Media release

From: Springer Nature

Male woolly mammoths had mating on the mind

Male woolly mammoths underwent musth, testosterone-driven changes associated with the mating season, just as their modern elephant relatives do, a study published in Nature suggests. Hormone fluctuations are identified in the dentin of a male mammoth tusk estimated to be approximately 39,000–33,000 years old. The findings demonstrate the value of analysing hormone levels in teeth (including protruding tusks) to investigate hormone-driven behaviours in ancient and modern animals.

Many features of woolly mammoth reproductive physiology and behaviour are unknown, such as whether they underwent musth episodes — periods of elevated testosterone associated with reproductive success in adult male elephants. Tusks are a promising source of information as they preserve a record of growth in layers of a bony material called dentin, which can be used to reconstruct details of mammoth life histories. To assess the potential value of this record, Michael Cherney and colleagues searched for signatures of hormone fluctuations in the tusks of a modern African elephant, a male woolly mammoth (estimated to have lived 38,866 to 33,291 years ago) and a female woolly mammoth (estimated to have lived 5,885 to 5,597 years ago).

In the African elephant, the analyses demonstrate that the male experienced increases in testosterone levels during adult life, but not in its younger years, consistent with periods of musth during mating seasons. Such increases were up to 20 times higher than testosterone levels at other points in the year. Samples from the male woolly mammoth tusk reveal similar fluctuations in testosterone during adult life, although the increases were lower (around 10 times higher than other periods) than that of the African elephant. These lower hormone levels in the male woolly mammoth may be a result of sample degradation, the authors suggest. In the female woolly mammoth, testosterone (as well as progesterone and androstenedione) levels were lower than in the male mammoth and elephant, and testosterone in the female showed very little variation.

These findings represent the first endocrinological evidence that woolly mammoths experienced musth, the authors report. The research also demonstrates the potential of dental growth records to reveal hormonal changes associated with life-history events, the authors conclude.