Animal origin theory challenged: Early animals needed almost no oxygen
Kristian SjĂ¸gren over at Science Nordic reports on an amazing discovery that seems to contradict what we thought we knew about the origins of animals.
A new Danish study of one of the oldest animals on the planet - a small sea sponge - shows that there is a big gap in the theory of how animal life arose on Earth.
Scientists have so far believed that animal life only became possible when the oxygen content of the atmosphere rose dramatically just over half a billion years ago. This was the second of two major rises of atmospheric oxygen in Earthâ€™s history.
However, the new study shows that oxygen was not the limiting factor for the evolution of animal life. The earliest animal life could get by with much less oxygen than there was in the atmosphere even before this rise.