Assignment Code: BANC-104/ASST/TMA/2022-23

Course Code: BANC-104

Assignment Name: Human Origin and Evolution

Year: 2022-2023

Verification Status: Verified by Professor

There are three Sections in the Assignment. Answer all the questions in all the three sections.

Assignment –I

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

a. Discuss fossils and their preservation.

Ans) Lamarck defined the term "fossil" (Latin for "fossil" is "to dig up") as "remains of plants and animals which have existed on the earth in prehistoric times and are found preserved within sedimentary rocks or superficial deposits of the earth," noting that this term includes not only the majority of petrified structures of organisms but also anything that was directly related to or produced by these organisms. The shape, size, appearance, and activities of the organism are inferred from fossils.

We have learned a lot about the evolution of life via the study of fossils. There are numerous ways in which fossils can form and provide evidence of ancient creatures. The earliest fossils discovered so far extend back more than 3 billion years and are known as microfossils because they are the tiny remains of microbes. The most significant link between our past and present is fossils; in fact, we can only trace our evolutionary history in relation to fossils. There are two types of fossils: the actual remains of animals, which are typically fragmentary and sometimes even include three-dimensional casts of their external bodies, and the remnants of an animal's activities, such as trackways. Trace fossils are the remains of an animal's activities. Physical anthropology, comparative anatomy, and the theory of evolution are used to evaluate fossils.

Taphonomy is the study of how fossils form and are preserved. There are numerous varieties of preservation, as well as numerous classification methods. To be able to predict what fossils might look like, it is crucial to be able to comprehend the various ways that they can form. It's important to keep in mind that a single fossil might fit into more than one of these groups. When it comes to geologically young fossils, where the surrounding sediments have not yet undergone lithification, original preservation, or preservation of the original chemical composition, is often restricted. Soft tissue preservation and original hard part preservation are two examples of this sort of preservation. Organs, skin, and hair can only be kept through soft tissue preservation under very specific circumstances.

These types of preservation techniques include mummification through freezing, chemical reaction, oxygen deprivation, extremely arid conditions, or dehydration and preservation in oily plant debris (as in the Geisel Tal Formation in Germany) or tar. Other methods of preservation include encasing objects in amber (as in the Rancho La Brea tar pits in Los Angeles). This only happens for geologically recent specimens, which are those that are no older than a few million or tens of millions of years. After that, only chemical traces of organic stuff will be left.

Technically speaking, the most famous instances of this kind of preservation are not fossils. A well-known illustration of soft tissue preservation is Otzi, the Iceman. The discovery of ice period mammals, including woolly mammoths, horses, caribou, and other species, in the tundra of Siberia, Alaska, and the Canadian Yukon is also included in this category. These discoveries provide the well-known examples of soft tissue preservation. They divide broadly into two categories, those that are 50,000–25,000 years old and those that are 15,000–10,000 years old and are occasionally confused for contemporary animals.

b. Discuss in brief Miocene hominoids.

Ans) Primitive ape evolution took place throughout the Miocene epoch, which lasted for around 18 million years (23.0-5.3 million years ago). The cycles of primate habitat size expansion and decline in the Mediterranean and Eurasia are one of this era's key characteristics. Between Africa, Europe, and Eurasia, land bridges arose and eventually vanished. The environment during the early Miocene was quite comparable to modern conditions, but a little warmer. But as glaciers started to emerge in Antarctica approximately 15 million years ago, the temperature started to get much colder and dryer. Tropical forests changed into a patchwork of woodland savannah, trees, and grass as a result. This cooling resulted in the spread of savannah-woodland habitats across Africa and Eurasia. Old World monkeys and apes split apart around this time, and the apes went through an adaptive radiation that resulted in 80–100 different species.

The final strategy, the topic of this analysis, involved incorporating Miocene apes into hypotheses of both modern ape and human origins. Miocene ape fossils and contemporary genera frequently support direct ancestor-descendant connections. For instance, it was believed that the early Miocene hominoid Proconsul was a relative of gorillas and chimpanzees (35, 98, 116, 128). The most notable example is Ramapithecus, which is now universally acknowledged to include individuals from Kenyapithecus from eastern Africa, Griphopithecus from Asia Minor, and Sivapithecus from southern Asia (12, 37, 63, 80, 81, 97, 114, 115, 117).

Results from comparative immunology (i.e., the molecular clock) disputed these hypothesised associations, showing that humans separated from gorillas and chimpanzees around ma, whereas the last common ancestor of all surviving hominoids emerged between 15 and 12 million years ago (ma) (110, 111). In addition, fossil-based evolutionary hypotheses frequently relied more on conjecture than accurate descriptions of the anatomy, food, locomotion, and social interactions of Miocene apes. Although there was few fossils evidence, it was claimed that the Ramapithecus chimaera shared many characteristics with humans (6, 14, 116, 117, 125).

The earliest ramapithecine (Kenyapithecus) was thought to have a focus on molar grinding similar to austra lopithecines, which was adapted to the consumption of hard objects. This is thought to be the cause of the alleged reduction in the size of the front teeth, especially the upper canines and lower incisors, facial abbreviation, and the appearance of thick-enameled molars (6, 14, 62, 117, 125).

Additionally, it was hypothesised that the shift in African apes' and humans' diets from soft fruit and leaves to hard nuts and grass seeds and from arboreal to terrestrial substrates was related to the expansion of increasingly wide-open country environments since the early Miocene (13). After it was shown that ramapithecines (Sivapithecus) lacked the presumed hominid-like skull morphology (99), elaborate hypotheses about the origins of humans were quickly abandoned. Numerous reconstructions of the habitats where Miocene ape fossils were found have been done in addition to research focusing on family relationships (10, 33, 60, 113, 134). It has been incorrectly assumed that such extensive environmental reconstructions are equivalent to the paleoecology of Miocene primates like Kenyapithecus, Sivapithecus, and Gigantopithecus.

c. Describe the craniofacial features of Neanderthals.

Ans) The Neanderthals showed indications of significant manipulation using the anterior dentition in addition to the archaic human upper limbs. Human populations maintained pronounced total facial prognathism and large anterior teeth during the broad transition from Middle Pleistocene archaic humans to the Neanderthals across Europe and western Asia, while their posterior teeth shrank, and their masticatory muscle attachments (such as zygomatic bones and anterior mandibular ramus margins) migrated posteriorly. This led to the development of the distinctive mid-facial prognathism of the Neanderthals, which featured a receding zygomatic region and a projecting midline that included the teeth, nasal opening, and mid- supraorbital torus.

Large retromolar spaces, anterior zygomatic roots above M2-M3, mental foramina below P4-MI, the absence of canine fossae and inferolateral maxillary notches, pneumatization of the maxillae and middle half of the supraorbital torus, flattened zygomatic bones, and largely horizontal nasal bones are some of the facial characteristics associated with this condition. Given that Neanderthal facial morphology indicates that they were routinely loading their anterior teeth, it appears that the Middle Pleistocene level of total facial prognathism was retained to ease the use of the anterior teeth as a vise.

These big anterior teeth, which included shovel-shaped incisors, were also designed for heavy use since they wore down gradually and could withstand strong amounts of bite power, especially force directed labially. The accelerated rate of wear compared to the associated posterior teeth, the pronounced labial rounding seen on older Neanderthal individuals' incisors, and the high frequency of labiolingually oriented striae and marginal microchipping on their anterior teeth are all indications that they were used in this way.

Although it is unclear what purpose the peculiar Neanderthal superior nuchal line morphology—which includes the absence of an external occipital protuberance and the existence of a suprainiac fossa—serves, it may be connected to the nuchal musculature's hypertrophy. The lower cervical vertebrae of Neanderthals consistently have robust, straight, and non-bifurcated spines, which is suggestive of an increase of nuchal muscles, perhaps for cranial stabilisation during anterior tooth use. Modern humans spread throughout the Neanderthal range, which resulted in the disappearance of the Neanderthal occipital-mastoid morphological complex, a decrease in the size of cervical vertebral spines, a decrease in absolute and relative anterior tooth numbers, a loss of the greater rate of wear on the anterior dentition, and a loss of mid-facial prognathism (Trinkaus, 1986).

It appears that successful adaptation was no longer dependent on the employment of the teeth for Para mastication. Given these factors, it is intriguing that total face prognathism decreased across Africa and eastern Asia during the later Middle and early Upper Pleistocene as facial robusticity diminished. It's clear that there wasn't enough selection pressure in those areas to keep a long face. Additionally, neither Africa nor eastern Asia ever witnessed the emergence of the characteristic Neanderthal complex of occipital-mastoid traits. Broken Hill 1, the only specimen that is sufficiently complete, displays prominent anterior dental wear and rounding that is similar to that of older Neanderthals. However, because of its early-period location, it can only suggest that the Middle Pleistocene African pattern of the ancestors was similar to that of the Neanderthals.

Assignment –II

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

a. Write short notes on the following

i. Potassium/Argon Dating Method

Ans) One of the most popular radiometric dating techniques for dating rocks, particularly igneous rocks that have formed from molten lava, is potassium/argon. It is a crucial tool for paleoanthropological, archaeological, and geological research. When lava flows or volcanic tuffs develop layers on top of strata containing signs of human activity, archaeologists and paleoanthropologists can benefit greatly from this technique.

This technique is based on how minerals and rocks convert radioactive potassium-40 (40K) to argon-40 (40Ar). Knowing the decay rate of K-40 and comparing the ratio of K-40 to Ar-40 in a sample of volcanic rock can be used to estimate the age of the rock. One of the most prevalent elements in the crust of the Earth is potassium (39K). There are three potassium isotopes that are naturally occurring: 39K (93.2581 percent), 40K (0.0117 percent), and 41K. (6.7302 percent ). From these isotopes, 40K decomposes into two stable "daughter elements," stable 40 Calcium and 40Ar, in a roughly 89:11 ratio.

Simply put, 11 40Ar atoms result from the disintegration of 100 40K atoms. Noble gases include argon. The 40Ar that is created as 40K decays is trapped in the crystals of the volcanic rocks' minerals. Whatever argon is created when the magma melts boil out into the atmosphere. The radiometric clock of rock starts when the argon created by the disintegration of 40K accumulates inside the rock after the cooling and solidification of the lava into rock. The amount of 40Ar atoms in the rock increases with time.

ii. Bipedalism

Ans) Humans are the only obligate bipedal species among all existing apes. Our upright bipedal stance resulted from the evolution of a knuckle-walking ancestor. Even though some primates can stand on two legs, they only do so briefly, as when they are gazing through thick grass or holding something in their hands. Although chimpanzees and gorillas may stay on two legs for far longer lengths of time, when they are on the ground, they often adopt a quadrupedal posture and knuckle walk. Only humans represent true bipedalism. These traits have separately evolved at various rates throughout the last several million years of evolution.

Evidence for Bipedalism

Our own technology, language, culture, or distance from our nearest relatives are not the main differences between us. It is because, according to palaeontologist Richard E. Leakey, "we stand straight, using our bottom limbs for support and mobility and our upper limbs free from those functions. Evolution of Humans in the Past Paleoanthropologists place the evolution of bipedalism five to six million years ago as the dividing line between apes and hominids. However, it took much longer to develop into a fully functional biped, and Homo erectus, who lived 1.8 million years ago, was the last.

Anatomical Changes

Have you ever paid attention to the way your limbs move as you walk? When the opposite leg swings, we balance on one leg. Only approximately 25% of the time, and this percentage gets increasingly lower as locomotion speed increases, are both feet on the ground at once. Thus, several dramatic structural and functional changes were required, particularly in the limbs and pelvis, in order to maintain a stable centre of balance during upright walking.

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

i. Cultural behaviour of Archaic Homo sapiens

Ans) Due to the climatic variations we described earlier in this section, the Middle Pleistocene is not a favourable time for the preservation of fossils. Since there are few observable cultural artefacts connected to Archaic H. sapiens, it is challenging to recreate their behaviour. Additionally, due to the relatively big brain capacity of ancient humans, we tend to judge them similarly to modern humans in terms of behaviour. However, the scant cultural artefacts discovered during excavation at numerous sites afforded us a peek of their tool technique and behaviour.

Stone Tools

The Middle Palaeolithic stone tool industry is known for its prepared core technique, in which the original core is altered by repeated hits with the purpose of removing flakes until the flake of the required size and form is obtained. The primary tool that is so produced is known as a Mousterian point, and the method is referred to as the Levallois technique. The Middle Palaeolithic industry is rife with tools made by soft hammering soft stone, antler, and bone to remove flakes in addition to prepared cores. The Lower Palaeolithic Oldtown and Acheulean industries are also still active today.

Although there hasn't been any concrete proof that Archaic Homo sapiens engaged in big game hunting or used bone or wooden tools, artefacts like wooden spears and flake tools, along with the butchered remains of ten horses from Schoeningen, Germany, may suggest that big game hunting may have been done by Middle Pleistocene hominins. Similar discoveries were made in Boxgrove, England, where hand axes and largely animal bones were discovered during excavation. This evidence demonstrates that early Homo sapiens were proficient tool users and manufacturers who were also able to kill enormous wildlife. This reveals inadvertently how cooperative they were, which was essential for big game hunting, one of their primary livelihood methods.

ii. Tool usage by the Australopithecus

Ans) The potential connection between Australopithecus garhi and the butchered remains of animals in Ethiopia approximately 2.5 million years ago is the first indication of tool use in the species Australopithecus. Pebble tools, combined with animal bones that were cut and cracked apart using stone tools, are among of the oldest stone tool fossils that have been found with Australopithecus garhi. So, it's probable that this species was among the first to use stone tools and begin eating giant animals' meat and bone marrow. Stone tools have been discovered at numerous locations in eastern and southern Africa alongside the bones of strong Australopithecines, sometimes even in the same beds.

We can infer from hand morphology that the strong Australopithecines may have been able to make tools. Earlier species of Australopithecus, such Au. Afarensis, lacked this morphology, but the robusts have thumb architecture that is similar to that of tool-making hominins like us and other members of the genus Homo. Although it doesn't tell us whether they did, this could suggest that the robusts were able to create stone tools.

The Australopithecines were at least as clever as modern great apes if the ability to produce tools demands complex cognitive abilities. But the earliest evidence of the use of stone tools doesn't appear until around 2.5 million years ago, well into the australopithecine radiation. Therefore, one of the main causes for the genus' emergence could not have been the expanded access to resources that these technologies offer. The main gain early hominins had over their quadrupedal ancestors appears to be the advantages of bipedalism as a foraging strategy.

iii. Morphological features of Homo erectus.

Ans) Skulls of Homo erectus show severe platycephaly (flat headedness). Due to the longer cranial vault, the flatness is less dramatic in Peking man, and the skeleton has a prominent sagittal keel. The keel was not reached by the temporal muscle. A sizable supraorbital torus, or continuous bar of bone, is present in the frontal region.

However, there is a tendency for this torus to split into two sizable supraorbital ridges in the Peking man. Javan people have a low frontal region, but Peking people show the beginning of an extension into a true vertical forehead. The huge occipital torus that marks the posterior edge of the skull indicates the limitations of the nuchal musculature, which appears to be required to support the weighty head and large prognathous jaws. The walls of the cranium bones are typically thick. The foramen magnum resembles modern man and is positioned in the centre, indicating that the creature was a typically erect, bipedal Hominid.

The Homo erectus has a broad, big face, a wide nasal opening, and a somewhat depressed nasal bridge. In comparison to the overall facial measurements, zygomatic bones are bigger. A diastema can occasionally be seen in the upper jaw in front of a canine that is slightly protruding and pointed in Java specimens. The canines exhibit Homo erectus' carnivorous behaviour. The molar teeth are more developed in morphology than those of Australopithecus africanus, but they also include taurodontism and enamel that is wrinkled or creneled (large pulp cavities and fused roots in the molar teeth). Huge and parabolic describes the palate.

Assignment –III

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

a. Discuss Norma basalis

Ans) The position of the foramen magnum, the dental arcade, the teeth, the palate, the nuchal surface of the occipital, as well as a variety of foramina and processes, are all described in the Norma basalis study. The incisor teeth, the superior nuchal lines of the occipital bone, the remaining teeth, the zygomatic arches and their posterior roots, and the mastoid processes all encircle the exterior of the base of the skull, except the mandible.

Although the surface of this Norma is highly uneven, it may be separated into anterior, middle, and posterior sections for the sake of description. The hard palate shapes the front section, which is lower than the remainder. A transverse line drawn along the anterior margin of the foramen magnum divides the remaining surface into a middle and a posterior section arbitrarily.

The palate is arched both anteriorly and posteriorly and transversally. The palatine vault is deepest and widest where the molar teeth are located. (ii) Anterior to the median plane is a deep fossa known as the incisive fossa. Four foramina—two medial, medial incisive foramina, and two lateral, lateral incisive foramina—are located within the fossa. (iii) The alveolar arch has sixteen alveoli, or sockets, for the tooth roots. Depending on the number of teeth they hold, these sockets can be solitary or separated by septa, and they range in size and depth.

Middle section: I The carotid canal, foramen ovale, foramen spinosum, and foramen lacerum are the most significant foramina in this region of the Norma basalis. (ii) The articular fossa (glenoid fossa) is broader and mildly concave laterally, with a deep anteroposterior concavity. (iii) The articular eminence, a transverse rounded elevation, is located anterior to this particular fossa. (iv) The external auditory meatus and articular fossa are separated by the temporal bone's tympanic portion.

b. Define Osteometry in brief Ulna.

Ans)  Osteometry, a subfield of anthropometry, entails measuring human skeleton bones other than the ones in the skull. Osteometry serves as the foundation for comparative anatomy with regard to the actual size of the bones, which is important because biological anthropology primarily aims to examine human variation and evolutionary development. These measurements also aid in the understanding of bilateral asymmetry and sexual dimorphism (in case of paired bones). While certain measures can be made directly on the bones, others must be made using accurate drawings of the bones. The human body has five different types of bones. They include sesamoid bones, flat bones, angular bones, long bones, short bones, and flat bones.

Ulna

It is thick, sturdy, and appears to have a hook-like upper end. The medial bone of the forearm, the ulna bone, faces anteriorly. Olecranon and coronoid processes are the two processes on the top end. The ulna's knob-like head is located at the lower end, which also articulates inferiorly with a disc of fibrocartilage and laterally with a notch of the radius. The ulna shaft is triangular in cross-section and gradually gets narrower from the top to the lower end.

1. Physiological Length: It calculates the straight distance between the deepest point on the distal articular surface and the deepest point on the upper surface of the coronoid process.

2. Instrument Used: Using a pelvimeter or spreading calliper, the bone is positioned with its volar surface facing upward. Then, the right arm's tip is placed on the proximal point and the left arm's tip is placed on the distal point of the calliper. The scale provides the measurement's value.

3. Girth of Ulna: It measures the least circumference, generally found at the distal end of the bone.

4. Instrument Used: Tape.

5. Caliber Index: Girth of Ulna/Physiological Length X 100

c. Discuss in brief different measurements on humerus and femur.

Ans) Together with tendons and ligaments, bone forms the bony framework. Bone is a type of connective tissue. Animal skeleton is the term used to describe this framework. Osteoblasts, a type of living cell, and a matrix rich in fibre make up the majority of the bones. Movement, support, protection, mineral storage, and blood cell production are among the primary roles of bone. The bones of the limbs, shoulders, and hips are considered to be part of the appendicular skeleton. The head, vertebral columns, and rib cage are considered to be part of the axial skeleton. The 206 bones of an adult human's skeletal system, along with ligaments that resemble straps and joints, hold the bones together. The humerus and femur are two of these bones that are part of the appendicular skeleton.

Femur

The longest and largest bone in the body is the femur. Due to its location in the upper leg, it is also known as the thighbone. Several tonnes per square inch of force may be tolerated by this bone because of its tremendous strength. It has been discovered that to break this bone, 15,000 to 19,000 pounds per square inch of pressure must be applied to the top of the bone. The head of this bone, which resembles a ball and fits nicely into the acetabulum of the ilium, creates a ball-and-socket joint. The tibia is connected to the other end. For the majority of its length, its axis of movement is well outside of its material.

Humerus

The humerus is the longest and largest bone in the upper extremity and the second largest bone in the body. The bone contains a number of processes at the distal end and a broad, smooth head at the proximal end. It is also relatively thick. The distal end attaches to the ulna, while the proximal end slides into an exposed socket in the scapula. The humerus' head is smooth and rounded to enable strong attachment of the muscles, ligaments, and scapula.