linguistic phylum. Environment Based on studies by glaciologist Lonnie Thompson, professor at Ohio State University and researcher with the Byrd Polar Research Center, a number of indicators shows there was a global change in climate 5,200 years ago, probably due to a drop in solar energy output. The Older Peron transgression was a period identified in 1961 happening between 6,000 and 4,600 years BP when sea levels were 3 to 5 metres higher than today. Plants buried in the Quelccaya Ice Cap in the Peruvian Andes demonstrate the climate had shifted suddenly and severely to capture the plants and preserve them until now. c. 3750 BC – The last North American mammoths, on Saint Paul Island, Alaska, go extinct. Tree rings from Ireland and England show this was their driest period. Ice core records showing the ratio of two oxygen isotopes retrieved from the ice fields atop Africa's Mount Kilimanjaro, a proxy for atmospheric temperature at the time snow fell. Major changes in plant pollen uncovered from lakebed cores in South America. Record lowest levels of methane retrieved from ice cores from Greenland and Antarctica. End of the Neolithic Subpluvial, start of desertification of Sahara (35th century BC). North Africa shifts from a habitable region to a barren desert. c. 3150 BC – a lesser Tollmann's hypothetical bolide event may have occurred. 3051 BC – The oldest currently (2013) living non-clonal organism germinated in the present-day Grove of the Ancients, Inyo County, California. Calendars and chronology 4000 BC – Epoch of the Masonic calendar's Anno Lucis era. 3929 BC – Creation according to John Lightfoot based on the Old Testament of the Bible, and often associated with the Ussher chronology. 3761 BC – Since the Middle Ages (12th century), the Hebrew calendar has been based on rabbinic calculations of the year of creation from the Hebrew Masoretic text of the bible. This calendar is used within Jewish communities for religious and other purposes. The calendar's epoch, corresponding to the calculated date of the world's creation, is equivalent to sunset on the Julian proleptic calendar date 6 October 3761 BC. 3114 BC – One version of the Mayan calendar, known as the Mesoamerican Long Count, uses the epoch of 11 or 13 August 3114 BC. The Maya Long Count calendar was first used approximately 236 BC (see Mesoamerican Long Count calendar#Earliest Long Counts. 3102 BC – According to calculations of Aryabhata