- Introduction: Hominization Process (Bio-cultural Evolution)
1.1 Anatomical and physiological changes.
1.2 Behavioural changes - Bipedalism
- Hand anatomy and Tool use
- Modification of Jaws and Teeth
- Enlargement of Brain
- Speech and Language
6.1 Speech.
6.2 Language.
Introduction
Homanization Process
The homanization process may be viewed as the evolutionary transformation from prehomind to
hominid status in the course of human evolution. It is also referred to as “aromophasis” by Severtson
(1939) and “anagenis” by Hur Oley (1942) and Rensch (1960). The original meaning of the word
‘hominization’ was the emergence of human among other living things. It means the threshold which
prehumans had to cross before becoming human. This process concerns the nature and adaptive
significance of major anatomical and physiological transformation in the evolution of the body from
an ape like higher primate to the single variable species, Homo sapiens.
The changes that have occurred in the evolutionary development of mankind since its divergence from
the last common ancestor and are shared with any living ape can be categorized into two groups
1.1 Anatomical and physiological changes.
1.2 Behavioural changes
I. Anatomical and physiological changes
A. Visible in fossils
B. Not readily visible in fossils
· Modification of hands and arms for more effective carrying and tool use.
· Changes in skin and skin glands.
· Reduction in body hair.
· Enlargement of the brain.
· Continuous sexual receptivity of female.
· Reduction and remodeling of the jaws.
· Partial reorganisation of the brain.
· Modification of the vocal tract.
II. Behavioural changes
A. Directly detectable by archaeology
B. Not directly detectable by archaeology
· Increasing dependence on manufactured equipment and tools
· Language
· Suitable control on display of emotions
· Great increase in expressing ideas.
Hunting- Meat eating:
- Co-operation and division of labour
- Increasing interdependence through food-sharing
- Greater increase in social bonding mechanism- marriage and Marriage kinship
reciprocation. - Re-organization of behaviour around a ‘Camp’ or Home-Base.
- Great increase in symbolism.
The Hominization process includes all those aspects of structural and behavioral changes that occurred in the Hominid line, finally leading to the emergence of modern human group. Over a century, the prevailing view among evolutionists has been that Bipedalism preceded encephalization. The last decade of hominid fossil discoveries has made some surprising refinements in this view. The most dramatic discovery is the pattern revealed by the 3.7 to 3.0 mya old Australopithecus africanus. The members of this group were bipedal, yet their absolute brain size was about one third that of modern Homo sapiens and teeth were intermediate between pongid and hominid. These bodily transformations during the process of hominization were affected at quite unequal rate (differential rate of somatic evolution) implying that human evolution came about in
mosaic from bearing on a certain number characteristics
All such changes can be broadly grouped into following heads.
- Bipedalism
- Hand manipulation and tool use (manual dexterity)
- Modification of jaw and teeth.
- Enlargement of brain
- Changes in vocal tracts, language and speech
1.Bipedalism
Analysis of postcranial elements of A. Africanus, A. Afarensis, A. Ramidus (Tim et al. 1994) and A. Anamensis (Leakey et al. 1995) clearly establishes Bipedalism to be one of the oldest of all hominid characteristics. The age of the earliest variant of australopithecines, A.Ramidus is estimated to be 4.4 mya. The appearance of this group took place perhaps one million years after the separation of ancestral lines leading to great apes and human. The branching out point between ape and human
ancestors is estimated to be 5-6 mya. According to Stanford (1995), A. ramidus was a biped; its lower body was clearly adapted for walking on the ground, though they may have continued to use trees for gathering fruits and for shelter at night. Postcranial elements especially limb and pelvis anatomy of A. afarensis shows characteristics of bipedal adaptations. For example, iliac blades were short and broad, ischium was short, anatomy of hand and ankle joints were favorable, big toe was parallel. In all such features afarensis was more human like than ape.
In addition to post cranial elements, the Laetoli (Tanzania) foot prints of A. afarensis, proved that
Australopithecine have existed around 3.77 mya, which is another proof of Bipedalism. It shows a
convergent big toe, heelstrikes, arches, etc. similar to humans in many aspects.
There are, however, certain features possessed by afarensis such as shorter hind limbs, longer foot,
longer toes, etc. that suggest that australopithecine Bipedalism was different from, human
Bipedalism. Such differences in the locomotory behaviour can be explained due to the habitat
supposed to have existed in eastern African-woodland, bushland and dry savannah with patches of
forest along rivers and lakes. Thus, they had to live somewhat less on the tree and more on the ground
2.Hand anatomy and Tool use
The earliest evidences of hand manipulations that are different from apes and similar to Homo can
be found in A. Afarensis. The hand proportion of the members of this group is approximately similar
to human proportions but differ from those of humans in having fingers more curved suggesting greater
power grip. The hand anatomy of afarensis also reveals that the precision grip was greater
among them compared to that of the chimpanzee, but lesser than that of the Homo. A. afarensis
spent more time on the land than on the trees hence the hand-anatomy had started overshadowing the
characteristics of hands of Homo and different from those of apes. Hominids with their manipulative
hands, precision grip and contemplating brains, had been able to expand their ecological niche so far
beyond the physical capabilities inherent in their makeup, one that no other animal has ever had the
potential to achieve.
The classical view of anthropologists has been that the use of tools led to the distinction between
human and ape that the split between the pongidae and the hominidae resulted from the acquisition
of tool-use by one of the ancestral hominoid populations. Others now feel that environmental
influence and adaptation to nonarboreal ecological niches were more important for early hominid
evolution. However these divergent views are ultimately resolved, it is interesting to learn how far
human technology and culture can be traced
Recent palaeo-anthropological findings reflect the use of tools, antedates the origin of the big brained Homo sapiens by at least a million and a half year. There is now indisputable evidence of the
occurrence of modified stone tools that is 2 million years old found in association with the bones
of Homo habilis. In other words, tool-use and tool-making developed before hominid brain
capacity had undergone remarkable increase. The old idea that a large brain and associated high
intelligence were prerequisites for tool use is no longer tenable. The use of tools by primitive
hominids may, in fact, have been a major factor in the evolution of the cerebral cortex and higher
intelligence, for once the use and making of tools began to favour survival, there would be high
selection pressure for neural mechanism promoting improved crafting and use of tools. The elaborate
brain of Homo sapiens may be a consequence of culture as much as its cause. Hominization process,
with respect to cultural attainments, had set in much before the modern man appeared on the earth.
Oldowan industry of earliest Homo habilis clearly proves the point.
Homo erectus had not only perfected stone tools considerably but had also learned how to control and
use fire, as revealed by radio isotope dated hearths in caves. With fire humans could cook their food
they could keep themselves warm in cold weather; they could ward off predators and they could
light up the dark to see. The hearth no doubt promoted the development of social organization
and allowed an opportunity for the beginning of communication through spoken language
Increasing brain size
Because more complete fossil heads than hands are available, it is easier to model increased brain size in parallel with the rich record of artifacts from the Paleolithic Period (c. 3.3 million to 10,000 years ago), popularly known as the Old Stone Age. The Paleolithic preceded the Middle Stone Age, or Mesolithic Period; this nomenclature sometimes causes confusion, as the Paleolithic itself is divided into Early, Middle, and Late (or Upper) periods. Hominin brain expansion tracks so closely with refinements in tool technology that some scholars ignore other factors that may have contributed to the brain’s increasing size, such as social complexity, foraging strategies, symbolic communication, and capabilities for other culture-mediated behaviours that left no or few archaeological traces.
Throughout human evolution, the brain has continued to expand. Estimated average brain masses of A. afarensis (435 grams [0.96 pound]), A. garhi (445 grams [0.98 pound]), A. africanus (450 grams [0.99 pound]), P. boisei (515 grams [1.13 pounds]), and P. robustus (525 grams [1.16 pounds]) are close to those of chimpanzees (395 grams [0.87 pound]) and gorillas (490 grams [1.08 pounds]). Average brain mass of H. sapiens is 1,350 grams (2.97 pounds). The increase appears to have begun with H. habilis (600 grams [1.32 pounds]), which is also notable for having a small body. The trend in brain enlargement continued in Africa with larger-bodied H. rudolfensis (735 grams [1.62 pounds]) and especially H. ergaster (850 grams [1.87 pounds]).
One must be extremely cautious about ascribing greater cognitive capabilities, however. Relative to estimated body mass, H. habilis is actually “brainier” than H. rudolfensis and H. ergaster. A similar interpretive challenge is presented by Neanderthals versus modern humans. Neanderthals had larger brains than earlier Homo species, indeed rivaling those of modern humans. Relative to body mass, however, Neanderthals are less brainy than anatomically modern humans. Relative brain size of Homo did not change from 1.8 to 0.6 mya. After about 600 kya it increased until about 35,000 years ago, when it began to decrease. Worldwide, average body size also decreased in H. sapiens from 35,000 years ago until very recently, when economically advanced peoples began to grow larger while less-privileged peoples did not.
| hominin | number of fossil examples | average capacity of the braincase (cc) |
|---|---|---|
| Australopithecus | 6 | 440 |
| Paranthropus | 4 | 519 |
| Homo habilis | 4 | 640 |
| Javanese Homo erectus (Trinil and Sangiran) | 6 | 930 |
| Chinese Homo erectus (Peking man) | 7 | 1,029 |
| Homo sapiens | 7 | 1,350 |
Overall, there were periods of stagnation and elaboration in stone tool technology during the Paleolithic, but, because of variations over time and between locations as well as the possibility that plant materials were used instead of stone, it is impossible to link brain size with technological complexity and fully human cognitive capabilities. Moreover, in many instances it is impossible to identify assuredly the hominin species that commanded a Paleolithic industry, even when there are associated skeletal remains at the site.
The unreliability of brain size to predict cognitive competence and ability to survive in challenging environments is underscored by the discovery of a distinctive human sample, dubbed H. floresiensis, in a limestone cave on Flores Island, Indonesia, in 2004. The diminutive H. floresiensis had brains comparable in mass to those of chimpanzees and small australopiths, yet they produced a stone tool industry comparable to that of Early Pleistocene hominins and survived among giant rats, dwarf elephants, and Komodo dragons from at least 38 kya to about 18 kya. If they are indeed a distinct species, they constitute yet another archaic human (in addition to H. neanderthalensis, the Denisovans [known from remains from Denisova Cave in Russia], and perhaps H. erectus) that lived contemporaneously with modern humans during the Late Pleistocene.
Refinements in tool design
In Africa the Early Paleolithic (3.3–0.2 mya) comprises several industries. The first tools (hammers, anvils, and primitive cutting tools) made way for the earliest human-made chipped flake tools and core choppers (2.5–2.1 mya). Double-faced hand axes, cleavers, and picks (collectively known as bifaces) appeared about 1.5 mya and persisted until about 200 kya. Archaeologists have detected some improvements of technique and product during the half-million-year span of core-flake industries. Although the major biface industry—the Acheulean—has been characterized as basically static, it too shows evidence of refinement over time, finally resulting in elegant, symmetrical hand axes that required notable skill to make.
By 1.8 mya a population of H. erectus lived in Eurasia at what is now Dmanisi, Georgia. The associated choppers, chopping tools, flakes, and scrapers recall the Oldowan core-flake industry of eastern Africa, but there are no bifaces among them. The braincase of the two Dmanisi specimens is smaller than that of African H. ergaster. New geochemical dates for classic hominin localities in Java indicate that H. erectus may have lived in Southeast Asia 1.5 mya, but no industry is certainly identified with them.
El ʿUbeidīya, Israel, provides evidence that people and bifaces had spread out of Africa by 1.4 mya. In Europe, Acheulean tools appear 500 kya and persist until about 250–150 kya; they also occur in South Asia. Sites in China (800 kya), Korea, and Japan contain bifaces, but they differ from Acheulean tools. No such technology has been found in tropical Southeast Asia, where bamboo tools may have sufficed.
In both Africa and Eurasia the Middle Paleolithic was long thought to have lasted from about 200 kya to as recently as 30 kya, depending upon location. While tools from the Early Paleolithic slowly changed across space and time, the Middle Paleolithic was characterized by an explosion of local and regional variations in size and shape and by frequencies of reshaped flakes, blades, scrapers, hand axes, and other tools. Projectile points began to be emphasized in some regions, with bone being used as well as stone; bone arrow points dating to more than 60,000 years ago have been found at Sibudu Cave in South Africa.
Although they vary across time and space, Middle Paleolithic tools as a whole are characterized by carefully prepared cores from which elegant flakes or blades were struck. Notably, tools of this type have been found at the Gademotta site in Ethiopia’s Rift Valley in stratigraphic levels that date to approximately 275 kya. Additional blades dating to roughly 315 kya have been found at Morocco’s Jebel Irhoud site.
Late Paleolithic industries dating to 50–10 kya comprise diverse blade and microblade tools, especially in Europe. Late Paleolithic peoples used a variety of materials for their tools and bodily ornaments, including bone, stone, wood, antler, ivory, and shell. Stone blades were long, thin, and very effective cutting tools. Often, when they became dull, someone retouched them via pressure flaking, which requires fine motor control and coordination. Microblades and other points were probably hafted to produce throwing and stabbing spears. Other composite tools of the period include atlatls, harpoons, fish weirs, and bows and arrows. Late Paleolithic people also developed techniques for grinding and polishing, with which they made beads, pendants, and other artistic objects. They also made needles (perhaps for sewing fitted clothing), fish hooks, and fish gorges.
Reduction in tooth size
The combined effects of improved cutting, pounding, and grinding tools and techniques and the use of fire for cooking surely contributed to a documented reduction in the size of hominin jaws and teeth over the past 2.5 to 5 million years, but it is impossible to relate them precisely. It is not known when hominins gained control over fire or which species may have employed it thereafter for food preparation, warmth, or protection against predators. It is very difficult to discern whether a fire was deliberately produced by hominins or occurred naturally. For example, in a wildfire, burned-out tree stumps might leave circular accumulations of charcoal residue that could be mistaken for hearths, whereas campfires built by mobile hominins would leave no lasting evidence.
Concentrations of charcoal, burned bones, seeds, and artifacts in China and France suggest that H. erectus, H. heidelbergensis, or both used fire as early as 460 kya. Certainly some Middle and Late Paleolithic peoples controlled fire, but hearths are rare until 100 kya. If claims for control of fire in South Africa 1.5 mya are confirmed, P. robustus or H. ergaster would be the first fire keepers.
At first glance early hominin skulls appear to be more like those of apes than humans. Whereas humans have small jaws and a large braincase, great apes have a small braincase and large jaws. In addition, the canine teeth of apes are large and pointed and project beyond the other teeth, whereas those of humans are relatively small and nonprojecting. Indeed, human canines are unique in being incisorlike, and the front lower premolar tooth is bicuspid. In apes and in many monkeys, however, the lower premolar is unicuspid and hones the upper canine tooth to razor sharpness.
Language, culture, and lifeways in the Pleistocene
Speech and symbolic intelligence
The origin and development of human culture—articulate spoken language and symbolically mediated ideas, beliefs, and behaviour—are among the greatest unsolved puzzles in the study of human evolution. Such questions cannot be resolved by skeletal or archaeological data. Research on the behaviour and cognitive capabilities of apes, monkeys, and other animals and on cognitive development in human children provide some clues, but extrapolating this information back through time is tenuous at best. Complicating the scenario further, it may be that today’s chimpanzees, bonobos, and other anthropoid primates have more sophisticated cognitive capabilities and behavioral skills than those of some early hominins, because they and their ancestors have had several million years to overcome many challenges and perhaps have become more advanced in the process. Speech has been inferred by some investigators on the basis of certain internal skull features, for example, in H. habilis, but jaw shape and additional traits suggest otherwise. Still other researchers claim that human speech was not even fully developed in early members of anatomically modern H. sapiens, because of the simplicity of their tool kits and art before the Late Paleolithic.
It is impossible to assess linguistic competency by observing the insides of reassembled fossil craniums that are incomplete, battered, and distorted—and in any case the brains probably did not fit snugly against the walls of the braincase. The apparent cerebral expansion in H. habilis and H. rudolfensis may imply a general increase in cognitive abilities, manipulative skill, or other factors besides speech. Particularly unreliable are claims that the specific internal cranial impressions of a Broca cap is evidence of speech. Prominent Broca caps exist among some chimpanzees, yet no ape has uttered a word, despite laborious attempts to get them to speak.
A humanoid vocal tract is undetectable in fossils because it comprises only soft tissues and leaves no bony landmarks. Although versatile human speech is reasonably linked to a relatively spacious pharynx and mobile tongue, the absence of such features is not a compelling reason to deny some form of vocal language in ancestral hominins. It is argued that articulate human speech is impossible without a lowered voice box (larynx) and an expanded region above it. If this presumption were true, even Neanderthals would be inept vocally and probably also quite primitive cognitively as compared with Late Paleolithic H. sapiens populations such as the Cro-Magnons. Gibbons and great apes do not speak, yet they have throat traits concomitant with speech, albeit to a lesser degree than humans’. The calls of gibbons are wonderfully varied in pitch and pattern, and, if such sounds were broken into discrete bits with consonants, they could emulate words. The same may be said for great apes. Orangutans, chimpanzees, and bonobos have sufficiently mobile lips and tongues; they simply lack neural circuitry for speech.
Conversely, if the theory that different abilities are governed by distinct and separate forms of intelligence (multiple intelligences) is correct, much of tool-using behaviour and artistic ability would have to be based upon neurological structures fundamentally different from those that support verbal ability. Human children begin to use language before they become sophisticated tool users. Similarly, a form of speech might have preceded forms of tool behaviour that are symbolically mediated. Visual arts such as painting and sculpture are expressions of spatial intelligence, which is centred principally in areas of the brain different from those related to speech. Therefore, one cannot expect the problem of language origins or language competence to be clarified by studying Paleolithic symbolism and imagery, despite the awesome array of cave art and polished bone, antler, ivory, stone, and shell artifacts associated with the period. Yet if the stunning proliferation and stylistic variability of tools, bodily ornaments, and artistic works during the Paleolithic do not point unequivocally to the specific use of speech, the presence of these symbolically mediated artifacts—among the earliest of which are shell beads found in Morocco and made about 82,000 years ago—does indicate that early humans were capable of complex conceptual and abstract thought.
Historically, all human groups manifest rich symbolically mediated language, religion, and social, political, and economic systems, even in the absence of elaborate material culture. The demands on the social intelligence of peoples who live in environments with relatively few artifacts are similar to demands placed upon those who depend upon complex technological gadgets and shelters for comfort. Consequently, prehistoric H. sapiens cannot be regarded as cognitively less capable than ourselves, and it is impossible to state which hominin species were “fully human” as symbol users. As a case in point, meticulously documented language studies of captive bonobos and chimpanzees demonstrate that they have the capability to comprehend and use symbols in order to communicate with humans and with one another, but the use of this potential in the wild remains to be demonstrated. Perhaps the human capacity symbolically to represent feelings, situations, objects, and ideas developed before being commandeered by the several intelligences and before it became a boon to vocal communication.
Archaeological evidence indicates that, like at least some of their Pliocene predecessors, the most recent hominins were probably omnivorous, though how much meat was in their diets and whether they obtained it by scavenging, hunting, or both are poorly documented until about 200–100 kya. Stone tools and cut marks on bones at archaeological sites attest to a long history of meat eating in the tribe Hominini, but this practice could have existed long before stone tools were invented. Like chimpanzees, bonobos, baboons, capuchins, and other primates, early Pliocene hominins may have killed and fragmented vertebrate prey with only their hands and jaws instead of tools. The extent to which our ancestors’ hunting, scavenging, or other activities were communal and coordinated via symbolic communication has not been determined.
There is no valid way to estimate group size and composition because there is little evidence of movement patterns, shelters, and graves until the Late Paleolithic. Archaeological traces of human-made shelters occur rarely from 60 kya, then become more common, particularly in regions with notable seasons of inclement weather. The first appearances and development of symbolically based spirituality are also highly elusive because they left no morphological or unarguable archaeological trace until the innovation of writing and ritual paraphernalia; however, there is evidence that Neanderthals used jewelry and other personal ornaments some 44,000 years ago. Although some Neanderthals buried their dead, there is little evidence of mortuary ceremony in their graves. Graves of H. sapiens from 40 kya sometimes contain grave goods.
Learning from the apes
Gorillas, chimpanzees, and bonobos are a rich resource for cultural anthropologists, biologists, and psychologists who speculate on the origins of human society. Gorillas appeal to theorists who stress male dominance and patriarchy. A characteristic gorilla group has one silverback (an older dominant male), one or more subordinate blackback males, adult females outnumbering males, and youngsters of various ages. The silverback is the hub of the cohesive group. Chimpanzee society is also dominated by males, which form a stable core of the group. Chimpanzees and bonobos live in larger groups numbering more than 100 individuals, though they forage, travel, and nest in much smaller bands that vary daily in number and composition. Among chimpanzees there is a top male, followed by several others whose ranks depend upon which other males are present. Bonobos have stronger affiliations between males and females than chimpanzees do, and the organizational hub of bonobo social groups is based on intimate relations among adult females, particularly mothers, which often retain strong bonds with their sons. Adult male bonobos are less strongly bonded with one another than chimpanzee males are. Because bonobos are more pacific and tolerant in social relationships and are highly sexual, they are popular with those who would model our heritage as free of “killer apes.” However, observers of apes, Old World monkeys, and other mammals have documented incidents of aggression as well as concern for others in their subjects. Both tendencies are deeply rooted among the higher primates.
The emergence of the human nuclear family has been a particularly knotty problem for Western evolutionary theorists. Like bonobos and chimpanzees, people probably are fundamentally promiscuous, though such mating behaviour is heavily proscribed by the cultures into which individuals are born and reside. Indeed, theorists who wish to construct models of the emergence of hominin societies on the basis of extant ape societies seldom tackle the overriding fact that humans utilize a wide variety of kinship, social, sexual, and political arrangements, all of which are maintained and expressed symbolically as well as practically. Researchers often fail to search for the cognitive basis of symbolic representation, manipulation, and invention in apes, citing instead forms of behaviour that appear to harbinger specific human conditions. It will take the efforts of several scientific disciplines and sophisticated technology, probably over many years, to discover the underlying nature of our mental faculties, their neurological basis, and their development over time. Apes can play important roles in this enterprise only if they are allowed to survive in their natural habitats and only if they are viewed as being on their own evolutionary paths and not merely as steps toward the human condition.