Evolution at its best
Is Evolution a Theory or a Fact?
History of the Earth
- 4,600 mya (Million Years Ago) - The earth forms and is impacted by meteorites and comets.
- 3,800 mya - Precursors of DNA form.
- 3,500 mya - Unicellular life evolves (bacteria)
- 555 mya - Multi-cellular marine organism are common. The diverse assortment of life includes bizarre looking animals.
- 500 mya - Fish like vertebrates evolve, and invertebrates.
- 450 mya - Arthropods begin to move onto land. Their descendants evolve into scorpions, spiders, mites and millipedes. (Insects)
- 420 mya - Land plants began to evolve, changing earths landscape from dirt to green vegetation.
- 360 mya - Four limed vertebrates move onto the land as seeding plants and large forest are beginning to appear. Also the oceans are now supporting large reefs.
- 250 mya - Pangaea Forms
- 248 mya - 90% of all the marine life and 70% of the terrestrial life (Land) go extinct.
- 225 mya - Dinosaurs and mammals evolve. Pangaea has already begun to break apart.
- 130 mya - Flowers evolve
- 65 mya - Dinosaurs go extinct
- 4 mya - Early hominid ("Lucy")
- 130 Thousand Years Ago - Modern humans evolve.
As you can see that from 4,600 mya to 130,000 years ago, we humans have evolved into who we are today.
Fossil Evidence of Evolution
Homologous and Vestigial Structures
Evolutionary theory has predicted that organisms that are closely related will share some similarities that are linked to their ancestry. Similar characteristics due to them being related is called homologous. Homologous can be revealed by comparing the anatomies of different living things, by looking at the cellular similarities and differences, studying embryological development, and also by studying vestigial structures within and individual organism. A vestigial structure is a feature that a organism has inherited from its ancestry and is now less functional than in the past years. Typically, vestigial structures are formed when a lineage experiences a different types of environmental factors than their ancestors experienced.