Answer:
Molecular biology (DNA sampling) is the best proof.
Explanation:
An study published in the journal of science found that 99.9% of humans are quite similar. The scientific team analysed DNA from 1,056 people from 52 populations in Africa, Eurasia (Europe, the Middle East, Central and South Asia), East Asia, Oceania and the Americas.
The phenotype ( visible appearance) results from a very small proportion of differences in genetic traits, hence the concept "race" is more a cultural concept than a biological concept.
