Modern mothers love to debate how long to breast-feed, a topic that stirs both guilt and pride. Now — in a very preliminary finding — the Neanderthals are weighing in.

By looking at barium levels in the fossilized molar of a Neanderthal child, researchers concluded that the child had been breast-fed exclusively for the first seven months, followed by seven months of mother’s milk supplemented by other food. Then the barium pattern in the tooth enamel “returned to baseline prenatal levels, indicating an abrupt cessation of breast-feeding at 1.2 years of age,” the scientists reported on Wednesday in the journal Nature.

While that timetable conforms with the current recommendations of the American Academy of Pediatrics — which suggests that mothers exclusively breast-feed babies for six months and continue for 12 months if possible — it represents a much shorter span of breast-feeding than practiced by apes or a vast majority of modern humans. The average age of weaning in nonindustrial populations is about 2.5 years; in chimpanzees in the wild, it is about 5.3 years. Of course, living conditions were much different for our evolutionary cousins, the Neanderthals, extinct for the last 30,000 years.

The findings, which drew strong skepticism from some scientists, were meant to highlight a method of linking barium levels in teeth to dietary changes. In the Nature report, researchers from the United States and Australia described tests among human infants and captive macaques showing that traces of the element barium in tooth enamel appeared to accurately reflect transitions from mother’s milk through weaning. The barium levels rose during breast-feeding and fell off sharply on weaning.