At www.sciencedaily.com/releases/2010/12/101221114807.htm … a paper in the journal Palaeography, Palaeoclimatology and Palaeoecology claims that woolly mammoths living north of the Arctic Circle in the Pleistocene epoch, in this instance between 150,000 and 40,000 years ago, began weaning infants up to 3 years later than modern day African elephants. Biologists looked around for a reason why this might have happened and this is what they decided. They did this due to the prolonged hours of darkness that prevail during Arctic winters. In addition, predatory animals such as sabre toothed cats, probably behaved like modern lions that prey on infant elephants at night. Therefore, as Arctic winters are both long and dark they weaned their young for a longer period – in order to thwart the predators. So, the explanation begins on the assumption the Yukon was in the Arctic Circle between 150,000 and 40,000 years ago. Then it assumes elephants, aka woolly mammoths, were living in a habitat where it was dark for six months of the year, with little or no vegetation on which to feed – and they shared their habitat with big cats.