ago in Africa In: Elias SA, editor. Encyclopedia of Quaternary Science. Oxford: Elsevier. p 63-72. Marciniak A. 2008. EUROPE, CENTRAL AND EASTERN. In: Pearsall DM, editor. Encyclopedia of Archaeology. New York: Academic Press. p 1199-1210. McNabb J. 2007. ARCHAEOLOGICAL RECORDS - 1.9 MYR-300,000 years ago in Europe In: Elias SA, editor. Encyclopedia of Quaternary Science. Oxford: Elsevier. p 89-98. Petraglia MD, and Dennell R. 2007. ARCHAEOLOGICAL RECORDS - Global Expansion 300,000-8000 years ago, Asia In: Elias SA, editor. Encyclopedia of Quaternary Science. Oxford: Elsevier. p 107-118. Shen C. 2008. ASIA, EAST - China, Paleolithic Cultures. In: Pearsall DM, editor. Encyclopedia of Archaeology. New York: Academic Press. p 570-597.

How to Install Ruby on the Linux Operating System

How to Install Ruby on the Linux Operating System Ruby is installed on most Linux distributions by default. However, you can follow the steps below to determine if Ruby is installed and, if not,  install the Ruby interpreter on your Linux computer. How to Install Ruby on Linux For an Ubuntu-based distribution, follow the following procedure to verify whether you have Ruby installed, and if not, to install it. Open a terminal window. One way open the terminal window (sometimes called a shell or bash shell) is to select Applications Accessories Terminal.Run the command which ruby.  If you see a path such as /usr/bin/ruby, Ruby is installed. If you dont see any response or get an error message, Ruby is not installed.To verify that you have a current version of Ruby, run the command ruby -v.Compare the version number returned with the version number on the Ruby download page.These numbers dont have to be exact, but if you are running a version thats too old, some of the features may not work correctly.Install appropriate Ruby packages.  This process differs between distributions, but on Ubuntu run the following command:sudo apt-get install ruby-full Verify That Ruby Works Correctly Open a text editor and save the following as test.rb. #!/usr/bin/env ruby puts Hello world! In the terminal window, change directory to the directory where you saved test.rb.  Run the command chmod x test.rb, then run the command ./test.rb. You should see the message Hello world! displayed if Ruby is installed correctly. Tips: Every distribution is different. Refer to your distributions documentation and community forums for help installing Ruby on distributions other than Ubuntu or its variants.For distributions other than Ubuntu, if your distribution doesnt provide a tool like apt-get then you can use a site such as RPMFind to find Ruby packages. Look for the irb, ri and rdoc packages as well, but depending on how the RPM package was built, it may already include these programs.