Evolution of The First Animals on Earth Caused Global Warming


Animal life has evolved some 520-540 million years ago in the ocean and began breaking down organic material on the seafloor, which leads to more CO2 and less O2 in the atmosphere. 100 million years thereafter conditions for these earliest animals became much harsher, as ocean oxygen depleted further and carbon dioxide caused global warming.

Scientists have revealed that humans are not the first animals to cause global warming. Shortly after the Cambrian explosion, the first animals to triggered climate change on Earth which existed more than 500 million years ago. The early creatures evolved in the sea and survived by breaking down the organic matter on the sea floor and producing carbon dioxide.

Tiny creatures on the seabed disturb, mix and recycle dead organic material – like worms in a garden, a process called as bioturbation. Because the effect of animals burrowing is so big, you would expect to see big changes in the environment when the whole ocean floor changes from an undisturbed state to a bioturbated state.

This meant that the first bioturbators had a massive impact. The researchers said this realization was the “missing piece of the puzzle,” and allowed them to construct a mathematical model of Earth around that time to look to the changes caused by these early life forms.

The evolution of these small animals did indeed decrease the oxygen in the ocean and atmosphere but also increased atmospheric carbon dioxide levels to such an extent that it caused a global warming event. This process made conditions worse for these animals, which possibly contributed to a number of mass extinction events during the first 100 million years of animal evolution.

Researchers say that there is a worrying ‘parallel’ between what happened more than 500 million years ago and how human activity is heating the planet today. These early animals pre-date complicated lifeforms on Earth, however they were capable of respiration a process which converts oxygen to carbon dioxide. The study was published in the journal Nature Communications.

Professor Lenton, director of Exeter’s new Global Systems Institute, said “There is an interesting parallel between the earliest animals changing their world in a way that was bad for them, and what we human animals are doing to the planet now” and further added, “We are creating a hotter world with expanding ocean anoxia (oxygen deficiency) which is bad for us and a lot of other creatures we share the planet with.”