2 Human Biological Diversity: A brief history

Ms. Sangeeta Dey and Prof. A.K. Kapoor

Contents:

1. Introduction

2. Place of origin of human diversity

3. Probable time of origin of human diversity

4. Human biological diversity: a brief history 4.1 Propliopithecus

4.2 Aegyptopithecus

4.3 Pliopithecus

4.4 Proconsul

4.5 Dryopithecus

4.6 Oreopithecus

4.7 Ramapithecus

4.8 Australopithecus

4.9 Homo habilis

4.10 Homo erectus

4.10.1.Java Man

4.10.2.Pecking man

4.11 Homo sapiens

4.11.1.Heidelberg Man

4.11.2.Neanderthal Man

4.11.3. Solo Man

4.11.4. Rhodesian Man

4.11.5. Cro – Magnon Man

5. Homo sapiens sapiens

6. Summary

Learning Objectives:

To describe Human biological diversity.
To understand the progressive evolutionary process.
To describe progression changes that occur in biological dimension of man.
To know about connecting links that lead to Homo sapiens sapiens.
To understand impact of evolution for the biological evolution of man.
To explore the importance of diverse human forms and variants.

1. Introduction

The course of human phylogeny or the human biological evolution like other mammals can be followed only from the fossil records. Though the fossil records are fragmentary, the paleoanthropologists have been able to piece them together and draw them an almost complete phylogeny of primates and of modern man, Homo sapiens sapiens. The early stages of human biological diversity can only be studies by comparative anatomy of fossils and also by comparative biochemistry of present day humans, apes and other primates. Information on the later stages in human evolution are based on artefacts that include stone tools, pottery, fire – hearths and the fossils of other animals along with human fossils.

Human biological diversity can be understand as the gradual process by which the present diversity of plants and animals arose from the earliest and most primitive organisms, which is believed to have been continuing for atleast the past 3000 million years. It is believed that every species was individually created by God in the form in which it exists today and is not capable of undergoing any change. This is referred as theory of special creation. Special creation was contradicted by fossil evidence and genetic studies, and the pseudoscientific arguments of creation science cannot stand up to logical examination. It was the generally accepted explanation of origin of the origin of life until the advent of Darwinism. However, Lamarck is the first biologist to publish a theory to explain how one species could have evolved into another. He suggested that changes in an individual are acquired during its lifetime, chiefly by increased use or disuse of organs in response to “a need that continues to make itself felt” and that these changes are inherited by its offspring. Thus the long neck and limbs of a giraffe are explained as having evolved by the animal stretching its neck to browse on the foliage of trees. This is also called as inheritance of acquired characteristics. But it was not until the publication of Darwin’s On the Origin of Species in 1859 that special creation was seriously challenged. Unlike Lamarck, Darwin proposed a feasible mechanism for evolution and comparative anatomy. The modern version of Darwinism which incorporates discoveries in genetics remains the most acceptable theory of evolution.

2. Place of origin of human diversity

The fossils of pre-human and ancestral human forms are obtained from widely diverse regions of Africa, Asia and Europe which indicates that man’s centre of origin was probably in Asia and Africa. More precisely human must have been originated from central Asia because the oldest known fossils have been obtained from Asia, China, Java and India (Siwalik hills); the number of domesticated animals and plants is maximum in Asia; A number of migrations of animals have occurred in the past from Asia; Asian culture appears to be the oldest culture; the climatic conditions in Asia and nearby places were most conductive for human evolution and rich fossil beds are discovered from rift valley in East Africa, where Hominid fossils have been found. These areas are – Olduvai Gorge, Lake Victoria and Lake Natrona in Tanzania and Lake Turkana in Kenya.

3. Probable time of origin of human diversity

Primates are presumed to have started evolving in Eocene of Tertiary Period between 75 and 60 million years ago or living in forests of Miocene. In late Oligocene, about 25 – 30 million years ago,when these evergreen forests were replaced by drier Savannah grasslands, some tree – dwelling primates returned back to the ground and became ancestors of apes and human. Thus, evolution of man and apes started together from some tree – dwelling common ancestors about 25 – 30 million years ago. Humanization or the achievement of human organization or appearance of genus Homo started about 5 million years ago.

Human Biological Diversity: A brief History

French anatomist, Marcellin Boule presumed that a generalized monkey like creature must have been our hominid ancestor but F. Wood Jones proposed that it would be easier to derive humans from a small – toothed generalized tarsier – like prosimian than explaining the reduction in the size of the teeth during the evolution of man from monkey like apes.

4.1 Propliopithecus

The fossil of first known ape was obtained from Fayam deposits of Egypt. It was described under the name propliopithecus. It lived from about 30 – 35 million years ago in Oligocene. It is represented by the fossil jaws and teeth. No doubt more or less ape – like, these were short statured with monkey – like teeth. Their dental formula is 2, 1, 2, 3.

Their incisors teeth were vertical rather than directed forward and molars has 5 cusps each. Swinnerton presumed that the apes have directly evolved from the tarsiers bypassing the monkeys. There are two different concepts of man’s Oligocene ancestry – that Propliopithecus directly gave rise to Ramapithecus; that Propliopithecus gave rise to Dryopithecus which in turn evolved into apes and human.

4.2 Aegyptopithecus

Its fossils were found by E.L. Simon and Richard in 1980 from Cairo. These were similar to Propliopithecus..

4.3 Pliopithecus

Their fossils were obtained from Fayum deposits of Egypt and some other places. These forms existed in Miocene and Pliocene periods. These are considered to be ancestors of gibbons and orang-utans.

4.4 Proconsul

Its fossils were described by Leakey (1930) from east Africa near Victoria Lake in Kenya from Miocene deposits. Its molars had five cusps each. Their face was prognathous. It walked on its four legs.

4.5 Dryopithecus

In early Miocene about 25 million years ago, there existed a group of apes, collectively known as Dryopithecus. D. Africanus, formerly known as Procunsul, exhibits close similarity to chimpanzee and is considered to be a common ancestor of man and apes or a direct forerunner of man. Although ape-like, it had arms and legs of the same length and its legs and heels indicate that it must have assumed a semi erect posture (knuckle walker). It has large canines and incisors, feeding on fruits and leaves. Dryopithecines from India and Europe in Miocene appear to the ancestors of modern apes. Several members of Dryopithecine have been discovered from Siwaliks. An almost complete lower jaw of a Dryopithecus has been discovered from Bilaspur district of Himachal Pradesh and is being studied by Chopra – Simon team at Punjab University. Sivapithecus is another fossil ape from Siwalik hills.

4.6 Oreopithecus

Oreopithecus exhibits still more resemblances with man. It has broad, basin – like pelvic girdle, man – like teeth and jaws and a short man like face. It might have walked erect. It lived in late Miocene and early Pliocene periods. Although, so man – like, it is regarded to represent an aberrant branch from the common ancestors of man and ape and its similarities to man have developed on account of parallel evolution.

4.7 Ramapithecus

Ramapithesus which is known only by few teeth and some fragments of jaw is considered to be the earliest man like primates and oldest of man’s ancestors which is on direct line of human evolution. Its fossil has been discovered from Siwalik Hills in India and date back to 14 – 15 million years ago in Miocene. Perhaps it walked erect on its hindfeet. Moreover, its teeth suggest a diet and life habits very similar to modern man. Its diet included seeds and nuts. Its canines were small but molars were broad and flattened with thicker enamel. Therefore, from the Miocene and early Pliocene fossils it has been now established that Dryopithecus gave rise to Ramapithecus which is on direct line of human evolution and represents the first man – like primate.

Unfortunately, fossil records of man’s ancestor from Pliocene are completely blank and once again reappear dramatically revealing the Pleistocene evolutionary sequence of man. The Pleistocene primarily witnesses the progressive enlargement of brain and increase in intelligence and the perfection of bipedal gait.

4.8 Australopithecus

Australopithecus were fully bipedal hominids with relatively small brains who lived from 4 to 1.5 million years ago. The brain size ranged from 500 – 700 c.c. of the size of the brain of modern gorilla. These were short statured forms, averaging about four feet. They walked nearly or completely straight. Their skeleton shows following adaptations for bipedalism:

Vertebral column had a distinct lumbar curve.
Their thighs and hips were well adapted for erect standing, walking and running.
Their ankle bones were designed to bear body weight in bipedal locomotion. In addition to that, their arms were somewhat less mobile than ours. Their ankle bones were intermediate between human and typical ape. Their big toes were still adapted for grasping. They lived in small groups containing a few dozedn individuals. All the Australopithecus had protruding jaws, heavy eye – brow ridges. Teeth were strikingly man like because the dental arch was smoothly rounded parabola; canines did not project beyond the level of other teeth; and a simian gap was absent.
But the jaws and teeth were larger than those of modern man. Face was prognathus and a chin was absent. Eyebrow ridges projected over the eyes. Their brain capacity ranged from 450 – 600 c.c. or slightly above. Thus Australopithecines represented man with an ape – brain.

4.9 Homo habilis

Homo habilis lived in early Pleitocene about 1.75 – 2 million years ago. It walked fully straight and had a cranial capacity of about 700 – 800 c.c. Its hands were similar to ours and it was starting to develop humanid manual dexterity. These were carnivorous had begun hunting for meat. For hunting, these had developed the most primitive stone tools. These were crude choppers, made by removing flakes along one side of a pebble having an irregular cutting edges. They lived in small bands or groups with stable camp sites. Perhaps they showed sexual division of labour and communicated with visual signals and simple audible sounds. The fossils of Homo habilis were found at Olduvai by Mary Leakey in 1961 and then Richard Leakey (1972) from east side of Lake Turkana in Kenya. Homo habilis is now considered to be on direct line to other Homo. Probably, Homo habilis and Australopithecus existed together in Africa evolving from africanus to robustus to habilis.

4.10 Homo erectus

Homo erectus include fossils obtained from diverse sites ranging from Olduvai George in Africa to Java, Algeria, China, Hungary and Germany. These fossils date back from 800,000 to 300,000 years. Its first fossil was described in 1891 by Eugene Dubois from Java. It was named Pithecanthropus erectus meaning ‘ape – man that walks erect.’ Similar fossils were found in a cave Choukoutein in near Peking in China and were named Sinanthropus pekinensis. But on account of their similarities with java ape – man these were renamed Pithecanthropus pekinensis. But Mayr (1950) has replaced these names by Homo erectus so that H. erectus is known as Homo erectus erectus and P. Pekinensis as Homo erectus pekinensis.

Homo erectus has skeleton much like ours but more primitive skull. They were hunters and food gatherers. They used stone tools for hunting and butchering deers, antelopes and even large ferocious animals such as bears, wild oxen and elephants. Their tools included handaxes, chopping tools, flakes, points, cleavers and even scrapers. They had started using bone and wooden tools as well. Signs of organised hunting have been found in Europe. H. erectus people had also learned the use of fire for cooking purposes for which evidences are available from Hungary and China.

Homo erectus have left clear records of a developing culture associated with the oldest or Abbevillian culture. They were nomads who roamed widely in small groups or extended families. These people had begun to clothe themselves with animal skins and some of them moved into caves to protect them from adverse cold conditions. They also used some kind of rudimentary visuals signals and language.

4.10.1. Java Man

Java man or Homo erectus or Pithecanthropus erectus. Its fossils were found in 1891 by Dubois on the bank of Solo River in eastern java. Its fossils include some teeth, skull cap and femur bone. It occurred in the Pleistocene deposits some 500,000 years to 1.5 million years ago. It has a cranial cavity of about 940 c.c. which is intermediate between that of Australopithecus (600 – 700 c.c.) and modern man (1400 – 1600 c.c.). It was more than five feet tall and weighed 70 Kg. Its forehead was low and slanting, the face was prognathus, and the jaws were massive with huge teeth. The chin was absent but bony eyebrow ridges present over the eyes were heavy. Their molars were smaller but frontal teeth (incisors and canines) were large and more prominent indicating omnivorous diet.

4.10.2. Peking Man

Homo erectus pekinensis or Pithecanthropus pekinensis or Sinanthropus pekinensis. Its fossils were discovered from caves near Peking in 1920 by Davidson Black. Their fossils include numerous skulls, jaws and post cranial bony fragments from the limestone caves near Choukoutein. These lived most probably about 1.5 – 5,00,000 years ago. It is very similar to Java man with heavy bony eyebrow ridges, low slanting forehead and chinless face. But their cranial cavity was much larger than Java man ranging from 850 – 1200 c.c. and averaging 1075 c.c.

In addition to these Gigantopithecus and Meganthropus are described to be related to Java and Peking ape man.

4.11 Homo sapiens

Homo erectus were succeeded by early Homo sapiens which were described under different names as Homo neanderthelensis, Homo heidelbergensis, Swanscombe man etc. But, since these appear to be very similar now they are grouped under Homo sapiens. Some transitional forms connecting Homo erectus with Homo sapiens have been uncovered from Europe.

Steinheim skull – It is fairly a complete skull found from Steinheim in Germany. Its cranial capacity is estimated to be about 1,000 c.c. It had puffy eyebrow ridges and a low forehead. Its face protrudes but is relatively straight tucked in under the brain case. The back of the skull was well rounded and the molars were modern but the incisors were rather large.

Swanscombe skull – This is known from three bones which form roof and back of the brain case. The bones are usually thick. Its cranial cavity is estimated to be about 1320 c.c. In other features it resembled Homo sapiens. The above two skulls were obtained from the 2nd interglacial period from late, middle or early upper Pleistocene.

3. Fontechvade skulls – These were discovered from Southern France from the 3rd interglacial period. The skull bones are unusually thick. But the skull lacked heavy eyebrow ridges and cranial capacity even greater than 1400 c.c.

4. Ehringsdone skull – It was found from Germany and had cranial capacity 1450 c.c. The skull had a fairly high forehead but with heavy eyebrow ridges. Thus it resembled Neanderthal man in eyebrow ridges and H. sapiens in forehead.

These fossils indicate that during the second and third interglacial periods there lived an assemblage of people that might have been the ancestors of both Neanderthal man and Homo sapiens. Now all of them together with others have been included in Homo sapiens. Therefore, it will be wise to call these forms as early Homo sapiens. Following distinct type of Homo appeared in due course, all of them have become extinct by now except Homo sapiens sapiens which have appeared quite late in the evolutionary period.

The fossils of primitive man were found in Europe, Asia and Africa. These all differ slightly but exhibit enough similarities to be grouped together as Neanderthaloids. The neanderthaloids include Heidelberg man, Neanderthal man, Solo man, Rhodesian man and Cro-magnon man.

4.11.1. Heidelberg man

It is known only from a massive lower jaw, which was found from Heidelberg, Germany. The jaw is large and heavy and lacks a chin. Teeth are like those of modern man. Heidelberg man is regarded as ancestors to Neanderthal man and is believed to be contemporary to Homo erectus

4.11.2. Neanderthal man

Neanderthal man existed in the late Pleistocene period and its fossils were found in the Neanderthal Valley in Germany. Previously it was named as Homo neanderthalensis but according to modern concept these are known as H. sapiens neanderthalensis. These arose some 1,50,000 years ago and flourished Europe, Asia and North America, but became extinct about 25,000 years ago. They were thick, forehead was low and slanting and the eye brow ridges were heavy. The jaw was deep with no chin. The cranial capacity was about 1450 c.c. roughly equal to that of modern man, but its lower and posterior portions were larger than the upper and anterior parts.

Culturally, they were more evolved. They show replacement of Abbevillian tradition by Acheulian culture and then by Mousterian Tradition. They used more symmetrical and sharp tools. Stone tools were finer and made from flakes. Invention of long wooden spear with a sharp stone tip was advancement in hunting. They killed the large animals either by a group attack or by driving them into pit traps. Neanderthals possessed the knives to butcher the carcasses and used fire for cooking and for warmth. They used animal hides for crude clothing. They buried their dead bodies. They had concept of life and death and followed rituals. Neanderthals made no progress either in agriculture or in domestication of animals.

4.11.3. Solo man

The fossils of Homo solonensis were found on the bank of Solo river in Java, a few miles away from the remains of Pithecanthropus and might have been descended from them. Solo man had heavy ridges over the eyes and a receding forehead. Its brain capacity was about 1300 c.c. It means that Solo man was more primitive than Neanderthal man.

4.11.4. Rodesian man

https://www.google.co.in/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj145vRscfVAhXHNY8KHQgZCTwQjRwIBw&url=http%3A%2F%2Fww w.skullsunlimited.com%2Frecord_variant.php%3Fid%3D4039&psig=AFQjCNGfPGuJ0Hdg 08biR_52QCqdelpogQ&ust=1502273119388496

The fossils of Homo rhodesiensis were found in Rhodesia in the large limestone cave. The skull had a cranial capacity of about 1300 c.c. with receding forehead and heavy eyebrow ridges. It might be even more primitive than Java man.

4.11.5. Cro – Magnon man

During last 30,000 years or even more, Homo sapiens close to modern man lived in Europe and also in other parts of the world. The forms living in Europe are known as Cro – Magnon Man. These succeeded Neanderthals and became extinct about 20,000 years ago. They were much more advanced than the Neanderthals and belonged to Homo sapiens.

Cro –Magnon man were about 180 am in height with a large skull, broad face, rounded forehead, narrow nose and a prominent chin. They lacked eyebrow ridges. The cranial capacity was about 1600 c.c. These were swift – footed, cave dwelling forms and are said to be expert hunters. They were conversant with art and could sketch pictures of their contemporary animals. They made tools from finely chipped stones. The tools consisted of spear heads and arrows. They made ornaments from ivory and decorated their body. They knew the use of hide of animals. They did not know agriculture and domestication but exhibited some cultural advance and had some religious and burial ceremonies. Cro – Magnon expressed themselves through paintings and sculpture. At last 12,000 years ago, they had learned to make paints out of clays, animal fats and metal oxides. Further evolution of man after Cro – Magnon involves the evolution of culture rather than that of anatomy. Techniques of manufacturing stone tools improved with time. The entire period through which man has improved the techniques of constructing instruments starting from stone bits till now has been divided into Paleolithic, Mesolithic and Neolithic Ages.

5. Homo sapiens sapiens

Evolution of modern man from Cro – Magnon is mainly a cultural and technical evolution. It has witnessed:

Advances in forming techniques.
Domestication of cattle, dogs and sheep, etc.
Establishments of towns.
Extraction of metals from ones and their use in arrows, potteries and even ornaments and jewellery. About 3000 B.C., the first alloy bronze was also prepared.

The modern man appeared 11 – 10,000 years ago in Asia near Caspian sea. From here it migrated in three directions and formed three distinct races:

White or Caucasoid race – The white race spread in west along shores of Mediterranean in Europe, South – West Asia and North Africa.
Black or Negroid race – this race developed in Africa and Malaysia.
Mongoloid race – This race spread in North and east in Siberia and China.

6. Summary

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