A just so story for my evolution paper!

According to the Baldwin Effect learning can guide evolution: being able to learn a trait can help a species evolve that same trait. This at first feels like Lemarkian nonsense, but it isn't.

Lets consider a very artificial example; imagine it is useful for a hen to be able recognize a snake and then stand up tall and dinosaur-like to scare it off. Imagine further, and implausibly, that each of these two traits can be produced by a single mutation. Every so often a hen is hatched that can recognize a snake. This trait does it no good since it doesn't know how to scare off that same snake. Similarly, imagine on other occasions a hen is hatched that can scare off snakes; again this trait is useless, it is no good knowing how to scare of a snake if you don't know how to spot one. Sadly it is much much rarer that a hen is hatched that has both traits at once and so the useless individual traits disappear from the population and evolutionary change does not produce snake-safe hens..

Now imagine that a hen can also learn, though experience, to scare off snakes, learning the required tall stance after a few close calls. In this case, inheriting the mutation that allows a hen to recognize a snake is useful, when it recognizes the snake and with a few frightening encounters and a little luck, it can learn to scare snakes off. Thus the potential to learn how to scare snakes makes the recognizing-snakes mutation useful and so this mutation will provide fitness and in the usual Darwinian way spread through the population. Furthermore, once the hens can recognize snakes, the mutation that makes them instinctively stand tall to scare snakes becomes useful too, it saves them the risky encounters required to learn the trait by experince. In this way, the fact they can learn the traits makes the species more likely to evolve this. This is the Baldwin Effect.

In 1987 Hinton and Nowlan wrote a very elegant paper describing the Baldwin Effect in a clear way and illustrating it with a nice mathematical simulation.

How learning can guide evolution
Geoffrey E. Hinton and Steven J. Nowlan
Complex Systems (1987) 3:495-502.

This paper was influential, for example, it formed part of the argument in Pinker and Bloom's powerful argument that language evolved through normal Darwinian mechanisms:

Natural language and natural selection
Steven Pinker and Paul Bloom
Behavioral and Brain Sciences (1990) 13:707-727.

In my paper I point out that there is a similar effect with cooperation. Perhaps in a flock of hens one hen gets the mutation that allows it to recognize a snake and when it sees one it squawks in alarm, another hen has the mutation that makes standing tall when under threat instinctive and so it scares away the snake, for the benefit of all. Both traits are benefitial and the usual Darwinian, survivalist, principles mean that they will become established. The two mutations are much more likely to occur in the same time in flock than in one individual animal. My paper uses the same sort of simulations described by Hinton and Nowlan to illustrate this effect. Thus, in addition to the obvious benefits of social behaviour in animals, cooperation broadens the evolutionary path to complex behaviours.