Language: Costs and benefits of a specialized system for social information transmission

Language is often thought of as the crowning human adaptation, the one that allowed Homo sapiens sapiens to conquer the globe. The assumption underlying such ideas is that verbal transmission of information provides unalloyed benefits by reducing the costs of learning about the environment. However, this raises the question of why no other species has discovered such a good trick. I argue that verbal transmission is only likely to be adaptive in a restricted range of circumstances. Even then it cannot be exclusively relied on, and it causes problems of deceit and instances of maladaptation. We should expect natural selection to have made us discriminating evaluators of verbal information who ultimately trust the evidence of our senses. Nonetheless, once language has become widespread, it can increase human adaptability by increasing the efficiency of individual learning.