What is lactase persistence?
The ability to continue producing lactase, which is the enzyme that breaks down lactose in milk in adulthood, allowing adult adults to digest lactose
What is lactose and why can’t it be absorbed directly into the bloodstream?
Lactose is the main sugar in milk. It cannot pass through intestinal walls, so lactase breaks it into glucose & galactose which can then be absorbed for energy
In a lactose persistent adult why does blood glucose increase after drinking milk?
Lactose breaks lactose into glucose galactose (simple sugars), which are absorbed into the bloodstream raising blood glucose levels
Do all lactase, persistent people carry the same genetic mutation?
No different populations have independent mutations enabling lactase persistence (Europeans vs Massai Africans)
Why did Europeans and Africans independently develop lactase persistence?
Domestication of dairy animals provided at nutritional advantage adults who could digest milk, survived, and reproduced more spreading the trait
What archeological evidence supports early milk consumption
Fats trapped in fragments of ancient pottery across Europe and Africa
How did dairy farming drive the spread of lactase persistence?
Dairy farming provided a steady food source adult adults who could digest milk had nutritional advantages leading to natural selection for lactase persistence
Why was consuming dairy a selective advantage for lactase persistent individuals?
Milk is a calorie protein and calcium rich source so it was a reliable food source during founded or scarce food periods. Improving survival and reproductive success.
What is lactose intolerance?
When the body cannot fully digest lactose due to insufficient lactase. Undigested lactose is fermented by gut bacteria, causing gas, bloating, cramps, and diarrhea.
Where does lactose come from in nature?
Only from dairy products
What is lactase non-persistence
The ancestral state were lactase production drops after childhood leading to lactose intolerance in adults
What is lactase persistence?
A genetic mutation that keeps the lactase gene active in adulthood, allow allowing milk digestion
How did domestication of animals contribute to the evolution of lactase persistence?
Milk became a regular food source. Those who could digest gained survival and reproductive advantages spread, spreading lactase, persistence, genes
Why didn’t all dairy hurting populations develop high lactase persistence?
Some processed milk into a yoghurt or cheese, reducing lactose content, so lactase persistence was less advantages
What evolutionary benefits helped lactose persistent spread
Nutrient access: rich in calories, protein, and fat
Hydration in dry environments
Calcium and vitamin D absorption, especially in low sunlight regions
Growth boost via IGF-1 which allowed earlier puberty, faster, growth, larger body size
Is lactose non-persistence a disease?
No, it’s the ancestral human condition modern guidelines may misrepresent milk as essential for everyone, but lactase non-persistence is normal biology
Explain convergent evolution in the context of lactase persistence
Different populations developed lactase persistence independently through distinct mutations because milk consumption provide provided. Survival advantages in multiple regions.
What is the relationship between milk and IGF – 1 and growth
Milk consumption can increase IGF –1 level levels by promoting earlier, puberty, faster, growth, and large, larger body size
Why should doctors use the term lactose non-persistence instead of calling it a deficiency
Because lactase non-persistence is a normal evolutionary trait, not a disease or poor absorption
