You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Somalis

Context:
The analysis of HLA antigens has also helped clarify the possible background of the Somali people, as the distribution of haplotype frequencies vary among population groups. According to Mohamoud et al. (2006):

Question:
In what year did Mahamoud publish his research?

2006