9.1: Learning, Genetics, and their Interaction

Learning Objectives

1. Describe several definitions of learning which vary depending on theoretical perspective.
2. Discuss the claim that behavior is not random, but orderly and lawful.
3. Describe the fundamental law that governs the organization of behavior and the origin of that natural law.
4. Explain the similarities and differences between information in genes and learned information.
5. Discuss the nature-nurture continuum.
6. Describe examples of "biological preparedness" or biological constraints on learning.

Overview

In this section, we examine learning and how it contributes to the adaptive organization of mind and behavior. To understand learning within its broader biological context, it is important to compare it with genetic information, the other major source of information that organizes behavior into adaptive patterns. Learning refers to behavioral change as a result of experience, but learning is not a single, unitary phenomenon. Instead there are many types of learning which are specialized to adapt to various features of the environment and to solve a variety of adaptive problems. In other words, learning evolved in many forms to serve a range of adaptive functions. Learned and genetic sources of information interact to organize behavior into adaptive patterns. The relative contribution of each varies with the species and the behavior in question.

Learned and Genetic Sources of Information Shape Adaptive Behavior

Learning is defined differently by different psychologists depending upon the theoretical emphasis of the psychologist. Strict behaviorists rejected explanations of behavior that involved reference to internal mental processes. Instead, they emphasized the measurable relations between observable behaviors and observable stimuli. Consequently, behaviorists usually define learning as a change in behavior as a result of experience (excluding changes due to fatigue or other special circumstances). Cognitive psychologists, partially in reaction against strict behaviorism, are more likely to define learning as acquisition of information as a result of experience. From an evolutionary perspective, learning can be thought of as the acquisition of information during the lifetime of the individual animal. Since information often leads to changes in behavior, learning can also be thought of as the acquisition of behaviors during the lifetime of the individual. These last two perspectives differentiate learned information from genetic information which is acquired over the evolutionary history of the species.

Behavior is not usually random. An evolutionary perspective emphasizes the role of learning as a means of achieving successful adaptation. Certainly, the ability to learn new behaviors in response to new situations is valuable to survival and therefore increases the chances for reproduction and the transmission of one's genes into future generations, including genes for learning itself. This is important because it suggests how and why learning evolved. It also suggests why behavior is usually orderly and lawful. Behavior is organized to promote survival and reproduction. This outcome is an inevitable product of the forces of evolution, most notably, natural selection. Thus, learning itself is an evolved property of nervous systems.

Figure \(\PageIndex{1}\): Dusky Langur infant and mother. In the first few months the infant is constantly breast-fed. The mother must teach her infant to eat leaves, as shown in this photo. (Image and caption adapted from Wikimedia Commons; File:Dusky Langur infant learning to eat leaves.jpg; https://commons.wikimedia.org/wiki/F...eat_leaves.jpg; by: Roughdiamond21; licensed under the Creative Commons Attribution-Share Alike 4.0 International license).

Behavior, and other traits of organisms, ultimately are organized by information. Just like a builder needs information in the form of structural plans to construct a building, information is required to build and operate an organism, including the guidance of its movement, its behavior. In short, behavior is not random, but orderly and lawful, because it is organized by information selected and filtered by two processes. Learning is one source of the information that organizes behavior into adaptive patterns. The second informational source for the adaptive organization of living things is in genes, as previously discussed. We know that genetic information is filtered over countless generations by natural selection and other processes of evolution so that the information transmitted across generations in genes generates traits that, in general, contribute to survival and reproduction. In short, information is required to organize living things and their functioning. This information comes from two sources: 1) genes and genetic evolution; and 2) learning and laws of learning (in those organisms that are capable of learning).

Let's briefly compare these two sources of information which organize behavior into forms which help an animal adapt to environmental demands (see Table 10.1.1 below). There are four main differences to examine.

Firstly, genetic information is available to all living organisms on earth, but learned information is available only to species whose brains are equipped with properties that make learning possible. Do flies learn? Do cockroaches? Do frogs? If they do, how much do they learn, how readily do they learn? How important is learning in the life of a frog compared to how important learning is in the life of a dog, a chimpanzee, or a human? In general, learning is more characteristic of the brains of the more complex animals, especially the mammals. Nevertheless, learning does occur even in many invertebrates (animals without backbones, such as insects or squid and octopus). Usually, however, the more complex the animal's brain, the more likely it is that the animal has well developed capacities for learning--capacities for the acquisition of information during its individual lifetime.

Secondly, genetic information has been acquired and transmitted over the entire genetic history of the species, whereas learned information is acquired during the short lifetime of the individual animal. For example, think of flies, or pelicans, both of whom are very good at flying. They ride the air currents perfectly and skim the ocean only inches above it, their paths rising and falling with the tops of breaking waves. How do these birds (and flies) know how to fly at all, and to fly and dive so well?

Figure \(\PageIndex{2}\): Brown pelican tucking its wings as it dives for a fish. Genetic information controls the complex, precisely timed movements involved (Image from Wikimedia Commons; File:Brown pelican (Pelecanus occidentalis occidentalis) diving.jpg; https://commons.wikimedia.org/wiki/F...is)_diving.jpg; By Charles J. Sharp, Sharp Photography; licensed under the Creative Commons Attribution-Share Alike 4.0 International license).

Over the evolutionary history of these diverse species (one an insect, the other a large bird), natural selection has preserved the genetic information that allows flies and pelicans to fly (they don't learn it); and it is the "correct" information needed to organize the complex movements of flight in these two very different species. How did the correct information that so perfectly organizes the movements required for flight, get into fly DNA and pelican DNA? The primary mechanism for acquisition of the correct (i.e., adaptive) genetic information, is natural selection. Its method of transmission is heredity.

By contrast, learned information is useful because some changes in the environment may be temporary or unique to the experience of only one or a few individuals and may impact chances for survival and reproduction (successful adaptation) . Such changes are far too rapid and too specific to one or a few individuals for the relatively slow processes of natural selection to operate. For example, learning where the local water holes are would certainly be very useful to a lion during the dry season. Dependence upon genetics for this type of information isn't likely to work very well. Learning mechanisms are required.

Figure \(\PageIndex{3}\): Lioness drinking from small water hole on the African savannah. Information about location of water on the savannah changes too rapidly to be incorporated into genes and therefore must be learned (Image from Wikimedia Commons; File:Lioness drinking.jpg; https://commons.wikimedia.org/wiki/F...s_drinking.jpg; By James Wagner; licensed under the Creative Commons Attribution-Share Alike 4.0 International license).

Thirdly, the mode of coding and storage is different for genetic information compared to learned information. Remember, DNA forms a molecular code for coding and storage of genetic information. Learned information is coded and stored in memory systems in brains. This storage of learned information is complicated and takes many forms. Current research suggests that in general, changes in existing synapses, making them more or less responsive, and/or formation of new synapses, stores learned information in memory. More on this process will be covered in subsequent sections of this chapter.

Lastly, genetic information is transmitted across generations by genetic transmission (heredity). By contrast, learned information, in a few species including us, can also be transmitted across generations--not by genetic transmission, but instead by what is known as cultural transmission (tradition, imitation of the old by the younger members of the social group, books, teaching and learning, storytelling, and so forth). Cultural transmission occurs in relatively few species. We can do it; chimpanzees can do it to a limited degree; Japanese macaque (ma-cack) monkeys can do it to a limited degree. However, rats, and most other species, can't do cultural transmission, and certainly no other species comes close to using cultural transmission to the extent that humans do.

Figure \(\PageIndex{4}\): Macaque monkey feeding. Learned behaviors can be transmitted across generations by cultural transmission by humans and a limited number of other species including macaques (Image from Wikimedia Commons; File:Artis Dining Japanese macaque (6807832054).jpg; https://commons.wikimedia.org/wiki/F...807832054).jpg; By Kitty Terwolbeck; licensed under the Creative Commons Attribution 2.0 Generic license).

Cultural transmission takes a special kind of brain but most species don't have the kind of brain circuit organization required for cultural transmission (the transmission of learned information from generation to generation). Language in humans, of course, plays a crucial role in human cultural transmission, but so do technological and social inventions such as writing, the printing press, film, video, formal education, research institutions, computers, and the internet. All have magnified human cultural transmission and played an enormous role in recent human adaptation (Koenigshofer, 2011). Just as swimming can be considered a defining adaptation of fish, cultural transmission is an adaptive specialty of humans.

Period of Acquisition Laws of Acquisition Mechanisms of Encoding/Storage Transmission Mechanism

Genetic information	acquired over generations (slow information acquisition process), producing species-wide, innate adaptations	acquired by the laws of evolution, primarily by natural selection, over the evolutionary history of the species	encoded and stored in a molecular code in DNA in the genes and chromosomes of the nucleus of cells	transmitted across generations by genetic transmission (heredity, inheritance)
Learned information	acquired during an individual's lifetime (fast information acquisition process) producing rapid and individualized adaptation	acquired by the laws of learning such as the law of effect and association by occurrence of events close in time	encoded and stored in changes in neural circuits probably involving changes in synaptic connections between neurons	transmitted across generations by cultural transmission

Table 10.1.1. Comparisons between genetic and learned information organizing behavior into adaptive patterns. Adaptations, including behavioral adaptations, are not random, but highly structured. This structure requires information. Two sources of information organize behavioral adaptations--genetics and learning, nature and nurture, in interaction (table and caption by Kenneth A. Koenigshofer, PhD; licensed under the Creative Commons Attribution-Share Alike 4.0 International license).

Types of Biological Adaptation

At this point it is useful to note that biological adaptations can be loosely categorized into three (overlapping) general types:

1. Anatomical adaptations (structural features of the organism such as having fur, or wings, or fins, or hands, or bones, or a liver, or a large brain with a well developed cerebral cortex). These are organized by genetic information and change (evolve) only relatively slowly (although small changes, for example, in beak size and thickness of finches in the Galapagos, can occur much more rapidly; Grant & Grant, 1993).
2. Physiological adaptations (internal dynamic processes of the organism such as photosynthesis in plants, digestive processes in animals, the immune system's operations, shivering in response to cold, sweating in response to excess heat, the circulatory system's operations, etc.). These are organized by genetic information and change (evolve) only relatively slowly, although the immune system shows significant plasticity during the individual lifetime to deal with newly encountered pathogens.
3. Behavioral adaptations (the goal-directed movements of the organism and the mental processes such as thoughts, plans, emotions, perceptions, reasoning processes, imagination, etc. that underlie and control these movements). As implied above, behavioral adaptations can be organized by genetic information (genetically preprogrammed, "instinct" and reflexes; flying in flies; swimming in fish; feeding in frogs; sex drive in humans) or by learned information (acquired during the lifetime of the animal), or by a combination of both of these sources. It is important to be aware that the abilities for learning in any species are themselves genetically evolved. Species that can learn can do so only because learning, and the properties of the nervous system that make learning possible, evolved in those species, including humans, as a result of natural selection.

Figure \(\PageIndex{5}\): Human sex drive is inborn. It can be thought of as a psychological adaptation involving intense emotions leading to reproductive behavior within the context of a pair-bond, increasing likelihood of surviving offspring. Learned cultural practices influence courtship practices and the expression of innate sex drive. (Image from Wikipedia Commons; File:Family love wiki008.jpg; https://commons.wikimedia.org/wiki/F...ve_wiki008.jpg; By Shagil Kannur; licensed under the Creative Commons Attribution-Share Alike 4.0 International license).

The behaviors of various animal species can be thought of as falling on a nature-nurture continuum, with some behaviors in some species (flies, roaches) being almost completely at the nature (innate) end of the continuum (i.e. behavior determined by genes and genetic evolution), while at the other end, the nurture end of the continuum, are behaviors which are dependent primarily on information acquired during the lifetime of the individual (i.e. learned information) See Figure \(\PageIndex{6}\): below.

Figure \(\PageIndex{6}\): Web construction by spiders is a complex set of movements directed by circuits in the spider nervous system constructed by information in the spider's DNA. The spider's behavior is so stereotyped that experts who study spiders can identify the species of spider from the structure of its web alone, even if the spider is not present. No learned information is required by the spider to construct its species-typical web. By contrast, human construction of structures is highly dependent upon learned information that has been culturally transmitted across generations. The human brain evolved mechanisms for learning, cultural transmission, comprehension of three-dimensional space, and the ability to visualize in imagination forms like the one depicted here. (Images from Wikipedia Commons; Source of image of spider and web: File:Spider weaving it's web.jpg; https://commons.wikimedia.org/wiki/F...it%27s_web.jpg; by Varun V Vasista; licensed under the Creative Commons Attribution-Share Alike 4.0 International license. Source of image of palace in Spain: File:Dawn Charles V Palace Alhambra Granada Andalusia Spain.jpg; https://commons.wikimedia.org/wiki/F...usia_Spain.jpg; by Jebulon; made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication license).

Slow (Genetics) vs. Fast (Learning) Mechanisms of Behavioral Change

Genetically organized behavioral adaptations (such as web-building in spiders), like anatomical and physiological adaptations, are organized by genetic information and therefore they change (evolve) only relatively slowly, over many generations by natural selection and other mechanisms of evolution. However, for many genes in the organism's phenotype, the gene's expression can be affected by multiple environmental factors. The study of this kind of gene-environment interaction is called epigenetics.

By contrast, learned behavioral adaptations can change moment to moment and, as discussed above, may be transmitted (in some species) to future generations by cultural transmission to the benefit of those future generations. For example, the agricultural practices--learned behavioral adaptations or "adjustments"--upon which we have come to depend for our food supply, were invented by people who died generations ago. However, the death of those who invented these behaviors did not result in the loss of the successful behavioral adaptations upon which we depend for our food supply. Instead, these learned behavioral adaptations have been passed on, and refined, over many generations, to our current generation to its adaptive advantage--not by genetic transmission, but by cultural transmission. All would impossible were we, humans, not so powerfully equipped by our brain evolution for efficient cultural transmission of learned behavioral adaptations across generations. By this means, the learning of prior generations is not lost, but remains over generations for each new generation to build upon. Just like flying is a specialty of birds, or swimming is a specialty of fish, cultural transmission is the specialty of the human species.

Summary

In short, learning describes processes whereby information is acquired during the lifetime of an individual animal. Learned information, along with genetic information, helps organize the animal's behavior into adaptive patterns, especially in response to short-term environmental changes where specific, frequently changing details are adaptively significant and therefore must be captured by the organism and put to adaptive use. For example, learning and remembering where a temporary water hole is located on the open savannah is essential to survival for innumerable species that live on the African plains. Because many short-term event details do not regularly recur over generations, such non-recurrent environmental details cannot drive natural selection for genetically evolved instinctual or reflexive adaptations. Instead adaptation to such novel idiosyncratic event details favors the evolution of learning mechanisms (Koenigshofer, 2017). Usually this learned information supplements hereditary (genetic) sources of information in the organization of successful behavioral adaptations--behavioral solutions to the problems of survival and reproduction. As noted above, behavior is one way that organisms (at least animals) adapt. Behavior becomes organized into adaptive patterns by information (i.e. behavior is not random, but guided by laws of nature which govern chances of survival and reproduction--laws of evolution and the laws of learning). The information that organizes behavior comes from the genes after having been perfected by eons of genetic evolution by natural selection. That organizing information can also come from learning by an individual animal during its lifetime (laws which govern learning are also organized to enhance survival and reproduction--see sections below).

Adaptive behaviors can be transmitted to future generations. If the behavior is organized by information in the genes, then that behavior can be transmitted by genetic transmission (heredity). If the information for a particular behavior comes from learning (and is stored in memory), then the behavior can be transmitted to future generations, not by genetic transmission, but instead by cultural transmission (in some species, as noted above). Thus behavioral adaptations in species capable of cultural transmission can undergo not only genetic evolution (true for behaviors organized by genetic information contained in DNA, and also true of anatomical and physiological adaptations) but also cultural evolution (examples of cultural evolution are the development of human technology, modern medical practices, agricultural practices, economies, science, governmental systems and so on, leading over time to generally improved human adaptation). Cultural transmission and the resulting cultural evolution gives our species great survival advantage. Cultural transmission accounts for the success of the human species more than any other single factor.

References

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Attributions

"Learning, Genes, and Adaptation" is original material written by Kenneth A. Koenigshofer, PhD. and is licensed under CC BY 4.0.