Final answer:
The beta globin gene has continued to evolve with the occurrence of the sickle cell mutation. The distribution of the sickle cell allele can be traced through beta-globin gene haplotypes.
Step-by-step explanation:
The beta globin gene has continued to evolve over time.
The sickle cell mutation, which is caused by a single amino acid substitution in the beta-globin gene, originated in Africa and spread to other regions. Studies have shown evidence for multiple origins of the sickle cell mutation in Africa.
The distribution of the sickle cell allele can be traced through the analysis of beta-globin gene haplotypes.