BERLIN, May 16 -- The female sex hormone estradiol boosts for language acquisition in two-month-old babies, said the University of Wurzburg on Friday.

Scientists from the University of Wurzburg and the Humboldt University of Berlin have made a discovery, which reveals a direct correlation between a high level of estradiol in infants at two months old and the first vocal utterances that are relevant to language acquisition.

The research has been published in the Biology Letters journal.

The higher the level of this hormone in the blood at that age, the more complex the cry melody patterns are, which is essential for language acquisition.

However, testosterone apparently plays no role in these processes, according to the research.

"In their first few months of life, infants lay important foundations for subsequent language acquisition," said Kathleen Wermke, a medical anthropologist from the University of Wurzburg.

The higher the proportion of complex melodies in a baby's crying, the better the child will later be at producing and understanding words and sentences.

However, this correlation is only valid for a certain age, said the study.

"We revealed in a previous study that melody complexity was only suitable for predicting language capability at two and a half years old when determined at two months old, not in the first month and not in the third or fourth month either," said Wermke.

Meanwhile, the researchers also found estradiol in the blood of male babies.

If the level of estradiol in the blood of male babies can even be well above the average value for girls in some cases, these boys then also showed an above-average number of pronounced melodic variations in the second month.

But at present, the scientists can only speculate about the ways in which estradiol influences the development of language capability in humans.

In order to advance the knowledge of the development of language and the differences between the sexes in early language development, the researchers will therefore conduct a further study to examine whether the influence of estradiol can still be proven at five months old, when babies take a decisive new step in their linguistic development.