The bones of humans are less dense than those of large mammals, and they are more readily affected by the freeze-thaw cycles that occur at the margins of permafrost zones.

Repeated freezing and thawing physically damages bone structure and accelerates the chemical processes that degrade DNA.

The specific burial conditions at Upward Sun River — including the depth of burial, the surrounding sediment matrix, and the specific temperature regime experienced by the remains over eleven and a half thousand years — would determine whether usable ancient DNA had survived.

The answer, for USR1, was a qualified yes.

The skeletal material preserved ancient DNA, but the preservation was imperfect.