https://allthatsinteresting.com/pygmy-woolly-mammoth
He told The Siberian Times, “I believe that this mammoth is related to the period of the heyday of the species, which was supposed to be in the Karginsky interglacial time (between 50,000 and 22,000 years ago). Our theory is that in this period the mammoths significantly rose in numbers – and this led to the biggest diversity of their forms. So we want to check this theory.”
There has been some theory that the “junk dna” allowed the mammoth to change in size several times during history.
Dwarfism and giantism is often associated with island living, that is, inbreeding due to isolation. The last mammoths known finally croaked out on Wrangel Island about 4000 years ago; remains of other dwarf or pygmy mammoths have been found on Kotelny Island (also off Siberia) and the Channel Islands off California, and on Crete (which also had dwarf hippos and a species of giant rat).