Something has always troubled me about Darwin’s theory and even modern revisions of his work – there is still no explanation for instinct. Ethologists call instincts innate releasing mechanisms or IRM, which in layman’s terms means “we’ll use big fancy words because we just don’t know.” The most common definition is, “The mechanism by which an organism responds to a key stimulus (KS) with a fixed action pattern (FAP).” Of course, this explains nothing. This is one of the limitations of Darwin’s theory – it always has been. An earlier theory of inheritance was posed by the French zoologist, Jean-Baptiste Lamarck (1744-1829). From Understanding Evolution:
