Diet
In addition to forcing changes in locomotion that led to walking upright, the increasingly dry climate of east Africa over the last six million years forced changes in the diet of early hominins from the soft fruits of the tropical rain forest to the increasingly fibrous and tough foods available in open habitats. Early hominin diets are reconstructed partly based on the surface areas of the molars and the cross-sectional area of the body of the lower jaw Collard amp Wood, 1999 . Tooth area...
Setting the Stage
To fully understand human evolution it should be seen as a recent installment in the much larger story of the evolution of life on Earth. Human evolution can then be understood as only one chapter in the larger story of vertebrate and mammalian evolution. Having said this, we must confine ourselves in this paper to setting the stage with those events just prior to the evolution of the last common ancestor of chimpanzees and humans. By 22 million years ago, in the early Miocene, apes had...
Why Teach Human Evolution
Modern science has reached the point where the broad outline of our origin is known. For each of us this scientific knowledge of human origins and evolution has a special significance, because central to each of our individual views of the world is a concept of who and what we are. The beliefs we hold about ourselves drive our attitudes and our actions and, as such, determine the kind of people we are and ultimately the kind of society we have. In the past we have answered the questions about...
Recommended Books
Johanson, D., amp Edgar, B. 1996 . From Lucy to Language. New York Simon amp Schuster. Although somewhat dated, this book includes David L. Brill's stunning photographs of the world's most important human fossils. Klein, R. G. 1999 . The Human Career Human Biological and Cultural Origins, 2nd Edition. Chicago University of Chicago Press. Klein's book is one of the most cited and important books on human evolution. It is somewhat technical but provides a complete and balanced view of human...
Current Research on Human Evolution
We have confined our review of human evolution to the period between the late Miocene eight million years ago m.y.a. and 100,000 years ago. This period marks the evolutionary transition from our last common ancestor with modern chimpanzees to the first fully modern humans. Because of limited space, and to do proper justice to the subject, we have not included the last hundred thousand years of human evolution and history. Our knowledge of this period is growing daily and is best left as a story...
Keywords
Teaching Evolution, Human Evolution, Hominin Evolution, Paleoanthropology, Review Introduction As science educators, we have two goals in writing this paper. The first goal is to show the importance of teaching human evolution to all students. The second goal is to provide up-to-date resources for classroom teachers to use in teaching the subject. Secondary biology textbooks suffer from the inherent limitations of mass produced books making it difficult for them to stay current with rapidly...
A Note about Species Names
New fossil discoveries of our early ancestors are occurring at an increasing rate, each with new names and claims of direct ancestry to modern humans. But even as paleoanthropologists shuffle species names to accommodate these new discoveries the general outline of human evolution remains sturdy. The astrophysicists James E. Peebles has suggested that rapidly changing sciences, like astronomy and paleoanthropology, are a sign of healthy activity. Shifts in opinion are not a reflection of some...
Hominid or Hominin
A 'hominid' is a member of the family Hominidae, which classically includes all creatures, living and extinct, that are more closely related to Homo sapiens than to the extant chimpanzees Pan troglodytes and P. paniscus , the closest living sister taxon to Homo. This classical solution is, however, more problematic for the great apes chimpanzees, gorillas Gorilla and orangutans Pongo which are lumped together in the family Pongidae. The problem is that some of these creatures chimps and...
Summary
It is highly unlikely that the general framework we have portrayed for human evolution will change in the near future, this in spite of the fact that the cast of characters will surely expand with new discoveries, and paleoanthropologists will surely readjust genus and species names to reflect our growing knowledge. And that is good news, for it reflects the healthy chaos of Peeble's busy construction site. By the same token, it is the broad framework of human evolution that all biology...
Encephalization Language and Speech
Brain sizes expressed as estimated cranial capacities are commonly reported for various species of hominin. Australopithecus afarensis and Australopithecus africanus have the smallest averages to date at 410 and 440 cubic centimeters cc , respectively Collard amp Wood, 1999 . Chimpanzee cranial capacity also averages 410 cc. But chimpanzees weigh about 24 more than the australopiths, thus complicating this simple comparison. The cranial volume of the robust hominins such as Paranthropus...
An Overview
The following elements provide a framework for the broad patterns of hominin evolution modified from Foley, 1999 . 1. The Late Miocene 8-5 m.y.a. witnessed the diversification of the African apes as the east African climate shifted from tropical rain forest to dryer conditions. 2. Bipedalism developed in late Miocene to early Pliocene hominins 6-4 m.y.a. on the eastern side of the African continent, possibly in response to more open habitats. 3. An adaptive radiation of African hominins took...
The Current Cast of Characters The Earliest Hominins
Modern apes and humans differ greatly, but the earliest hominins contrasted in subtle ways from living apes primarily in their increasing reliance on walking upright known as bipedalism. The skeletal indicators of bipedalism include a forward placement of the hole at base of skull where the spinal column enters the foramen magnum , and a shortening and broadening of the pelvis to make it bowl-shaped. These changes were accompanied by shifts in muscle groups particularly the gluteal and...
Australopiths
All later hominins, including members of the genus Australopithecus, are characterized by bipedal locomotion, and the numerous species reflect differences in diet and presumed ecological specialization. In general, the older species share more primitive traits with their Miocene forebears. Among these older species are Australopithecus anamensis 4.2-3.9 m.y.a. from Kenya Leakey, et al., 1998 and Ethiopia White, et al., 2006 , and another closely related species, Australopithecus afarensis...
Schningen site II Recovery of a Wooden Spear
Photograph courtesy of NLD Hannover The oldest wood tools, found in deposits near Schoningen, Germany, are 2 meter long spears 6-1 2 ft made 400,000 y.a The were made from spruce trees and resemble the javelin, weighted for precision throwing. They are the oldest and most complete hunting weapons ever found. The spears were made by the ancestors of the Neanderthals, The Oldowan and Acheulean tool traditions are lumped into the Lower Paleolithic. After 300,000 y.a. tools become more complex and...
A anamensis First fully Modern Humans
The first catarrhine primates evolved sometime after 50 million years ago and before 33 million years ago when it's estimated the New World monkeys split from the Old World monkeys. Most primate fossils from this period have been found in a region of northern Egypt known as Al Fayyum or the Fayum . A primate group known as Propliopithecus, one lineage of which is sometimes called Aegyptopithecus, had primitive catarrhine features that is, it had many of the basic features that Old World...
Major Trends in Hominin Evolution Cultural Evolution
Bipedalism appeared 5 to 6 m.y.a. and it is likely that these earliest hominins achieved a level of technology consistent with contemporary chimpanzee tool use Ambrose, 2001 . The earliest stone tools date to 2.5 m.y.a. from Ethiopia, and likely as early in Kenya de Heinzelin et al., 1999 Klein, 1999 . The site in Ethiopia provides evidence of the disarticulation and defleshing of large mammals and of long bones that were smashed open presumably to obtain the marrow. These early stone tools are...
This map can be enlarged for greater detail
Above is a relief map of Africa and the Arabian peninsula showing the East African Rift System running north-south just right of center. The East African Rift System extends from Jordan in the Middle East south to Mozambique in southern Africa. It is some 4,000 mi 6,400 km long and averages 30-40 mi 48-64 km wide. The rift has been forming for some 30 million years, as Africa and the Arabian Peninsula separate. The system's main branch, the Eastern Rift Valley, is occupied in the north by the...
The Moderns
At some point between 200,000 and 100,000 years ago a population of early humans in Africa crossed the morphological threshold to fully modern humans. The timing of this watershed event is supported by a variety of genetic studies Cavalli-Sforza 1998 . These same studies estimate the number of individuals in this population to be from 20,000 to as few as 2,000 individuals Harpending, 1998 . A population of two thousand individuals is about the size of a large high school in America today. It...
Later Australopiths and related Genera
Specimens of the 3.5-3.3 m.y. old Kenyanthropusplatyops, recovered from the Turkana Lake region of Kenya, include a temporal bone, two partial upper jaws, isolated teeth and most of a cranium Leakey et al., 2001 . The 3.5 m.y. old site includes both former grassland and wooded habitats. Kenyanthropus platyops had a small ear hole, like Australopithecus anamensis, and thick enameled cheek teeth, small brains and flat nasal margins like Australopithecus afarensis and Australopithecus anamensis...
Early Homo
Homo habilis above remains have been found in Tanzania, Ethiopia, and Kenya, from deposits dated to 2.4-1.6 m.y.a. Wood amp Richmond, 2000 . H. habilis, which means handy man, was originally assumed to be the first stone tool maker as the name implies. There is, however, no unequivocal evidence that Homo habilis made stone tools. There is also some question as to which genus Homo habilis should be assigned to, either Homo or Australopithecus. In general this species has a slightly larger...