Babies are Bayesians?

From the abstract of a recent paper in Science:

When 12-month-old infants view complex displays of multiple moving objects, they form time-varying expectations about future events that are a systematic and rational function of several stimulus variables. Infants’ looking times are consistent with a Bayesian ideal observer embodying abstract principles of object motion. The model explains infants’ statistical expectations and classic qualitative findings about object cognition in younger babies, not originally viewed as probabilistic inferences.

Group Selection Explains "Why We Celebrate a Killing"?

In an otherwise thoughtful piece in the New York Times on the reactions to Bin Laden's killing, Jonathan Haidt throws in a weird flourish

There’s the lower level at which individuals compete relentlessly with other individuals within their own groups. This competition rewards selfishness.

But there’s also a higher level at which groups compete with other groups. This competition favors groups that can best come together and act as one. Only a few species have found a way to do this. ...

Early humans found ways to come together as well, but for us unity is a fragile and temporary state. We have all the old selfish programming of other primates, but we also have a more recent overlay that makes us able to become, briefly, hive creatures like bees. Just think of the long lines to give blood after 9/11. Most of us wanted to do something — anything — to help.

So,

last week’s celebrations were good and healthy. America achieved its goal — bravely and decisively — after 10 painful years. People who love their country sought out one another to share collective effervescence. They stepped out of their petty and partisan selves and became, briefly, just Americans rejoicing together.

The claim seems to be that the origins of these reactions in group selection means that displaying these reactions now is "good and healthy" because group selection benefits groups? Not the best argument, I would say.