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Canine Epigenetics

Canine-Epigenetics

Epigenetics [Greek epi– ἐπι- = above, over, on, in addition to] is the study of heritable gene functions that cause stable phenotypic variations without affecting the DNA sequence of the organism.

Conrad Waddington coined the term in 1942 before we knew that DNA was the molecular basis of genes. He proposed that genes are differentially turned on and off by another level of “epigenetic” processes to produce different cells in the developing embryo.

 

Epigenetics, Environment, Phenotypic Plasticity

Behavioral epigenetics studies the role of epigenetics in forming behavior. It seeks to explain how nurture may shape nature. It attempts to provide a framework for understanding how the environment may influence gene expression to produce individual differences in behavior.

However, we must be careful with the term ‘environment’. To a geneticist, the environment is everything that isn’t the cellular environment of the DNA. To a social scientist, the environment catches everything from parental care to the stock market climate. That the cellular environment might be essential for understanding gene expression does not imply that one’s housing conditions have a similar impact.

The environment influences particular changes in gene action. For example, in alligators and specific turtles, egg incubation temperature affects the gene expression defining the sex of the individual. In these cases, the state of the gene passes down through cell divisions within a single organism, but it resets in eggs or sperm most times, so it does not transfer between generations. Thus, the mechanism does not influence evolution. An epigenetic state must carry over into the progeny to have any evolutionary relevance. For instance, molecules that bind to DNA and transfer to the offspring partially control the coat color of mice, Rattus norvegicus.

We must not confuse ‘epigenetics’ with ‘phenotypic plasticity,’ i.e., the capacity of one genotype of producing different phenotypes depending on the environment.

 

Belyayev’s Experiments

Belyayev’s experimented with silver foxes, Vulpes vulpes, which he bred based on a selection for tameness. He tested the animals, gave them a tameness score, and placed them in one of three groups. By the 20th generation, 35 percent of the animals were in the higher class, the ‘elite’ group; and as of 2009, ‘elite foxes’ made up 70 to 80 percent of the population. In addition, the changes in the tame foxes over the generations were not only behavioral but also physiological.

Belayev didn’t prove the effect of epigenetics in domestication. He proved the probability of domestication having occurred through selective breeding. In his own words, “It seems possible that the high frequency of the star mutation is due to strong selection intentionally applied for behavior.” (Belyaev et al. 1981). His experiments are a unique resource for studying the genetics of domestication.

The question of epigenetics goes deeper. Genes controlling plasma glucocorticoids were probably the targets during selection for tameness and the effects showed at all levels from phenotypic parameters to the gene expression of the corticotropin-releasing hormone (CRH), proopiomelanocortin (POMC), and the glucocorticoid receptor (GCR). Trut et al. conclude that “It appears plausible that the phenotypic novelties in the experimental fox population could be due to changes in gene activity, largely in its epigenetic modification.” (Trut et al. 2009).

If environmental conditions prefer a gene expression which parents pass to their progeny, and which, in turn, is more environmental independent than in the previous generation, then we can talk of a genuine epigenetic effect. If it is not, then we are talking about phenotypic plasticity and not epigenetics.

Most epigenetic changes occur only within the course of one individual organism’s lifetime—and that’s it. They can, though, pass to the organism’s offspring (transgenerational epigenetic inheritance). Also, if gene inactivation occurs in a sperm or egg cell that results in fertilization, this epigenetic modification may transfer to the next generation.

 

Conclusions

Do epigenetics make Lamarck right and Darwin wrong? To answer that, we must determine whether usage or selection causes epigenetic effects. Evidence supports the latter. Thus, epigenetic factors are yet another source of heritable natural variation. Darwin would have appreciated it. In fact, in 1868 he cautiously proposed ‘Pangenesis’ to cover the possibility that acquired characters might transfer to the progeny (whereby gemmules passed from somatic to reproductive cells). Modern discoveries seem to confirm that Darwin was right again.

At the time of writing, I have not found conclusive studies showing the effect of epigenetics on canine (Canis lupus familiaris) behavior, although Belyayev’s and subsequent studies make it plausible. I would appreciate if my reader has relevant information that may clarify this topic.

In popular writings appealing to the broad public, epigenetics seems to be everything that is not in the genes. However, that is not the scientific view, one requirement being that an effect is only epigenetic if it impacts the evolution of a trait. Therefore, I would recommend prudence when analyzing any statement claiming ‘epigenetic’ effects. These days, the term ‘epigenetic’ (like ‘quantum’) is prone to arouse the fantasy of quacksalvers.

References

Belyayev, D.K., Ruvinsky, A.O., and Trut, L N. 1981. Inherited activation/inactivation of the star gene in foxes. Journal of Heredity, 72: 264-274.

Chandler, V.L. 2007. Paramutation: from maize to mice. Cell. 128 (4): 641–45. doi:10.1016/j.cell.2007.02.007. PMID 17320501.

Cimarelli, G., Virányi, Z., Turcsán B., Rónai, Z., Sasvári-Székely, M., Bánlaki, Z. 2017. Social Behavior of Pet Dogs Is Associated with Peripheral OXTR Methylation. Front Psychol. 2017 Apr 10;8:549. doi: 10.3389/fpsyg.2017.00549.

Darwin, C. R. 1868. The variation of animals and plants under domestication. London: John Murray. 1st edition, second issue. Volume 1.

Dias, B.G., & Ressler, K.J. 2014. Parental olfactory experience influences behavior and neural structure in subsequent generations. Nature Neuroscience, 17(1), 89-98. doi: 10.1038/nn.3594.

Dupont C., Armant D.R., Brenner, C.A. 2009. Epigenetics: definition, mechanisms and clinical perspective. Seminars in Reproductive Medicine. 27 (5): 351–57. doi:10.1055/s-0029-1237423. PMC 2791696. PMID 19711245.

Florean, C. 2014. Food that shapes you: how diet can change your epigenome. Science in School, Issue 28.

Hughes, V. 2014. Epigenetics: the sins of the father. Nature, 507, 22-24.

Kaplan, G. 2017. Why is my dog this way, does it matter if we know, and what can we do? IAABC journal.

Pörtt, D., Jung, C. 2017. Is dog domestication due to epigenetic modulation in brain? Dog Behavior. Vol 3, No 2 (2017). ISSN 2421-5678.

Trut, L.N. 1996. Sex ratio in silver foxes: effects of domestication and the star gene. Theor Appl Genet (1996)92:109-115. ISSN
1432-2242.

Trut, L., Oskina, I., and Kharlamova, A. 2009. Animal evolution during domestication: the domesticated fox as a model. Bioessays. 2009 Mar; 31(3): 349–360.

Featured image by Anton Antonsen, photo by Hitdelight.

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“Creation,” the Movie About Charles Darwin—too Controversial for Religious USA?

(originally published September 12, 2012)

 

Creation opened the Toronto Film Festival 2009 and had British premiere on September 25. The movie relies on the book “Annie’s Box—Charles Darwin, his Daughter and Evolution,” first edition from 2001, written by Randal Keynes, a great-great-grandson of Darwin.

Creation has been sold in almost every country around the world. However, US distributors purposefully passed on the film, which they expected to prove hugely controversial in a country where only 39% of Americans accept the theory of evolution (according to a Gallup poll conducted in February 2012). Finally, the movie was released in the USA on January 22, 2010.

The creationists’ attacks on Darwin and evolution are unscientific and irrational, using tricks to stir strong emotions up and numb reason (with very few exceptions). Movieguide.org, an influential site, which reviews films from a Christian perspective, described Darwin as the father of eugenics and denounced him as “[…] a racist, a bigot and a 1800s naturalist whose legacy is mass murder.” His “half-baked theory” directly influenced Adolf Hitler and led to “atrocities, crimes against humanity, cloning and genetic engineering,” the site stated. The movie has sparked fierce debate on US Christian websites, with a typical comment dismissing evolution as “[…] a silly theory with a serious lack of evidence to support it despite over a century of trying.”

Jeremy Thomas, the Oscar-winning producer of Creation, said he was astonished that such attitudes exist 150 years after On The Origin of Species was published.

For the full article on the Telegraph.co.uk, by Anita Singh, Showbusiness Editor, September 11, 2009, please click here.

 

Darwin’s Dangerous Idea*

*This is the title of a book by Daniel Dennett from 1995, a book this author recommends to all who want to know the full extent of Darwin’s magnificent idea.

 

 

Acceptance of Darwin’s theory of evolution by natural selection, or just evolution, is remarkably low in the USA as various polls and statistics have shown. Please, see statistics below from the New York Times here, Science 11 August 2006, Vol 313, here, and the National Geographic, here.

 

 

A recent study commissioned by the British Council reveals interesting facts (see the full spreadsheet). The study asked samples of a population of 10 countries different questions about Darwin and evolution. From among the many answers, the two below are maybe particularly interesting: as to whether people had heard of Darwin and they agreed we had scientific evidence supporting evolution.

The first column indicates the answers ‘No’ to ‘Have you heard of Darwin?’ The second column indicates the answers ‘No’ to ‘Do we have scientific evidence for evolution?’ All columns show percentages of the asked population.

 

Steve Kramer analyzed the full results for statistical significances (click here).

That 28% of the Spanish and 16% of the USA populations had not heard of Darwin is staggering. On the other side, it may surprise westerners that 90% of the Chinese and 93% of the Russians had heard of Darwin. 24% of the USA citizens deny the massive amount of scientific evidence in favor of evolution gathered throughout the last 150 years. This figure is impressive because since only 39% of all the USA population accepts evolution, this means that there are many who take the evidence for evolution as valid and yet refuse to accept it—an apparent contradiction and proof of irrational behavior for if A => B and B => C, then A => C.

Only 5% of the Chinese and 2% of the Indians disputed the scientific evidence. As to South Africa and Egypt, the figures may reflect these countries’ enormous social and economic struggle and, therefore, insufficient school and information systems—they have more pressing issues at hand than thinking of Darwin or evolution—which is not the case in the rich Western countries. However, among the South Africans that know about Darwin and evolution, only 4% dispute the scientific evidence.

It may appear surprising for westerners, not proficient in Asian culture, that Chinese and Indians seem to accept evolution much better than many westerners, even though Darwin was a western born and educated scientist. His theory of evolution by means of natural selection is a typical western idea, maybe the most brilliant product of western scientific thought.

 

The Asian Acceptance of Evolution

The Asian acceptance of evolution becomes less surprising, though, when we realize that most arguments against evolution are religious. Christianity and Islam are the religions with the highest numbers of followers, and both have a god creator and omnipotent.

Asia has Hinduism and Buddhism, and none of them precludes the notion of evolution, nor conflicts with it. In Hinduism and Buddhism, there is no god creator. In this sense, regarding Hinduism and Buddhism as religions might even be misleading. Both are more philosophies of life, a list of codes of conduct, help to self-help, than real religions based on faith alone rather than arguments of reason. Therefore, Buddhists and Hindus are more liable to welcome a sound explanation of the origins of life and evolution, when offered one, than Christians and Islamists. Western mainstream ideology and traditions are to a great extent based on matters of belief, religious oppression, faith rather than fact. That may seem paradoxical since most of the great scientific discoveries happened in the western world.

Hinduism is a way of living according to the understanding of the principles of Vedas and Upanishads. Veda is revealed knowledge, just as the knowledge of gravity was revealed to Newton. Hinduism is the world’s oldest ‘religion’. It has no single founder; it is a mixture of various traditions, practices, and lineages.

Buddhism, the largest ideology in Asia, derives from Hinduism and began with Siddhartha Gautama (Buddha) who told people to assume responsibility for their lives, to search the end of suffering by modifying their lifestyle and seeking knowledge. He led by example, as human as anyone else. He gave people choices, a manual to self-help, the four noble truths and the eightfold path, all making perfect sense, no mysteries, no secrets, no threats, no holy wars.

 

Western Religion and Evolution

The Western World had an excellent chance to emulate Buddha, when Jesus of Nazareth came around some 500 years later, but didn’t. It could have given people a manual to self-help, like Buddhism’s. Instead, it made Jesus the son of God, the creator, the omnipotent, and omnipresent. The ensuing fanaticism and the church did not inspire people to seek their own fortunes by actively improving their lifestyle and searching for results. It took their responsibilities away, put all the burden on the shoulders of Jesus of Nazareth, declared him the savior of humanity, God himself (according to the Bible). Then, it created a lot of mysterious occurrences like the descent into hell and resurrection. It scared people senseless and exercised coercion—like the infamous Inquisition and the Crusades (holy wars)—declared the holiness of the church, and told the followers, “believe, repent and leave the rest to us” (or otherwise you’ll burn in hell—if we don’t burn you on Earth).

It took many years for westerners to liberate themselves from the iron hand of the church and some did it better than others for various reasons. While Europe managed that to an extent, the USA still finds it disturbing. Still, religion alone does not explain why USAnians more than Europeans find it difficult to accept evolution. Many religious Europeans reconcile their faith with evolution (and so do some USAnians). The explanation lies rather in the way USA politicians have used, and use, religion to achieve their goals. “Believe (in us) and leave the rest to us” suits them perfectly well.

 

Evolution in the USA

The USA is a country of strong emotions, of great economic and political manipulation and clever demagogues. It is maybe fitting, not by accident, that, in the USA, Darwin is also often misquoted and the “survival of the fittest” becomes “the survival of the strongest.” USA fundamentalism differs from mainstream Protestantism in both the USA and Europe. The biblical fundamentalism in the United States considers Genesis, as a true and accurate account of the creation, superseding any scientific evidence.

In contrast, mainstream Protestants in Europe (and in the USA), as well as the Catholic Church are more contemporary in the sense that they keep pace, until a certain degree, with the evolution of the world and scientific discoveries. They consider Genesis as a metaphor and are more likely to reconcile their faith with the work of Darwin and other scientists. Furthermore, evolution has been politicized in the USA in a manner never seen in Europe or anywhere else. The conservative wing of the Republican Party has adopted creationism as a part of their program to consolidate their support. In the 1990s, the Republican plans in seven states included explicit demands for the teaching of creation science (see 1 and 2). There are Christian political parties in Europe, but none, at least major party, uses opposition to evolution as a part of its political program.

Creation (the title is somehow unfortunate, and I’m sure Darwin would find it too pretentious) will stir up some (evolutive) discussions. We have had them in Europe (we still have them), and we grew fitter, I believe. What (most) Europeans don’t accept any longer is, “believe and leave the rest to us.” It will happen one day in the USA as well—it’s only a question of time.

Oppression, censorship, conformism, in their many facets, are not evolutionarily stable strategies (ESS), not in the Christian world, not in the Islamic world, not in any world. Variation leads to ESS and has proved it again and again. Evolution is in no rush, time works for it, and its algorithm is relentless.

Learn more in our course Evolution. Evolution is the process of change in all forms of life over generations; behavior is as a tool in the struggle for survival and reproduction. This is an indispensable course to understand how behavior originates, develops and evolves. Evolutionary biologist Roger Abrantes wrote the textbook included in the online course as a beautiful flip page book. This is a free course. Start today.

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Evolutionarily Stable Strategies and Behavior

Evolutionarily Stable Strategies and Behavior (DovesAndHawks).

Evolutionary biologists imagine a time before a particular trait emerges. Then, they postulate that a rare gene arises in an individual, and they ask what circumstances would favor the spread of that gene throughout the population. If natural selection favors the gene, then the individuals with the genotypes incorporating that particular gene will have increased fitness. A gene must compete with other genes in the gene pool, and resist any invasion from mutants, to become established in a population’s gene pool.

In considering evolutionary strategies that influence behavior, we visualize a situation in which changes in genotype lead to changes in behavior. By ‘the gene for sibling care’ we mean that genetic differences exist in the population such that some individuals aid their siblings while others do not. Similarly, by ‘dove strategy’ we mean that animals exist in the population that do not engage in fights and that they pass this trait from one generation to the next.

At first sight, it might seem that the most successful evolutionary strategy will invariably spread throughout the population and, eventually, will supplant all others. While this does occur, it is far from always being so. Sometimes, there is no single dominant strategy. Competing strategies may be interdependent in that the success of one depends upon the existence of the other and the frequency with which the population adopts the other. For example, the strategy of mimicry has no value if the warning strategy of the model is not efficient.

Game theory belongs to mathematics and economics, and it studies situations where players choose different actions in an attempt to maximize their returns. It is a good model for evolutionary biologists to approach situations in which various decision makers interact. The payoffs in biological simulations correspond to fitness—comparable to money in economics. Simulations focus on achieving a balance that evolutionary strategies would maintain. The Evolutionarily Stable Strategy (ESS), introduced by John Maynard Smith in 1973 (and published in 1982), is the most well known of these strategies. Maynard Smith used the hawk-dove simulation to analyze fighting and territorial behavior. Together with Harper in 2003, he employed an ESS to explain the emergence of animal communication.

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An evolutionarily stable strategy (ESS) is a strategy that no other feasible alternative can better, given that sufficient members of the population adopt it. The best strategy for an individual depends upon the strategy or strategies that other members of the same population adopt. Since the same applies to all individuals in that particular population, a mutant gene cannot invade an  ESS successfully.

The traditional way to illustrate this problem is simulating the encounter between two strategies, hawk and dove. When a hawk meets a hawk, it wins on half of the occasions, and it loses and suffers an injury on the other half. Hawks always beat doves. Doves always retreat against hawks. Whenever a dove meets another dove, there is always a display, and it wins on half of the occasions. Under these rules, populations of only hawks or doves are no ESS because a hawk can invade a population made up entirely of doves and a dove can invade a population of hawks only. Both would have an advantage and would spread in the population. A hawk in a population of doves would win all contests, and a dove in a population of hawks would never get injured because it wouldn’t fight.

However, it is possible for a mixture of hawks and doves to provide a stable situation when their numbers reach a certain proportion of the total population. For example, with payoffs as winner +50, injury -100, loser 0, display -10, a population comprising hawks and doves (or individuals adopting a mixed strategy of alternating between playing hawk and dove strategies) is an ESS whenever 58,3% of the population are hawks and 41,7% doves; or when all individuals behave at random as hawks in 58,3% of the encounters and doves in 41,7%. The percentages (the point of equilibrium) depend on costs and benefits (or the pay-off, which is equal to benefits minus costs).

Evolutionarily stable strategies are not artificial constructs. They exist in nature. The Oryx, Oryx gazella, have sharp pointed horns, which they never use in contests with rivals and only in defense against predators. They play the dove strategy. Up to 10% per year of Musk Ox, Ovibos moschatus, adult males die because of injuries sustained while fighting over females. They play the hawk strategy.

An ESS is a modified form of a Nash equilibrium. In most simple games, the ESSes and Nash equilibria coincide perfectly, but some games may have Nash equilibria that are not ESSes. Furthermore, even if a game has pure strategy Nash equilibria, it might be that none of those pure strategies are ESSes. We can prove both Nash equilibria and ESS mathematically (see references).

Peer-to-peer file sharing is a good example of an ESS in our modern society. Bit Torrent peers use Tit-for-Tat strategy to optimize their download speed. They achieve cooperation exchanging upload bandwidth with download bandwidth.

Evolutionary biology and sociobiology attempt to explain animal behavior and social structures (humans included), primarily in terms of evolutionarily stable strategies.

References

Featured image: The traditional way to illustrate Evolutionarily Stable Strategies is the simulation of the encounter between two strategies, the hawk and the dove.

Learn more in our course Ethology. Ethology studies the behavior of animals in their natural environment. It is fundamental knowledge for the dedicated student of animal behavior as well as for any competent animal trainer. Roger Abrantes wrote the textbook included in the online course as a beautiful flip page book. Learn ethology from a leading ethologist.

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Laughter is the shortest distance…

LaughterSpecies

As you have figured out by now, I enjoy finding proof that humans are not that different from other forms of life. We share many characteristics with the other living creatures on our blue planet. Today, I have one more example for you—laughter.

Laughing is an involuntary reaction in humans consisting of rhythmical contractions of the diaphragm and other parts of the respiratory system. External stimuli, like being tickled, mostly elicit it. We associate it primarily with joy, happiness, and relief, but fear, nervousness, and embarrassment may also cause it. Laughter depends on early learning and cultural factors.

The study of humor and laughter is called gelotology (from the Greek gelos, γέλιο, meaning laughter).

Chimpanzees, gorillas, bonobos, and orangutans display laughter-like behavior when wrestling, playing or tickling. Their laughter consists of alternating inhalations and exhalations that sound to us like breathing and panting.

Rats display long, high frequency, ultrasonic vocalizations during play and when tickled. We can only hear these chirping sounds with proper equipment. They are also ticklish, as are we. Particular areas of their body are more sensitive than others. There is an association between laughter and pleasant feelings. Social bonding occurs with the human tickler, and the rats can even become conditioned to seek the tickling.*

A dog’s laughter sounds similar to a regular pant. A sonograph analysis of this panting behavior shows that the variation of the bursts of frequencies is comparable with the laughing sound. When we play this recorded dog-laughter to dogs in a shelter, it can contribute to promoting play, social behavior, and decrease stress levels.*

Victor Borge once said, “Laughter is the shortest distance between two people.” Maybe, it is simply the shortest distance between any two living creatures.

 

__________

* Panksepp & Burgdorf, 2003, ‘Laughing’ rats and the evolutionary antecedents of human joy?; Simonet, Versteeg & Storie, 2005, Dog-laughter: Recorded playback reduces stress related behavior in shelter dogs.

Featured image: We laugh, but we are not the only ones.

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Learn more in our course Ethology. Ethology studies the behavior of animals in their natural environment. It is fundamental knowledge for the dedicated student of animal behavior as well as for any competent animal trainer. Roger Abrantes wrote the textbook included in the online course as a beautiful flip page book. Learn ethology from a leading ethologist.

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How Wolves Change Rivers

The Wolves Changed the Rivers (WolfByRonanDonovanNG).

In 1926, there were no longer wolves in Yellowstone, once the natural habitat of this species. Between 1977 and the re-introduction in 1995, we have reliable reports of wolves being seen throughout the park. Most of them were either lone wolves or pairs, probably only transiting. Finally, in 1995, grey wolf packs were reintroduced in the Lamar Valley of Yellowstone National Park and Idaho.

Before the extermination, the wolves living within the park belonged to the subspecies Northern Rocky Mountains wolf, Canis lupus irremotus. The reintroduced species of 1995 belong to the subspecies Mackenzie Valley wolf, Canis lupus occidentalis.

The reintroduction of the wolves produced a more significant impact on the biodiversity of the Yellowstone than anticipated.

The wolves’ predation on the elk population, until then unchallenged, produced a significant increase of new-growth in various plants. Aspen and willow trees, previously grazed by the elks more or less at will, got suddenly a chance to grow. With the presence of the wolves, the elks stopped venturing into deeper, and for them dangerous, thickets where they could easily be surprised. They began to avoid areas of low visibility, which would increase the chances of wolf attacks.

The elks began avoiding open regions such as valley bottoms, open meadows, and gorges, where they would be at a disadvantage in case of an attack from a wolf pack. William J. Ripple and Robert L. Bestcha dubbed this process top-down control. In ecology, top-down control denotes that top predators regulate the lower sections of the trophic pyramid. In other words: a top predator controls the structure or population dynamics of a particular ecosystem.

With new vegetation growing and expanding came subtle changes in the waterways running through the park. That had an impact on other species as well. Various bird species came back to Yellowstone national park with the increased number of trees. The beaver, previously extinct in the region, returned to the park. Their dams across the rivers attracted otters, muskrats, and reptiles.

Probably due to the wolves keeping the coyote populations at bay, the red fox got suddenly a chance to survive because the number of rabbits and mice grew considerably. The raven, always the wolf follower, came back to the park as well, now able to feed on the leftovers of the wolves.

The wolves changed the rivers in as much as they readdressed the lost balance within the region, one we had created when we exterminated them. With a better balance between predator and prey, top meat eaters and top grazers, came the possibility for other species to thrive. With the increased vegetation growth, erosion decreased, and the river banks stabilized.

Every time we produce drastic changes in nature, we interfere deeply with the whole eco-system.

Nature is indeed a beautiful act of balance.

 

References and further reading

Featured image: The wolves changed the rivers of the Yellowstone. Picture by photographer Ronan Donovan, NG.

Learn more in our course Ethology. Ethology studies the behavior of animals in their natural environment. It is fundamental knowledge for the dedicated student of animal behavior as well as for any competent animal trainer. Roger Abrantes wrote the textbook included in the online course as a beautiful flip page book. Learn ethology from a leading ethologist.

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The 20 Principles of Genes, Environment and Breeding

The 20 Principles of Genes, Environment and Breeding

Genes code for the traits an organism will show, physical as well as behavioral, but genes are not all. The environment of that organism also plays a crucial role in the way some of its genes will express themselves.

Genes play a large role in the appearance and behavior of organisms. Phenotypes(the appearance of the organism) are determined, in various degrees, by the genotype program (the sum of all genes) and the interaction of the organism with the environment. Some traits are more modifiable by environmental factors, others less. For example, while eye color is solely determined by the genetic coding, genes determine how tall an individual may grow, but nutritional, as well as other health factors experienced by that organism, determine the outcome. In short: the environment by itself cannot create a trait, and only a few traits are solely the product of a strict gene coding.

The same applies to behavior. Behavior is the result of the genetic coding and the effects of the environment on a particular organism. Learning is an adaptation to the environment. Behavioral genetics studies the role of genetics in animal (including human) behavior. Behavioral genetics is an interdisciplinary field, with contributions from biologygeneticsethologypsychology, and statistics. The same basic genetic principles that apply to any phenotype also apply to behavior, but it is more difficult to identify particular genes with particular behaviors than with physical traits. The most reliable assessment of an individual’s genetic contribution to behavior is through the study of twins and half-siblings.

In small populations, like breeds with a limited number of individuals, the genetic contribution tends to be magnified because there is not enough variation. Therefore, it is very important that breeders pay special importance to lineages, keep impeccable records, test the individuals, and choose carefully, which mating system they will use. Failure to be strict may result in highly undesirable results in a few generations with the average population showing undesired traits, physical as well as behavioral.

We breed animals for many different purposes. Breeding means combining 50% of the genes of one animal (a male) to 50% of the genes of another animal (a female) and see what happens. We can never choose single genes as we wish and combine them, so we get the perfect animal, but knowing which traits are dominant, which are recessive, and being able to read pedigrees helps us.

siberian_husky_puppies_31

Litter mates share on average 50% common genes, but only on average. Each got at random 50% of its genes from the male (father) and 50% from the female (mother), but not necessarily the same 50% from each (Photo by TheHusky.info).

Here are some guidelines for breeding (inspired by “20 Principles of Breeding Better Dogs” by Raymond H. Oppenheimer). The objective of the following 20 principles is to help breeders strive for a healthy and fit animal in all aspects, physically as well as behaviorally.

1. The animals you select for breeding today will have an impact on the future population (unless you do not use any of their offspring to continue breeding).

2. Choose carefully the two animals you want to breed. If you only have a limited number of animals at your disposition, you will have to wait for the next generation to make any improvement. As a rule of thumb, you should expect the progeny to be better than the parents.

3. Statistical predictions may not hold true in a small number of animals (as in one litter of puppies). Statistical predictions show accuracy when applied to large populations.

4. A pedigree is a tool to help you learn the desirable and undesirable attributes that an animal is likely to exhibit or reproduce.

5. If you have a well-defined purpose for your breeding program, which you should, you will want to enhance specific attributes, but don’t forget that an animal is a whole. To emphasize one or two features of the animal, you may compromise the soundness and function of the whole organism.

6. Even though, in general, large litters indicate good health and breeding conditions, quantity does not mean quality. You produce quality through careful studies. Be patient and wait until the right breeding stock is available, evaluate what you have already produced and above all, have a breeding plan that is, at least, three generations ahead of the breeding you do today.

7. Skeletal defects are the most difficult to change.

8. Don’t bother with a good animal that cannot reproduce well. The fittest are those who survive and can pass their survival genes to the next generation.

9. Once you have approximately the animal you want, use out-crosses sparingly. For each desirable characteristic you acquire, you will get many undesirable traits that you will have to eliminate in succeeding generations.

10. Inbreedingis the fastest method to achieve desirable characteristics. It will bring forward the best and the worst of your breeding stock. You want to keep the desirable traits and eliminate the undesirable. Inbreeding will reveal hidden traits that you may consider undesirable, and want to eliminate. However, be careful, repeated inbreeding can increase the chances of offspring being affected by recessive or deleterious traits.

mother-wolf-regurgitatinghumansforwolves

Adult wolves regurgitate food for the cubs to eat. Many dog mothers do the same (Photo by Humans For Wolves).

11. Once you have achieved the characteristics you want, line-breeding with sporadic outcrossing seems to be the most prudent approach.

12. Breeding does not create anything new unless you run into favorable mutations (seldom). What you get is what was there to begin with. It may have been hidden for many generations, but it was there.

13. Litter mates share on average 50% common genes, but only on average. Each one got at random 50% of its genes from the male (father) and 50% from the female (mother), but not necessarily the same 50% from each.

14. Hereditary traits are inherited equally from both parents. Do not expect to solve all of your problems in one generation.

15. If the worst animal in your last litter is no better than the worst animal in your first litter, you are not making progress.

16. If the best animal in your last litter is no better than the best animal in your first litter, you are not making progress.

17. Do not choose a breeding animal by either the best or the worst that it has produced. Evaluate the total breeding value of an animal by means of averages of as many offspring as possible.

18. Keep in mind that quality is a combination of soundness and function. It is not merely the lack of undesirable traits, but also the presence of desirable traits. It is the whole animal that counts.

19. Be objective. Don’t allow personal feelings to influence your choice of breeding stock.

20. Be realistic, but strive for excellence. Always try to get the best you can. Be careful: when we breed animals for special characteristics, physical as well as behavioral, we are playing with fire, changing the genome that natural selection created and tested throughout centuries.

Featured image: Hereditary traits are inherited equally from both parents. However, the mother will have more influence on the puppies’ behavior than the father because she spends more time with them.

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Canine Ethogram—Social and Agonistic Behavior

Canine Ethogram—Social and Agonistic Behavior is a catalog of a class of canine behaviors. It includes the most commonly observed behaviors but it’s not an exhaustive list.

Behavior is the response of the system or organism to various stimuli, whether internal or external, conscious or subconscious, overt or covert, and voluntary or involuntary.

Behavior does not originate as a deliberate and well-thought strategy to control a stimulus. Initially, all behavior is probably just a reflex, a response following a particular anatomical or physiological reaction. Like all phenotypes, it happens by chance and evolves thereafter.

Natural selection favors behaviors that prolong the life of an animal and increase its chance of reproducing; over time, a particularly advantageous behavior spreads throughout the population. The disposition (genotype) to display a behavior is innate (otherwise the phenotype would not be subject to natural selection and evolution), It requires, though, maturation and/or reinforcement for the organism to be able to apply it successfully. Behavior is, thus, the product of a combination of innate dispositions and environmental factors. Some behaviors require little conditioning from the environment for the animal to display it while other behaviors require more.

canineethogramsocialagonisticphotos

Pictures illustrating canine social and agonistic behavior. For the classification of the behavior, please see ethogram below. Behavior is dynamic (not static). All interpretations are therefore only approximate and as pictures allow.

An organism can forget a behavior if it does not have the opportunity to display it for a period, or the behavior can be extinguished if it is not subject to reinforcement for a period.

Evolution favors a systematic bias, which moves behavior away from a maximization of utility and towards a maximization of fitness.

Social behavior is behavior involving more than one individual with the primary function of establishing, maintaining, or changing a relationship between individuals, or in a group (society).

Most researchers define social behavior as the behavior shown by members of the same species in a given interaction. That excludes behavior such as predation, which involves members of different species. On the other hand, it seems to allow for the inclusion of everything else such as communication behavior, parental behavior, sexual behavior, and even agonistic behavior.

Sociologists insist that behavior is an activity devoid of social meaning or social context, in contrast to social behavior, which has both. This definition does not help us much. All above-mentioned behaviors do have a social meaning and a context unless ‘social’ means ‘involving the whole group’ (society) or ‘a particular number of its members.’ In that case, we should ask how many individuals we need in an interaction to classify it as social. Are three enough? If so, then, sexual behavior is not social behavior when practiced by two individuals, but becomes social with three or more being involved, which is not unusual in some species. We can use the same line of arguing for communication behavior, parental behavior, and agonistic behavior. It involves more than one individual, and it affects the group (society), the smallest possible consisting of two individuals.

Agonistic behavior includes all forms of intraspecific behavior related to aggression, fear, threat, fight or flight, or interspecific when competing for resources. It explicitly includes behaviors such as dominant behavior, submissive behavior, flight, pacifying, and conciliation, which are functionally and physiologically interrelated with aggressive behavior, yet fall outside the narrow definition of aggressive behavior. It excludes predatory behavior.

Dominant behavior is a quantitative and quantifiable behavior displayed by an individual with the function of gaining or maintaining temporary access to a particular resource on a particular occasion, versus a particular opponent, without either party incurring injury. If any of the parties incur injury, then the behavior is aggressive and not dominant. Its quantitative characteristics range from slightly self-confident to overtly assertive.

Dominant behavior is situational, individual and resource related. One individual displaying dominant behavior in one specific situation does not necessarily show it on another occasion toward another individual, or toward the same individual in another situation.

Dominant behavior is particularly important for social animals that need to cohabit and cooperate to survive. Therefore, a social strategy evolved with the function of dealing with competition among mates, which caused the least disadvantages.

Aggressive behavior is behavior directed toward the elimination of competition while dominance, or social-aggressiveness, is behavior directed toward the elimination of competition from a mate.

Fearful behavior is behavior directed toward the elimination of an incoming threat.

Submissive behavior, or social-fear, is behavior directed toward the elimination of a social-threat from a mate, i.e. losing temporary access to a resource without incurring injury.

Resources are what an organism perceives as life necessities, e.g. food, mating partner, or a patch of territory. What an animal perceives to be its resources depends on both the species and the individual; it is the result of evolutionary processes and the history of the individual.

Mates are two or more animals that live closely together and depend on one another for survival.

Aliens are two or more animals that do not live close together and do not depend on one another for survival.

A threat is everything that may harm, inflict pain or injury, or decrease an individual’s chance of survival. A social-threat is everything that may cause the temporary loss of a resource and may cause submissive behavior or flight, without the submissive individual incurring injury. Animals show submissive behavior by means of various signals, visual, auditory, olfactory and/or tactile.

Canineethogramsocialagonisticsep12-4

Canine ethogram for social and agonistic behavior. The colors illustrate that the categories are constructed by us. When a behavior turns into another one is a matter of convention and interpretation (illustration by Roger Abrantes).

The diagram does not include a complete list of behaviors (please, click on the diagram to enlarge it).

_________________
PS—I apologize if by chance I’ve used one of your pictures without giving you due credit. If this is the case, please e-mail me your name and picture info and I’ll rectify that right away.

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Pacifying Behavior—Origin, Function and Evolution

Pacifying-Behavior

Pacifying behavior (Latin pacificare, from pax = peace and facerefacio = to make) is all behavior with the function of decreasing or suppressing an opponent’s aggressive or dominant behavior or restoring a state of tranquility. There are two ways of classifying pacifying behavior: (1) to include all behaviors with the function of diffusing social conflict, and (2) to restrict it to a particular range within the broader spectrum of conflict decreasing behavior (see diagram below). This author prefers the latter because the broad use of the term in the first option makes it synonymous with conflict decreasing behavior in general, without reference to any particular sub-class of this behavior.

RogerAbrantesAndRottweiler

This Rottweiler female shows the author a friendly behavior licking his face and ear. He shows that he accepts her friendly behavior by turning his face away from her, closing his eyes and mouth and making champing noises. Mostly, dogs show friendly and pacifying behavior to humans as they do to other dogs (photo by Lisa J. Bain).

Pacifying behavior is closely related to friendly behavior (including greeting behavior), insecure, submissive and fearful behavior. In general, the differences between these behavior displays are quantitatively small, but we can classify them separately and qualitatively according to their respective sub-functions. An animal pacifies another using a complex sequence of different behaviors as we can see in the diagram below. An animal very seldom shows a single behavior. Also, the same behavior may achieve different functions depending on its intensity, and the sum of all behaviors displayed at a given moment.

Pacifying behavior did not originate as a deliberate and well-thought strategy to manipulate an opponent. Initially, it was probably just a reflex. Like all phenotypes, it happened by chance and evolved thereafter.

pacifyingbehaviorcanids1

Pacifying behavior in dogs: licking own lips, licking and pawing (images by Alanic05 and Colorado Great Pyrenee Rescue Community).

Natural selection favors behaviors that prolong the life of an animal and increase its chance of reproducing; over time pacifying behavior spread throughout the population. Evolution favors a systematic bias, which moves behavior away from the maximization of utility and towards the maximization of fitness.

pacifyingbehavioranimals1

Many species show pacifying displays in their behavior repertoire (photos by J. Frisch, AFP and Aleixa).

The origin of pacifying behavior—Animal A facing aggressive opponent B registers (sensory system) B’s behavior, processes it (neurological system) and responds with a behavior. The aggressive animal B registers this behavior (probably an infantile behavior); some behaviors tend to pacify it (probably eliciting parental behavior) while others do not. The pacified state of B benefits A and reinforces its behavior, i.e. it is likely it will repeat the same behavior in similar circumstances. Most importantly, animals that show appropriate pacifying behavior (such as A) survive conflicts and avoid injury more often than not and subsequently pass their genes onto the next generation.

Pacifying behavior also pacifies the pacifier, which is an important feature of this behavior. By displaying pacifying behavior, an insecure animal attempts to regain some security (homeostasis) by displaying a behavior it knows well and has previously served to reassure it.

dogs-cats-08malau

Cat and dog use the pacifying behavior of their own species to communicate with one another successfully because of the common characteristics of the behavior (photo by HDANIMALSWALLPAPERS).

Some pacifying behavior has its origins in neonatal and infantile behavior and only becomes pacifying behavior through redirection and eventually ritualization. Other forms of pacifying behavior rely on concealing all signs of aggressive behavior. Sexual behavior can also function as pacifying. Young animals of social species learn pacifying behavior at a very early age; it is important for young animals to be able to pacify adults when they begin interacting with them. The disposition (genotype) to display the behavior is innate (otherwise the phenotype would not be subject to natural selection and evolution), although it requires reinforcement for the young animal to be able to apply it successfully. In canines, adults (initially the mother at the time of weaning) teach the cubs/pups the intricacies of pacifying behavior, a skill they will need to master in order to prevent or resolve hostilities that could cause serious injuries.

Even though pacifying behavior is more relevant and developed in social species, we also find pacifying displays in the behavior repertoire of less social species. Animals successfully use the pacifying behavior characteristic of their species with individuals belonging to other species (if possible) because of the common elements of pacifying behavior across species. It is not unusual to see our domestic animals, dogs, cats and horses interacting peacefully and exchanging pacifying signals. Dogs also show friendly, insecure, pacifying or submissive behavior to their owners and other humans with their species characteristic displays. Licking, nose poking, muzzle nudging, pawing and twisting are common behaviors that dogs offer us.

This diagram shows the placement of pacifying behavior in the spectrum of behavior in canids. The diagram does not include a complete list of behaviors. A conflict is any serious disagreement, a dispute over a resource, which may lead to one or both parts showing aggressive behavior. Resources are what an organism perceives as life necessities, e.g. food, mating partner or a patch of territory. What an animal perceives to be its resources depends on both the species and the individual; it is the result of evolutionary processes and the history of the individual.

pacifyingspectrum

The spectrum of pacifying behavior in canids (by R. Abrantes). The colored background illustrates and emphasizes that behavior is a continuum with fading thresholds between the various behaviors. The vertical lines are our artificial borders, a product of definition and convention.

References

  • Abrantes, R. 1997. The Evolution of Canine Social Behavior. Wakan Tanka Publishers.
  • Abrantes, R. 1997. Dog Language. Wakan Tanka Publishers.
  • Abrantes, R. 2014. Canine Muzzle Grasp Behavior—Advanced Dog Language.
  • Abrantes, R. 2014. Canine Muzzle Nudge, Muzzle Grasp And Regurgitation Behavior.
  • Abrantes, R. 2014. Why Do Dogs Like To Lick Our Faces?
  • Coppinger, R. and Coppinger, L. 2001. Dogs: a Startling New Understanding of Canine Origin, Behavior and Evolution. Scribner.
  • Darwin, C. 1872. The Expressions of the Emotions in Man and Animals. John Murray (the original edition).
  • Fox, M. 1972. Behaviour of Wolves, Dogs, and Related Canids. Harper and Row.
  • Lopez, Barry H. (1978). Of Wolves and Men. J. M. Dent and Sons Limited.
  • Mech, L. D. 1970. The wolf: the ecology and behavior of an endangered species. Doubleday Publishing Co., New York.
  • Mech, L. David (1981). The Wolf: The Ecology and Behaviour of an Endangered Species. University of Minnesota Press.
  • Mech, L. D. 1988. The arctic wolf: living with the pack. Voyageur Press, Stillwater, Minn.
  • Mech. L. D. and Boitani, L. 2003. Wolves: Behavior, Ecology, and Conservation. University of Chicago Press.
  • Scott, J. P. and Fuller, J. L. 1998. Genetics and the Social Behavior of the Dog. University of Chicago Press.
  • Zimen, E. 1975. Social dynamics of the wolf pack. In The wild canids: their systematics, behavioral ecology and evolution. Edited by M. W. Fox. Van Nostrand Reinhold Co., New York. pp. 336-368.
  • Zimen, E. 1982. A wolf pack sociogram. In Wolves of the world. Edited by F. H. Harrington, and P. C. Paquet. Noyes Publishers, Park Ridge, NJ.

Featured Picture: Artwork by Anton Antonsen (photo by M. Robinson, graphic element by Creative Hat).

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Is it possible for all of us to become givers—no takers at all?

Is-it-possible-for-all-of-us-to-become-givers-no-takers-at-all

Wouldn’t it be nice if we all gave expecting nothing in return? What a beautiful world we would have. At one time or another, most of us have embraced such thoughts. But is it possible at all? Is it possible for all of us to become givers—no takers at all?

An evolutionary biologist will tell you, right away, it is not possible. Every behavioral strategy, when adopted by everyone in a group, is vulnerable to any variation or mutation that will carry a slight advantage. Were we all to become givers, we would be at the mercy of the first taker that would show up. More takers would follow for if it works for one, it also works for others.

All relationships are a trade, a “give and take.” How much we give and how much we take depends on the benefits and costs involved. The goal is to come out of any trade with a profit. Occasional deficits are acceptable as long as the overall balance stays on the plus side. That is the law of life. We spend energy to gain energy, to keep alive. Sometimes, we need to plan long-termed. There are both benefits and costs that we do not incur immediately. The law is still the same: the balance must end up on the positive side, or life will end.

Apart from our dream of a better world full of unselfish givers, it looks at first sight as taking and not giving is the most profitable strategy. The problem is that we cannot all be takers. Takers can’t take from takers; they can only take from givers. Thus, it would appear that the givers would always be at a loss, but that is not the case. Givers receive from other givers, and they don’t spend energy fighting with takers. On the other side, takers spend energy when facing other takers, gaining nothing. While giver/giver allows both to come out on the plus side of the balance, taker/taker always comes out with a deficit.

Givers and takers keep each other at bay. The ideal number for each, so that there is stability, depends solely on the value of benefits and costs.

To analyze how different strategies influence one another, the evolutionary biologist strips the strategies to their core and assigns some values to the variables, i.e., benefits and costs.

Let’s assume that when a taker meets a taker, they benefit nothing and spend much energy. When a giver meets another giver, they both give and take equally, and they spend some energy (they have both benefits and costs). When a taker meets a giver, the taker benefits 100%, and the giver spends energy (costs). We set the value of benefits and costs as follows:

  • benefit (b) 20 (conferred by the givers to anyone)
  • cost (c) -5 (the cost of giving)
  • taker/taker cost (e) -50 (this is the energy takers spend when fighting one another to take without giving).

Let’s now calculate the percentage of takers and givers necessary to achieve an equilibrium so that both strategies give the same profit.

The proportion of takers = t
The proportion of givers (g) = (1-t)
The average payoff for a giver (g) is G = ct + (b+c)(1-t)
The average payoff for a taker (t) is T = et + b(1-t)
There is an equilibrium (stability) when G=T.

 

Strategy Opponent’s strategy
Takers Givers
Takers e b
Givers c b+c

 

Example 1—With the above values for benefits and costs, a combination of 10% takers and 90% givers gives both a profit of 13, and there is stability. If the cost of takers fighting one another decreases, then it pays off (for more individuals) to become a taker.

Example 2—The figures in example 1 seem to suggest that takers should avoid one another as much as possible. Let’s say they do it in three out of four times. Then, and still with the same values, the number of takers can rise to 40%, and we still have an equilibrium, i.e. an ESS (Evolutionarily Stable Strategy). However, the profit will be less for both givers and takers, namely 7—more takers equals less profit for all.

That is a good example of what happens in a capitalistic human society dominated by greed, taking more and more. Takers take all they can but end up poorer than if they took less. The capitalistic instinct says, “take more,” but a more rational approach shows that taking less amounts to more profit. The strategy of taking maximally works only for a limited time. After a time, it backfires (depression, recession, etc.) because it upsets the balance between the feasible strategies, which, by then, have become evolutionarily unstable.

Example 3—Encounters between takers are very expensive. What if takers would avoid takers all the time? In this case, the number of takers can rise to 80%. Beyond that, the strategies become evolutionarily unstable. The interesting is that even though there would be stability with such a high number of takers, both takers and givers would come at a loss of -1. That is not at all a healthy strategy for any individual, let alone a group. It’s the sign of a society in decay. It’s what happens in a group dominated by greed and selfishness.

Example 4—Since our wish is a world full of givers let us see how we can maximize the number of givers. We need to change the values for benefits and costs. Let’s decrease the cost of giving and increase the costs incurred by takers when fighting one another.

  • benefit (b) 20 (remains the same)
  • cost (c) -1 (lower cost than above)
  • taker/taker cost (e) -100 (much higher cost than above)

With these values, we can reach a maximum of 99% givers versus 1% takers. Both will have a profit equal to 18.80. Note that this the highest achieved payoff in all our simulations.

The only variables that reduce the number of takers are the cost (e) and the probability of facing another taker. If we keep the values of benefits and costs the same as initially (b=20, c=-5) the costs of the struggle between two takers must rise to -500 for the strategies to be evolutionarily stable. Then, the profit becomes 14.80 instead of 18.80.

These are artificial figures to analyze the needed conditions for an Evolutionarily Stable Strategy to emerge. We may question the unlikeliness of the costs of any interaction to rise as high as we have set the taker/taker encounters. And yet, conflicts between male Northern elephant seals, Mirounga angustirostris, often end with a critical injury or the death of one of the parties. The costs are high, but so are the benefits: in Northern elephant seals, fewer than 5% of the males perform 50% or more of the copulations. A red deer stag, Cervus elaphus, has about a 25% chance to incur a permanent injury from fighting (like in our example 2).

Also interesting is that the value of the benefits does not change the proportion of takers versus givers, only the profit. For example, with b=40, the profit is 34.60 (versus18.80 and 14.80 for the other values for benefits in the examples). The values we used are all fictive, but it doesn’t matter. They show the trends created by increasing or decreasing a variable. To test real situations, we can use realistic figures whenever we can get them. We can assign values to benefits and costs according to gain or loss of calories, body weight, the number of progeny, available mating partners, fitness or even quality of life (if we find a reliable way to measure it).

The conclusion is that there will always be givers and takers—or that any strategy needs a counterpart to form an ESS. We can influence the trend of adopting one or the other strategy with the benefits and costs involved, but we can’t eliminate either one completely—and this is the universal law of life. In other words, every mountain has a sunny and a shady side.

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The Mathematician Rat—An Evolutionary Explanation

ratbyxavierrossi

JG is a rat, a Cricetomys gambianus or Giant Gambian Pouched Rat; she is also a Hero Rat, a landmine detector at Apopo in Tanzania. In December 2009, she performed uncharacteristically badly and puzzled everybody as Hero Rats don’t make mistakes. What was the problem with JG? Had she lost it? Had the trainers made a crucial mistake?

Apopo in Morogoro, Tanzania, trains rats to detect landmines and tuberculosis and the little fellows are very good at what they do. In Mozambique, Apopo has so far cleared 2,063,701 square meters of Confirmed Hazardous Areas, with the destruction of 1866 landmines, 783 explosive remnants of war and 12,817 small arms and ammunition. As for tuberculosis, up until now, the rats have analyzed 97,859 samples, second-time screened 44,934 patients, correctly diagnosed 7,662 samples and discovered 2,299 additional cases that were previously missed by the DOTS centers (Direct Observation of Treatment, Short Course Centers in Tanzania). More than 2,500 patients have since been treated for tuberculosis after having been correctly diagnosed by the rats.

In December 2009, I was working full time at Apopo in Morogoro. I wrote their training manual, trained their rat trainers, supervised the training of the animals and analyzed standard operating procedures. At the time of writing, I still do consultancy work for Apopo and instruct new trainers from time to time. Back then, one of my jobs was to analyze and monitor the rats’ daily performance and that’s when I came across the peculiar and puzzling behavior of JG in the LC3 cage.

 

Problem

LC3 is a cage with 10 sniffing holes in a line and the rats run it 10 times. On average, 21 holes, randomly selected by computer, will contain TNT samples. We train rats in LC3 every day, recording and statistically analyzing each session. We normally expect the rats to find and indicate the TNT samples with a success rate of 80-85%. Whenever the figures deviate from the expected results, we analyze them and try to pinpoint the problem.

On December 19, we came across a rat in LC3 that did not indicate any positive samples placed from Holes 1 to 6. She only indicated from Holes 7 to 10. In fact, from Hole 1 to 6, Jane Goodall (that’s the rat’s full name) only once bothered to make an indication (which was false, by the way). From Hole 7 to 10, JG indicated 10 times with 9 correct positives, only missing one, but also indicated 11 false positives. Her score was the lowest in LC3 that day and the lowest for any rat for a long time. What was the problem with JG? She seemed fine in all other aspects and seemed to know what she was doing. Why then did she perform so poorly?

ratbysilvainpiraux

Giant Gambian Pouched Rat searching TNT in a line cage (photo by Silvain Piraux).

Analysis of searching strategies

Whenever an animal shows such a behavior pattern, and it appears purposeful rather than emotional, I become suspicious and suspect that there is a rational explanation.

In order to analyze the problem, I constructed simulations of two searching strategies: (1) searching ALL HOLES, and (2) SKIPPING Holes 1 to 5 (I didn’t want to be as radical in my simulation as JG). In addition, I ran simulations with two different sample placement configurations: (1) evenly distributed between the two halves, i.e. two positives in Holes 1 to 5 and two positives in Holes 6 to 10; and (2) unevenly distributed — one positive in the first five holes and two positives in Holes 6 to 10.

In order to run the simulation, I needed to assign values to the different components of the rat’s behavior. I chose values based on averages measured with different rats.

  • Walking from feeding hole to first hole (back walk) = 3 seconds.
  • Walking from covered hole to covered hole = 1 second.
  • Walking from uncovered hole to uncovered hole = 2 seconds.
  • Analyzing a hole = 2 seconds.
  • Indicating a positive = 4 seconds.
  • Walking from last hole to feeding hole = 1 second.
  • Eating the treat = 4 seconds.

All time variables were converted into energy expenditure in the calculation of energy payoff for the two strategies and the different configurations. Also the distance covered was converted into energy expenditure. The reinforcers (treats) amounted to energy intake. In my simulation I used estimated values for both expenditure and intake. However, we could measure all values accurately and convert all energy figures into kJ. 

 

The results

rattable11

In terms of energy,  (in this simulation I make several assumptions based on reasonable values, e.g. the total energy spent is a function of distance covered and time spent), the results show that when the value of each treat is high (E gain is close to the sum of all treats amounting to the sum of energy spent for searching all holes), it pays off to search all holes (the loss of -5.50 versus -7.88). The higher the energetic value of each treat, the higher the payoff of the ALL HOLES strategy.This is a configuration with four positives (x) and six negatives (0). The results show that neither strategy is significantly better than the other. On average, when sniffing all holes, the rat receives a treat every 31 seconds, while skipping the first five holes will produce a treat every 31.5 seconds. However, there is a notable difference in how quickly the rat gets to the treat depending on which strategy the rat adopts. ALL HOLES produces a treat on average 5.75 seconds after a positive indication. SKIPPING produces a treat 3.5 seconds after a positive indication. This could lead the rat to adopt the SKIPPING strategy, but it’s not an unequivocally convincing argument.

rattable21

However, when the energetic value of each treat is low, skipping holes will reduce the total loss (damage control), making it a better strategy (-17.88 versus -25.50).

rattable31

However, if we run a simulation based on an average of three positives per run, with one in the first half and two in the second half  (which is closest to what the rat JG was faced with on December 12), we obtain completely different results. This first analysis does not prove conclusively that the SKIPPING strategy is the best. On the contrary, it shows that, all things considered, ALL HOLES will confer more advantages.

rattable41

The energy advantage is also detectable in this configuration, even when each treat has a high energetic value (a gain of 3.13 versus a loss of -0.75).With this configuration, the strategy of SKIPPING is undoubtedly the best. On average, it produces a reinforcer every 27.5 seconds (versus 28.7 for ALL HOLES) and 2.5 seconds after an indication (versus 5 seconds).

rattable51

Conclusion

This second simulation proves that JG’s strategy was indeed the most profitable in principle. However, the actual results for JG are completely different from the ones shown above, as they also have to take into account the amount of energy spent indicating false positives (which are expensive).

It is now possible to conclude that the most advantageous strategy is as follows. Whenever the possibilities of producing a reinforcer are evenly distributed, search all holes. It takes more time, but on average you’ll get a reinforcer a bit quicker than if you skip holes. In addition, you either gain energy by searching all holes, or you limit your losses, depending on the energetic value of each reinforcer. Don’t be fooled by the fact you get a treat sooner after your indication when searching all holes then when skipping.

Whenever the possibilities of producing a reinforcer are not evenly distributed, with a bias towards the second half of the line, skip the first half. It doesn’t pay off to even bother searching the first half. By skipping it, you’ll get a lower total number of reinforcers, but you’ll get them quicker than searching all holes and, more importantly, you’ll end up gaining energy instead of losing it.

Finally, avoid making mistakes by indicating false positives. They cost as much as true positives in spent energy, but you don’t gain anything.         

 

An evolutionary explanation

Of course, no rat calculates energetic values and odds for certain behaviors that are reinforced, nor do they run simulations prior to entering a line cage. Rats do not do this in their natural environment either. They search for food using specific patterns of behavior, which have proven to be the most adequate throughout the history and evolution of the species. A certain behavior in certain conditions, depending on temperature, light, humidity, population density, as well as internal conditions such as blood sugar level etc., will produce a slightly better payoff than any other behavior. Behaviors with slightly better payoffs will tend to confer slight advantages in terms of survival and reproduction and they will accumulate and spread within a population; they will spread slowly, for the time factor is unimportant in the evolution of a trait. Eventually, we will come across a population of individuals with what seems an unrivalled ability to make the right decision in circumstances with an amazing number of variables, and it puzzles us because we forget the tremendous role of evolution by natural selection. Those individuals who took the ‘most wrong decisions’ or ‘slightly wrong’ decisions inevitably decreased their chances of survival and reproduction. Those who took ‘mostly right’ or ‘slightly righter’ decisions gained an advantage in the struggle for survival and reproduction and, by reproducing more often or more successfully, they passed their ‘mostly right’ or ‘slightly righter’ decisions genes to their offspring.

This is a process that the theory of behaviorism cannot explain, however useful it is for explaining practical learning in specific situations. In order to explain such seemingly uncharacteristic behaviors, we need to recur to the theory of evolution by natural selection. This behavior is not the result of trial and error with subsequent reinforcers or punishers. It is an innate ability to recognize parameters and behave in face of them. It is an ability that some individuals possess to recognize particular situations and particular elements within those situations, and correlate them with specific behavior. What these elements are, or what this ability exactly amounts to, we do not know; only that it has been perfected throughout centuries and millennia, and innumerable generations that accumulate ‘mostly right’ or ‘slightly righter’ decisions—and that is indeed evolution by means of natural selection.

Featured image: Giant Gambian Pouched finds a landmine (photo by Xavier Rossi).

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