The origin of homochirality

What makes this fascinating

• Life picked a hand — Biology uses only left-handed amino acids and right-handed sugars; their mirror images are nearly absent.

• Why that hand? — Non-living chemistry makes both forms equally, so how life broke the symmetry is a mystery.

• Clues from space — Meteorites show slight excesses of one form, hinting the bias may even predate life itself.

Frequently asked questions

What is homochirality?

Many of life's molecules come in left- and right-handed mirror forms, but life uses almost exclusively one — left-handed amino acids and right-handed sugars. Why life picked a single handedness is unexplained.

Why does life use only one handedness?

Unknown. Proposals include small initial biases amplified over time, chiral influences from polarized light or mineral surfaces, and chance — but no explanation is established.

Why does it matter?

Homochirality is essential for biology to function and is a key clue to the origin of life; it also matters in drug design, where the two mirror forms of a molecule can have very different effects.

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