Physical Evolution of Human Species

Homo sapiens Chimpanzees (Pan) H. heidelbergensis H. neanderthalensis H. erectus H. floresiensis Paranthropus boisei 1 H. antecessor P. robustus H. habilis 2 H. ergaster Au. garhi H. rudolfensis P. aethiopicus 3 Kenyanthropus platyops Au. africanus Australopithecus bahrelghazali Millions of Years 4 Australopithecus anamensis Au. afarensis Ardipithecus ramidus Archaic and Modern Humans: Rapid advances in brain size; suite of new behaviors. Anatomically modern humans emerge from one of the many regional variants. Erectines: Body height of modern proportions. Increasing brain volume. Sophisticated tools are manufactured and used to kill and process small sized game. Australopithecines: Possessed a gracile body form and were probably opportunistic omnivores/scavengers. Habilines: Brain enlargement, first recognizable stone tools, body remains small/slight. Paranthropines: Early hominids specialized for eating a bulky, low-grade vegetarian diet. Developed powerful chewing muscles and a generally robust skull. Early Hominids: Brain size similar to modern chimpanzees, body remains small/slight. Hominid status may be in question. 5 Orrorin tugenensis 6 Sahelanthropus tchadensis 7 8

Human Evolution Timeline A number of fossil hominid species from the period 3.5 to 6.5 million years ago have been discovered in recent years. They have been assigned to the following genera: Sahelanthropus Orrorin Ardipithecus Australopithecus

Human Evolution Timeline In 2001, the 6-7 my old remains of a nearly complete skull with gorilla-like features was unearthed in Chad. Nicknamed “Toumai” and assigned to a new genus, Sahelanthropus tchadensis, scientists debate whether it is human or the remains of a proto-gorilla. Photos courtesy of: SkullsUnlimited.com

Human Evolution Timeline Orrorin tugenensis, or ‘Millennium man’ was discovered in late 2000 in Kenya. It is claimed to be the oldest hominid yet described. Photos courtesy of: SkullsUnlimited.com

Human Evolution Timeline Originally given the name Australopithecus ramidus, it was reclassified under a new genus, Ardipithecus. Two subspecies have been identified: A. ramidus ramidus (4.4 my old) and A. ramidus kadabba (5.8 my old) Regarded by some researchers as ‘simply an ape with some unusual characteristics’.

Human Evolution Timeline Discovered at Kanapoi, Kenya in 1994, this earliest known species of the genus Australopithecus had a mixture of primitive, ape-like features and advanced, human-like features.

Human Evolution Timeline The last 3 million years have seen a series of adaptive radiations among the more advanced hominid groups:

Human Evolution Timeline Discovered in Kenya, a new genus Kenyapithecus appears to be an offshoot from the main evolutionary branches Photos courtesy of: SkullsUnlimited.com

Human Evolution Timeline As many as four species from the genus Australopithecus emerge, with a wide geographic distribution, ranging from southern Africa, through East Africa, to Chad in the north.

Human Evolution Timeline A group of species from the genus Paranthropus emerge in southern and eastern Africa. Superbly adapted to exploit low grade vegetarian diet, they coexist with the emerging genus Homo.

Human Evolution Timeline From a probable Australopithecine ancestor emerges the first species of genus Homo. A small-brained species with fully developed bipedal locomotion, it has a talent for shaping tools from stone. This hominid does not venture out of Africa.

Human Evolution Timeline What followed was an adaptive radiation of the genus Homo, leading to increased body height, brain capacity, complex social behavior, and a geographic distribution that extended well beyond Africa.

Human Evolution Timeline A recent discovery in 2003 of a ‘pygmy’ species of human that lived on the Indonesian island of Flores between 95 000 - 13 000 years ago. Photos courtesy of: SkullsUnlimited.com

Research: