Earth and Life Science
Earth is filled with life. It sustains an enormous number of organisms, most of which are not yet discovered, explored, catalogued or studied by science. This lesson, will discuss the evidences of evolution and the causes of this multitude of life to emerge and diversify.
Evolution is the change in heritable traits of a biological population over successive generations. It is responsible for the diverse forms of life on Earth. Although life is so diverse, patterns of similarities exist to demonstrate that life emerged from one common ancestor. Similarities in anatomical structures support the notion of evolution and common lineage among organisms. Likewise, pattern of differences among and between life forms manifests adaptation as evolutionary mechanism for survival of the population.
Environmental factors are the drivers of evolutionary process. In response to these environmental factors, organisms develop adaptive strategies by physical, physiological, and behavioral mechanisms. The perpetuation of life depends on the ability of the species to adapt to the changing environment
Scientists believed that the first life-forms appeared on Earth about 3.5 billion years ago. Since then, the Earth and its organisms have changed and evolved over a period of time. Modern – day species are believed to have evolved from older species, and that all species descended from a common ancestor. Evolution is about changes in the genetic makeup of the organisms. The genetic makeup of the organisms is encoded in their DNA. The encoded information in the cells determines the characteristics of that organism.
The lesson focuses on the evidences that support evolution. These evidences include homology, DNA/protein sequences, plate tectonics, fossil records, embryology and artificial selection/agriculture.
Homology
One of the strongest proofs that life on earth underwent gradual evolution is the presence of homologous structures among different groups of animals called homology or similarities in the structure between parts of different organisms. Homology is indicative of shared ancestry which is the first material evidence of evolution.