I am a fan of Sarah Palin’s. I think she has the right to energize the Republican Party and become the Ronald Reagan of the 21st century. I bet, in a couple of years, we will be hearing a lot about the “Palin Democrats.” I certainly hope that, despite her sudden and mysterious resignation as Governor of Alaska, she will run for and then win the White House in 2012, unless either Ann Coulter or the Michigan Congressman Thaddeus McCotter runs. (That Palin’s election as President will undoubtedly bring back Tina Fey to SNL for hopefully eight years is just one of the benefits.) As much as I like Sarah Palin, however, in the recent controversy between Palin and Letterman, my loyalty is firmly with Letterman, of whom I have been a devoted fan for a quarter of a century. Palin was simply wrong to take on Letterman on this issue.

Before discussing what Palin got wrong, I need to point out what she got right. Palin and other critics of Letterman and CBS were absolutely correct to point to the well-known strong liberal in the media. There is no way that Letterman would have made similar jokes about Democratic politicians, and, had he had the folly to do so, he would have been fired by CBS in a nanosecond. Feminist organizations like NOW only defend liberal women, and are always conspicuously silent when conservative women are attacked. So Palin and her supporters were correct to point out the liberal hypocrisy in the media.

Having said that, however, Palin was wrong on at least two fronts. First, as I explain in an earlier post, there is no such thing as an offensive joke. Jokes are either funny or unfunny or somewhere in between. The only purpose of a joke is to make people laugh, so the only legitimate criterion on which to evaluate jokes – all jokes – is whether and how well it succeeds in accomplishing their goal of making people laugh. I personally thought that Letterman’s jokes at Palin’s and her daughter’s expense were funny, but reasonable people can certainly disagree on the judgment. But the worst thing that anyone – including Palin – can say about the jokes is that they were not funny. Jokes – like scientific theories – cannot be offensive, sexist, racist, dangerous, or any other adjective.

Second, from a purely biological perspective, it was odd that a large part of the controversy apparently hinged on whether, in making fun of Palin’s “daughter,” Letterman meant the 18-year-old Bristol or the 14-year-old Willow. Many critics of Letterman seemed to agree that it would have been perfectly fine for Letterman to make sexual jokes about the 18-year-old Bristol, because she was “of age,” whereas it was completely inappropriate to make similar jokes about the 14-year-old Willow, because she was “underage.” While I can understand this distinction from a legal or social perspective, it is one that makes no biological sense.

There are only two meaningful and qualitatively different developmental life stages for humans: and adulthood. And what marks the qualitative transition from childhood to adulthood is . Purely biologically speaking, any human past puberty is an adult, fully capable of sexual intercourse and reproduction. That’s the whole purpose of puberty, to make the human capable of and ready for reproduction. There is nothing magical or biologically meaningful about the age 18 (or any other age of consent or legal adulthood). Nothing happens on the 18th birthday, and an 18-year-old on her birthday is essentially exactly the same as she was a day, a week, or a month before.

From a purely biological perspective, 14-year-old girls (past puberty) are no different from 18- or 21- or 25-year-old girls. True, 14-year-olds on average tend to be less mature than 18-year-olds, but then 30-year-olds on average tend to be less mature than 40-year-olds, but nobody thinks of treating 30-year-olds as children incapable of making their own decisions. Biologically, 14-year-olds are fully adults, and the choice of 18 as the age of legal majority is entirely arbitrary.

Whether Palin and other critics of Letterman like it or not, 14-year-old girls in the United States and the rest of the world are having every day. In fact, throughout human evolutionary history, the modal age of for women was probably shortly after puberty (although puberty likely happened much later than it does in Western industrial nations today), and the statistically most typical marriage in the ancestral environment was between a newly pubescent 14-year-old girl and a 40-year-old band (as in the leader of a hunter-gatherer band, not Paul Shaffer), who takes her as his third or fifth wife. The difference between a 14-year-old girl and an 18-year-old girl is a wholly socially constructed one without any biological merit.