Such a system, Dr Dale thinks, could be the ancestor of the ribosome and, if wrapped in a fatty membrane, of the cell.

ECONOMIST: The origin of life

Since 30% of the fatty constituents of nerve-cell membranes are DHA molecules, keeping your DHA levels topped up is part of having a healthy brain.

ECONOMIST: Eat your way to a better brain

Cell membranes are made of fatty molecules, but the details vary from one organism to another.

ECONOMIST: Nanotechnology in biology

Both breast-fed and formula-fed babies who had been given n-3 fatty acid enriched egg yolks had 30-40% greater red cell membrane DHA levels than those fed normal egg yolks.

BBC: Egg boost for babies