The dawn of multi-cellularity
Single-celled archaea and bacteria had dominated the globe for billions of years, but Snowball Earth changed everything. In an evolutionary blink of the eye, multi-cellular life appeared in the form of the most basic animals: sponges. As Snowball Earth came to an end, glaciers which had picked up tonnes of rock and churned it into sediment melted, carrying the nutrient-rich sediment into the ocean. The nutrients acted as a fertilizer, causing photosynthetic, oxygen producing bacteria similar to algae to multiply and fill the oceans. They pumped oxygen into the atmosphere, changing the course of evolution forever.
- Eukaryotes – A video mini-lecture explaining how the first single-celled eukaryotic organisms, ancestors of animals, fungi and plants evolved from bacteria.
- Algal blooms – Fertilizers flooding into water systems cause photosynthesizing algae to bloom out of control, just as photosynthesizing cyanobacteria bloomed after Snowball Earth.
- Collagen – This protein, found only in animals, can only be made using oxygen. It allowed cells to stick together for the first time.
- Sponges – These 650 million year old sponge fossils are thought to have been the first multi-cellular animals on Earth.
- The Heron Island Research Centre – Here research scientists are studying the evolution of the earliest sponges.