EXPLORATIONS AN OPEN INVITTION TO BIOLOGICALANTHROPOLOGYBeth Shook Kat - PDF document

1 . EXPLORATIONS: AN OPEN INVITTION TO BIO
. EXPLORATIONS: AN OPEN INVITTION TO BIOLOGICALANTHROPOLOGYBeth Shook, Katie Nelson, Kelsie Aguilera and Lara BraffAmerican Anthropological Association(2!-
{
\f\f\f\fSSS\rATLHKN=PEKJO\r=IANE?=J=JPDNK\rKNC �JBAD3F;A@E
�;E
;57@E76
G@67D
3�D73F;H7
A??A@E
FFD;4GF;A@\t&A@A??7D5;3
\n\f
�!@F7D@3F;A@3
$;57@E7\b
7J57BF
I:7D7
AF:7DI;E7
@AF76\n Describe how early Pleistocene climate change influenced the evolution of the genus HomoIdentify the characteristics that define the genus HomoDescribe the skeletal anatomy of Homo habilisHomo erectusbased on the fossil evidence.Assess opposing points of view about how early Homoshould be classified.Describe what is known about the adaptive strategies of early members of the Homogenus, including tool technologies, diet, migration patterns, and other behavioral trends.The boy was no older than 9 when he perished by the swampy shores of the lake. After death, his slender, long-limbed body sank into the mud of the lake shallows. His bones fossilized and lay undisturbed for 1.5 million years. In the 1980s, fossil hunter Kimoya Kimeu, working on the western shore of Lake Turkana, Kenya, glimpsed a dark colored piece of bone eroding in a hillside. This small skull fragment led to the discovery of what is arguably the worldÕs most complete early hominin fossilÑa youth identified as a member of the species Homo erectus. Now known as Nariokotome Boy, after the nearby lake village, the skeleton has provided a wealth of information about the early evolution of our own genus, Homo (see Figure 10.1). Today, a stone monument with an inscription in three languagesÑEnglish, Swahili, and the local Turkana languageÑmarks the site of this momentous fossil discovery. Figure 1

2 0.1 Skeleton of a young male Homo erectu
0.1 Skeleton of a young male Homo erectus known as ÒNariokotome Boy,Ó along with an artistÕs depiction of how he may have looked during his life. This is the most complete hominin fossil from this time period ever found. The previous chapter described our oldest human ancestors, primarily members of the genus Australopithecuswho lived between 2 million and 4 million years ago. This chapter introduces the earliest members of the genus Homo, focusing on the species Homo habilisHomo erectusEarly Members of the Genus Homo | 2 DEFINING THE GENU HOMO e our discipline is fundameny cd with what makes us human, defining our own genus takes on spe e for anists. The genus is the next leel up from species in the classiftion system orig d by Carolus Linnaeus. In the 1758 public Systema N , Linnaeus assigned humans the genus name Homo , meaning Ó Under this classiftion scheme, Linnaeus included seal ape species, as well as wild children and al humans such as celling trtes. In the pry classiftion, the apes and monster people ha long been rd, and our spe omo sapiens , remains as its only living re. But eer since scien e acknod the ee of et species of humans, they hae debad which of these display suf ÒhumannessÓ to merit classification in our genus. hen grouping species into a common genus, biologists will consider criteria such as phal char ), ee of rt common anc, and adaptive stry (use of the en). H, there is t about which of those criteria should be priorid, as well as how speic fossils should be ind in light of the criteria. e is general agrt that species classifd as Homo should share charteristics bry similar to our spe These include the following: ¥ a relatively large brain size, indicating a high degree of intelligence; ¥ a smaller and flatter face; ¥ smaller jaws and teeth; and ¥ d re on culture, pary the use of stone tools, to et a grter

3 divy of en (adaptive zone). Some rcher
divy of en (adaptive zone). Some rchers would include larger oall body size and limb prtions (longer legs/shorter arms) in this list. e is also an appart decline in sexual dimorphism (bode difes been males and f). While these teria seem ry cle-cut, eting them in the fossil rd has prd more dificult, pary for the liest members of the genus. There are seal rasons for this. First, many fossil specimens dating to this time period e incte and poory prd, making them dificult to ete. Seond, e Homo ossils appear quite v in brain size, facial fes, and teth and body size, and there is not yt consensus about how to best make sense o this div. Finall, there is grwing ee that the eolution of the genus Homo d in a mosaic patern: in other wds, these charteristics did not appear all at once in a single species; r, they we pay distribute in dift species from dift rions and time periods. Conse, dift rchers hae come up wi tion schemes depending on which cri n this chapter, we will take seal pays tod examining the origin and eolution of the genus Homo . First, we will e the ental ctions of the Pene epoch in which the genus Homo d. Nxt we will e the fossil ee for the to principal species try idend as ey H omo habilis and omo er . Then we will use data from fossils and aral sites to rt the behavior of ey members o Homo , including tool manuface, subsistence pres, migry paterns, and social struce. Finall, we will c these together in an atempt to chare the ky adaptive stries of e Homo and how they put our e ancestors on the trajectory that led to our own species, Homo sapiens . 3 | Early Members of the Genus Homo TE CHANGE AND HUMAN EV A ky goal in the study of human origins is to learn about the ental pres that may hae shaped human olution. As indicd in Chapter 7, scientists use a vy of techniques to rt ancient ents. These include stable isoto

4 pes, ce samples from ocans and lakes, wi
pes, ce samples from ocans and lakes, windblown dust, analysis of geal ftions and anoes, and fossils of ancient plant and animal cties. Such studies hae prd valuable inftion about the environmental context of early Homo . The ey hominin species cd pr, such as dipithecus r and alopithecus af , e during the late Pene epoch. The Pene (5.3 million to 2.6 million yars ago) was mard by cooler and drier tions, with ice caps forming permaneny at the poles. Still, Ears climate during the Pene was c warmer and wetter than at present. The subse Pleistocene epoch (2.6 million yars to 11,000 yars ago) usherd in major ental change. The ene is populary rd to as the Ie Age. Se the term ÒIe AgeÓ tends to ce up images of g and wy mammoths, one would nay assume that this was a period of unify cold climate around the g ut this is not acy the case. Iad, climate beame much more variable, ccling abruptly been w/w lacial) and c/dry (glacial) ccles. The climate patern was liky infd by changes in Ears elliptical orbi ound the sun. As is shown in Figure 10.2, each ccle ad about 41,000 yars during the ey Pene; the cles then lengthened to about 100000 yars starting around 1.25 million yars ago. Se mountain ranges, wind terns, ocan currts, and vanic acy can all infe climate patern, climate change had eeme efts on the environment in some regions but less effects on others. For a pry example with which you migt be familiar, consider the El Ni–o wther patern. This is wher arming of the Pic Oan in the etor rion infes rainfall, hurricane fr, and other wther ac in dift parts of the wld. During El Ni–o yars, some aras get more rainfall than aage and some get less. A t El Ni–o in 2017 prd cophic flooding along the Pvian coast, and one in 2015 led to drt and e bushfes in Australia. If El Ni–os, despite being a prtable and wwn oce, can cuse so much disruption to our tey add s

5 ocie, imagine how vulnerable our ancesto
ocie, imagine how vulnerable our ancestors must hae been to clima change. An adaptive strategy that could buffer against this kind of uncertainty would have been extremely valuable. e estimates during the last five million year data. Note both the lower temperatures and the increased temperature oscillations starting at 2.6 million , the start of the Pleistocene epoch. Glacial/inter are shorter, each averaging about 41,000 years. ta on ancient gey and climate help us understand how our ancestors mod and migrd to dift par f the wld, and the cts under which they operd. When periods of global cooling dominad, sea le e loer as more wter was cd as glacial ice. This ed ctal marins and opened pays be Early Members of the Genus Homo | 4 Figure 10.3 A savanna grassland in East Africa. Habitats such as this were becoming increasingly common during the Pleistocene. land masses. During glacial periods, the large Indonesian islands of Sa, Ja, and Borneo we cd to the ast Asian mainland, while Nw Guinea was part of the southern landmass known as grter Australia. There was a land bridge ction been Btain and ctal Europe, and an ic, treless plain known as Beringia c thern Asia and Alaska. At the same time, gtion made some northern aras inacessible to human habition. For xample, there is ee that hominin species we in Btain 950000 yars ago, but it does not appear that B as cy ocd during this period. These ey humans may hae died out or been fd to abandon the region during glacial periods. n Africa, palete rch has ded that grasslands (wn in Figure 10) ed and shrank multiple times during this period, een as they ed oer the long term (al 2014). From studies of f ists hae been able to rt Pene animal cties and to consider how they we af y the changing climate. Among the African animal populations, the number of grazing animal species such as an d. Se our ey anc

6 estors we also part of this animal c, it
estors we also part of this animal c, it is infe to consider how clima change cd changes in the home ranges and migrtion paterns of animals. Although the African and Eur ts are cd by land, the Sahara desert and the mountainous topogry of Nth Africa sere as na barriers to crossing. But the fossil rd shows that animal species mod back and fth been Africa and Eur during the Pene and Pene epochs. During the ey Pene, there is ee of African mammal spe such as baboons, hippos, antelope, and African buffalo migrting out of Africa into Eurasia during periods when drier conditions extended out from Africa into the Middle East (Belmaker 2010). This changing ent was undoubtey challenging for our estors, but it od new opporties for hominins to make a living. One solution adopted by some hominins was to spee in ding on the new types of plants grwing in this landscape. As d in the prvious chapter, the robust a y ded their large molar teth with thick enamel in der to et this particular diey niche. Chemical analyses o obust ath teth show an isotopic signae of a diet wher grasses and sedges are prominent, such as papyrus. embers of the genus Homo took a dift route. Facd with the unstable African climate and shifting landscape, they ed bigger ains that enabled them to ry on cultural solutions such as ting stone tools that opened up new fing opporties. This y of behaal fy serd them well during this unprtable time and led to new innotions such as increased meat-eating, cooperative hunting, and the exploitation of new environments outside Africa. HOMO HABILIS: THE EARLIEST MEMBERS OF OUR GENU omo habilis has try been cd the eliest species placd in the genus Homo . H, as we will se e is substantial disagrt among paleists about the fossils classifd as omo habilis , including whether they come from a single or multiple species, or even whether they should be

7 part of the genus Homo at all. d to
part of the genus Homo at all. d to the acines in the prvious chapter omo habilis has a somet larger brain sizeÐan a f 650 cubic cters () cd to less than 500 cc f Australopithecus . Addi, the skull is mor d and the face less prthic. H, the postcranial remains show a body size and prtions similar to Australopithecus . 5 | Early Members of the Genus Homo Figure 10.4 Map showing major sites where Homo habilisfossils have been found. Known dates for fossils identified as Homo habilisrange from about 2.5 million years ago to 1.7 million years ago. Recently, a partial lower jaw dated to 2.8 million years from the site of Ledi-Gararu in Ethiopia has been tentatively identified as belonging to the genus Homo(Villmoare et al. 2015). If this classification holds up, it would push the origins of our genus back even further. Discovery and Naming The first fossils to be named Homo habiliswere discovered at the site of Olduvai Gorge in Tanzania, East Africa, by members of a team led by Louis and Mary Leakey (Fig. 10.4). The Leakey family had been conducting fieldwork in the area since the 1930s and had discovered other hominin fossils at the site, such as the robust Australopithecus . The key specimen, a juvenile individual, was actually found by their 20-year-old son Jonathan Leakey. Louis Leakey invited South African paleoanthropologist Philip Tobias and British anatomist John Napier to reconstruct and analyze the remains. The fossil of the juvenile shown in Figure 10.5 (now known as OH-7) consisted of a lower jaw, parts of the parietal bones of the skull, and some hand and finger bones. Potassium-argon dating of the rock layers showed that the fossil dated to about 1.75 million years. In 1964, the team published their findings in the scientific journal Nature (Leakey et al. 1964)As described in the publication, the new fossils had smaller molar teeth

8 that were less ÒbulgyÓ than australop
that were less ÒbulgyÓ than australopithecine teeth. Although the primary specimen was not yet fully grown, an estimate of its anticipated adult brain size would make it somewhat larger-brained than australopithecines such as A. africanusThe hand bones were similar to humansÕ in that they were capable of a precision grip. This increased the likelihood that stone tools found earlier at Olduvai Gorge were made by this group of hominins. Based on these findings, the authors inferred that it was a new species that should be classified in the genus Homo. They gave it the name Homo habilismeaning ÒhandyÓ or Òskilled.Ó Figure 10.5 Homo habilis fossil specimens. From left to right they are: OH-24 (found at Olduvai Gorge), KNM-ER-1813 (from Koobi Fora, Kenya), and the jaw of OH-7, which was the type specimen found in 1960 at Olduvai Gorge, Tanzania. Early Members of the Genus Homo | 6 Location of Fossils Dates Ledi-Gararu, mya Partial lower jaw with evidence of both AustralopithecusHomotraits; tentatively considered oldest Early Homofossil evidence. Olduvai Gorge, Tanzania 1.7 mya mya Several different specimens classified as Homo habilis, including the type specimen found by Leakey, a relatively complete foot, and a skull with a cranial capacity of about 600 cc. Koobi Fora, Lake Turkana Basin, Kenya mya Several fossils from the Lake Turkana basin show considerable size differences, leading some anthropologists to classify the larger specimen (KNM-ER-1470) as a separate species, Homo rudolfensisSterkfontein South African cave sites 1.7 mya South African caves have yielded fragmentary remains identified as Homo habilis, but secure dates and specifics about the fossils are lacking. Figure 10.6 Key Homo habilis fossil locations and the corresponding fossils and dates. Controversies over Classification of Homo habilis How Many Species of Since this initial

9 discovery, more fossils classified as Ho
discovery, more fossils classified as Homo habilis were discovered in sites in East and South Africa in the 1970s and 1980s (Figure 10.6).. As more fossils joined the ranks of Homo habilis, several trends became apparent. First, the fossils were quite variable. While some resembled the fossil specimen first published by Leakey and colleagues, others had larger cranial capacity and tooth size. A well-preserved fossil skull from East Lake Turkana labeled KNM-ER-1470 displayed a larger cranial size along with a strikingly wide face reminiscent of a robust australopithecine. The diversity of Homo habilisfossils prompted some scientists to question whether they displayed too much variation to all remain as part of the same species. They proposed splitting the fossils into at least two groups. The first group resembling the original small-brained specimen would retain the species name Homo habilis; the second group consisting of the larger-brained fossils such as KNM-ER-1470 would be assigned the new name of Homo rudolfensis (see Figure 10.7). Researchers who favored keeping all fossils in Homo habilisargued that sexual dimorphism, adaptation to local environments, or developmental plasticitycould be the cause of the differences. For example, modern human body size and body proportions are influenced by variations in climates and nutritional circumstances. Given the incomplete and fragmentary fossil record from this time period, it is not surprising that classification has proved contentious. As a scholarly consensus has not yet emerged on the classification status of early Homo, this text will make use of the single (inclusive) Homo habilisspecies designation. 7 | Early Members of the Genus Homo Homo habilis : Homo or Australopithecus ? e is also disagrt on whe omo habilis y belongs in the genus Homo . Most of the fossils f d as omo habilis d mainl

10 y of skulls and teth. When arm, leg, and
y of skulls and teth. When arm, leg, and foot bones we later found, making t possible to estimate body size, they turned out to be quite small in stae with long arms and short legs. Anal f the re strength of limb bones suggested that the species, though bipedal, was much more adapted to arbor climbing than omo er and omo sapiens f 2009). This has prd some scientists to question whe omo habilis d more like an ath a shorter gait and the abiliy to moe around in the tr ood and Collard 1999). They also questioned whether the brain size o omo habilis as ry that much lar than that o Australopithecus . They hae prd rying some or all of the omo habilis ossils into the genus Australopithecus , or even placing them into a newly created genus (Wood 2014). Figure 10.7 Cast of the Homo habilis cranium KNM-ER-1470. This cranium has a wide, flat face, larger brain size, and larger teeth than other Homo habilis fossils, leading some scientists to give it a separate species name, Homo rudolfensis. Other scholars hae ind the fossil ee dif. A rt rysis o omo habilis/rudolf fossils d that they sort into the genus Homo ther than Australopithecus e 10). In par, sta ysis perfd indictes that the omo habilis ossils difer signify in aage cranial cy from the cines. They also note that some acine species such as the ry disc Australopithecus sediba e ry long legs, so body size may not hae been as signift as brain- and tooth-size difes ( et al. 2014). Early Members of the Genus Homo | 8 HomininDates 2.5 million years ago to 1.7 million years agoegion(s) East and South Africa Famous iscoveries Olduvai Gorge, Tanzania; Koobi Fora, Kenya; Sterkfontein, South Africa Brain Size 650 cc average (range from 510 cc to 775 cc) Dentition Smaller teeth with thinner enamel compared to Australopithecus; parabolic dental arcade shape Cranial Features Rounder

11 cranium and less facial prognathism tha
cranium and less facial prognathism than Australopithecus Postcranial Features Small stature; similar body plan to Australopithecus Culture Oldowan tools Figure 10.8 Summary features of Homo habilis. CULTURE AND AYS Early Stone Tools The larger brains and smaller teeth of early Homo are linked to a different adaptive strategy than that of earlier homininsÑone dependent on modifying rocks to make stone tools and exploit new food sources. Based on what we know from nonhuman-primate tool use, it is assumed that all hominins used tools of some sort. For example, australopithecines could have used digging sticks to extract the roots and tubers that were part of some speciesÕ diets (though tools made from perishable material would leave no trace). As discussed in the previous chapter, stone tools almost certainly predated Homo habilis(possibly by Australopithecus garhior the species responsible for the tools from Kenya dating to 3.7 million years ago). However, stone tools become more frequent at sites dating to about 2 million years ago, the time of Homo habilis (Roche, Blumenschine, and Shea 2009). This suggests that these hominins were increasingly reliant on stone tools to make a living. Stone tools are assigned a good deal of importance in the study of human origins. Studying the form of the tools, the raw materials selected, and how they were made and used can provide insight into the thought processes of early humans and how they modified their environment in order to survive. Paleoanthropologists have traditionally 9 | Early Members of the Genus Homo d ctions of stone tools into industries, based on their form and mode of manuface. There is not an t ce been a tool industry and a hominin species; ho, some general associations can be made been tool industries and particular hominins, loctions, and time periods. The names for the four primar tool in

12 dustries in human eolution (om oldest to
dustries in human eolution (om oldest to most r) are the Oldoan, Acheulean, Mousterian, and Upper Paleolithic. The oldest stone tool industry is the Oldowan , named after the site of Olduai Gorge where the tools we f d. The time period of the Oldoan is genery cd to last from about 2.5 mya to 1.6 mya. The tools f this industry are described as Òfe and chopperÓ toolsÑthe choppers consisting of stone cobbles with a fw f struck of them (Figure 10). To a casual obser, these tools migt not look much dift from ry br ocks. H, they are harder to make than their crude appee suggests. The rock seled as the ce must be struck by the rock serving as a hammerstone at just the rigt angle so that one or more ft fes are r This res seleting rocks that will fre pry instead of chunking, as well as the abiliy to plan ahead and vision the steps ned to crte the fd prt. The press lees both the ce and the fes with sharp cutting edges that can be used for a variety of purposes. Figure 10.9 Drawing of an Oldowan-style tool. This drawing shows a chopper; the flakes removed from the cores functioned as cutting tools. se and the Diet of Early Homo t we the hominins doing with the tools? One ky acy seems to hae been butchering animals. Animal bones th cutmarks start appearing at sites with Oldoan tools. Studies of animal bones at the site show leg bones are o d open, suggesting that they we eting the marrw from the bone cties. It is inesting to c ther the hominins hund these animals or acd them thrh other means. The butcherd bones come from a y of African mammals, ring from small antelope to animals as big as wildebeest and elephants! It is dificult to vision slo, small-bodie omo habilis th their Oldoan tools bringing down such large animals. One possibiliy is t the hominins we scing casses from lions and other large cts. Pist Rt B has ed the scing hypothesis by diry o

13 bserving the behavior of pry animal ces
bserving the behavior of pry animal ces and engers on the African saanna. From this, he infd that there we scing opporties for P hominins. When lions abandon a kill after eting their fill, scing animals arrive almost immey to pick apar the cass. By the time the slod hominins arrivd on the scene, the cass would be mostly stripped of me , if hominins could use stone tools to brak into the leg bone cties, they could get to the marr, a fa calorie-dense source of protein (Blumenschine 1987). Early Members of the Genus Homo | 10 ting acties that happened millions of yars ago is oby a dificult undertaking, and there is an ac te among anists about whether scing or hunting was more cy prd during this time. dless of how they we acquiring the met, all these acties suggest an import diey shift from the wy tha the acines we eting. The Oldoan toolmakers we eting a new eal niche that prd them th more protein and calories. And it was not just limid to metingÑstone tool use could hae made a ous other subsistence opporties. A study of micropic war paterns on a sample of Oldoan tools indic t they we used for pressing plant materials such as wood, roots or tubers, and grass seds and stems (Lemorini t al. 2014). In fact, it has been poind out that the Oldoan toolmakersÕ cutting abiliy (ther for the purposes o onsuming met and plants or for making tools, shelters or clothing) rts a new and unique innotion, ne seen before in the natural world! (Roche, Blumenschine, and Shea 2009). all, incrasing use of stone tools allod hominins to expand their eal niche and et more col o their environment. As weÕll see shortly, this pattern continued and became more pronounced with Homo erectus . HOMO ERECTUS: BIOLOGICAL AND CUL ter 2 million yars ago, a new hominin apped on the scene. Known as omo er , the prailing scienic vie as that this species was much more like us. Thes

14 e hominins we ed with bigger brains and
e hominins we ed with bigger brains and large bodies wi limb prtions similar to our own. Phaps most impor, their wy of life is now one that is ry human, with more advanced tools, hunting, use of fire, and colonizing new environments outside of Africa. As will be appart belo, new data suggests that the story is not quite as simple. The fossil rd f omo er is much more abundant than that o omo habilis , but it is also more cx and vdÑboth with rd to the f as well as the geaphic cxt in which they are found. We will first summarize the anaal charteristics tha define omo er , and then discuss the fossil ee from Africa and the primary geaphic rions outside Afric where the species has been located. Homo erectus Anatomy d to omo habilis , omo er d incrd brain size, smaller teth, and a larger bod. H, it also displayed key differences from later hominin species including our own. h the head o omo er as less ape-like in appee than the acines, neither did it r modern humans (Figure 10). Compard to omo habilis , omo er had a larger brain size (age of about 900 c d to 650 cc to 750 c). Iad of having a rd shape like our skulls hae, the erectus skull was long and lo e a football, with a rding fad, and a horiztal ridge cd an tal torus t gae the back of the skull a squarf appee. The cranial bones are thicker than those of modern humans, and some omo er skulls e a sligt thickening along the sagtal suture cd a ttal k . Lge, shelfe brw ridges hang oer the e The face shows less prognathism , and the back teth are smaller than those o omo habilis. ad of a poind chin, like ours, the mandible of Homo erectus recedes back. 11 | Early Members of the Genus Homo Figure 10.10 Replica of Homo erectus from Java, Indonesia. This cranium (known as Sangiran 17) ximately 1.3 million to 1 million year ago. Note the large brow ridges and the occ

15 ipital torus that gives the back of the
ipital torus that gives the back of the skull a squar appearance. t from these distince fes, signift vtion is prt be Homo erectus ossils from dif ions. Scientists hae long noted difes been the fossils from Africa and those from Indonesia and China. For xample, the Asian fossils tend to hae a thicker skull and larger brw ridges than the African specimens, and the sag el described aboe is more pr omo er ossils from the Republic of Geia (d in the ne ) also display distince charteristics. As wi omo habilis , this divy has prd a classiftion deba about whether or not omo er should be split into multiple species. When Afric omo er is char as a separte species, it is c omo er , while the Asian vt rtains the erectus cies name beuse it w discovered first. This text will use the species name Homo erectus for both variants. omo er as thougt to hae a body size and prtions more similar to modern humans. Unlik omo habilis and the acines, both of whom we small-stad with long arms and short legs, omo er ws e f being fully cd to life on the ground. This met long, poy muscled legs that enabled these hominins to er more ground ef. Id, studies of the omo er y form hae linkd seal charteristics of the cies to long-distance running in the more open saanna ent (Bamble and Lieberman 2004). Many e think that hominins around this time had lost much of their body hair, we pary eft at swting, and had d skinÑall trts that would support the ace lifle of such a lard hominin (e S Topic box). Much of the inftion about the body form o omo er omes from the Notome fossil of the omo er outh, described at the beginning of the chapter (e Figure 10.1). H omo er ossils are turning out to be e vd than pry thoug omo er ossils from sites in Africa, as well as from Dmanisi, Geia, sho smaller body sizes than the Notome bos. Even the Notome skton itself has been r

16 d to be qui a bit shorter (prd to be clo
d to be qui a bit shorter (prd to be closer to 5 ft 4 inches when fully grwn, rther than oer 6 f), although there is still disagrt about which met is more acte. One etion for the range of body sizes could be tion to a range of dift local ents, just as humans today show rd body size in poor nutri environments (Anton and Snodgrass 2012). omo er also shows some ee of a rtion in sexual dimorphism in body size cd to the e Early Members of the Genus Homo | 12 cines. In other w omo er males we only sligy larger in body size than females. The degr f sexual dimorphism among ey hominin species is a ctious issue. It is a dificult charteristic to mee and assess in the fossil rd, since fossils hae to be cte enough to determine both body size and sex. H, if omo er as less sey dimorphic, it may signify changes in social ortion within the species. If you r om the chapter on primates, higy dimorphic species are those where males cte iny for mating acess to emales. Ded sexual dimorphism suggests that the lifle o omo er y hae been dift from that o earlier hominins. SPECIAL TW WE BECAME HAIRLESS, SWEA PRIMATES As an any instruc, one question about human eolution that students oten ask me c human body hairwhen did our ancestors lose it and why? It is assumed that our eliest ancestors w as hairy as modern-day apes. T, though, we lack thick hair on most parts of our bodies eept in the t and pubic rions and on the tops of our heads. Humans acy hae about the same number f hair follicles per unit of skin as chimpanzes. But, the hairs on most of our body are so thin as to be y invisible. When did we deelop this peculiar patern of hairlessness? Which selee pres in our ancestral environment were responsible for this unusual characteristic? y ets beliee that the driving fe behind our loss of body hair was the ned to efy c es. Along with the lack of hair, h

17 umans are also distinguished by being ey
umans are also distinguished by being ey swy: we sw ger quanties and more efy than any other primate. Humans hae a larger amount of e t glands than other primates and these glands generte an enormous volume of wy swt. S es liquid on the skin that cools you of as it etes. It seems liky that hairlessness and sw d toge, as a rt DNA analysis has idend a shard genetic pay been hair follicles and eccrine sweat gland production (Kamberov et al 2015). hich particular ental ctions led to such adaptations? In this chapter, we led that the te was a driving fe behind many changes seen in the hominin lineage during the Pene. A t time, the climate was incry arid and the fest cy in parts of Africa was being rd wi a more open grassland ent, resulting in incrd sun ee for our ancestors. Compard to the elier acines, members of the genus Homo we also deeloping larger bodies and br starting to obtain meat by hunting or scavenging carcasses, and crafting sophisticated stone tools. ding to Nina Jablonski, an et on the eolution of human skin, the loss of body hair and incr ting cy are part of the package of trts charterizing the genus Homo. While larger brains and d bodies made it possible for humans to cer long distances while fing, this new body f had to cool itself efy to handle a more ace lifle. Prting the brain from oting w y crial. The abiliy to kep cool may hae also enabled hominins to fage during the hottest par of the day, giving them an advantage over savanna predators, like lions, that typically rest during this time. hen did these changes occur? Although hair and sot tissue do not ty fe, there are se t methods that hae been used to ee this question. One method tracks a human skin color gene. e chimpanzes hae ligt skin under their hair, it is probable that ey hominins also had ligt skin 13 | Early Members of the Genus Homo . Apes and other mammals wit

18 h thick fur cts hae prtion against the s
h thick fur cts hae prtion against the suns rys. As our anc lost their fur, it is liky that incrd melanin pigmention was seled for to shield our ancestors fr harmful ultrt rtion. A rt genetic analysis ded that one of the genes responsible f melanin production originated about 1.2 million years ago (Jablonski 2012). Another line of ee tracks the colution of a rther unplet human companionÑthe louse. A tic study idend human body louse as the youngest of the thre vties of lice that infest humans, ting of as a distinct vy around 70000 yars ago (Ki, Ka, and Stoneking 2003). Be human body lice can only sprad thrh clothing, this may hae been about the time when humans star to ry war clothing. H, the split been human head and pubic lice is estimad to ha d much e, about thre million yars ago (Rd et al. 2007). When humans lost much of their y hair, lice that used to roam fry around the body we now cd to to aras: the head and pubic region. As a result of this ÒgeographicÓ separation, the lice population split into two distinct groups. Other etions hae also been suggested for the loss of human body hair. For example, being hair has other adtages such as making it more dificult for skin partes like lice, fas, and ticks to live on us. Addi, after bipey ed, hairless bodies would also make re organs and f e visible, suggesting tha Homo erectus in Afric h the eliest disceries o omo er ossils we from Asia, the grtest quany and best-prd f f the species come from East African sites. The eliest fossils in Africa idend as omo er ome from the East an site of Koobi Fora, around Le Tkana in Kya, and are dad to about 1.8 million yars ago. Other f emains hae been found in East African sites in Kya, Tanzania, and Ethiopia. Other notable Afric omo er finds e a female pelvis from the site of Gona, Ethiopia (impson et al 2008), and a cranium from Olduai Gorge known as t

19 to be about 1.4 million y omo er Õ pre i
to be about 1.4 million y omo er Õ pre in South Africa is not well documend, though fossils thougt to belong to the species hae also been uncovered from the famed South African Swartkrans cave site along with stone tools and burned animal bones. overies Outside Afric t is genery agrd tha omo er as the first hominin to migrte out of Africa and ce Asia and later Eur h rt disceries in Asia may challenge this vie). Ky loctions and disceries o omo er ossils, along with the fossilsÕ estimated age are summarized below, and in Figure 10.12. Early Members of the Genus Homo | 14 ap showing the locations of Homo erectus fossils around Africa and Eurasia. Indonesia The first discy o omo er as in the late 1800s in Ja, Indonesia. A Dutch anatomist named Eugene Dubois d for human fossils with the belief that since orangutans livd there, it migt be a good place to look for r f ey humans. He discd a portion of a skull, a f, and some other bone frts on a riverbank. W the femur lookd human, the top of the skull was smaller and thicker than a modern persons. Dubois named the f opus er t ape-manÓ), popularizd in the media at the time as ÒJa Man.Ó After later disc f similar fossils in China and Africa, they we cd into a single species (taining the erectus ) under the genus Homo . omo er has a long history in Indonesia; further disceries of fossils from Ja we dad by argon dating to about 6 million to 1.8 million yars. A cache o H. er ossils from the site of Ngandong in Ja has yielded vy r tes of 43,000 yars, although a more rt study with dift dating methods cd that they we much en 140000 and 500000 yars old. Still, the possible ee of isolad, yd hominin tions in the rion is of grt inest to paleists, espey gen the discy of the tin Homo floresiensis ossils discd on the ney island of Flores, Indonesia, and the vy rt announct of possible tin

20 y hominin fossils from the island of Luz
y hominin fossils from the island of Luzon in the Philippines. 15 | Early Members of the Genus Homo China e is ee o omo er in China from seal rions and time periods. omo er ossils from nor China, cy known as ÒPeking Man,Ó are some of the most famous human fossils in the wld. Dd to about 000 yars ago, they we ed from the site of Zhoukoudian, near the outskirts of Beijing. H f bones and teth, including six ney cte skulls, we ed from the ce in the 1920s and 1930s. Much f the fossilsÕ fame comes from the fact that they disapped under mysterious cires. As Japan ad to China during Wld War II, Chinese aties, cd for the sey of the fossils, packd up the bo and arrd for them to be trd to the Unid Stes. But in the chaos of the w, they vd and w er hed about again. Wt ey happened to them is mure are seal cting acts. For an anatomist named Frans Weich who had pry studied the bones had made casts and mets o the skulls, so this valuable inftion was not lost. Me rt etions, at Longgushan ÒDragon Bone CaÓ a oudian, of tools, living sites, and food remains, hae rd much about the lifle o omo er during this time. te this lengthy history of scienic rch, China, cd to Africa, was perd as somet peripher to the study of hominin eolution. Althoug omo er ossils hae been found at seal sites in China, with da t make them cable to those of I omo er , none sed to apprte the any of Afric tes. The notable finds at sites like Notome and Olorgesaille took cter stage during the 1970s and 80Õs, as tists fd on elucidating the speciesÕ anay and adaptations in its African homeland. In cast, f research projects were focused on East Asian sites (Qiu 2016). , isolad claims of vy ancient hominin oction kept cropping up from dift loctions in Asia. W some we dismissed beuse of problems with dating methods or straphic cxt, the 2018 publiction of the y of stone tools from China dad

21 to 2.1 million yars ct es ation. Dd by p
to 2.1 million yars ct es ation. Dd by pale chniques that date the associad soils and windblown dust, these tools indicte that hominins in Asia prd those t Dmanisi by at least 300000 yars (Zhu et al. 2018). In fact, the tools are older than an omo er ossils an e no fossils we found with the tools, it isnÕt known which species made them, but it opens up the in y that hominins elier than omo er ould hae migrd out of Africa. These eting new disc are shaking up previously held views of the East Asian human fossil record. Western Eurasia An ey ction of fossils from the site of Dmanisi in the Republic of Geia has rd the pre o omo er in Western Eurasia been 1.75 million and 1.86 million yars ago. Dmanisi is locd in the Ca tains in Geia. When arists began eting a meal set near the town in the 1980s and ame across the bones of et animals, they shifd their focus from the historic to the prehistoric era, but the y did not ante going back quite so far in time! The first hominin fossils we discd in the ey 1990s, and since that time, at least five relatively well-preserved crania have been excavated. e are seal surprising things about the Dmanisi fossils. Compard to Afric omo er y hae smaller ains and bodies. H, despite the small brain size, they show clear signs o omo er ts such as hevy br ridges and rd facial prthism. Pists hae poind to some aspets of their anay (such as the ) that appear rther primie, although their body prtions seem fully cd to terrestrial bipe One etion for these difes could be that the Dmanisi hominins rt a vy ey form o omo er that left Africa before increases in brain and body size evolved in the African population. Early Members of the Genus Homo | 16 Second, although the fossils at this location are from the same geological context, they show a great deal of variation in brain size and in facial features. One skull

22 (Skull 5) has a cranial capacity of only
(Skull 5) has a cranial capacity of only 550 cc, smaller than many Homo fossils, along with larger teeth and a protruding face. Scientists disagree on what these differences mean. Some contend that the Dmanisi fossils cannot all belong to a single species because each one is so different. Others assert that the variability of the Dmanisi fossils proves that they, along with all early Homo fossils, including H. habilisrudolfensis, could be grouped into Homo erectus(Lordikipanidze et al. 2013). Regardless of which point of view ends up dominating, the Dmanisi hominins are clearly central to the question of how to define the early members of the genus HomoEurope Until recently, there was scant evidence of any Homo erectuspresence in Europe, and it was assumed that hominins did not colonize Europe until much later than East Asia or Eurasia. One explanation for this was that the harsh ice age climate of Western Europe served as a barrier to living there. However, recent fossil finds from Spain suggest that Homo erectuscould have made it into Europe over a million years ago. In 2008 a mandible from the Atapuerca region in Spain was discovered, dating to about 1.2 million years ago. A more extensive assemblage of fossils from the site of Gran Dolina in Atapuerca have been dated to about 800,000 years ago. In England in 2013 fossilized hominin footprints of adults and children dated to 950,000 years ago were found at the site of Happisburgh, Norfolk, which would make them the oldest human footprints found outside Africa (Ashton et al. 2014). At this time, researchers arenÕt in agreement as to whether the first Europeans belonged to Homo erectusproper or to a later descendent species. Some scientists refer to the early fossils from Spain by the species name, Homo antecessorRegion Sites Dates Significance of Fossils East Africa East and West Lake Turkana, Kenya; O

23 lduvai Gorge, Tanzania mya Earliest evid
lduvai Gorge, Tanzania mya Earliest evidence of H. erectus; significant variation in skull and facial features. Western Eurasia Dmanisi, Republic of Georgia 1.75 mya Smaller brains and bodies than H. erectusfrom other regions. Western Europe Atapuerca, Spain (Sima del Elefante and Gran Dolina caves) 1.2 myaÐ 400,000 Partial jaw from Atapuerca is oldest evidence of erectusin Western Europe. Fossils from Gran Dolina (dated to about 800,000 years) sometimes referred to as H. antecessor. Indonesia Ngandong, Java; Sangiran, Java 1.6 mya Early dispersal of H. erectus erectus features. Zhoukoudian, China; Loess Plateau (Lantian) 780,000 Ð 400,000 2.1 mya Large sample of H. erectusfossils and artifacts. Recent evidence of stone tools from Loess Plateau suggests great antiquity of Homo17 | Early Members of the Genus Homo Now, our examination of Homo erectuswill turn to its lifewaysÑhow the species utilized its environment in order to survive. This includes making inferences about diet, technology, life history, environments occupied, and perhaps even social organization. As will be apparent, Homo erectus shows significant cultural innovations in these areas, some ool Technology: Acheulean Tool Industry In early African sites associated with Homo erectus, stone tools such as flakes and choppers identified to the Oldowan Industry dominate. Starting at about 1.5 million years ago, some Homo erectus populations began making different forms of tools. These toolsÐclassified together as constituting the tool industryÐare more complex in form and more consistent in their manufacture. Unlike the Oldowan tools, which were cobbles modified by striking off a few flakes, Acheulean toolmakers carefully shaped both sides of the tool. This type of technique, known as bifacial flaking, requires more planning and skill on the part of the toolmaker; he or she would need to be

24 aware of principles of symmetry when cr
aware of principles of symmetry when crafting the tool. One of the most common tool forms, the handaxe, is shown in Figure 10.13. As with the tool illustrated below, handaxes tend to be thicker at the base and then come to a rounded Figure 10.13 Drawing of an Acheulean handaxe. This specimen is from Spain. When drawing a stone tool, artists typically show front and back faces, as well as top and side profiles. One striking aspect of Acheulean tools is their uniformity. They are more standardized in form and mode of manufacture than the earlier Oldowan tools. For example, the aforementioned handaxes vary in size, but they are remarkably consistent in regard to their shape and proportions. They were also an incredibly stable tool form over timeÑlasting well over a million years with little change. Early Members of the Genus Homo | 18 , the Acheulean tools so prt at African sites are mostly absent in omo er tes in East Asia. I ype choppers and scrapers are found at those sites. If this tey sed to be so import to Afric omo er , why didnÕt East Asian omo er also use the tools? One rason could be ental dif en the to rions. Phaps the rocks aailable in Asia wÕt of the material suitable for making the Acheule es. It has been suggested tha sian H erectus tions used perishable material such as bamboo to mak tools. Another possibiliy is tha omo er or een an elier hominin) migrd to East Asia befe the Acheule y ded in Africa. The rt discy of the 2.1 million-y-old tools in China ges cre to this last explanation. se and Cognitive Abilities of Homo erectus t (if anthing) do the Acheulean tools tell us about the mind o omo er ? Cle, they took a fair amount o skill to manuface. Apart from the actual shaping of the tool, other decisions made by toolmakers can ral their use f ft and planning. Did they just pick the most ct rocks to make their tools, or d

25 id they sech out a ticular rw material
id they sech out a ticular rw material that would be ideal for a particular tool? Analysis of Acheulean stone tools suggest that at some tes, the toolmakers seled their rw materials celing to particular rock outcrops to quarry stones and haps een rving large slabs of rock at the quarries to get at the most desirable material. Such cx ac ould re add planning. They also liky rd ction and ction with other individuals, as such actions would be dificult to cy out solo. H, other omo er tes lack ee of such sele ad of treling een a short distance for beter rw material, the hominins tended to use what was aailable in their immediate area (Shipton et al. 2018). n cast to omo er tools, the tools of ey modern omo sapiens during the Upper Pthic displa emendous divy across rions and time periods. Addi, Upper Pthic tools and arts c tion such as status and group membership. Such innotion and social signaling seem to hae been absen in omo er , suggesting that they had a dift rtionship with their tools than did omo sapiens (Coolidge and Wynn 2017). Some scientists assert that these casts in tool form and manuface may signify ky c differences between the species, such as the ability to use a complex language. Subsistence and Diet n rting the diet o omo er , rchers can drw from multiple lines of ee. These include stone tools used b omo er , animal bones and ocy plant remains fr omo er tes, and the bones and th of the fossils themseles. These data soures suggest that cd to the a omo er d more animal protein. Coinciding with the appee o omo er ossils in Africa are aral si with much more abundant stone tools and larger concentrations of butchered animal bones. Meat Eating and Increased Brain Size t makes sense that a larger body and brain would be cd with a diey shift to more cy dense foods. This is beuse the brain is a vy enery gry organ. Id, our

26 own human brains re more than 20% of on
own human brains re more than 20% of one alorie total ine to maintain. When biologists consider the eolution of ine in any animal species, it is o 19 | Early Members of the Genus Homo Figure 10.14 Excavations at the site of Olorgesailie, Kenya. Dated from between 1.2 million years ago and 490,000 years gesailie has some of the most abundant and well-preserved evidence of Homo erectus activity in the world. Fossils of large mammals, such as elephants, along with thousands of Acheulean tools, have been uncovered over the decades. d as a c/beneft analysis: In order for large brains to ee, there has to be a compelling beneft to having them and a way to generate enough energy to fuel them. One solution that would allow for an incrase in human brain size would be a cesponding rtion in the size o the digestive trt (gut). Acding to the Òe tissue hÓ iniy fd by Leslie Aiello and P eler (1995), a smaller gut would allow for a larger brain without the ned for a cesponding incrase in the s metabolic rte. Judging from their skton, acines hae a wider rib cage and trunk rion mor similar to apes than humans. It is thougt that the acines had large gut sizes similar to todas grt apes use they we eting mainly plant foods, which re more gut bacteria to digest. Me met in the diet w w for a smaller gut and could also fuel the larger brain and body size seen in the genus Homo . Some r also beliee that body fat pertages incrd in hominins (pary f) around this time, which would ha d them to be beter bufd against ental disruption such as food shortages (ton and Sass 2012). or Dietary Versatility in Homo erectus As indicd aboe, ee from ary and the infes about omo er y size suggest incr t eting. Hw much hunting did omo er engage in cd to the elier Oldoan toolmakers? Althoug ts ctinue to debate the re impore of hunting versus scing, there seems to be st

27 ronger e f hunting for these hominins. F
ronger e f hunting for these hominins. For example, at sites such as Olorgesailie in Kya (Figure 10), there are numer associations of Acheulean tools with butchered remains oge animals. However, omo er y ate more than just met. My hun er societies hae been used as models for considering the behavior pa and ental cts of our ey ancestors. Pt foods make up the bulk of calories for most modern-day huner societies, since they are a much more reliable food soure. It would make sense that we would see similar patterns among early hominins. tudies of the tooth surfaces and micropic war paterns on hominin te te tha omo er te a vy of foods, including some hard, britle plan oods (Unger and Sct 2009). This would make sense, considering the t was changing to be more dominad by grasslands in some ar oots, bulbs, and tubers (known as underound storage or) of open sa ts may hae been a primary food soure. Id, huner groups such as the Hadza of Tanzania ry hey on such foods, espey during periods when game is sce. In the unstable ent of the ey Pene, die versatility would be a definite advantage. ool Use, Cookin One ky charteristic of the genus Homo is smaller teth cd to Australopithecus . Wy would teth get smaller? Besides the change in the type o oods eten, there may hae also been changes in how food was prd and d. Think about how you would et if you didnÕt hae acess to cutting tools. Wt you cÕt rip apart wi our hands would hae to be biten of with your tetions that would re bigger, more poerful teth and j Early Members of the Genus Homo | 20 During this time, stone tools we beoming incry import. If hominins we using these tools to cut up, tenderize, and process meat and plants, they wouldnÕt have to use their teeth so vigorously. Cooking food could also hae cd to the rtion in tooth and jw size. In fact, anist Richar ham (2009) asserts that cooki

28 ng plad a crucial role in human eolution
ng plad a crucial role in human eolution. Cooking prvides a head start in the e press beuse of how het begins to brak down food befe food een enters the bod, and it can help the y et more nutrients out of met and plant foods such as stary tubers. Acding to Ws model, this d diet had a number of faraching ces for human eolution. Most impor, it allod for the larger brain and body size (and smaller gut size) seen in Homo erectus . y cooking res fe, and the eliest use of fe is a fascinating topic in the study of human eolution. Fire, o ourse is not limid to humans; it occurs nay as a result of ligtning strikes. Like other wild animals, ey hominins must hae been terrifd of wildfes, but at some point in time led to col fe and put it to good use. Cooking, th, and scaring of wild animals are just some of the benefts of fe. Consider the potential social benefts of ha a ligt soure after dark. Rather than just going to sleep, members of the group could repair tools, plan the next da ties, or socializeÑjust as you migt do siting around a ce with family or friends. IÕt it intriguing to think about how such activities might have encouraged the development of language? ting the eliest ee of fe has been a ctious issue in ary beuse of the dify in distinguishing been human-cd fe and naal burning at hominin sites. Bd aras and ash deposits must e dirt associations with human acy to make a case for deliberte fe use. Examples migt include the pr f wood ash in ces where tres donÕt nay gr, deep ash deposits in heths lined with stones, or burned pie f stone tools and butcherd animal bones (Gao 2017). Unf, such ee is re at ancient hominin si which hae been pry alterd by humans, animals, and geal fes oer millions of yars. R, ne thodsÑincluding micropic analysis of burned rock and boneÑhae rd clear ee of fe use at K ting to 1.5 million y ation out of Afric omo er is gen

29 ery thougt to be the first hominin speci
ery thougt to be the first hominin species to lee the ct of Africa and setle in Eur in places such as the Republic of Geia, Indonesia, and northern China. We pry discussed the timing and f e for the appee o omo er t those sites; now we can address why the species trd such v es to these farlung rions. To do this, we hae to consider what we hae led about the biolog, cultur and ental cires o omo er The larger brain and body size o omo er e fueled by a t consisting of more met, and longer more poerful legs made it possible to walk and run longer distances to e food. Se they we eting higher on the food chain, it was ney for them to extend their home r to find suft game. Cultural dets including beter stone tools and new tey such as fe gae them ter fy in adapting to dift ents. Finall, the major Pene climate shift discussed e in the chapter cy plad a role. Changes in air tempere, prtion, acess to wter soures, and other t altertion had faraching efts on animal and plant cties; this include omo er . If hominins were relying more on hunting, the migration patterns of their prey could have led them increasingly long distances. Life History The e histor f a species rers to its oall patern of grwth, det, and rtion during its lif 21 | Early Members of the Genus Homo Figure 10.15 Hadza men practice bowing. Native to Tanzania, the Hadza have retained many traditional lthough most do not subsist entir upon wild foods today, their way of life may shed light on how humans lived for most of their evolutionary history. th the assumption being that these charteristics hae been shaped by naal seletion. Our spe omo sapiens , is chard by a unique life history patern of slow det, a long period of juenile dependence, and a long espan. Unlike the grt apes whose ofspring achiee ey self, human children are dependent on their ts long after waning. Addi, huma

30 n fathers and grts (pary post-menopausal
n fathers and grts (pary post-menopausal gr devote substantial time and energy to caring for their children. uman behaal eco who study modern huner societies hae obserd that fing is no e business (Figure 10.15). Members of these groups engage in cx fing techniques that are dificult and take man ars to master. An ed juenile period ges children the time to ace these skills. It also allows time for lar human brains to grw and mae. On the back end, a longer detal period results in skilled, sucessful adults, apable of living a long time (Hill and Kaplan 1999). Despite the time and enery demands, females could hae o at more closely spaced intervals if they could depend on help from fathers and grandmothers (Hawkes et al. 1998). t can the study o omo er al about its life histor ? Wd fossils such as the Notome boy c vide some insigts. We know that apes such as chimpanz ach may more quickly than humans, and there is some e that the acines had a grwth rte more akin to that of chimpanzes. Scientists hae cd e studies of the Notome sks bones and teth to assess wth and det. On the one hand, etion of the long bone ends () of the skton suggested that he w an ey adolesct with a ry large body mass, thoug wth had not yt been cd. On the other hand, study o the dention, including met of micropic laers o tooth enamel c perikymata , rd a much younger age o 8 or 9. Acding to Christopher Dean and Hy Sth (2009), the best etion for this discry been the dental and tal age is tha omo er had its own distinct gr aching may more sloy than chimpanzes but faster than omo sapiens . This suggests that the human lif y patern of slow mation and lengthy dependency w a more rt det. Me wk remains on rining this tern for e Homo , but it is an import question, as it she t on how and when we ded our unique life histor characteristics (Figure 10.16). Early Members of the Genus Hom