How did life evolve on Earth and how has life survived for billions of years on our planet? These are some of the most fundamental questions in science, yet we still only have a very limited understanding of how we got here. Beyond ourselves, understanding how our planet has remained habitable to life over Earth’s long history is a crucial part in the search for life elsewhere.
It’s clear that the evolution of life on Earth is intimately tied to conditions in Earth’s surface environments; our continents, oceans, atmosphere and climate. Over long time scales, the evolution, radiation and extinction of life appears to be linked to broad changes in our climate, and the composition of our oceans and atmosphere. However, deciphering environmental conditions from billions of years ago is difficult, as the only record of this is locked up in ancient rocks.
Ashleigh Hood is a field-based geologist who incorporates multidisciplinary methods to broadly understand the long-term evolution of the Earth’s environments, climates and ecosystems using sedimentary rocks. Dr. Hood is interested in the impact of large changes in the Earth system–including climate change and the oxygenation of the atmosphere-ocean system–in driving environmental evolution and the radiation and extinction of life.
This research uses ancient reef systems and sediments preserved in the geological record as windows into ancient ecosystems. Dr. Hood’s group’s research on Precambrian reefs reveals ancient oceans full of metals; an anoxic world transitioning from microbial to animal ecosystems. This collaborative research shows how the oceans gradually gained oxygen and supported more complex life over billions of years, and how trees became the true engineers of our modern environment.
At the moment, Dr. Hood is mapping strata in the Flinders Ranges which were formed at the dawn of animal life. These rocks represent Earth’s most extreme ice age, a frozen planet known as “Snowball Earth”. Her work aims to uncover these ancient frozen ocean habitats, investigate how complex life might have survived, and understand how Earth’s rock cycle regulates recovery from severe climate change.