Lehrmann versus Lorenz Isolation experiments

Developmental systems theory originated with Daniel Lehrmann’s (1953) cri- tique of Konrad Lorenz’s isolation experiments (e.g. Lorenz 1950). Lorenz is famous for, among other things, being a pioneer of cognitive ethology. He set out to discover which animal behaviours were innate, and in order to do this, he designed experiments where animals were raised in isolation from their normal environmental developmental cues, and observed them to see which behaviours manifested themselves as normal in such artifi cial circumstances. He concluded, seemingly reasonably, that, since the animals did not have the opportunity to acquire the behaviours from their environment, those behav- iours must be innate. For example, rats raised in isolation, when they are coming near to giving birth, will gather up material and use it to build nests, even when it is their fi rst pregnancy. Th ey cannot have learned this behaviour from previ- ous experience, or from observing other rats doing it, so, Lorenz concluded, it must be an innate behaviour.

However, Lehrmann showed that this behaviour still required specifi c types of interaction with an environment in order to develop. In particular, the rats had had experience of carrying food pellets, and of moving their own drop- pings out of the way. Lehrmann set up an experiment whereby the rats’ food was powdered, and the rats were raised in cages that had mesh fl oors, so that the droppings fell through. In this new situation, they no longer built nests; the material they might have used was left lying around. Th e moral of this story is that sometimes the environmental interactions needed to develop a trait are far from obvious.

Th is moral was reinforced by a further fi nding by Lehrmann: he discovered that rats, by licking their own bodies during pregnancy, obtained potassium salts. But this behaviour also seemed to be required for them to acquire the behaviour of licking the bodies of their young. Rats who had been raised with special collars that prevented them from licking themselves did not lick their young either. So the emergence of a trait in an isolation experiment would only show that whatever environmental resources are needed to develop that trait are present in that particular artifi cial set-up.

Lehrmann argued that rather than dividing traits into two types, innate and acquired, one should ask of any trait which resources were necessary for it to develop. In the case of the rat developing these behaviours, the relevant resources do not include seeing the example of other rats doing the same thing, but do include prior exposure to objects that can be picked up and carried around. Th e fact that these are the relevant resources is no reason to say that the traits are not “learned”, if learned is supposed to mean “as opposed to instinc- tive”, and no reason to call the traits innate as opposed to acquired. Nothing is gained by assigning these traits to the categories “innate” or “acquired”, or “learned” or “instinctive”.

Th e “learned versus instinctive” dichotomy has been entrenched in thinking about animal behaviour at least since the nineteenth century. It is encapsu- lated in William James’s famous defi nition of instinct, for example: “Instinct

is usually defi ned as the faculty of acting in such a way as to produce certain ends, without foresight of those ends, and without previous education in the per- formance” (James [1890] 1981: vol. 2, 1006, original emphasis). According to

Lehrmann, such defi nitions serve only to obscure the need to look at the specifi c

developmental process by which a trait comes about, and tempt one to set up the

dichotomy between innate and acquired. He argues that we should not bother asking the question “Which traits are innate?” or its modern version “Which traits are the product of genes?” Both questions are meaningless.

Lorenz (1965) returned to the fray with an attempt to account for innateness in terms of information contained in the genes. According to such an account – which can also be seen in popular form in Dawkins’s comparison of genes to a recipe – the way an organism will turn out can, under ideal conditions, be

“read off ” its genotype. “Ideal conditions” here does not just mean conditions in which we know exactly which genes do what. It also means situations where the environmental conditions are such that they can be treated as a neutral back- ground against which genes do their work. Lorenz accepted the obvious point that input from the environment was necessary for any trait to develop at all:

No biologist in his right senses will forget that the blueprint contained in the genome requires innumerable environmental factors in order to be realised … During his individual growth the male stickleback may need water of suffi cient oxygen content, copepods for food, light, detailed pictures on his retina, and millions of other conditions in order to enable him, as an adult, to respond selectively to the red belly of a rival. Whatever wonders phenogeny can perform, however, it cannot extract from these factors information that simply is not contained in them, namely the information that a rival is red underneath.

(Ibid.: 37) Lorenz considered that environmental factors should be treated as “channel conditions” and the genotype as a “signal”. Th e analogy here is with, say, a radio, where if it is working correctly the signal – that is, the music or the talk or what- ever – will come through clearly. Crackles and pops due to a malfunction of the radio or a problem with the transmission are interferences due to the channel conditions, rather than part of the signal.

However, as developmental systems theorists such as Susan Oyama (1985) have argued, the problem here is that deciding what counts as signal and what counts as channel conditions depends on what you are interested in. If you are a radio engineer trying to fi x the radio, then you may be interested in the clicks and pops, as they may enable you to discover what is wrong with it, and whether you have fi xed it. You will probably tune the radio to static so that the sounds from the transmitted programmes do not interfere with the information you are interested in. In this case, what the radio receives – that is, static, or nothing – is part of the channel conditions, and the crackles and pops are part of the signal. Likewise, if we hold environmental conditions constant in order to see what happens when we manipulate the genome, we can consider the environment to be channel conditions. But we might alternatively hold the genome constant to see what happens when we manipulate some aspect of the environment, in which case we can consider the genome to be part of the channel conditions.

Lehrmann argued that any trait whatsoever requires environmental condi- tions to be a certain way in order to develop, and will develop diff erently or not at all if the environmental conditions are varied in certain ways. Th is point can be seen to be trivially true, boringly obvious, if one considers that in the absence of food or oxygen, no trait would develop at all. But the idea that some traits

are innate and some are acquired pervades our biological thinking, so much so that even a great scientist such as Lorenz accepted it.

Abandoning the innate/acquired dichotomy

Developmental systems theory rejects the distinction between the innate and acquired. Paul Griffi ths (2002) has recently argued that this distinction belongs to folk biology, that is, it is a pre-scientifi c idea, like the pre-Darwinian idea of biological species as fi xed and immutable kinds. Rather than asking whether a trait is innate or acquired, developmental systems theorists urge that we should ask: what is its developmental history? And what resources does it need in order to develop? Every textbook on genetics, evolution or evolutionary psychology nowadays carefully points out that the expression of a gene depends on the envi- ronment. But developmental systems theorists wonder whether such statements are merely paying lip-service to the idea, or whether the implications of this have been truly taken to heart. Th e idea that genes are what control the process of development retains a powerful grip on our imaginations, and it is this grip that developmental systems theory seeks to break.

We saw in Chapter 2 how it is an integral part of the Hamilton–Williams view that genes contain the information for building an organism. It is admitted by all biologists, including those who are inspired by Hamilton and Williams, that the actual development of an organism depends not just on the genes, but also requires that the right environmental and other extra-genetic resources be present. A creature that does not eat will die, no matter what information its genes contain. Moreover, it is obvious to everyone and universally acknowl- edged that in developing in the womb a mammal needs the resources the womb provides to develop. To say, as Lehrmann does, that environmental resources make a big diff erence, hardly seems to impugn the notion that genes contain the information. A cake could not be made without the eggs and fl our and so on, and a building could not be built without the bricks and mortar and so on, but that does not impugn the idea that it is the recipe, or the architect’s plan, that contains the information determining how the ingredients are put together. We can accept the validity of Lehrmann’s experimental fi ndings and say that what the genes provide – or, as we might otherwise put it, what is innate – is the propensity to respond to a certain environmental circumstance in a certain way. Th e person who has genes for being tall, say, will not be tall in just any set of environmental circumstances, but will, given the right diet and so on, be tall. All biologists accept this. Indeed, it has become standard practice in perfectly orthodox textbooks on evolution and evolutionary psychology to insist that the distinction between innate and acquired is meaningless. For example:

As with all interactions, the product simply cannot be sensibly analyzed into separate genetically determined and environmentally determined

components or degrees of infl uence. For this reason, everything, from the most delicate nuance of Richard Stauss’s last performance of Beethoven’s Fift h Symphony to the presence of calcium salts in his bones at birth, is totally and to the same extent genetically and environmentally code- termined. (Tooby & Cosmides 1992: 83–4) Here is another example (from a recent textbook on “biopsychology”):

Like earlier versions of the nature–nurture question, the how-much-of- it-is-genetic-and-how-much-of-it-is-the-result-of-experience version is fundamentally fl awed. Th e problem is that it is based on the premise that genetic factors and experiential factors combine in an additive fashion – that a behavioural capacity, such as intelligence, is created through the combination or mixture of so many parts of genetics and so many parts of experience, rather than through the interaction of genetics and expe- rience. Once you learn more about how genetic factors and experience interact, you will better appreciate the folly of this assumption.

(Pinel 2000: 24) Th is is despite the fact that most evolutionary psychologists are perfectly ortho- dox adherents of the Hamilton–Williams view of evolution. Th is view is some- times referred to as the “interactionist consensus”, and is ably defended by Matt Ridley in Nature via Nurture (2003b). What, then, it might be asked, is so dis- tinctive about developmental systems theory?