Identify and describe four crucial events in evolutionary history without which our current existence would have been highly unlikely. Explain your reasoning clearly.

FOUR CRUCIAL EVENTS IN EVOLUTIONARY HISTORY
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Science in a unique way describes the world based on series of events and activities that can be retrieved from confirmable data. Evolution history is an interesting piece that explains how life came into being since three and a half billion years ago. There are four pivotal occurrences which define evolution, they include:
The Cambrian Evolutionary Radiation
According to Collins (1996), the origin of Cambrian evolution which started with Walcott’s uncovering of Burgess Shale. In it, there is a distinguished well-kept Cambrian fossil worldwide (Collins, 1996). These discoveries use the knowledge of the next appearance of fossils to define the biogeographical that defines interactable correlation and stability difficulties. It is characterised with chronic biofacies control and regionalism of taxa which encompasses a stable lower chronostratigraphy.
The End-Permian Mass Extinction Event.
It was manifested through the abolishment of 95% of the marine lives and 70% of the earth-bound species, Lepore (2012) states that almost half of the taxa families available by then disappeared this was as a result of temperature crises, alteration of the carbon circle and larger population of methane explosion producing microbes. After most of the animals were all dead, the remaining population constitutes the current community.
Evolution of Limbs from fins and pedestrianisation
It defines how fish evolved to become the earliest land creatures and the first manipulation of these creature’s DNAs for their survival on land.

After research, it was evident that the fish showed some characteristic anatomical changes, Territorialized fish walked efficiently with their fins next to their bodies and with their heads raised higher. Skeletal changed to become stronger across their chest; due to exposure to the stressful environment.
The Evolution of Hominins and Conscientiousness.
This explains adaptations and trends that made humans evolve; their evolution was contributed by environmental changes which added to hominin distinctive traits. The tests were carried out on skulls found at places like Turkana, the original habitats of the hominin. This explains the evolution of human beings to the current lifestyle. Environmental behavior influences the behavior of hominin exhibited through technological invention and cultural rites and behavioral rectification.
References
Lepore, J. (2012). The Mansion of Happiness: A History of Life and Death. Vintage.
Collins, D. (1996). The “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.). Journal of Paleontology, 70(2), 280-293.