Writing in The New York Times, Harvard evolutionary biologist Daniel Lieberman defends Mayor Michael Bloomberg's proposed 16-ounce restriction on soft drink servings, arguing that "we have evolved to need coercion":
Since sugar is a basic form of energy in food, a sweet tooth was adaptive in ancient times, when food was limited....
Humans evolved to crave sugar, store it and then use it. For millions of years, our cravings and digestive systems were exquisitely balanced because sugar was rare....
The food industry has made a fortune because we retain Stone Age bodies that crave sugar but live in a Space Age world in which sugar is cheap and plentiful. Sip by sip and nibble by nibble, more of us gain weight because we can’t control normal, deeply rooted urges for a valuable, tasty and once limited resource.
Lieberman deserves credit for candidly acknowledging that Bloomberg's "paternalistic plan" relies on "coercion." The mayor, by contrast, wants to have it both ways, getting credit for doing something about obesity while denying that he is limiting freedom in any meaningful way. On Friday he told NBC's Matt Lauer:
We're not banning you from getting the stuff. It's just if you want 32 ounces, the restaurant has to serve it in two glasses. That’s not exactly taking away your freedoms. It’s not something the Founding Fathers fought for.
As I said last week, Bloomberg's restrictions cannot possibly work unless the inconvenience they impose leads people to consume less soda than they otherwise would. By insisting that his restrictions will have no real effect on consumers, he is admitting his plan is doomed to fail.
Writing in Slate, Daniel Engbe asks what science tells us about the pint-sized plan's prospects. The focus on soft drinks, he explains, starts with the premise that liquid calories are less filling and that people therefore are less likely to compensate for them by cutting back elsewhere in their diets. While there is some evidence to support that idea, it is not clear that sugar-sweetened beverages are disproportionately responsible for rising obesity rates: Bloomberg may be convinced they are, but the research on that point is equivocal. Even if he is right, that does not mean his plan will have a measurable impact on New Yorkers' waistlines. As Engbe notes, the city unrealistically assumes that 100 fewer soda calories mean a net dietary reduction of 100 calories, ignoring the question of whether and to what extent people will compensate with calories from other sources. It is doubtful that Bloomberg's regulations can even reduce total liquid calories, especially given all the exceptions: for refills and additional containers, for fruit juices and milk-based drinks (which typically have more calories per ounce than soda), and for beverages sold in supermarkets and convenience stores—including 7-Eleven's Big Gulp, the very epitome of the sweet, bubbly excess that Bloomberg decries.
Lieberman, for his part, does not address the issue of whether Bloomberg's plan can accomplish its ostensible goal (a question that some boosters dismiss as irrelevant). If anything, Lieberman suggests that the mayor's pop policy goes too far, saying, "I think we should focus paternalistic laws on children." Still, he writes, "Adults need help, too, and we should do more to regulate companies that exploit our deeply rooted appetites for sugar and other unhealthy foods." Here Lieberman indulges in some Bloombergian dishonesty, since protecting adults from Big Food's sinister plot to sell them food they like actually means protecting them from their own choices—for example, "by imposing taxes on soda and junk food." In short: paternalism, which Lieberman has just said should be limited to children.
Lieberman's justification for treating adults like children has breathtakingly broad implications, since it is self-evident that humans have evolved to enjoy not just sugar but all of the things they like. Hence every pleasure can legitimately be taxed, regulated, restricted, or banned to prevent people from overindulging in it. By arguing that "an evolutionary perspective" shows governments must restrain people's choices for their own good, Lieberman tries to put a modern scientific veneer on an ancient moral argument. Evolutionary pressures clearly gave humans a taste not only for sweets but also for meddling in other people's lives.
More on Bloomberg's campaign against big sodas here.