Let’s stipulate for this conversation that everything the experts say about evolution is true. Creatures that are the most successful at reproducing pass their traits to the next generation, and so on.
But I have another hypothesis that I think is testable. What if there is another influence that also contributes?
I wonder if a creature’s aspirations can somehow have an impact on what her genes pass to the next generation. We know that thoughts are associated with feelings, and feelings are associated with body chemistry. It’s not impossible that wanting something in your lifetime can make it more likely the child achieves it.
Recently I read that certain environmental conditions can increase the odds that women will give birth to boys. So we know that external conditions can influence body chemistry which in turn can influence the genetic makeup of the kid.
So I wonder about the giraffe with its long neck, to pick an easy example. The classic explanation is that giraffes with longer necks could reach leaves higher in trees, and had a survival advantage when food was scarce. That seems reasonable enough. But I wonder if the giraffes that strained and wished they had longer necks experienced some sort of stress, and giraffe-style wishfulness, that released any chemicals that could influence the odds of producing a long-necked child. In other words, do creatures guide their own evolutionary path through their desires?
It seems hugely unlikely that such a complicated and specific system could exist in a creature. But everything about creatures with brains is ridiculously complicated and specific and unlikely. It seems to me entirely plausible that creatures with brains evolved a heretofore undiscovered ability to translate their aspirations in this life to physical traits in their children.
You could test this in female rats. One group is the control, and the other is kept frustratingly a half inch from some delicious cheese. Both rats are fed enough to guarantee equal survival, so the normal mechanism for evolution is turned off. Would the rat who aspired to have a longer snout to reach the cheese produce, on average, longer snouted offspring?
Someone probably tested that already in fruit flies or something.
[Update: Lamark didn't deal with a person's aspirations. He was all about the traits you acquire during life, whether you wanted them or not. -- Scott]