Earth may be habitable because it got unbelievably lucky with its chemistry from the very start.

Earth may have won a cosmic chemistry lottery. Researchers found that during the planet’s earliest formation, oxygen had to be in an extremely narrow “Goldilocks zone” for two life-essential elements, phosphorus and nitrogen, to stay where life could use them. Too much or too little oxygen, and those ingredients could be lost or trapped deep inside the planet. This could reshape the search for life by showing that water alone is not enough.

Life cannot begin on a planet unless certain chemical elements are available in large enough amounts. Two of the most important are phosphorus and nitrogen. Phosphorus helps build DNA and RNA, which store and pass along genetic information, and it also plays a key role in how cells manage energy. Nitrogen is a major part of proteins, which are essential for building cells and helping them function. Without enough phosphorus and nitrogen, life cannot emerge from nonliving matter.