The History of Our Tribe Hominini Textbook Part IV Pleistocene Epoch Chapter 23 Homo habilis

23 . Homo habilis Homo habilis ( human I handy , able , etc . SITES Ethiopia ( and possibly ) Kenya Fora Gorge South Africa and PEOPLE Mary and Louis , Donald , Tim White , and others Figure reconstruction of Homo habilis . habilis by is licensed under . 144

Of the two species of Early Homo , Homo is the favored ancestor of Homo and all subsequent species . PHYLOGENY While the origin of Homo habilis has been in a state of flux in recent years , the discovery of Au . has raised more questions about the origin of our genus . The discovery of Lucy in the early led some researchers to turn away from Au . in favor of Au . as the ancestor of genus Homo . In recent years , the idea that a event had occurred with Au . leading to Au . and the more derived robust forms on the one hand and genus Homo on the other , gained in popularity . Au . iba now seems to have bridged the gap between the and genus Homo , sharing characteristics with Au . and . The similarities with the two Homo species may help resolve the problem as to which of the two species of Early Homo gave rise to . There are proponents in support of each of the evolutionary scenarios , with their share of pros and cons . Figure 1813 , om , by Borg is in the public domain . DISCOVERY AND GEOGRAPHIC RANGE Louis and Mary discovered the first fossil material in 1960 at their site in Gorge , Louis had been recovering stone tools from the site for years , but the manufacturer of those tools had eluded him . He named the species Homo habilis or . Fossils attributed to have also been found at ( and possibly ) Ethiopia Fora , Kenya ( see Figure ) and the South African sites of and . PHYSICAL CHARACTERISTICS exhibited a high degree of sexual dimorphism , with males and females weighing 114 and 70 and standing ' and ' respectively . Their skull , face , and dentition were more gracile than the . Their teeth and dental arcades were very . The skull base was flexed , as seen in Au . and the more derived robust and , relative to past species , the skull was rounder and higher , 23 . Homo habilis 145

reflecting architectural changes in the brain . Cranial capacity ranged from 500 to 800 with a mean of 631 . This gave them an of . At this point in evolutionary history , we see increased in the two hemispheres of the brain , termed lateralization or left dominance . The left side of our brain is involved with language and analytical processes . Like all Old World monkeys and apes , habilis possessed area , which is involved with language production . However , it was larger than in past species , and they also possessed area , which plays a role in language . They thus had the neural capacity for language . The left hemisphere is also related to . They may have exhibited our tendency to hold objects with our left hand while working on them with our right . The frontal lobe , important in association processes , was expanded and resulted in more of a vertical forehead . The enlarged brain may have been facilitated by a decrease in gut volume , combined with a diet that resulted from increased cognitive capabilities and an expanded technology base . habilis had a smaller supraorbital torus and its face was more orthognathic than its supposed ancestor , Au . but they retained some prognathism in the lower face . They had fairly large incisors , but their canines , and molars were reduced in size . The mandible was more gracile , reflecting their reduced masticatory capabilities . Like the majority of the , habilis possessed elongated arms , possibly suggesting continued reliance on an arboreal environment . While the digits were still curved , they had increased gripping for tool manufacture and use , as evidenced by the pronounced attachment site for the muscle , which acts to flex the thumb . The femoral head was enlarged and the neck shortened . Those changes are thought to have been the result of increased strain generated by an expanded pelvis for birthing infants . However , no pelvic fossils have been found . Their foot was more modern , in that the hallux was no longer gent but rather aligned with the lateral four digits , and the toes were shorter . They had less mobility in their feet , in that the foot had become more of a support structure like our own . The metatarsals were thick to modern feet , and the morphology of the third metatarsal suggests that they did not yet exhibit the degree of weight transfer and propulsive capabilities seen in modern humans . Review of Primitive Characteristics Some prognathism . Large incisors . Curved phalanges . Long arms and short legs . Thick metatarsals . Review of Derived Characteristics Gracile characteristics a Thin skull vault . 146 The History of Our Tribe

More globular cranium . Expanded frontal lobe . Left dominance . Enlarged and areas . Reduced supraorbital torus . Smaller mandible , canines , and cheek teeth . Parabolic dental arcade . Increased manual dexterity . Larger femoral head ( and hence acetabulum ) and shorter neck . More stable foot Loss of divergent hallux . Shorter toes . ENVIRONMENT AND WAY OF LIFE Certainly one of the most interesting things about habilis is the appearance of a much more extensive archaeological record . The cultural period at that time , and extending through Homo erectus , is termed the Early Paleolithic , or the early portion of the Old Stone Age . While other species apparently preceded habilis in the manufacture of tools , it was thought for many years that they were the first to do so . The or tradition ( industry and technology are also used synonymously with tradition ) named after Gorge , consisted of simple core tools and flakes . The technique involved the tion of a cobble ( a rock ) followed by the use of a hammerstone to remove the outer rough surface ( see Figure ) or cortex and then to shape it into a core tool , by the removal of flakes . The flakes that are removed may be suitable for cutting and slicing . The process is called hard percussion , and the shaping is known as lithic reduction . Lithic refers to stone and is also used to denote a stone tool . Stone resources for the manufacture of tools were chosen for their suitability and transported across the landscape . Of course , this indicates a level of cognitive complexity , but we must remember that chimps and orangutans choose sticks and grass of particular widths and strengths , trim them to the appropriate length , and transport them in their mouths to their site of intended use . Apes learn by trial and error , and imitation , and cultural transmission , traits spread throughout a group by observation . transmission of innovations is even seen in monkeys , Japanese macaques washing sweet potatoes , skimming grain kernels floating on the surface to separate them from beach sand , and bathing in volcanic springs . While we do not know which species was the first to invent stone tools that were modified from their original form via lithic reduction and shaping , we can see the precursors of innovation and cultural transmission in our primate relatives . The real skill comes with having the manual dexterity to do so , ing a tool that can accomplish a variety of uses , and the ability to teach others . I would argue that the liest members of our genus had theory of mind , ie . the realization of another thoughts . There is only one example of teaching in nonhuman primates and that was a mother chimp in the Tai Forest of the Ivory Coast that helped her daughter crack a nut , using their unique hammer and anvil technique . Our closest relatives , with all of their intelligence , symbolic capabilities as demonstrated in language studies , and to our own behavior , do not know enough to teach their children . They are not capable of ing that I know something that you don know and vice versa . We go on and on about in the lineage and technological advancements in the archaeological record over time , but what may have been the true dividing line between ourselves and the apes , whether bipeds or not , was the ability to teach our young , kin , and other group members and thus increase their chance of survival . The vehicle for developing a theory of mind is language . Human children develop a theory of mind at three or four years of 23 . Homo habilis 147

age . Prior to that time , they do not realize that they or others may have incomplete information . Here is a fun anecdotal account that I always relay to my students My brother Michael was visiting my brother Jimmy . Jimmy was nowhere to be found when Michael realized that Jimmy son had messed his diaper . Jimmy older son must have been about three years old at the time . He helped Michael find everything that he needed to clean the baby . After Jimmy had and Michael had left for the day , the older boy remarked to his dad , Uncle Mike is so dumb ! When asked what he meant by that , he replied , He did know where the towels were he didnt even know how to use the Diaper a gizmo that turns dirty diapers into plastic coated magical ! This indicates that my nephew had not developed a theory of mind . He did not understand that Michael did not know things that he knew . I Figure 233 Hard hammer percussion . Hard Hammer by is in the public domain . Homo habilis was the first species to exhibit enlarged and areas . They thus may have had the motor control that allowed more lingual activity and the ability to comprehend the resulting sounds they could produce . Great apes can comprehend symbols , this stands for that even though this bears no resemblance to that . They have been taught American Sign Language , various computer languages , and spoken language . Where they fall short is in can not string together symbols into ful sentences . I firmly believe that the descendant species of Early Homo , Homo , had theory of mind , based on their stereotypical production of tools . There had to be teaching , learning , and training involved in order to produce an implement that is readily recognized as an hand axe ( see Figure ) Thus , since we see an earlier stage of tool production in Early Homo , I would argue that they had mentary language and theory of mind . The tradition lasted from approximately to but survived in some areas until 600 kya . Tools consisted of crude choppers ( see Figure ) and , as well as simple flake tools , some of which indicate that they were retouched , secondarily shaped sharpened . In addition , there is evidence of possible wooden digging sticks or spears at the site of Fora , in the East Lake region of Kenya and possible bone tools at Gorge . Tools were likely used for acquiring and processing both animal ( scavenging , butchering , disarticulation , skinning , cutting flesh , chopping bones open , etc . and plant ( digging tubers , cutting stalks , pounding to break down fiber , etc . foods . Indications of having butchered and scavenged animals comes from several lines of evidence . First , tools have been found with habilis remains . Second , there are of tools and fossilized animal bones that exhibit signs of cutting , disarticulation , and marrow 148 The History of Our Tribe

Figure hand axe . en mime by Jose Alvarez is licensed under tion . Mary mapped one such area with a high accumulation of stone tools and bones , known as site . Third , the high frequency of particular bones at some sites is indicative of the having brought back the good stuff , skulls for brain and limb bones for meat and marrow . Fourth , microscopic analyses indicate that cut marks on some bones overlay predators teeth marks , showing that the arrived afterward . How they got meat away from scary scavengers is anyone guess . Finally , experiments with stone tools in the style reveal ( that it is possible to butcher an elephant and ( wear patterns that result from the butchering process match those found on ancient tools . The following sites contain evidence of stone tools and their manufacture , Lake region , Kenya ( cores , anvils , and flakes . Gona , Ethiopia ( stone artifacts . Ethiopia ( tools were found with a habilis mandible . Gorge , numerous tools . Fora , Kenya high concentration of flakes suggesting repeated use . habilis are thought to have been that collected wild plant foods , hunted small animals opportunistically , and scavenged carcasses from large predators . While there is evidence of sites , meaning that individuals returned to particular areas to meet , they are not thought to have settled in any one area but rather moved about the landscape in their quest for food . They may have made use of those sites for a variety of communal or individual activities , such as grouping for central place foraging activities ( from the animal literature , meaning to move out from and possibly return to a particular place ) making new and using cached tools , butchering carcasses , sharing food , etc . Mary believed that her Site was indicative of a home base . While it is a romantic notion to look to modern with modern intelligence and advanced weaponry as being able to stay in one place until resources became scarce , it is not likely that those primitive were camped out on a lake shore . It would have been a very dangerous place to be for long periods of time . 149

. Figure Homo habilis Leopard by Taylor . While they could have climbed trees and made sleeping nests in trees or on the ground . we do not know how much time they spent in the two . 150 The History of Our Tribe Figure choppers . Pierre by is licensed under . THE FIRST FAMILY OF PALEOANTHROPOLOGY THE Louis ( was born to British missionary parents residing in Kenya . He and his wife Mary made names for themselves with their pioneering work , searching for and ing fossil in East Africa . Louis is credited with the discovery of three species , the first of which is considered to be a possible basal or stem ape , Proconsul ( before Consul a famous chimp at the London Zoo from Africa ) Louis was an early believer in an African human origin ( and Smith 2009 ) He became interested in the search for ancient after his discovery of stone tools that he attributed to human ancestors . The worked at Gorge in for many years . When Mary discovered the robust that she named ( later to be changed to and later to ) Louis proclaimed to the world that they had found his man the toolmaker . According to legend , he was ridiculed by some because they felt that ( also known as Dear Boy or Nutcracker Man ) as the specimen came to be known , was an herbivorous ape that would not have had the mental capabilities to manufacture the tools that became known as the technology . Louis was later rewarded with the of fossils of a more derived with a larger cranial capacity . He named the species Homo habilis ( Handy man ) as the first tool makers . There was and still is some controversy surrounding the classification of the species . He and his colleagues were accused of using versus physical attributes to justify their inclusion of the fossil material in our genus Homo . Some still believe the species should be assigned to genus . Regardless of the controversies , Louis made a name for himself and added to our knowledge of human 23 . Homo habilis 151

ancestry . At , he also discovered the cranium ( missing its face ) of a individual . Another great accomplishment was sending the three grand dames of ape into the field . He correctly believed that we can learn about ourselves from our closest relatives . He thus funded Jane to study the chimps of , Dian for her work with mountain gorillas in the Volcano region of and to study the orangutans of . Mary ( nee Mary Douglas , is described on the website ( as one of the world most distinguished fossil hunters . She is credited with the discovery of two species of early , Au . at and at , as well as the footprints . is also in . Mary had an early interest in archaeology and , like Louis , excavated stone tools in her case in France as a mere child . By age 17 , she was auditing university courses in archaeology and geology . She met Louis in 1933 and accompanied him to Kenya to illustrate stone tools for a book he was writing . They married several years later and had three sons , Jonathan , Richard , and Philip . Jonathan hunted fossils along with his parents and discovered the first habilis specimen , a mandible known as Jonny Child Richard moved into Kenya to work at sites around Lake , and his team discovered the oldest specimen ( in the West Lake region . In tion to his paleoanthropological work , he is a champion of wildlife conservation . His wife is a renowned paleoanthropologist with several species discoveries to her credit , and their daughter , Louise , is well on her way to making a name for herself ( 152 The History of Our Tribe