Nigel travels back 10,000 years to the end of the Great Ice Age when Britain was still attached to Europe. As the Earth warmed up it forced the last remaining mammoths back to colder, more remote places like Siberia. Weighing in anywhere between four to six tonnes these herbivores needed plenty of grass and shrubs to sustain their huge bulk and with the Earth warming, forests were overwhelming the grasslands, denying them vital food and threatening their survival. But as Nigel finds out, it wasn't just the climate that threatened these once highly successful creatures.