Most Adults Cannot Digest Milk
Milk is the white liquid mammals feed their young. The ability to drink it as an adult is unusual.
Milk is the nutrient-rich liquid produced by female mammals for their young. Most humans lose the ability to digest it after childhood: the enzyme lactase switches off, as it does in every other mammal. Adults who keep producing it carry a genetic mutation that spread in dairying populations over the last several thousand years, and worldwide such people are a minority. The verb *milk*, meaning to exploit for all it is worth, is recorded from the 1500s.
- A mammal's liquid food. *Cow's milk.*
- Plant milks. *Almond milk.*
- To milk an animal. *Milking.*
- To exploit. *Milking the situation.*
- Old English — *meoluc*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | milk | Milk. |
| Verb | milk | Milking. |
| Adjective | milky | Milky. |
| Compound | buttermilk | Buttermilk. |
| Old English | meoluc | Milk. |
- She drank a glass of milk.Food.
- Lactase switches off in most adults.Biology.
- He milked the story for laughs.Figurative.
About lactase persistence
- Lactase breaks milk sugar into digestible parts
- In most mammals it stops being produced after weaning
- A mutation keeps it active into adulthood
- It is common in northern Europe and parts of Africa
- It arose separately in more than one dairying population
Old English *meoluc*, of Germanic origin, related to Dutch *melk* and German *Milch*.
Why can some adults drink milk and others cannot?
A genetic mutation keeps the enzyme lactase active after childhood. It spread in dairying populations, but worldwide it remains a minority trait.
What does it mean to milk something?
To extract every possible advantage from it, a figurative use recorded since the 1500s.