There is now even more evidence that life on Earth may have been seeded by material from asteroids or comets.

Prior research has shown how amino acids - the building blocks of life - could form elsewhere in the cosmos.

These molecules can form in two versions, but life on Earth exclusively uses just one of them.

Now an Astrophysical Journal Letters paper shows how conditions around a far-flung star could favour the formation of one type over another.

Amino acids are corkscrew-shaped molecules that can form twisted to the left or right, and chemistry does not inherently favour one corkscrew direction over another. But without exception, life on Earth makes use of the left-handed version.

A famous experiment in 1952 showed how a spark across a soup of simple chemicals representing the primordial Earth could form amino acids - but like many that followed, it formed equal numbers of left- and right-handed types. [ BBC NEWS ]