Assignment Code: BANC-104/ASST/TMA/2021-22

Course Code: BANC-104

Assignment Name: Human Origin and Evolution

Year: 2021-2022

Verification Status: Verified by Professor

There are three Sections in the Assignment. You have to answer all the questions in all the three sections.

Section – I

Answer the following questions in about 500 words each. 20x2

Q1) Define Palaeoanthropology. Discuss in brief process of fossilisation.

Ans) Palaeoanthropology, also called Human Paleontology, interdisciplinary branch of anthropology concerned with the origins and development of early humans. Fossils are assessed by the techniques of physical anthropology, comparative anatomy, and the theory of evolution. Artifacts, such as bone and stone tools, are identified and their significance for the physical and mental development of early humans interpreted by the techniques of archaeology and ethnology. Dating of fossils by geologic strata, chemical tests, or radioactive-decay rates requires knowledge of the physical sciences.

Process of Fossilisation

The first signs of life are extremely fragile and rare. The majority of our evidence dates from later in time, and the majority of these fossils are fragments of shells, bones, or teeth, all of which were partially made of mineral even when the animal was alive. After the organism died, these "hard" tissues were further impregnated with other minerals, eventually transforming into a stone-like composition. This is referred to as mineralization. The process by which an organism's body is converted into a fossil is known as petrification, or the gradual addition or replacement of organic material by inorganic substance. Soft parts decompose during the fossilisation process, so organisms need hard parts like a skeleton, nail, tooth, bone, and so on. To avoid being destroyed, a dead organism must be buried as soon as possible. Because the majority of dead organisms are deposited in water, the sea provides the best conditions for fossilisation. When an organism's tissues are replaced by minerals, this is known as fossilisation. Bacteria can sometimes preserve soft tissue replicas by coating them with a mineral coat of phosphate or pyrite.

On the other hand, fine-grained sediments may occasionally preserve an organism's hardened external cast. Hard parts (pollen, shell, bone, teeth) are more prone to fossilisation, but other materials, such as wood, can also be fossilised. In some areas, fossil wood may be abundant enough to allow for a partial reconstruction of an ancient forest. Mineralization does not always occur in fossil wood. Despite the fact that the cellulose has broken down, lignin may still be present. A partial swamp cypress (Taxodium) forest has been preserved as lignin stumps in 8 Mya deposits in Hungary. The trees were quickly buried in sands, preserving some of the plant material until it could be buried. Rudapithecushungaricus, one of the last survivors of Europe's once-diverse fossil ape radiation, lived in Hungary's Late Miocene swamp forests. However, there are numerous other ways in which life-forms have left their mark. Insects were occasionally trapped in tree sap, which hardened and chemically changed over time. Because there was little or no oxygen inside the hardened amber, the insects have remained remarkably well preserved for millions of years, even with soft tissues and DNA still present. This fascinating circumstance inspired author Michael Crichton to write the novel and film Jurassic Park. Leaf imprints in hardened mud, similar impressions of small organisms, and even traces of dinosaur feathers are examples of fossils.

Q2) Discuss hominization.

Ans) Hominization, also known as anthropogenesis, is a term that refers to the process of becoming human. It is used in a variety of contexts in the fields of palaeontology and paleoanthropology, archaeology, philosophy, and theology, with varying degrees of success.

Bipedalism

Among all extant primates, humans are the only obligate bipeds. An erect bipedal posture evolved from a knuckle-walking ancestor. Some primates can stand on two legs for brief periods of time, such as when peering over tall grass or carrying objects in their hands, but only for a short time. Chimpanzees and gorillas can walk for much longer periods of time than humans, but they are quadrupedal and walk on the ground with their knuckles in a knuckle walking stance. The only animals that can walk on two legs are humans. Over the course of millions of years of evolution, these characteristics have evolved at different rates. Mosaic evolution describes how physiological and behavioural systems evolve at different rates. Bipedalism was the result of a slew of adaptive musculoskeletal traits that completely transformed the human lineage. Long-term changes in the vertebral column, pelvis, lower limb, and foot have resulted in such adaptive traits.

Opposable Thumb and Manual Dexterity

The hand of a primate has a small thumb and long, curved fingers, which are typical of the species. On the other hand, the human hand has an opposable thumb as well as shortened and straightened fingers. Despite the fact that apes have opposable thumbs, humans are the only ones who can grasp objects firmly enough to manipulate them. The human thumb is more mobile than the thumbs of other primates, making it unique and distinguishable. In the early 1960s, the discovery of fossil hand bones attributed to a 1.8-million-year-old Homo habilis specimen at Olduvai Gorge established a consensus that the anatomical reconstruction of the hand during human evolution was somehow linked to tool behaviour. This theory is supported by evidence that early hominid bipedal behaviour 'freed the hands,' allowing for more tool use.

The hand underwent significant changes over a long period of evolution that adapted it for grasping objects with enough strength to withstand a violent impact while maintaining precise control of release. According to Napier, these grips are known as 'power' and 'precision' grips. The object can be pinched between the flexor aspects of the fingers and the opposing thumb in the precision grip, which is formed by partially flexed fingers and the palm, with counter pressure applied by the thumb lying more or less in the plane of the palm. When the core or other weapons were thrown to strike an enemy, precision grip would have been required. The most common names for these grips are cylinder (power) and ball (precision). Humans have the flexor pollicislongus muscle, which provides strength and control to the thumb's movement.

Section – II

Answer any two of the following questions in about 250 words each. 10x2

Q1) Write short notes on any two of the following

Q1. i) Potassium/Argon Dating Method

Ans) The potassium/argon dating method is widely used for dating rocks, especially igneous rocks solidified from molten lava. Geological, archaeological, and paleoanthropological research abounds. Archaeologists and paleoanthropologists can use this technique when lava flows or volcanic tuffs form layers overlying human activity strata. In minerals and rocks, radioactive potassium-40 (40K) decays to argon-40 (40Ar). The ratio of K-40 to Ar-40 in a volcanic rock sample can be used to estimate the age of the rock. Potassium is a common element in the Earth's crust (39K). Three potassium isotopes exist naturally: 39K (93.2581%), 40K (0.017%), and 41K (0.017%). (0.0117 percent ). 6.7302 % 40K decays into two ‘daughter elements': stable 40 Calcium and 40Ar in an 89:11 ratio. In other words, 1 in 100 40K atoms decay into 40Ar. Argon is a noble gas.

The 40Ar produced by 40K decay is trapped in volcanic rock crystals. When the magma melts, any argon produced boils away into the atmosphere. After cooling, the argon produced by 40K decay accumulates within the rock, and the radiometric clock of rock begins to tick. As the rock ages, it accumulates 40Ar atoms. The number of 40Ar atoms in a volcanic rock sample is counted to determine its age. Potassium-40 has a half-life of 1,300 million years, or 1.3 billion years. Due to its long half-life, this method is ideal for estimating planet age. For rocks younger than 100,000 thousand years, it may not be suitable because the amount of argon produced is too small to measure accurately.

Q1. ii) Ramapithecus

Ans) Ramapithecus is a fossil primate that lived during the Middle and Late Miocene periods (about 16.6 million to 5.3 million years ago). In the 1960s and 1970s, Ramapithecus was thought to be a separate genus that was the first direct ancestor of modern humans (Homo sapiens), before it was replaced by Sivapithecus, the orangutan ancestor.

The first Ramapithecus fossils (fragments of an upper jaw and a few teeth) were discovered in the Siwlik hills of northern India in 1932. The fossils were given no significance until 1960, when Yale University anthropologist Elwyn Simons began studying them and putting the jaw fragments together. Simons proposed the theory that Ramapithecus represented the first step in the evolutionary divergence of humans from the common hominoid stock that produced modern apes and humans, based on his observations of the shape of the jaw and the morphology of the teeth, which he thought were transitional between those of apes and humans.

1. Geographical Distribution: For a long time, it seemed Ramapithecus was an Indian hominid only. But in 1961, Dr. Leakey discovered some fossil maxillae with teeth. This is from the Fort Ternan site in Kenya, 40 miles east of Lake Victoria. Leakey's new species was named Kenyaoithecus.

2. Controversy Over Ramapithecus Taxonomy: Taxonomy of Ramapithecus has some disagreements based on facts. Since G. Edward Lewis discovered Ramapithecus in 1934, little more than two dozen fragments, mostly teeth and jaw parts, have been discovered.

3. The Hominid Status of Ramapithecus: According to Pilbeam, Ramapithecus was a hominid. Ramapithecus had dental and facial features similar to later hominids, according to the Ramapithecus material. Based on scant paleontological evidence, it could be on the line that led to Australopithecus and Homo. So, whether Ramapithecus is a hominid depends on how the split between hominid and pongid stock is defined.

Answer any two of the following questions in about 150 words each. 5x2

Q1) Evolution and Extinction of Australopithecus

Ans The earliest hominids began to evolve around -1 million years ago, from the late Miocene through the Pliocene and into the Pleistocene. These diverse hominids had increasingly specialised diets, which was reflected in their cranial morphology. They didn't have any noticeable changes in brain or body size.

As a result, evolution concentrated on mastication. Homo habilis, a new genus and species of hominid with a larger brain and reduced chewing complex, first appeared. Australopithecines were diverse, evolving, and a prominent presence on the African landscape at the time. Homohabilis, a gracile hominid, is thought to have descended from an australopithecine, with A. garhi as a possible ancestor. This point in human evolution is critical because it is the earliest evidence of a remarkable adaptive radiation that resulted in the most prolific and widespread primate species, which is the United States.

From Late Australopithecine to Early Homo:

Changing Trends

1. Increase in Brain Size

2. Reduction in the size of face

3. Reduction in chewing complex.

Q3) Fossil evidence and distribution of Neanderthals.

Ans) Lime workers discovered the first Neanderthal human fossil in the Feld Hofer cave of the Neander Valley, near Düsseldorf, Germany, in 1856. The fossil remains discovered included a robust cranial vault, massive brow ridge, facial skeleton, and several limb bones. With large articular surfaces on the ends of the limb bones, the structure was sturdy. Extinct mammals' remains and primitive stone tools have been found to be comparable in size to human fossils. After a preliminary examination, the fossils were thought to be the oldest known human beings who lived in Europe.

More fossils that looked like Neanderthals were discovered in the Feld Hofer and Spy caves in the late nineteenth and early twentieth centuries. Neanderthals are divided into two groups: conservatives and progressives. These two can be distinguished based on morphology. Several fossils of these two types of Neanderthal man have been found in different parts of the world. La Chapelle-aux-Saints, La Moustier, La Quina, and La Ferrassie, for example, are conservative Neanderthals, whereas Krapina, Ehringsdorf, and Steinheim are active Progressives.

Section – III

Answer the following questions in the about 250 words 10x3=30

Q1) Define craniometry. Discuss any two norma positions.

Ans) Craniometry is the measurement of the cranium (head). It is a subset of cephalometry, which is a subset of anthropometry, or body measurement.

The skull is the uppermost part of our skeleton. The mandible is a single loose bone in the facial skeleton. A cranium is a skull skeleton sans mandible. The calvarium is the brain box, and the calotte is the top of the skull, also known as the skull cap. The human cranium is studied morphologically from five positions: verticalis, frontalis, lateralis, occipitalis, and basalis. These normas studies help understand the cranium's shape from various angles. Second, such research shows how different cranial bones contribute to a particular feature's structure. Finally, surface characteristics of a specific cranium can be studied. To sum up, norma studies are vital in comparative craniology and in understanding evolutionary changes in the cranium.

Two Norma Positions are listed below:

1) The norma frontalis explains the elevation of the forehead, supraorbital ridges, orbits, nasal aperture, maxillae, zygomatic, and many other surface features of that part. The upper, which is mostly formed by the frontal bone, and the lower, which is very irregular and contains two orbits and the anterior bony aperture of the nose, have a more or less oval shape, wider above than below, and can be divided into two parts: the upper, which is mostly formed by the frontal bone, and the lower, which is very irregular and contains two orbits and the anterior bony aperture of the nose. The mandible is responsible for the majority of the facial part's lateral margins and lower border.

2) A norma lateralis study can determine the height of the skull, the nature of the forehead slope, the projection of the occipital region, the nature of the temporal line, the depth of the temporal fossa, the protrusion of the zygomatic bone, the elevation of the nasal bones, the nature of the mastoid process, and the amount of facial prognathism.

Q2) Describe fibula.

Ans) The fibula is a long bone in the lower extremity that is located on the lateral side of the tibia. It is used for walking and running. Because it is much smaller and thinner than the tibia, the fibula is often misunderstood. In the knee joint, it is located just behind the tibial head. It then runs down the lateral aspect of the leg until it reaches the ankle joint, where it terminates. The interosseous border is formed by a ridge on the medial surface of the fibula, which connects the fibula to the tibia via the interosseous membrane. This connection forms a syndesmotic joint, which means that it has very little mobility compared to other joints.

The fibula's structure can be divided into four parts: the head, the neck, the shaft, and the distal end of the fibula (see illustration). During the process of the skull becoming narrower distally, the fibular neck is formed. The fibular shaft is located distal to the neck and has three surfaces: the lateral, medial, and posterior surfaces of the fibular shaft. The attachments of the muscles to the fibular shaft determine the shape of the fibular shaft. Initially, it has a triangular shape, but as it moves away from the centre, it becomes more irregularly shaped. It is the distal end of the fibula that forms the lateral malleolus, which articulates with the lateral talus and contributes to the formation of the lateral ankle joint. It is formed by the posterior and lateral tibias, which are referred to as the posterior and medial malleoli, respectively.

Q3) Define osteometry. Describe the procedure to measure the physiological length of femur.

Ans) Anthropometry's branch of osteometry is concerned with taking measurements of bones other than those of the skull in the human skeleton. Osteometry is the foundation of comparative anatomy in terms of physical dimensions of the bones, which is important in biological anthropology because it focuses on human variation and evolutionary development. These measurements also aid in the understanding of sexual dimorphism and asymmetry on both sides (in case of paired bones). Some measurements are taken directly on the bones, while others are taken using scientific drawings of the bones.

Procedure to measure the physiological length of femur

Femur: The femur is the longest bone in the human body. The femur extends from the hip joint to the knee joint. It consists of upper and lower ends and a shaft. The upper end has a large, rounded head, a neck and a greater and a lesser  trochanter. The head of the femur projects medially into the acetabulum of the hip bone. The lower end of the femur consists of the two condyles – the lateral and medial condyles, which articulate with the head of the tibia (of the lower leg) and then patella (kneecap).

The shaft of the femur at the anterior side is nearly cylindrical and convex while it is thinnest at the middle and widens more near the lower end when compared to above.

Physiological Length: It measures the projective distance between the highest point of the head and the tangent to the lower surface of the two condyles.

Instrument Used: Osteometric Board.

Method: The bone is placed in the Osteometric board with the condyles touching the transverse vertical wall and the anterior surface upward. The bone will naturally lie obliquely. Then the movable vertical piece is made to touch the head. Value of the measurement is recorded directly from the graph paper.

Least Girth of Shaft: It measures the circumference of the shaft at its thinnest part. It usually lies below the middle of the bone i.e., in-between the middle and distal epiphysis.