The correct answer is B; due to the rarity of the -13910*T allele lactase persistence would have been very rare in European Neolithic hunter-gatherers, but the increased frequency of the -13910*T allele in modern Europeans shows that lactase persistence must have started to increase in frequency at some point between the Neolithic and modern-day. This would only have happened to the extent shown if the lactase persistence increased the survival chances of the historic humans, making it more likely that the -13910*T allele would be passed on and leading to its increase in frequency.

There is a statistically significant increase in the frequency of the -13910*T allele between Neolithic hunter-gatherers and modern day humans in Europe; this is shown by the lack of overlap between the standard deviation values.

It is possible that lactase persistence gave a survival advantage to European Neolithic hunter-gatherers but the table doesn't tell us at what point the frequency of the -13910*T allele began to increase so we cannot be sure. At the point at which the allele begins to provide a survival advantage the chances of its being passed on the increase and its frequency will therefore begin to increase.

The low frequency of the -13910*T allele means that it is unlikely that milk had been a significant part of the adult human diet in the time leading up to the Neolithic but, as with the previous point, we do not know when the allele frequency started to increase so we, therefore, cannot say at what point from the Neolithic onwards the selection pressure of adult milk consumption was introduced.

	European Neolithic hunter-gatherers	Modern Europeans
*Frequency of -13910T allele**	0.03 (+/- 0.11)	0.74 (+/- 0.06)

Natural Selection (SL IB Biology)

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