It could be that the White Sands dates, while strongly supported, need additional independent confirmation.

It could be that the relationship between the White Sands people and the founding population represented by USR1 is more complex than either a single founding event or a complete population replacement would suggest.

Resolving this tension requires ancient DNA from pre-Clovis contexts — from sites old enough to represent the people who made the White Sands footprints or their close contemporaries.

No such ancient DNA has been successfully analyzed, because sites from this period are rare, because the relevant sites have mostly been found in environments hostile to DNA preservation (exposed surface sites, underwater sites), and because the specific bones or teeth needed for ancient DNA analysis have not been recovered.