One of the basic assumptions about life on Earth may be due for a revision. Scientists have discovered a type of bacteria that thrives on poisonous arsenic, potentially opening up a new pathway for life on Earth and other planets.

If you thumb through an introductory biology textbook, you’ll notice that six elements dominate the chemistry of life. Carbon, hydrogen, oxygen and nitrogen are the most common. After that comes phosphorus, then sulfur. Most biologists will tell you that these six elements are essential: life as we know it cannot exist without them.