Human Evolution

Similarities and Differences between Modern Humans and Chimpanzees Both species have broad rib cage from side to side and shallow from front to back. In other words their rib cage extends beyond the vertebral column.

Like chimpanzees, humans are also omnivorous. Humans are sexually dimorphic just like great apes. Both species have the scapulae on the back, and the shoulder joints oriented to the sides. In humans the foramen magnum opens at the base of the skull whereas in chimpanzees it opens towards the rear of the skull. Secondly, the cranial capacity of humans is 1000cc while for chimpanzees it is 400cc. In a chimpanzee; the tibia is thin and angled while in a human the tibia is thick and straight.

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Culture and Evolutionary Process The anthropologists agree that culture presents a lot to the evolutionary process. This argument is based on the fact that culture affects all aspects of life, ranging from eating habits to behavioral activities. Culture significantly affects the gene frequencies of a population. For instance, the Northern Europeans and some African societies who have a long history of keeping cattle for milk have been known for adult lactose genotype. Other societies have the normal mammalian genotype.

Over the past decade, civilization has accelerated genetic change in humans. Cultural differences in the societies have led to individuals adopting different survival mechanisms which in turn affect their evolution process. Differences between Australopithecus and Homo Erectus Australopithecus has brain size of 415cc while Homo erectus has brain size of 780-1225 cc . Australopithecus were herbivores eating hard foods like seeds, nuts and roots. Homo erectus is known for stone tools. The stone tools they had were used for the purpose of hunting and scavenging.

This clearly suggests that they were carnivorous. They also regularly used fires and made tools such as hand axes. This further suggests that they had communication skills. While Australopithecus were forest dwellers, Homo erectus lived in home-like settings. Complete the following sentences: If a given species tends to have a larger brain-body ratio than another, it has a larger value of the cranial factor.

Humans, gorillas and_ chimpanzees (apes) are closely related; _research_ on the examinations of the hominids suggest that we had a common ancestor a little more than 8 to 6_ million years ago. The first hominid appeared around 2.3_ million years ago, with the development of stone tools_. We call him The Homo Erectus. The development of stone tools, which was very important for the further development of the brain, followed about 4 million years ago. All the hominids existing in the past can be grouped into four main “genera”: 1.

Pan, 2. orilla, 3. Homo_ 4. Pongo Apparently, the first hominids to use tools were the The Homo Erectus Brains enlarged rapidly when the hominids started to eat cooked food. Homo erectus made elaborate stone_ tools, used fire and killed large animals.

Their fossils and tools are found throughout three continents, but Homo sapiens_ are found only in Africa. The first burials appeared with the Neanderthals, and the first manifestation of abstract thought, represented by the appearance of the first paintings on the cavern walls, also came with the Neanderthals. The first hominid able to speak as the modern human was Homo sapiens . The Lluc is a hominid only found in Spain (and possibly in Italy). He is an immediate ancestor of chimpanzees. Miguelon is a famous _nickname of the complete skull of Homo heidelbergensis_ found in Atapuerca.

Today we know that the modern human is probably a hybrid between Neanderthal and Denisova, although only a 1-4% of our genes are from the Denisovans. TOPIC 8: Histology of Nervous Cells – What are the main cell components? List them and mention their main function. A cell has four main components, namely membrane, cytoskeleton, genetic materials and organelles. Membrane protects and separates a cell from its adjacent environment. Cytoskeleton helps to maintain and organize the shape of a cell; it helps during endocytosis and in the process of cytokinesis. Cytoskeleton helps the cell parts to move during motility and growth.

Organelles are also anchored in place by the cytoskeleton. Genetic materials consist of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA). DNA is used for information storage in long-term and RNA is used during information transportation. Organelles are a group of little organs which are specialized in or adapted to performing additional vital functions.List of 10 Important Characteristics of Glial Cells.

Glial cells have the following characteristics: They have astrocytes for mechanical and metabolic support. They also help in the repair of neurons. Microglia constitute a section of the brain and act as immune defense through a process known as phagocytosis. Oligodendroglia are found in central nervous system as myelinated axons. Schwann cells are myelin found in the peripheral nervous system. Satellite cells act as a brain-barrier inside the CNS,they repair and support neurons.

Ependymal cells make up a lining of the epithelium oof CNS. They also produce the cerebrospinal fluid. Myelin sheath, found in an axon, is formed by the Schwann cell. Astrocytes produce scar tissue. Ionic and chemical environment is regulated by the Astrocytes.

Synapse encapsulation is also done by Astrocytes. This type of neuron is known as multipolar neuron. It has an axon and several dendrite processes. It has cell bodies which are found in the spinal cord and also in the brain. Some of these neurons function as interneurons because they transmit a message from a certain part of spinal cord or the brain to another. Dendrites, cell body and the axon of this neuron are located in the central nervous system.

Some of the multipolar neurons function like the motor neurons. They carry an impulse from the spinal cord or the brain to the effectors or organs. The larger part is the dendrites. Feelings and sensory effects are received from this point. The feelings then travel through the axon towards the terminals to convey the effect. – Complete the following sentencesMost neurons possess three major parts: the dendrites (input); the Axon terminals (output) and the Soma or Cell body (integration zone, containing the nucleus).

Neurons can be classified on the basis of function, structure and axon length. Unipolarneuron can have a single dendrite and a single axon. They are found, for example, in the skin and joints_. Multipolar neurons have multiple dendrites and are the motor_ class of neurons.Bipolar neurons have a single branch extending in two directions and are, for example, a part of the system mediating _ sensory neurons.

Neurons whose axons innervate muscles or glands are called motor neurons. Neurons that respond to environmental stimuli are calledsensoryneurons. Neurons that communicate strictly with other neurons are called interneurons. Unlike neurons, new glial cells have been found to be produced in the nervous system. One type of glial cell, the astrocytes is found in close proximity to the blood vessels of the brain and may serve as a conduct between the nervous system and neurons. Microglias are very small and they serve to remove debris from the sites of the brain’s immune system.

– What type of nervous cell are you seeing? Show their different parts and components and explain their main function.