The given below are the events that are involved in the evolution of life which includes climate variation, geographical events, major extinction, and changes in the position of the continents.
4.6 billion years before, the earth is formed after bombardment with comets.
3.8 billion years before, the formation of replicating molecules occurred.
3.5 billion years before, the unicellular organisms formed and the photosynthesis started to occur.
555 million years before, many marine living animals started to dwell.
500 million years before, the vertebrate started to evolve from the invertebrates.
450 million years before, the marine lives started to move to lands which are arthropods.
420 million years before, the earth landscape started to change.
360 million years before, the forest started to appear and four limbed animals started to dwell.
248 million years before, the earth's largest extinction took place where 90% of marine lives and 70% of lives living in land has went extinct.
225 million years before, the mammals and dinosaurs started to dwell.
65 million years before, the dinosaurs went extinct; and bird and mammals survived.
4 million years before, many mammals went extinct and ice age began.
130,000 years before, cave man started to live and the initiation of modern human took place.
<em>Each trait of an organism is determined by discrete units called genes and individuals carry two alleles for each gene. (Mendel didn't actually discover genes though). Each gamete of an individual carries only one allele of each gene (this is Mendel's Law of Segregation).</em>
