Bristlecone pine. View of a bristlecone pine tree Pinus aristata at sunrise. This remarkable species lives at an altitude of 2100 to 3600 metres, and is one of the longest-living organisms on Earth. Some specimens have been estimated as being nearly 5000 years old. Studies of wood from bristlecone pines has provided much data on ancient climates. Whilst studying the bristlecone, it was discovered that climates more than 3600 years ago had a different carbon dioxide content, leading to a revision of the ages derived from carbon-14 dating.