How Early Life Evolved on Earth?

When we see the vast majority of species of plants and animals, it makes us wonder, where they have sprung from. The truth is, this is, a much complex process involving constant evolution of microorganisms over a great period of time. The earliest biotic substances were graphite and microbial mats. Graphite is a close relative of carbon and microbial mats are sheets of microorganisms such as bacteria and archaea, which are single celled organisms. Photosynthesis developed after this and oxygen became abundant in the atmosphere. Eukaryotes(single celled organisms with organs) developed after this and they too started consuming oxygen from the atmosphere. After this, multicellular organisms evolved with different cell membranes with different activities. Reproduction was asexual among this class of organisms. Sexual reproduction developed after this and formed from the combination of male and female gametes into a zygote-this process is called fertilization. Microrganisms developed new ecosystems and land plants also developed during this period. Vertebrates developed during the Cambrian period with a front and a back. This was the beginning of modern life as we know it now. Ancestors of mammals developed after this. Many grew into extinction. This was followed by archosaurs-the group of dinosuars that dominated the jurassic and cretaceous period. The dinosuars were pushed into extinction and mammals developed fast after this. This is the complete evolution of early life as we know it now.