Lactose Basics
Main sugar found in Milk
Lactose
Change in gene frequencies in a population over time.
Evolution
This continent includes many populations where over 80% of adults are lactose tolerant.
Europe
Milk is rich in these two nutrients that support strong bones and growth.
Calcium & Protein
The enzyme that breaks down lactose in the small intestine.
Lactase
This gene contains the instructions for making lactase.
LCT gene
Pastoralist groups in this region of Africa evolved their own versions of lactase persistence.
East Africa
In times of crop failure, milk helped people survive by providing this.
Extra calories & hydration
Gas, cramps, and diarrhea after drinking milk are signs of this condition.
Lactose intolerance
Lactase persistence spread because it helped people survive. This is an example of this process.
Natural Selection
Herders in this region between Africa and Asia also show high lactose tolerance.
Middle East
In some places, milk was safer to drink than this often-contaminated liquid.
Water
Most mammals stop producing large amounts of lactase after this life stage.
Early childhood
When cultural practices like dairying help shape our genes, we call it this.
gene-culture coevolution
Many populations in this region have high lactose intolerance because dairying was not a long-term tradition.
East Asia
Fermenting milk reduces lactose because these tiny organisms eat some of the sugar.
Bacteria
The scientific term for being able to digest lactose as an adult.
Lactase Persistence
Different populations evolved lactose tolerance separately.
convergent evolution
Before fresh milk was common, early farmers often lowered lactose by turning milk into this.
Cheese or Yogurt
Lactase persistence spread quickly because people who had it were more likely to do these two things.
Survive & have more children