J. M. Baldwin (1861-1934) was an American philosopher who found a way, consistent with Darwin, for learned behavior to evolve biologically.
Was speech invented or were its origins biological? Since language depends on many biological supports, it would seem to have evolved; however, the Baldwin Effect is a theoretically plausible way for learned activity to develop a biological basis. If speech began this way, people first invented words and then developed the useful biological support that makes speech easier and more efficient.
When I began this blog I expected to have a fair amount to say on the Baldwin Effect, but I have hardly mentioned it as more familiar processes usually seem adequate explanations. I have reported on research indicating that the Baldwin Effect cannot work if language evolution outpaces biological evolution (see: Language Adapted to Us) and that finding seemed to end the likelihood of the Baldwin Effect contributing much to our story. Other work, however, found that the most stable language features last longer than the most rapidly changing genetic features, so the Baldwin Effect remains a theoretical possibility. (See: Speech’s Stabilizing Forces) So might language have been invented after all?
The Baldwin Effect is a four-step process.
- Something happens.
- In response, individuals change their behavior.
- Genetic variation supports the ability to perform the new behavior.
- Natural selection favors those genetic varieties and the new behavior becomes biologically supported in the population.
It is an iron rule of genetics that learned behavior cannot be inherited, but this four-step process shows a way for behavioral changes to result in biological changes. An example provided by Terrence Deacon, the most influential researcher into the Baldwin Effect and language origins, shows the process. Step 1: An earthquake closes off a traditional migratory route. Step 2: Migratory animals change their route and end up in a colder location. Step 3: Some of the animals are better able to withstand the cold. Step 4: Natural selection favors those animals and the population adapts to their new circumstance.
The logic of the Baldwin Effect seems sound, but the complicated story puts it down toward the bottom of the list of likely explanations. There are many different types of evolutionary explanations, but Occam's Razor says we should go with the simplest applicable one. Thus, we can organize evolutionary explanations into a hierarchy of going from the simplest to the most complicated.
Genetic drift: Explanation uses genetic variation only. Random biases in distribution can alter neutral (non-adaptive) traits. Drift’s simplicity makes it the default explanation in accounting for a change. For instance, the loss of a gene that supports tonal languages in populations might well have been the result of drift without adaptive benefits. To argue for a more complicated explanation, you must first show that a change was adaptive.
Adaptation: Explanation uses genetic variation + natural selection. When a beneficial variation happens to appear, selection favors it. Thus, bird wings become more aerodynamically shaped and beaks take on a form well suited to their meal. Examples in the evolution of speech probably include the loss of air sacs attached to the throat (a change that increases the range of intelligible sounds) and improved control of the tongue (increases the probability of making a desired sound).
Responsive adaptation: Explantion uses adaptation + an account of environmental change). Something happens in the environment that causes natural selection to favor previously-neutral or even once-harmful genetic variations. In speech origins, an account of the evolution of the FOXP2 gene must account for genetic varities that once would have been rejected but suddenly became prefered.
Baldwin Effect: Explanation uses responsive adaptation + a behavioral step that occurs between something happened in the environment but the selection of genetic variation. An animal alters its behavior and selection responds to that alteration. There are often contradictory scenarios that favor responsive or Baldwinian adaptation. For example, did humans become bipedal in response to an environmental change or in response to a change in behavior? We don’t know, but without evidence directly favoring Baldwin, the default choice for the time being must be the simpler one that bipedal evolution was responsive adaptation to life in a changed environment. Reason’s bias against going for the more complex account is the main reason the Baldwin Effect has had so little presence in this blog.
Intelligent design: Use only in case of emergency.
After the March conference in Barcelona (see: Evolang 2008) and the newly improved status of Deacon I again thought I would be talkin more about the Baldwin Effect. In The Symbolic Species Deacon is a strong proponent of the co-evolution of brain and language. He puts it starkly, “An idea changed the brain.” [p. 322] There you see the Baldwin Effect stripped to its radical soul: the basis for the change is not physical. A little less dramatically, Deacon’s argument is that “our brains and sensorimotor ability exhibit many adaptations for language.” [p 328]
Steven Pinker’s The Language Instinct, which Deacon identifies as his target, is two levels simpler. Pinker holds that we evolved language as an adaptation to social living. Primates have been engaged in social living for perhaps 50 million years; language is merely a further refinement of a long-building process. Occam’s Razor should lead me to favor Pinker, except that I am in complete agreement with Deacon that Pinker resolves none of the many impediments to the evolution of a universal grammar. Furthermore, explaining speech as social adaptation does not explain why it was not found long ago among other social animals, especially other social primates. Chimpanzees have complicated social lives, but they do not talk, not even at the level of protolanguage. Why not?
Saying they never got the right mutation (bad luck) won’t do, because it moves the explanation for speech itself down a level in the explanatory hierarchy, to simple drift. Drift cannot explain adaptations, which was what Pinker set out to explain in the first place.
Regulars on this blog know that I have my own opinions on verbal adaptation: summarized quickly, I hold that something happened (the climate grew paradoxical [see: Humanity’s Pump]) and eventually tipped the human lineage into a multilevel selection process [see: A Vote for Group Selection] that favored cooperative communities. Speech is an adaptation to the rise of cooperative communities.
Was it a responsive adaptation or a Baldwinian one? In other words, did the biological changes that support the start of speech come first, or did we first push the envelope by inventing words and then develop the biological capacity that made speaking so easy? We were not there, but Occam's Razor still favors the simpler idea that the capacity for speech gave us words and not the other way around. The more complicated Baldwin Effect is not needed to explain speech origins.
In a later post I will look at whether the Effect seems necessary once speech had gotten underway.
Comments