Evolution

Human Origin & Evolution

Dr Tanushree Saxena

Associate Professor Department of Zoology

Swami Shraddhanand College Alipur Village,Delhi-110036

1

“What a piece of work is a man! How noble in reason! How infinite in faculties! Inform and in moving, how express and admirable! In action how like an angel! In apprehension how like a God! The beauty of the world! The paragon of animals!”

- William Shakespeare

Hamlet, II, ii (1564 – 1616)

Indeed, man occupies the loftiest pinnacle of the evolutionary fabric and is considered to be a paragon of animals but the story of our origin is still clouded with many unanswered queries (shrouded) .Where did man come from? This question has preoccupied human thought for tens of thousands of years but the picture is still hazy because of the maddening scarcity of human fossils in sedimentary rocks and excavation work at sites is time consuming and demanding. Nevertheless, the evidences, new informations about missing links are growing faster than it can be analyzed, but there are still surprises in store and unsolved problems. All this makes the understanding of the story of human evolution still more fascinating and exciting.

Primate Evolution and Classification (The classification of Homo)

In 1859, when the “Origin of Species” was published, it was already obvious that if humans shared a common ancestry with other species, their closest relatives must be great apes of the order Primates of class Mammalia.

Characteristics of Primates

• Independent mobility of the digits

• An opposable first digit in both hands and feet (thumb, big toe)

• Replacement of claws by nails to support the digital pads on the last phalanx of each

finger and toe.

• Teeth and digestive tract adapted to an omnivorous diet – i.e. simple cusp pattern in

molar teeth 32- 36 teeth.

• A semierect posture that enables hand manipulation and provides a favourable

position preparatory to leaping.

• Centre of gravity positioned close to the hind legs.

• Well developed hand - eye motor coordination.

• Optical adaptations that include overlap of the visual fields to gain precise three –

dimensional information on the location of food objects and tree branches.

2

• An eye completely (anthropoids) or fractionally (prosimians) encased by bone (bony

orbits).

• Shortening of the face accompanied by reduction of the snout.

• Diminution of the olfactory apparatus in diurnal forms.

• Compared with practically all other mammals, a very large and complex brain in

relation to body size.

• Lengthened period of maturation, low reproductive rate.

Two alternative classifications of living primates

I. Traditional classification (Fleagle, 1988)

Order Primates Sub-order Prosimii (nocturnal, arboreal, low organization claw on the second digit, long muzzles and furry faces).

Infra-order – Lemuriformes [lemurs or “half-monkeys” (most ancient primates) lorises.

- Tarsiformes (Tarsiers).

Sub-order Anthropoidea - 32-36 teeth, closed orbit, 2 pectoral mammae, prehensile feet, convoluted cerebral hemispheres covering cerebellum.

Infra-order: Platyrrhini (New-World monkeys) e.g. Marmosets etc.)

- wide nasal cartilage between the mostrils, prehensile tails, restricted to Central & South America probably descended from Eocene lemurs.

Infra-order: Catarrhini (Old-World monkeys)- Apes & Hominids

- narrow nasal septum, non-pre-hensile tails often short, natives of Africa & Eurasia.

Super-Family: Cercopithecoidea (Old World monkeys, Macaca, baboons)

“ “ : Hominoidea (Apes & Hominids)

Family : Hylobatidae (Lesser apes e.g. Gibbon (Hylobatus)

“ : Pongidae (Great apes e.g. Chimpanzee Pan Gorilla, Orangutan (Pongo)

“ : Hominidae (Only 1, Species extinct)

Homo sapiens

4 recognized races – Australian, Negroid, Mongoloid & Caucasians

(India – Caucasians in North & Australoid in South)

3

II Recently Proposed Classification

Order: Primates

Sub order: Prosimii

Super family: Lemuroidea: Lemurs

“ : Lorisoidea: Lorises, galagos (bush babies)

“ : Tarsioidea: Tarsiers.

Sub order: Anthropoidea

Infra order: Platyrrhini (New World)

Super family: Ceboidea

Family: Callitrichidae: marmosets tamarins

“ : Cebidae: Capuchins, howler monekys, spider

monkeys

Infra order: Catarrhini (Old World)

Super family: Cercopithecoidea

Family: Cercopithecidae: macaques, baboons, vervet monkeys

Family: Colobidae: langurs, colobines

Super family: Hominoidea

Family: Hylobatidae: gibbons, siamangs

“ : Pongidae*: Orangutans, gorillas, chimpanzees

“ : Hominidae: Humans *In some molecular classifications based on immunological studies and DNA sequencing (Miyamoto et al., 1987) researchers put all the great apes together with humans in a single

4

family, Hominidae, which they then divide into 2 subfamilies

Ponginae (Orangutans) and Homininae (Humans, Chiampanzees & Gorillas)

(Tattersall et al., & Ruvolo, 1997, Goodman et al., Shoshani et. al., 1996). Human Phylogeny/ Phylogenetic Relationships

About 65-70 million years ago, in the Paleocene epoch, some early insectivorous mammals became arboreal, (like modern tree shrews) presumably because of intense competition on the ground and availability of rich, untapped source of food on the trees. This brought about radical changes in them viz. replacement of claws by flat nails, development of limbs into grasping organs, opposable, more flexible digits with tactile pads, shortening of snout, rounding of skull, development of stereoscopic vision, growing importance of sight over smell, anteriorly directed eyes and so on. Gradually, as the years passed by the climate became colder in Oligocene era causing the forests to dwindle. This triggered a splitting or divergence in the parental stock of Primates. Some retained their arboreal mode of living while others such as man took to a more adventurous and progressive route – the terrestrial habitat. This descent from trees in turn brought about several changes in them. Thus, we are a product of the primate arboreal adventure Characteristics of Homo sapiens

Despite our place in the animal kingdom, humans are unique among animals and dominate the entire planet, because of some very special and unique characteristics which are the following:

(1) Bipedal Locomotion – Balanced bipedalism is uniquely human. Bipedal locomotion coupled with upright posture gave freedom to the forelimbs (arms) which were subsequently used for more complicated manipulative and creative tasks – for e.g. gripping a tool, holding, gesturing, playing a violin etc. or simply feeling (as it is also a prime organ of touch). Thus, the hands were liberated from the locomotor function and used for many different purposes.

(2) Upright posture – It involved many anatomical changes i.e.

a) balancing of skull on the upper part of vertebral column.

b) Therefore, the foramen magnum shifted forward.

c) Development of spinal curvatures – There are four such curvatures developed in the spinal column, making it S – shaped. These curvatures acted as shock – absorbers.

d) Basin-shaped pelvis to support the viscera.

e) relatively short forelimbs (in contrast to apes where they reach below knees).

f) Plantigrade foot

g) loss of opposability of great toe (et. Anthropoids)

h) development of shock absorbing arch.

i) tendency towards monodactyly.

5

j) widened but shortened ilium bringing sacrum closer to acetabulum.

(3) Brain: Human brain has a large cranial capacity ~1350cm3 on an average, with the cortical matter, considered to be the seat of intelligence, reasoned behaviour, memory, abstract thought and delicate as well as accurate muscular movements, is highly “convoluted” complex and well developed. Further, there is increase in the size of frontal lobes of cerebral hemispheres resulting in a relatively high forehead.

Warren McCulloch, an American student of brain has put it, “The brain is like a computing machine, but there is no computing machine like the brain”.

(4) Vision: Only human beings and their nearest primate relatives have the special combination of full stereoscopic vision and Colour vision which enables them to focus in fine detail upon particular and distant objects.

(5) Teeth & Jaws of humans have undergone immense modifications to suit an omnivorous diet. The differences between apes and man are underlined below:

Apes Man

Incisors Large Small

Canines Large projecting Small, not projecting

Premolars & Molars straight rows rounded rows

jaw shape u – shaped rounded parabola

Diastema (gap between incisors and canines)

yes no

Simian shelf (supporting shelf behind incisors & canines)

Yes no

1st pre-molar cutting type not cutting type

face (facial angle) prognathus (protruding)

orthognathus(nearly vertical)

Chin

no chin, since upper edge of lower jaw extends further than does the lower

Present, because lower margin of jaw protrudes

tori

present-these provided support for chewing

No tori

6

(6) Language: The great significance of the combination of human brain and body is perhaps best shown by its most important innovation: the language/articulate speech. Apes lack the kind of pharynx, (long), tongue (thick), soft palate to articulate. It was the major biological characteristic to evolve.

(7) Cultural Adaptation – With the gift of speech, we acquired an immensely powerful tool for cultural evolution. The ability to speak facilitated and speeded up, cultural evolution – to communicate, to hunt, to modify environment to suit themselves to make weapons etc. but most importantly to learn from the accumulated experience of other people and groups.

This in turn, resulted in development of communal life, use of fire and gave independence from climatic conditions and hence led to dispersal.

(8) Other Characteristics a) loss of hair in some parts – need of clothing to overcome winter.

b) loss of pigment in some races

c) vestigial organs – viz; vermiform appendix reduced (caecum), muscle etc.

Therefore, the evolutionary trends that one observes in the phylogeny of human beings are:

- Increase in size and complexity of brain specially frontal lobes.

- Erect posture

- Shorter arms

- Perfection of thumb opposability

- Reduction in size of teeth and muzzle

7

- Diminution of brow ridges

- Loss of jaw power

- Development of chin prominence

- Increase of skull capacity

- Diminution in strength of zygomatic arch

- Development of articulate speech.

The Early Apes/Human-Ape Comparisons

Table 20-4, Pg. 469 – Strickberger

The Fossil Record

Although scanty, the story of human origin and evolution is remarkably complete.

According to the fossil record, many Mesozoic mammals were very much like extinct tree shrews adapted to insectiveorous lifestyle inhabiting both the forest floor and tree shrubs. Primates evolved from these early forms. However, Paleocene deposits showed the presence

8

of an early archaic primate group of the suborder Plesiadapiformes with unique auditory region and dentition different from related insectivorous forms. By the Eocene, some such groups evolved still further by developing bony orbital rings and digital nail. This split into two families – Adapids (which gave rise to modern lemurs and lorises and – Omomyids (to tarsiers).

The next evolutionary stage, leading to platyrrhine and catarrhine anthropoids is the subject of considerable debate. Some primatologists believe that both anthropoid groups had a monophyletic origin but controversies like whether they arose from adapids or omomyids or whether the platyrrhine monkeys arrived in the New World from North America or Africa is still raging. However, at present omomyid anthropoid ancestry is more acceptable but there is no general agreement (Kay, et al., ).

In any case, both paleontological and molecular dating suggest that anthropoid lineage is quite ancient (Paleocene epoch, 50 million years ago).

OLIGOCENE

This period is characterized by the divergence of old world monkeys from apes and man and there were fossils of Proto-monkeys and Proto-Apes.

• Oligopithecus – This is one of the earliest fossils in the primate line characterized by small size, mixed dental features with some showing cutting first premolar, characteristic of anthropoids.

• Propliopithecus ~ 35 million years old found at Fayum in Egypt.

MIOCENE

a) Aegyptopithecus (belongs to early Miocene)

(“Dawn Ape”)

It was discovered from Fayum by Elwyn Simons in 1966, consisting of virtually complete skull, headbones, upper and lower jaw and an almost full set of teeth. It’s the most primitive ape yet discovered.

Characteristics: a) long canine teeth in the front of upper jaw fitting with the lower jaw allow shearing like modern apes.

b) spaniel-sized

c) skull shaped like a monkey

d) long tail

9

It probably diverged in early Miocene to a group of species now put under Dryopithecus. There are 6 species known from East Africa (17-20 million years ago) and 1 from South East Asia. It is believed that while one species. , earlier called Proconsul discovered on Rusinga Island in Lake Victoria (Africa) gave rise to Pan/Chimpanzee, another to gorilla and still another to hominoids.

b) Dryopithecus (middle Miocene, ~ 20 million years ago)

It was first discovered in Africa (although number of fossils were found in France earlier) and was widespread in Europe, Asia and Africa about 14 million years ago. Post cranial skeleton is scarce.

Characters – 1) blend of monkey and ape characteristics

2) various sized

3) jaws U-shaped ape-like

4) palate flat characters

5) arboreal life

6) poor brachiator (arms shorter than legs like man)

However, it seems to be the best contender for the position of hominid ancestor. It is probable that the apes arose from moderate brachiators viz. Dryopithecus on one line of radiation and man arose on another.

Man, in fact, resembles modern old-world monkeys more than the modern apes, leading some to suggest that the human line diverges earlier (in Eocene) along with the old-world monkeys, leaving Dryopithecus from direct lineage.

c) Ramapithecus (~ 9-15 million years ago)

This fossil (right upper jaw fragment with 4 attached teeth) was discovered by G.E. Lewis in Siwalik Hills of India in 1932 with another fossil Bramapithecus (lower jaw).

Fossil evidence also came from Fort Ternan in Kenya (upper and lower jaw) by Louis & Mary Leakey (Kenyapithecus), from Athens, Greece (European member of the genus Ramapithecus) from Italy (Oreopithecus – more primitive (~ 10-12 million years) and probably not in the hominid line) from Potwar plateau in Pakistan, from Candir & Pasalar in Turkey in Rudabanya (Hungary) & from Lufeng County in Yunnan. This showed that Ramapithecus was fairly widespread.

10

Miocene epoch, particularly mid-miocene was a key factor for hominid development as it was characterized by the retraction of Tethys sea establishing contact between Africa and Europe as well as Africa & Asia.

Characters: It was definitely a non-pongid & more of a hominid:

(1) mandibles relatively low & wide

(2) maxilla strongly buttressed, protruding

(3) relatively short face (prognathus)

(4) non-shearing premolars & molars

(5) wearing of teeth in older specimens

(6) tough herbivorous diet

(7) canines ape-like but didn’t project much beyond the teeth line (occulusal plane)

(8) very small diastema

(9) small canines & incisors – relatively short jaws.

(10) wide-curving jaw with arched palate. .

It was speculated earlier that hominid adaptation took place in Africa and then spread through the land corridor to Europe & Asia or Dryopithecus like form migrated out of Africa whereas Ramapithecus evolved in Arabian Gulf Area and then radiated to Europe, Asia & Africa. This hypothesis seemed more probable because Ramapithecus was fairly widespread in all the places simultaneously.

However, with the recent discovery of more complete ramapithecine fossils, researchers are of the view that this group linked to a much earlier ape like lineage that may have been ancestral to Orangutans (Wolpoff, 1982; Andrews, 1983; Pilbeam, 1984). African apes & humans may therefore have diverged a long time after the ramapithecine radiations (supported by molecular data, Ruvolo et al., 1994).

Fig. 20-5, Pg. 470, Strickberger + Fig. 26.2 Pg. 730, Futuyma.

11

d) Sivapithecus: It was an ape that developed someway along the same road as Ramapithecus and was very similar to it but retained its long canine teeth and had thick-enameled molar teeth. However, it never succeeded in fully adapting to open habitats- the savannas – and their particular food resources and became extinct ~ 8 million years ago.

The specimen formerly classified as Ramapithecus are now usually included in the genus Sivapithecus which in turn is thought to be a close relation of the ancestors of modern orangutans.

Fig. 15.25b Ridley (3rd edn.)

e) Gigantopithecus – This open-habitat form was most successful. It was quite like a gorilla, large-formed and survived as a successful quadraped in Asia for about 9 million years ago and became extinct only about 1 million years ago. But its extinction has been questioned by those who believe in Yeti of the Himalayas or Sasquatch of Northwest American Coast.

Characters – ground living savanna ape

• thick enamel Ramapithecus

• short canines characters

• immense molars (tough, fibrous vegetable diet)

It was probably a pongid which developed hominid dental characters as a parallel evolution but became extinct when hominids invaded Asia. Last remains have been detected from S.E. Asia, China and one species (G. bilaspurensis) from Siwaliks.

PLIOCENE

Australopithecines (Southern Ape). The earliest fossil hominids are called australopithecines. Fig. 26.4 Pg.731, Futuyama.

Since Miocene apes were represented only by jaw fossils, they didn’t give us any clue about bipedalism but somewhere in late Miocene and Pliocene, the adaptations of bipedalism made their appearance in at least one kind of primate, which ultimately led to Homo.

(a) Australopithecus afarensis,: ( 3 – 3.9 million years ago)

12

These are a series of fossils found in East African sites at Laetoli (Tanzania) (“footprints”) and Afar (Hadar) region of Ethiopia [extremely famous fairly complete skeleton( 40%) of “Lucy”].

Characters :

• small brain (400 cc)

• heavy eye brow ridges

• low forehead

• prognathus jaw/face

• canines larger in males than female but sexual dimorphism less pronounced than apes.

• thick enamel

• small, muscularly powerful body, 3.5 – 4 ft. high

• longer arms than man

• flat cranium

• curved bones in fingers and toes.(indicating they climbed trees)

1. but still fully bipedal.

(b) Australopithecus africanus (1.75 to 2 million years ago)

The first tangible evidence about a bipedal primate came again from Africa – from a place called Transvaal region in S. Africa, discovered by Raymond Dart. (The famous “Taung child”). It was named A. africanus which later came to be known as “gracile” form. Australopithecines also found at Swartkrans.

Characters :

- brain capacity – 450 – 500 cm3

- foramen magnum situated near the centre of skull.

- face projecting but no muzzle (prognathus)

13

- small canines

- milk teeth human-like (multi-cusped) (anterior molar)

- shoulder adapted for arboreal locomotion.

- upright posture

- predominantly bipedal gait

- lunate sulcus (anterior border of visual area in the brain further back.

c) robustus was discovered from few km. from Sterktontein Kromdraii area by Dr. Robert Broom. It was called as Paranthropus robustus (robust near-man) by him because it was heavy jawed with extremely large molars, later renamed as A. robustus.

Characters - large size

- weight 150 pounds

- cranial capacity 530 cc.

- molars extremely large

- heavy jaws with large jaw muscles

- anterior teeth smaller than in gracile type

- canines ,skull with a bony ridge or crest

-

14

-

Dia from Campbell, Fig. 6 -5 Pg.

15

12 7.

(d) A. boisei (1.75 million years ago) was another fossil evidence (skull) discovered from Olduvai Gorge (East Africa) at Koobi Fora, Kenya by the husband and wife team of Louis & Mary Leakey

Characters:

• Morphologically closer to “robust” type charleCharles Boise, who financed Leakey’s research). Later the skull was called A. boiesi.

(1) A. aethiopicus (2.5 m years ago) from deposits at Lake Turkana, Kenya.

• molars large

• shortening of face, more vertical

• massively built

They probably evolved separately but parallel to africanus – robustus lineage.

(2) Ardepithecus ramidus (4.3 – 4.5 million years ago) (mya)

- fossil evidence (teeth) is perhaps the most primitive hominid like fossils from Ethiopia.

Characters :

• reduced sexual dimorphism for canine teeth

• forward positioning of foramen magnium

• Erect posture

16

All these evidences, in any case indicate that Ramapithecus was probably an ape-like ancestor and hominids diverged from apes about 15 million years ago while Australopithecines were the first bipedal tropical apes evolved either from Ramapithecus or Ramapithecus – like forms. Also, there is little question that A. afarensis stands at or very near the base of hominid phylogeny. However, australopithecines definitely diverged along different lines. There are at least three hypotheses of the phylogenetic relationships among fossil hominids, advocated by different authors. Hypothesis ‘C’ is perhaps most widely accepted, though with little uncertaintly about whether A. africanus is a separate lineage from Homo habilis or its direct ancestor. (After Grine 1993 & Jones et al., 1992).

(A) (B) (C)

Fig.26.6. Pg.732 (Futuyma)

Origin & Evolution of Homo

A number of species of the genus Homo appeared in the evolutionary scene and became extinct before the origin of modern man, Homo sapiens. These are called as pre-historic species of man. Some of them evolved as direct ancestors of the modern man, while others were merely off-shoots of the main line of human evolution.

The earliest fossils referred to as genus Homo range from 2.4 to 1.6 Mya (latest Pliocene & early Pleistocene and came from Tanzania, Ethiopia, and South Africa).

a) Homo habilis

Early in 1960s, Jonathan Leakey (Louis Leakey’s Son) uncovered some teeth and bone fragments from the same strata in Olduvai Gorge (East Africa) not far away from the region where more heavily built A. boisei was discovered. It clearly represented a distinct species but far closer to humankind than “gracile” A. africanus. It was described as Homo habilis, the “handy” man (the tool maker).

Characters:

• Small brained ~ 650 cc (small for human but larger than A. africanus (450cc)

• 120 – 180cm tall (4.5 ft. tall)

17

• delicate lower jaw

• dentition modern man-like (short tooth row)

• omnivorous

• tool maker (patterned stone tools)

• Olduwan technology Oldowan Industry

• reduced prognathism

It’s the epitome of missing link no longer missing (Wood, 1992)

b) Homo erectus (1.6mya to 300,000 years).

H. habilis grade into later hominid fossils, referred to as H.erectus of mid-pleistocene era.

The fossil (Jaw bone, including several teeth, part of the skull and thigh bone-femur) was unearthed by a Dutch anatomist, Eugene Dubois in 1891 from the bank of Solo river at Trinil in Java and was named Pithecanthropus erectus initially (Java ape man).

Charactes:

• flat and rounded skull

• brain capacity ~800 – 1000cc.

• speech centre (Broca’ s area) well developed

• face steeper and less prognathous with no chin

• teeth smaller except larger canines of lower jaw

• beetling brows, prominent brow ridges

• heavy neck muscles

• brain deficient in pre-frontal and parietal areas (seat of higher mental faculties) and heavy in rear part of skull (implying lack of delicate balance)

• Height – 5`8`` (150cm.)

• Weight – 154 pounds

• lips thick and protruding

• made more sophisticated tools of stones and bones including axes (Acheulean type)

• lived in small groups in caves

• Omnivorous and probably a cannibal

• first to make use of fire for hunting, defense and cooking.

18

It appeared that H. erectus grade hominids had moved to the temperate West European areas by 0.5 million years.

c) Homo heidelbergensis (Heidelberg man)

The fossil (toothed lower jaw) ~ a million years old was discovered from middle Pleistocene sand beds at Mauer Heidelberg in Germany in 1907.

Characters:

• massive ape-like jaw

• dentition man-like, small

• chin sloping, area of muscular attachment powerful

• teeth with short divergent roots and large pulp cavity like the teeth of cattle (perhaps an adaptation for harsh food).

These characters are not found anywhere except Neanderthal man, to which Homo heidelbergensis may be an ancestor. Presumably it’s an offshoot of the main human evolutionary line.

d) Homo erectus pekinensis (Peking man)

The story of human evolution from Java continued in China as fossil teeth of lower middle Pleistocene of about 600,000 years old in Cave Choukoutien (Beijing) .It was discovered by W. C.Pei working with Davidson Black (1924) and named as Sinanthropus Pekinenesis. It was very much similar to Java ape man and the two are considered to be variants of the same type and often placed in the same genus.

Character

• 155cm high, lighter and weaker than Java man

• skull very thick, cranial vault more rounded

• cranial capacity ~ 1075cc.

• forehead low, tori more pronounced

• inconspicuous chin

• canine teeth large

• omnivorous – cannibal

• used sharp chisel – shaped tools of bones, stones and quartz (Oldovian industry)

• fire for cooking

• lived in caves in small groups

19

• used non-syllabic and non-articulate language

• probably an ancestor of modern man goloids (Franz Weiden reich).

e) H. erectus mauri tanicus (Atlantic Man or ternifine man)

These fossils (three jaws and a parietal bone) were discovered from ~ 600,00 years old Pleistocene deposits in Algeria (1975). Later, more fossils of this type were discovered from Casablanca, Morocco.

Characters:

• most primitive ape man found so far in North Africa

• more advanced than Java or Peking man

• low cranial dome

• heavy projecting jaws

• no chin.

Thus, Homo erectus grade hominids were very widespread over Asia, Africa and Europe between 1.5 and 0.5 million years ago. The first hominids were found in temperate regions, even at altitudes of upto 2500 metres. By the end of Pleistocene era, they had refined hunting techniques, certainly used stone tools and fire was also used at some sites for cooking. However, it’s still controversial whether Homo habilis diverged into H. erectus & H. sapiens or they were directly in the line of evolution of modern man.

Homo sapiens

Fossils of a form intermediate between H. erectus & H. sapiens are called as archaic modern man or pre-sapiens and were mainly discovered from Britain and China.

Most hominid fossils from about 0.3 mya onward as well as some African fossils about 0.4 my old are referred to as Homo sapiens. The best known populations of archaic H. sapiens are:

a) The Neanderthal/Neandertal (modern spelling) Man

The first Neandertal was discovered in 1856 in Dusseldorf (Germany) near the Neander Valley (:. the name Neandertal) and was handed over to local science teacher, J.K. Fuhlrott who consulted an expert, Hermann Schaaffhausen. It was named Homo neanderthalensis by William King. The name however is now applied to all the fossil material dating from the end of third inter-glacial and fourth glacial period.

Subsequently specimens have been discovered from Belgium, France, Spain, Romania etc., thus giving Neandertals a European distribution. Later, however specimens were also unearthed from Broken Hill in Zambia (1921) with the same characteristics. This was named as “Rhodesian Man”.

20

In 1931-32, the specimens were discovered from Java, who however showed an early evolutionary level than Neandertals (Solo Man) and in 1938, there were similar discoveries from Central Russia (Teshik-Tash) ,Isreal (Mt: Caramel and Shanidar). So far ~300 Neandertals individuals are documented.

Thus, there are basically two types of Neandertals –

1. West European Type & 2. Non European Type

Characters of West European “Classic” Type

• Large cranium (could accomodate brain of modern size) ~ 1500cc.

• different shape with lower flatter crown bulging backwards to which neck muscles are attached as a bun or chignon the Neandertal “bun”

• Receding Chin

• Large projecting Jaws & face

• Large teeth & palate

• Round orbits for eyes

• Extremely prominent brow ridges covering each eye and meeting across the bridge of nose (beetle browed look)

• Short (5ft. tall) but powerfully built body

• Long dense bone robust and slightly curved giving Bandy-legged appearance. The first specimen had curved bones leading people to think that Neandertals were pro-simians but later specimens didn’t show this characteristic. It was later established that the earlier specimen was an old man suffering with arthritis.

• Hands large, short stubby fingers

• Thick skull

• Use of variety of stone tools (Mousterian culture)

• Elaborate culture, skilful hunters

• probably practiced ritualized burial of the dead with flowers and ornaments (thus probably believing in spiritual immortality).

Their remains date from an earlier age (about 110 Kya) in the Middle East than in Europe (~50 Kya).

Their “footprints” are also nicely preserved pointing to stocky proportions of feet (Picture).

21

Characters of Non-European Neandertals

• Less massive

• Taller and more finely made

• legs and arms not as robust and curved

• skull more lofty

• face smaller, bony features like modern man.

Thus, Neandertals were a varied and widespread group. However, little is known about the abrupt disappearance of Neandertal. Some of their populations may have died out, whereas others may have merged into the new dominant forms. One hypothesis suggests that they represent a separate offshoot of human line, differing from both the Homo sapiens groups that preceded and followed it (Stringer & Gamble). In support of this view are findings that recovered sequences of Neandertal mtDNA are outside the limits of normal H. sapiens variability. According to Krings & Coworkers, this evidence indicates that “Neandertal” mtDNA and the human ancestral mtDNA gene pool have evolved as separate entities for substantial period of time and gives no support to the notion that they should have contributed mtDNA to modern human gene pool. Rak pointed out that extraordinarily large face was probably a biological innovation to exert stronger biting forces on front teeth whereas heavy wearing of incisors and canines indicated processing of tough food or hides or both. The expanded nasal chamber in their face may have served as a radiator, warming and humidifying inspired air in the dry, cold glacial climates that many European Neandertals inhabited. In other words, the “classic” type characters were an adaptation to the environment (“cold”). Many anthropologists, however feel that the Neandertals probably deserve a full membership in H. sapiens as H. sapiens neanderthalensis.

Homo sapiens sapiens

The modern sapiens anatomically virtually indistinguishable from today’s humans, appeared earlier in Africa (~170Kya) than elsewhere. It overlapped with Neandertals in the Middle East for much of Neandertal’s history, but abruptly replaced them in Europe about 40Kya. By 12,000 years ago, and possibly earlier, modern humans had spread from northeastern Asia across the Bering Land Bridge to north-western North America and then rapidly throughout the Americas.

Evidence of early populations of Homo sapiens sapiens tends to be concentrated in Europe for historical reasons, therefore, the tendency has been to use European samples to typify the morphology of modern humans.

22

Cro-Magnon

he fossils of modern man were discovered first from Dordogne in S. France (in 1868) in a rock shelter called Cro-Magnon after a local harbit Magnon. Although they are probably the best known evidence in the upper Paleolithic, material is now known from sites right across Europe into Russia, from Kanjera and Kanam on the river Omo in (Africa), from Niah (Malaysia) and Wadjak (East Java) in Asia from Lake Mungo and Kow Swamp in Australia and from S. California (“Laguna skull”), Taber and Alberta in Canada in America.

Characters- height 6ft. (males) & 5ft.5” (females)

• lower leg longer than Neandertals (indicating swift footedness)

• skull with high forehead

• distinctive chin

• no heavy tori

• orthognathous

• teeth and jaw modern

• skull large but narrow

• broad face hence disharmonic

• brain large, high type

• Burial elaborate

• Use of stone tools and that made of bone (Aurignacian industry)

• More Asiatic in character, reached Europe as invaders from Asia

• Paleolithic art in caves (shows employment of artificial illumination in dark caves)

23

The shape of the face changed because of:-

• Brace’s hypothesis – Neandertals used teeth to hold and cut as a plier but with the use of tools, face suddenly straightened up.

• Pilbeam’s hypothesis – Use of speech particularly articulate speech necessitated development of pharynx which in turn brought about

• changes in skull shape. This’s more plausible.

Cro Magnon (upper Paleolithic age)

• stone implements

• cultural evolution

• use of agriculture, domestic animals.

Summary of Hominid Evolution

24

Table 20-4, pg. 482 (Strickberger), Fig. 20-15, pg.483 (Strickberger)

Origin of Homo sapiens

There are 2 main views of the origin of modern humans from a Homo erectus ancestor:

1. The Single-Origin Hypothesis also known as the “Out of Africa” or “Noah’s Ark” model proposes that modern humans (coloured sections) originated in one locality (Africa) and then migrated to other continents where they replaced relict Homo erectus populations (grey sections) that had entered these continents one million or more years ago.

This can also be termed as replacement hypothesis, because it holds that after H. erectus spread from Africa to Asia and Europe and evolved into archaic H. sapiens, modern sapiens evolved from archaic sapiens in Africa, spread throughout the world in a second expansion, and replaced the populations of archaic sapiens without interbreeding with them to any substantial extent. (Vigilant et. al., 1991)

Diagram from Stickberger Box 20-1

That is, modern sapiens that evolved from archaic sapiens in Africa was reproductively isolated from Eurasian populations of archaic sapiens- i.e. it was a distinct biological species. Most of the world’s populations of archaic sapiens became extinct due to competition, and most genes in contemporary populations are descended from these carried by the population of modern sapiens that spread from Africa.

The support for this hypothesis are following facts:

25

1. All the non-African mtDNA sequences are variants of the African sequence.

2. Most mtDNA sequence variability occurs among African populations suggesting that these are oldest mtDNA populations.

Interestingly, like “Mitochondrial Eve” the “Y-chromosome Adam” was also of African origin but African populations also received Y-chromosome returning from Asia.

3. Nei & Roychaudhry also suggested a single African Origin for H. sapiens with subsequent widespread geographic divergence (by calculating genetic distances between 26 human populations for 29 different nuclear genes).

4. Mountain & coworkers presented similar findings by working out polymorphism for Alu chromosomal DNA sequences specific to human’s (Batzer, et.al.).

Although the dispute continues, Cann and coworker’s general conclusion for a single African origin of H. sapiens still seems generally favored.

Taking all the many hominid variations into account, it is clear that “Instead of a ladder with humans at the pinnacle, there is bush with humans as one little twig” (Foley, 1995).

II. The Multiple-Origin Hypothesis/”Candelabra” Model (because of its shape)

Modern humans originated in different localities independently of other such groups. However, if each population evolved independently, how did they become so similar? Modern humans may differ in color and other minor attributes, but they all share basic H. sapiens traits. In answer some proponents or paleontologists of multiple origins (the “Multiregional” Model, Wolpoff, 1989) suggest that probably some genes exchanged between continental populations via cross migration(gene flow),enabling all these various evolving groups to reach the same H.sapiens grade.

Conclusion

Human beings developed language, apart from other functions, which allowed him to transmit knowledge and information to successive generations, in contrast to other animals. Not only this, a more developed brain allowed the information to be stored and language helped to build upon the accumulated experience of earlier generations. This acclerated the pace of cultural adaptation and humans were no longer dependent on biological evolution.

A Note on cultural adaptation

A highly specialized hand, and bipedalism (which led to “freeing” the specialized hand so that it could be used for other purposes e.g. making tools) are of course, important pre-requisites for making tools. However, the real breakthrough came about with a large brain (1000cc. and beyond). Tool manufacture calls for a high degree of motor skills and coordination of various parts of the body as well as enormous concentration as well as certain measure of conceptualization.

26

I. Oldowan [Paleolithic (early stone age) 1.5 – 2.0 culture] found in East Africa

Characterized by hunting & plant gathering

Tools were crude, rudimentary small-sized made from pebbles used mainly for cutting plant foods, breaking nuts, digging roots, scrapping wood & obtaining honey. Also used for skinning the meat of animals and extracting bone narrow

II. Acheulian [named after a site in North France (St. Acheul)] found in East, South and West Africa, in Spain, France and several other parts of Europe and in West Asia, India and some other regions of South Asia

Characterized by a predetermined “design” on the stone.

Most important tool was “handaxe”. These were pear-shaped or tear drop shaped pointed at one end and broad at the other. Tools much larger and remarkably symmetrical. Hand axe was a “core” tool (made from larger block or “core”). The other type was “flake tools” fashioned from small bits of flakes which come off a block of stone on hitting.

III. Clactonian* & Levalloisian** cultures (lower “Paleolithic” cultures) found in some parts of North Europe and far East

700,000 years ago Characterized by turtle shaped* or round shaped** made of wood and bone

IV. Mousterian Culture (middle Paleolithic) (named after a French site of Le Moustier) found in West Asia and Africa independently

A product of Neanderthals Quarternary period P*and H**

*Pleistocene epoch (1.64mya – 12,000ya) **Holocene (12,000ya to present)

Very specialized tools. Sixty varieties identified careful disposal of dead bodies

V. Aurignacian Upper

Solutrean Paleolithic

Magdalenian

Cultures

35,000 years ago

- 30,000 years ago

Tools increasingly specialized made for specific purposes, highly refined. A typical tool was “burin” (a kind of chisel). Tools were small blades with parallel and extremely sharp edges, sharp “leaf point”,

27

Discovered in France

(South) and Spain

*developed/evolved in Eastern Europe (Hungary, Yugoslavia) and South West Asia, reached a peak in Western Europe

a) No Aurignacian paintings but other beautifully carved objects viz – ivory beads used for ornamentation and flute like wind instrument from bone

b) Solutrean Culture – cave paintings major art form colors used were natural pigments – expert at carving figures on walls of caves (technique known as “bas-relief” or low – relief)

c) Magdalenian Culture

- Cave paintings reached fullest development

- paintings deep inside caves using animal fat lamps depicting fantastic animals, humans engaged in hunting and some geometric patterns

[V. Gordon Childe refers to the Magdalenian as the most brilliant culture created by hunter- gathers]

22,000 – 18,000 years ago

18,000 – 11,000 years ago

harpoons used for fishing. Tools made of wood, bone, ivory and antler. Composite tools composed of several parts viz. leaf points joined to wooden rods making spear-like weapon. Arrows often poisoned. Tools also made for crude clothing (from hides), for chiseling wood, bone, ivory and antler for decorative purposes culture also known for earliest examples *of art (development of thought and imagination) Cave paintings (on the roof of a cave in Altamira) discovered by Don Marcelino de Sautuola (1879) Heri Breuil researched on 200 paleolithic cave painting. Other art objects also found viz. – handles of tools, statuettes and clay figures with animal or geometric designs.

Throughout the Paleolithic period, one feature of social organization stood out – Collective effort and sharing. However, the concepts began to undergo changes with the beginning of food production lead to individual control.

Table 11.10: Brief inferences about adaptions, behavior, and ecological factors in hominid evolution

28

Reference:

1. Campbell, Bernard, G. (1982), Humankind Emerging, Third Edition, Little Brown & Campany, Boston/Toronto.

2. Farooqui, Amar (2001), Early Social Formations, Second Edition, Manak Publications Pvt. Ltd., New Delhi.

3. Futuyma, Douglas, J. (1997), Evolutionary Biology, Third Edition, Sinauer Associates, Inc. Publishers, Sunderland, Massachusetts.

4. Lull, R.S. (1977), Organic Evolution, MacMillan Co., New York.

5. Moody, P.A. (1978), Introduction to Evolution, Third Edition, Kalyani Publishers, New Delhi.

6. Strickberger, M.W., (2000), Evolution, Third Edition, Jones & Barlett Publ. Int.

29

7. Wood, B.A. (1978), Outline Studies in Biology – Human Evolution, Chapman & Hall (London), John Wiley & Sons, New York.

30