Geologic Timeline Individual Reflection

3 of the major events of Earth's history include the Cambrian Explosion, the Permian Extinction, and the Cretaceous extinction. The Cambrian Explosion was highly significant and is often referred to as the most significant evolutionary event on Earth due to the rapid appearance of many animals with mineralized, fossilized remains. The evolution of skeletal structures that leave behind fossils is essential to the study of fossils. The Permian Extinction is highly significant because it was the largest extinction event in all of Earth's history, with 96% of all marine species becoming extinct. The Cretaceous extinction is also very significant because without the extinction of the dinosaurs, mammals would have never radiated and humans would have never came to be.

Earth's history relative to human history is much more grand than I had first expected. On the timeline extending from one end of the classroom to the other, our little sliver of time is absolutely negligible.

However, despite this short period of time that humans have been on this planet, they have had massive effects. Ice caps are melting, many places are flooding, nature all around us is being destroyed and used instead for industry. At this rate, I feel that the human population will not be able to sustain itself for much longer until we choke ourselves to death.

One question I wonder about is why it took so long for humans to evolve, to come to be. So much of Earth's history involved only single-celled organisms, which seems a bit counterintuitive as multicellular organisms seem more likely to dominate.

Below I have attached a couple photos of the timeline: