Short-term climatic changes recorded by mammoth hair in the Arctic environment

Well-conserved mammoth carcasses can be found only in particular environments such as the Arctic region where the ground is frozen to depths of hundreds of meters and only a thin superficial layer of about 1.0/1.5 m thaws out during the short Arctic summer. In this environment soft tissues such as hairs can be preserved and therefore analysed to obtain information about the short-term (seasonal) environmental changes during the short period right before the animal's death. This study reports the results of a set of about 240 analyses carried out on 4 hairs of a 42,700±1300 radiocarbon years old mammoth from the Bol'shoy Lyakhovsky Island (New Siberian Islands). The hairs were analysed for their C and N stable isotope composition to obtain information about seasonal and annual changes in the mammoth's diet. Isotope analyses were performed on small growth increments along the full length of the hair, which represents a continuous record of the food intake over the growth period of this tissue. The isotope oscillations found represent seasonal changes in the isotope composition of plant food consumed according to the different plant-type availability between the cold and warm season and/or to a physiological adaptation of the plants and the animal to different environmental conditions. Small differences in the isotope values of mammoth food intake from one year to the next are also apparent. By counting the number of oscillations it is possible to define the hair age. The longest hair is representative of the last 39 months of mammoth's life. The mean C isotope composition calculated for the vegetation at the base of the mammoth diet during the Middle Valdai is different by about 2‰ to that of the present vegetation in Northern Siberia suggesting different climatic conditions.