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Glossary

Peto's paradox

Defined in topic 22

The puzzle that animals with a thousand times more cells than humans do not get proportionally more cancer. African elephants carry at least 20 copies of the tumor suppressor TP53.

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Where this comes from

In the reference topic that owns this term

Reference topic 22, Cancer in a New Environment, states the mismatch as a card: what the system evolved to expect, what it gets instead, and what happens in the gap.

Mismatch card

What it expects

A body of ancestral size and lifespan; menarche in the mid-teens, many pregnancies, years of breastfeeding; no tobacco and little alcohol.

What it gets

Longer lives; earlier menarche, fewer and later births and shorter breastfeeding (three to four times the Dogon's menstrual cycles); excess body fat; tobacco and alcohol.

What happens in the gap

More hormone-driven, obesity-related, tobacco and alcohol cancers; much of the remaining rise reflects age and closer looking.

The full card, and the topic behind it

What that chapter recommends

3 of the 10 graded recommendations in Reference topic 22, strongest evidence first. How the grades work.

  1. Don't smoke; quit at any age

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Smoking causes about one US cancer in five and more than a quarter of cancer deaths. Ask about yearly low-dose CT screening if you are 50 to 80 with a 20 pack-year history and smoke now or quit within 15 years.

    Read it in full

  2. Drink less

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    "It is best not to drink alcohol," says the American Cancer Society. For those who do: "no more than 1 drink per day for women or 2 drinks per day for men."

    Read it in full

  3. Limit adult weight gain

    StrongEvidence grade: Strong. Multiple randomized controlled trials, or consistent large cohort studies with a well-understood mechanism.

    Stay in a healthy range and avoid gaining through adult life. Skip crash diets, get clinical support if you have an eating disorder, and treat weight-loss drugs as a decision for you and a clinician (Chapter 13).

    Read it in full

Related terms

The argument behind this term, its studies and its notes are in Reference topic 22 of the reference library. The book gives the practical version. Get the book.