A new study has found that there was lack of oxygen on the early Earth and this may have prevented several species of the animals from growing and flourishing sooner than 800 million years ago on the planet.
According to the researchers, the animals began to flourish about 800 million years ago towards the end of the Proterozoic period. But many researchers believe plenty of oxygen existed before that.
The study was conducted by the researchers at the Yale University and led by researcher Noah Planavsky.
They found that the level of oxygen during that period was only 0.1 percent of today’s scenario.
In simpler terms, the atmosphere of Earth couldn’t have backed a diversity of creatures, regardless of what sort of genetic advancements were poised to occur.
Study co-lead author Planavsky and Christopher Reinhard from the Georgia Institute of Technology, said, “There is no question that ecological and genetic innovation must ultimately be behind the growth of animals. But it is equally unavoidable that animals need a certain level of oxygen.”
For the study, the scientists analysed chromium (Cr) isotopes in ancient sediments samples from Australia, Canada China and the US.
Chromium is found in the continental crust of the Earth, while chromium oxidation is directly associated to the presence of free oxygen in the atmosphere.
The study team examined the samples that were deposited in iron-rich ocean areas near the seashore. These data were then compared with other samples that were gathered from younger locales known to have higher oxygen levels.
Tim Lyons, study co-author from the University of California-Riverside, said, “If we are right, our findings will really change how people view the origins of animals and other complex life, and their relationships to the co-evolving environment. This could be a game changer.”
The findings were reported in the journal Science.