They found that Negritos, the hunter-gatherer group, had unusually well-preserved olfactory receptor genes. [...]

The findings suggest there is a strong evolutionary pressure to maintain these genes among Negritos compared with other populations, likely because smell plays a crucial role in foraging and hunting.

In addition, Negritos were more likely to carry genes associated with detecting earthy, fruity, and herbal smells, scents common in rainforest environments and often associated with edible plants and ripe fruit.

— Read more in Human sense of smell evolved with diets and lifestyle, genetic study suggests at Phys.org.