* Comment is free Series: Unthinkable? Previous | Index Unthinkable? Banishing breastfeeding guilt

The theory of evolution makes it a reasonable guess that breast milk will be the ideal food for a baby. The same theory, however, would also suggest that mothers will do all they reasonably can to keep their infants healthy, but unending hectoring about rearing children takes little account of that second insight. Feathers were ruffled yesterday when a paper concluded that weaning on to solid food might usefully start a little earlier than is currently advised. It was a modest suggestion grounded in the sort of serious work which scientific progress relies on, and yet on the Today programme a top midwife shrugged it off with half a hint that the formula-milk industry must lie behind any challenge to the view that breast milk alone is always and everywhere best. The industry's advertising is rightly restricted, but beyond that the debate should be free. It is settled fact that breast milk protects babies in some specific ways, but few of the thousands of studies that get hyped up as saying that formula babies will grow up fat, sick or stupid control adequately for the manifold confounding factors that could be at play. Family income can be straightforwardly measured and adjusted for, but not so the attentiveness of the parents. Ingenious methods have been proposed to isolate the nutritional effect, but this remains new science. Wherever it leads, new mothers who struggle to breastfeed because of separation from a sick baby or anything else don't deserve criticism and guilt, but the milk of human kindness.