Woolly mammoths changed their nursing habits because of environmental changes.
ScienceDaily (Dec. 21, 2010) — New research from The University of Western Ontario leads investigators to believe that woolly mammoths living north of the Arctic Circle during the Pleistocene Epoch (approx. 150,000 to 40,000 years ago) began weaning infants up to three years later than modern day African elephants due to prolonged hours of darkness.
This adapted nursing pattern could have contributed to the prehistoric elephant's eventual extinction. The findings were published recently in the journal, Palaeogeography, Palaeoclimatology, Palaeoecology.
By studying the chemical composition of adult and infant mammoth teeth, Jessica Metcalfe, an Earth Sciences PhD student working with professor Fred Longstaffe, was able to determine woolly mammoths that once inhabited Old Crow, Yukon didn't begin eating plants and other solid foods before the age of two (and perhaps as late as three) and considers predatory mammals like saber-toothed cats and a lack of sufficient vegetation to be the secondary reasons for delayed weaning.