Can bone structure determine who is Native American?
No, bone structure alone cannot determine with 100% accuracy if someone is Native American.
Bone structure alone cannot determine if someone is Native American with 100% accuracy. This is due to:
1) Diversity within human populations
2) Mixed ancestry of people
3) Certain populations better studied than others/sample size
1) There is a tremendous amount of diversity in humans, and this includes within specific populations of humans. While we may be able to say that, generally speaking, people of European descent are taller than people of Asian descent or people of European descent are more likely to have overcrowding of teeth compared to those of African descent, these are generalizations. While the traits described may be true much of the time, they are not always true.
A great example of when skeletal features did not align with an individual's origin is the famous Kennewick man, remains found in Washington state that were thought not to be Native American based on skeletal features. However, DNA analysis has finally lead to the conclusion that Kennewick man is Native American. Read more here.
2) We know the most about groups of people we have studied the most. Thus, while we have studied the bones of many Europeans, we have not studied as many individuals from Laos or the Beothuk indigenous tribe. The more we study, the more we know. We may currently believe the tibia of one ethnicity are longer on average than a second ethnicity, but, with a larger sample size, we may find out this is not true.
3) Many people cannot call themselves 100% of any one ethnicity. Native Americans came into contact (and are still in contact) with people from other continents. They reproduce with people from various ethnicities, resulting in a mix of traits in the same way that can be expected if a Chinese person and a Danish person reproduce.
There are some general traits many Native American share. Native Americans typically have rounded eye orbits and prominent cheekbones compared to individuals from Sub-Saharan Africa, who typically have eye orbits that are of a rectangular shape and who lack prominent cheekbones. They tend to have a wider face than Europeans. It can be challenging to distinguish Native Americans from East Asians. It is important to remember that these traits are generalizations and not rules!