Review Human Evolution

Continental Drift According to the theory of plate tectonics, the continents embedded in underlying plates on the earth’s surface have moved in relation to one another over the history of life on earth. They are still moving today.

Mammalian Primate Evolution Climate changes led to the appearance of primates about 65 million years ago. These were small, arboreal, nocturnal, insect eaters. About 23 million years ago, hominoids, the primates that include all living and extinct apes and humans began to appear in Asia, Africa, and Europe. DNA studies have confirmed that the African apes are our closest living relatives. Bipedalism preceded brain expansion and played a pivotal role in setting us apart from the apes. UPDATE

Note: Figure represents the timeline of mammalian primate evolution.

Human Evolution In the past 35 years, studies have confirmed that the African apes (chimpanzees, bonobos, and gorillas) are our closest living relatives. Between 8 and 5 million years ago, humans, chimpanzees, and gorillas began to follow separate evolutionary courses. Humans and their ancestors are distinct among hominoids for bipedalism, a form of locomotion on two feet.

Ardipithecus ramidus Dated to 4.4 million years ago. The remains show that some of the earliest bipeds inhabited a forested environment.

Changes in Anatomy Associated with Bipedalism Position of foramen magnum

Changes in Anatomy Associated with Bipedalism Shape of spine Shape of pelvis

Australopithecines The genus including several species of early bipeds from southern and eastern Africa living between about 4.3 and 1.1 million years ago, one of whom was directly ancestral to humans.

Robust Australopithecines Known for the rugged nature of their chewing apparatus (large back teeth, large chewing muscles, and bony ridge on their skull tops for the insertion of these large muscles).

Gracile Australopithecines Members of the genus Australopithecus possessing a more lightly built chewing apparatus. Likely had a diet that included more meat than that of the robust australopithecines.

Homo habilis “Handy human.” The first fossil members of the genus Homo appearing 2.5 million years ago, with larger brains and smaller faces than australopithecines. May have been a tertiary scavenger.

Oldowan Tools The first stone tool industry. Marked the start of the Lower Paleolithic (or Old Stone Age) beginning about 2.6 million years ago. LOWER PALEOLITHIC: Spanning from about 2.6 million to 250,000 or 200,000 years ago.

Homo erectus “Upright human.” A species within the genus Homo first appearing just after 2 million years ago in Africa and spreading through the Old World. Had a brain close in size to that of modern humans. Had sophisticated behaviors including use of fire for warmth, cooking, and protection. Made smaller and lighter tools.

Homo erectus Sites

Homo sapiens Between 400,000 and 200,000 years ago, evolving humans achieved the brain capacity of contemporary Homo sapiens. Several variations of the genus Homo existed around this time, and they are ancestral to both Neandertals in Europe and the Middle East, and Modern Humans.

The Neandertals A distinct group within the genus Homo inhabiting Europe and Southwest Asia from approximately 125,000 to 30,000 years ago. Represented as the classic cavemen. They had modern-sized brains with faces and skulls that were very different from later fossilized remains. Associated with the Mousterian tool industry.

Neandertal Culture The use of fire was essential to their survival in cold climates. They lived in small bands or single family units, in the open and in caves. They likely used language to communicate. They buried their dead, reflecting ritual behavior. Fossil remains of an amputee discovered in Iraq and an arthritic man excavated in France imply they cared for the disabled.

Mousterian tool tradition The tool industry of the Neandertals and their contemporaries of Europe, Southwest Asia, and northern Africa from 125,000 to 40,000 years ago. Mousterian tools are lighter and smaller than those of earlier traditions. Previous industries obtained only two or three flakes from an entire stone core, Mousterian toolmakers obtained many smaller flakes, which they retouched and sharpened.

Brain size over time From left to right: gracile australopithecine, Homo habilis, Homo erectus, archiac Homo sapiens, a Neandertal, and an anatomically modern Homo sapiens.

Upper Paleolithic The last part (40,000 to 10,000 years ago) of the Old Stone Age, featuring tool industries characterized by long slim blades and an explosion of creative symbolic forms.

Mousterian and Upper Paleolithic Tools

Homo sapiens Evidence indicates that at least one population of archaic H. sapiens evolved into modern humans. Whether this was due to the biological evolution of a new species or a simultaneous worldwide process involving all archaic forms is debated.

The Multiregional Hypothesis The hypothesis that modern humans originated through a process of simultaneous local transition from Homo erectus to Homo sapiens throughout the inhabited world.

Recent African Origins Hypothesis The hypothesis that all modern people are derived from a single population of archaic H. sapiens from Africa. These H. sapiens replaced other archaic forms due to superior cultural capabilities. Also called the “Eve” or “Out of Africa” hypothesis.