The History of Our Tribe Hominini Textbook Part III Pliocene Epoch Chapter 15 Australopithecus africanus

15 . southern ape I Africa ) Figure Cast of . Cast of mung child by is licensed under . SITES , and , South Africa PEOPLE Raymond Dart , Robert Broom , and Brain INTRODUCTION was the first fossil discovered in Africa . In 1924 , Raymond Dart ( see his biographical sketch this chapter ) identified the face , mandible , and as being that of a juvenile bipedal ape ( see Figure ) Eugene discovery of the Javanese Homo erectus fossils in 1891 refuted the reigning belief that we got smart before we stood Once Dart claims were accepted , the world 102

realized the extent to which that idea was false . The Au . showed that early were bipedal apes as opposed to quadrupedal humans . Unlike East African material that can be dated using a variety of techniques , primarily due to past volcanic activity , South African fossils and sites are much more difficult to date . Most dates can only be represented as ranges hence the date for the earliest Au . specimens falls between and . PHYLOGENY Au . is considered to be a gracile by some and a robust by others . the species was favored as the immediate ancestor of the Homo lineage , specifically of Homo . However , some researchers have always believed that Au . was the common ancestor of both Au . and the Homo lineage , suggesting a event had occurred at Au . This schema has gained popularity in recent years . However , with the new evidence being put forth for Au . it seems that the Au . a Homo scenario was closer to the truth in that Au . and Au . are undoubtedly related and Au . shares many characteristics with genus Homo . While there is some port for Au . as ancestral to the more derived robust forms , that still leaves unresolved those shared between Au . and both and Au . see Au . Chapter 17 ) DISCOVERY AND GEOGRAPHIC RANGE Au . is known only from sites in South Africa ( see map showing the major fossil sites in Chapter , Figure ) Material from more than 200 individuals has been collected over more than 80 years . Most of the fossils came from caves , some of which were discovered during mining and blasting activities . Those caves formed via underground water activity . Fossilization was facilitated by water dripping on bones and , just as stalagmites form . Over millennia , many of the caves filled in with deposits and as the ground surfaces eroded , the underlying deposits were exposed and mined and then later excavated for fossils . BIOGRAPHICAL SKETCH RAYMOND DART ( and the CHILD Raymond Dart was the first to recognize a fossil in Africa . While his claim to have covered a human ancestor was not initially accepted by the scientific community , he was when Robert Broom began finding similar material at other South African sites . The work of Dart and Broom played a pivotal role in directing attention to Africa as the birthplace of humanity , as Charles Darwin had earlier predicted . Raymond Dart was a renowned Australian anatomist who was teaching at the University of in South Africa at the time of the discovery . have read several accounts over the years of the fateful day when the fossil material landed in Dart hands . The material was brought to him by either quarry workers or a colleague while he was dressing for the wedding of his daughter or friend , depending on the source you read . He is said to have attempted to use his wife knitting needles to extract the fossils from the surrounding matrix . I am not sure 103

why we need to know what he was doing when he got his hands on the goods . We certainly do not know what most were doing when they were presented with fossil finds . However , it conjures up amusing possibilities in my mind ! The fossilized remains came from the Quarry in the process of blasting for lime . When presented with the material , Dart established that it was the face , mandible , and ( interior of the cranial vault ) of a juvenile . He based this on the anterior position of the foramen magnum and aspects of brain morphology reflected on the interior of the skull vault . Dart named his find , meaning southern ape of Africa , and the specimen became known as the Child . Figure Raymond Dart . Smithsonian Institution Archives from the Smithsonian Institution Archives is in the public domain . The child was two to three years old when it died . We now know that the caves of South Africa were formed by underground water activity and that dropped or were dragged into those subterranean caves became fossilized during the process of formation . Over millennia , the caves filled with mineral deposits , and via erosion , the contents and underground cavities surfaced . Many fossils were likely destroyed during quarrying ties , but we are lucky that many were preserved . Raymond Dart is also renowned for his Killer Ape theory and the ( culture . Dart believed that animal long bones and carnivore mandibles that were found with remains had been used as weapons to fight and kill one another . We now know that was not the case . They were most likely opportunistically hunting small prey and scavenging larger kills , and they were prey for larger animals . Dart is credited with the 1924 discovery and naming of Au . His now famous Child came from the quarry site . The to juvenile is represented by its face , skull fragments , and mandible , and an of its brain . Dart also worked at the site of . His 104 The History of Our Tribe

temporary , Robert Broom ( see biographical sketch below ) worked at the caves at ( see Figure ) where he discovered a complete , female cranium known as . along with other Au . material . Broom also worked at the sites of and the latter is where he discovered the first , Brain , a famous , also worked at . discounted Dart views of the as killer apes . He believed that bones either dropped into caves as part of large cats prey or were dragged in by rodents for gnawing . Some individuals are thought to accidentally been trapped in underground caverns . Some speculate that those individuals that show no evidence of having been preyed upon , due to their degree of completeness ( 573 from and the Au . party from the site ) surely became trapped . The six Au . individuals are thought to have possibly been attracted to the cave by water . a more recently discovered site , yielded an almost complete cranium as well as material from approximately 80 individuals . A fifth site associated with the species is . BIOGRAPHICAL SKETCH ROBERT BROOM ( Figure Robert Broom . Robert from the American Museum of Natural History is in the public domain . Robert Broom was a Scottish medical doctor and paleontologist who subsequently made a name for himself as a paleoanthropologist , even though the term did not exist at the time . He taught geology and zoology at a South African college until he was let go for his controversial beliefs in evolution that were contrary to the religious teachings at the college . Subsequent to his termination , his finances went downhill until Raymond Dart secured him a tion at the Transvaal Museum . While his specialty was reptiles , he became increasingly involved with fossil . Together , Dart and Broom made 15 . 105

cal history , discovering the first and second species of African , respectively . Broom worked at the Au . sites of and the sites of and . All of those sites are now contained within the Cradle of Humankind World Site . He was the first to discover and name , and his work with Au . helped to support Dart claims to have discovered a bipedal ape and human ancestor . Broom most famous Au . find was . possibly a male ) which he originally named or primitive human of the Transvaal . If accounts of Robert Broom are to be believed , he was a colorful character . He is said to have worn attire while excavating and when media were present , he conveniently upon important discoveries . Supposedly , one of his team buried an artifact that was already labeled with a catalog number . Oh , to have been on the scene and witnessed what must have been an embarrassing situation ! Not to mention that , according to numerous online sources , he thought nothing of stripping naked when it became Africa Hot ! I picked up that term from a couple of comedy movies but it is now in the Urban Dictionary . It is interesting that Broom did not believe in Darwinian evolution but rather , what we would now call Intelligent Design ( Wikipedia contributors ) Figure Cave . Caves , photograph by Mike Peel ( is licensed under . 106 The History of Our Tribe

PHYSICAL CHARACTERISTICS Au . was more derived than Au . This is not surprising considering that they lived at least one million years later , as well as the trend within the lineage to become more and manually dexterous over time . Au . were habitual bipeds with all of the corresponding lower limb adaptations . They also retained climbing characteristics , such as shoulder joints long arms relative to legs and long , curved hand and finger bones . However , in general their hands were more than those of Au . While the brain was small relative to later species , Au . was not only more than past species , with a cranial capacity of 450 ( range ) but also possessed an enlarged cerebral tex in the frontal and parietal regions ( see Figure ) Their quotient ( was . The quotient is a method for comparing brain size among species . Anything greater than means that the brain is larger than would be expected based on body size ( our is ) area is an area of the left lateral frontal cortex that is involved with the production of language ( see ) It is present in all Old World monkeys and apes , but it is enlarged in Au . relative to previous species . These are all important developments , in that they herald the appearance of more complex thought processing and likely communication skills . There is debate over whether the lunate sulcus ( see Figure ) a fissure on both sides of the occipital lobe that is involved with vision , was more or . The sulcus is smaller in humans than in monkeys and apes . I RON I Figure of the brain . by is licensed under BY . 107

Motor and Sensory Regions of the Cerebral Cortex Primary motor Primary sensory cortex ( precentral gyrus ) gyms ) Somatic motor association area Somatic sensory association area ( cortex ) Visual association area ( production ol speech ) Auditory association area area Auditory cortex ( understand speech ) Figure and areas ( see areas surrounded by dotted lines ) Brain by Medical Communications , is licensed under BY staff . Journal of Medicine . 29013762 . I al in Figure Lunate sulcus , also known as the simian or lateral occipital sulcus , outlined in red . by based on drawing by Henry Carter is in the public domain . The external skull reflected the cerebral expansion by becoming more rounded and exhibiting more of a forehead . In addition , the sagittal and pronounced nuchal muscle crests seen in Au . were not sent . However , some males had convergent temporal lines that suggest that they may have had a slight 108 The History of Our Tribe

Homo habilis Homo Figure species . Illustration by Taylor . sagittal crest . There is debate over whether the cranial base was ( see Figure ) or whether that was a development seen only in more derived forms of Homo . The species face was prognathic with a distinctive concavity in the midfacial region ( see Figure ) The dental arcade was more parabolic , and the teeth were smaller than those of Au . The first premolar is considered to have been bicuspid , versus in Au . However , their faces were more heavily for chewing a tougher diet , and some researchers thus consider them to be robust . Figure Concave facial of ( Au . 3204 by is licensed They retained the primitive condition of long arms and their finger bones were somewhat curved . However , their hands were more and they possessed our power thumb , giving them increased pinching and gripping capabilities . This was accomplished via better developed intrinsic thumb muscles , within the hand versus coming from the forearm to act on the thumb , and a specialized first metacarpal While they were considered to be habitual and very likely obligate bipeds , they still retained a divergent hallux . According to and Berger ( 1998 ) and Green et al . 2007 ) they may have been more arboreal than Au . Au . were less sexually dimorphic than Au . with males averaging ' 138 ) tall and 90 ( 41 ) and females at ' 115 ) and 67 ( 29 ) 109

Review of Primitive Characteristics . Arboreal characteristics a shoulder joints . a Long arms relative to legs . a Long , curved metacarpals and phalanges . Review of Derived Characteristics Skull changes a More rounded skull vault . Increased . Frontal and parietal expansion . More of a forehead . Loss of sagittal crest and less pronounced nuchal crest . Facial . More of a parabolic dental arcade and reduced anterior dentition . Power thumb intrinsic thumb muscles . Specialized first metacarpal . Reduced sexual dimorphism . ENVIRONMENT AND WAY OF LIFE While there is some controversy as to how much time Au . spent in open versus closed ( forest ) environments , their facial robusticity and molars reflect a greater reliance on tougher , more plant foods than earlier . They retained climbing adaptations and thus could have used trees for safety , sleeping , and food . When on the ground , it is thought that they were , foraging for plant foods and small prey and scavenging remains of carnivore kills . Crude stone tools have been found at the sites of and , and while there is no evidence of tool manufacture , it appears that they were using stones for hammering and cutting . They are thought to have relied on tubers for part of their diet and they likely used digging sticks to unearth them , in much the same way as modern African peoples , such as the groups of the Desert . 110 The History of Our Tribe

As mentioned , it is thought that may have fallen through the surface into subterranean caves or bones were dragged in by rodents for gnawing . While it is possible that they used open caves for shelter from sun and rain , there is no evidence that they lived in caves . In nature , extractive have relatively large brains . Examples within the primate world include the ( a prosimian of Madagascar ) that hunts insects via a combination of audition ( hearing ) and tion ( see for multiple videos ) New World capuchin monkeys that steal young animals from tree holes and rip bark from trees to get at insects baboons that dig for tubers and the brainy orangutans and chimps that use a variety of tools to extract a range of foods , from ants to honey ( see Figures and for videos of chimps and ) Chimps have even been observed using sticks to spear ( small nocturnal African ) in tree holes ( see How Smart Are Planet Apes ?

on ) The same can be seen in some bird species , most notably crows and . Since our last common ancestor with chimps and bonobos was already smart , I believe that while was in response to diminishing habitat and resources , was in response to having to locate and learn to process new foods . Beginning with Au . and the subsequent , we see an upward trend for and expansion of those portions of the brain involved with association , complex thought processing , as well as increasing strength and dexterity for manipulating tools and objects . Thus we stepped out and then had to find and fix dinner ! We tend to think of evolution by means of natural selection as being a positive aspect of life , survival of the However , when there is a rapid response to a changing environment , many individuals die out while those few survive . Videos A YouTube element has been excluded from this version of the text . You can view it online here ?

Figure Ant dipping by , 111 A YouTube element has been excluded from this version of the text . You can view it online here ?

Figure Orangutan using tool by Alain Compost , 112 The History of Our Tribe