Risk Genetics

Risk Genetics

We have all experienced our own small conflicts with risk aversion. You plan to get something done. You have your plan A and some contingencies, one of which includes doing something a bit risky. When your plan A fails and you are faced with implementing your contingency plan, you realize that you are not going to do what you had planned. The risk – when actually faced with it – seems to big and nothing that you do to motivate yourself makes any difference. Suddenly you don’t want what you did want. Suddenly you have a different perspective on possible outcomes. Suddenly you know that while you do have a free choice, there are just things that you will never choose.
This situation can be a bit disrupting to the balance of your ego.

It can make it clear that there are things that you can never actually do, even if you can imagine yourself doing them quite easily. Few people ever find a way to handle this kind of limit with any degree of control. Most people resort to having enough experience so that this phenomenon becomes rather predictable at a certain level of risk. But there are lots of theories around as to how this works, and why you are so damned risk averse even when you want to be brave. Most of them are rather superficial and partly wrong.

risk genetics

One would state that your risk aversion is at a set value determined by your genetic makeup.

 

If we want to inject a bit of fact into the thinking about risk aversion it might be a good idea to have a look at research into risk genetics. That will reveal to us the way that different environments have resulted in different risk profiles and different risk taking behaviors. Essentially biological evolution is adaptation to the various risks that might prevent the survival of the gene pool in a species. At a more concrete level biological evolution is adaptation to the risks and life conditions that the individuals of a species faces on his or her journey towards having offspring who can sustain themselves as they themselves get old and die. It is based on selection of those genes that is carried through growth, survival, reproduction and initial care for their offspring. The deselection is “done” by the risk and the resulting failure of some individual to survive and reproduce. This is genetics 101.

 

Because we see how risk and failure lies at the core of genetics and is central to shaping the genome we should expect that biological instinctual reactions to risk, danger and threats are a quite accurate reflection of the actual risk situation for a given species. That is, that human instincts and instinctual reactions are adapted to the challenges that might kill off humans before they can mature and have offspring.

 

In theory humans should be quite good at risk avoidance: We have large brains that makes detailed analysis of the environment based on visual information, sounds, smell, taste and tactil information. If you wanted a species that was optimally equipped to do a lot of risk avoidance, you would want to build something like a human: Not only can we perceive the environment in huge detail, but we also have the capacity for detailed analysis and for integrating competing motivations. And I am sure that there are many people who think that that is what humans really are: That we are the species that is best equipped and do the best and most careful risk avoidance of any species, that we avoid risk better than anybody else, and that we have come to dominate the planet, just because of that.

 

And they would be wrong.  If you are a bit nervous your brain can easily switch into a risk detection machine that will not only see all dangers present in the environment but also make interpretations of anything in your field of view in terms of its potential danger. While in this state, there is nothing better than risk avoidance and your brain is fully activated to do just that. If that is a regular occurrence it is easy to think that this is the noble cause that your brain is here to serve. But it would be wrong. This is the simple view that all it takes to be successful is that you avoid getting injured and killed and that being extremely good at that is all you need. But when you take a closer look at risk genetics it is actually a bit more complicated than that.

 

It is inherently difficult to pinpoint behavior to specific genes, and there has been very little progress in efforts to do so. The general picture is that a large number of genes each have a small effect on behavior. Another challenge is that early experience affect the relevant behaviors in both animals and humans. Mounting evidence shows that the environment plays a significant role in the way that the genotype is expressed in behavior. The early hope that research into specific genes and their related behaviors could reveal the basic patterns for inheritance of risky behavior has not been borne out by the results over the last few decades. These limitations have plagued behavioral genetics in general and have also limited the progress of a genetic understanding of risk behavior.

 

 

This situation has lead Alison M. Bell (2009) and her colleges to adopt a new model system model system based on stickleback fish, which is more focused on the effects of the natural environment on risk behavior. The thesis is that sticklebacks have environmentally responsive genes that shape risk taking behaviors and are shared with other animals and humans. The sticklebacks are chosen as a model because they have an unusual evolutionary history that has produced a replicated natural experiment. Freshwater sticklebacks all decent from a common ancestor that populated freshwater environments in Scotland while they were connected to the ocean. Following the glacial retreat 12.000 years ago they have each developed in accordance with the specific environmental pressures in their isolated habitat. Scotland is especially well suited for the study of risk taking behavior because there is so many lakes that have been created by the post glacial rise of the land masses.

 

risiko variation

 

This situation has given rise to a large variety between closely related populations, but also a variety of similar solutions to similar environmental challenges in different populations. This situation alleviates what is normally a problem in behavioral genetics, the lack of replication: While you can normally point to a specific selective pressure and a corresponding specific adaption, it is usually not possible to show that a similar selective pressure would produce such an adaptation in other or all instances. In the lakes of Scotland we find a number of independent populations that show similar adaptations and thus supports a generalized model.

 

exploratory movements

 

 

Risk taking behaviors in sticklebacks

 

Fearlessness, disinhibition, impulsivity and sensation-seeking are some of the tendensies that are expressions of low risk aversion in humans. Resembling risk accepting features in sticklebacks are measured as agression and predator inspection.

 

Individual sticklebacks differ in their propensity for risk taking behaviors: Some individuals actively move about in unfamiliar and dangerous environment while others tend to stay in relative safety of their refuges. Bell also points out that behavior when confronted with a potential predator also differs among individuals: “Some hide in the presence of a predator, other swim up to the predators mouth and face the predator head-on.” (A.M.Bell, 2009).

 

A third variable is how much aggression an individual will exhibit towards same species individuals in competition for food or for territories. So some individuals show a tendency towards more risk taking, either as exploration, as “predator inspection” or as aggression towards other sticklebacks. Individual differences can also be seen in how the benefit of feeding is balanced against the risk of predation: Risk prone individuals are more willing to assume the risk of predation in order to get food than the more risk averse individuals. These differences in behavior can be quantified and used as a measure for risk taking tendencies and individual sticklebacks can be classified as either risk-prone or risk averse in these and several other contexts.

 

The crucial point in all this is that the different tendencies are not independent as they show clear covariation. This parallels the covariation found between antisocial behavior, substance dependence, impulsivity and behavioral disinhibition found in humans. The comorbidity of these disorders and the covariance between risk related behavioral traits in sticklebacks suggest that these expressions of inheritable genetic factors: In humans there is evidence that the broad underlying tendency is more heritable that the particular manifestations  (Krueger et al., 2002). In other words, we seem to inherit a individual genetic disposition that will express itself according to the specific environment that we grow up in. The specific individual expression would then seem to reflect both a genetic component and an influence from the specific environment that we adapt to through learning.

 

time in freezing

 

 

The evidence for a genetic basis for the risk taking behavior of sticklebacks is based on several kinds of research.  One line of research has shown that measurements of their risk taking behavior is repeatable. Measurements of how long individual sticklebacks spends in freeze mode (remaining motionless in face of danger) shows stable values for each individual, while there are marked differences between the individuals. That is, an individuals willingness to accept risk is a stable trait, supporting the view that there is a genetic basis for the behavior.

 

Another line of evidence is based on the measurement of exploration of new environments by a number of members of either same or different families. Family members, who obviously share genes supporting risk taking, show similar levels of risk taking while members of other families show a level of risk taking clustered around different values for each family. This shows that risk taking behavior is a heritable genetic variation.

 

A third line of research has looked at feeding behavior in presence of a predator. There were marked differences between sticklebacks from different populations and these differences was maintained in lab-reared offspring of the different populations. Which again shows that a genetic inheritance is underlying these differences. It also illustrates another important point that we will discuss more later on: That the differences in risk taking behavior is related to the differences in predator pressure in the specific environment of each population.

 

It has also been shown that differences in anti predator behavior is innate and arise in each individual even in the absence of actual predators or threatening situations. Finally there is  a strong link between the risk taking behaviors and aggressive behaviors, which are widely seen as having a genetic basis.

 

 

It is also worth noting that orphan sticklebacks in areas with high predation pressures show a very different level of risk avoidance  compared to sticklebacks reared by their father. There are a clear parallel between this pattern and the effect of social exclusion on risky and impulsive behaviors in humans. More about this later.

 

 risk genetics

 

The crucial point about adaptation to an optimal level of risk acceptance is that we actually see more risk taking behaviors in populations that are adapted to environments with higher levels of predation. In fact predator pressure is one of the most important selective forces shaping the genetic basis for behavior. And the effect of predator pressure is perhaps not what you would expect: Lakes with a large number of predators have sticklebacks with a high level of risk taking behaviors. Lakes with a lower number of predators have a sticklebacks with a lower level of risk taking. This obviously violates the common sense conception of risk avoidance as something that is necessary if and when a danger is present and the notion that a safe environment should lead to a relaxation of your risk aversion tendencies.

 

It might seem strange that extra risk taking should lead to greater survival rates, but this is actually predicted by life history theory. The key to understanding this lies in the difference between surviving the day and surviving long enough to produce offspring. The reason is that small individuals are especially vulnerable to predation and that growth rates are improved by risk acceptance. You simply don’t find enough food by staying in the shadows, and a certain higher level of risk acceptance seem to be necessary for optimal growth in an area with high risk of predation. While you can not enhance the chance of getting through traffic without a collision by speeding up, you can actually overcome risk of predation by taking on extra risk. In other words, the adaptation is aiming at an optimal growth rate, not a fixed optimal level of risk taking, because optimal growth leads to a reduction in actual risk.

 

You should also note that this adaptation is a function of the actual risk level in the natural environment: With higher levels of predation danger comes higher levels of risk taking because risk taking in this kind of environment is a necessity. The behavior seems to adapt to the minimum level of risk taking necessary for optimal growth, not the mininal level for surviving the day.
It is also worth noting that – contrary to popular belief – the optimal point for adjustment of risk aversion in a safe environment seems to be at its maximum. The commonsense conception would be that in safety you don’t need risk aversion, but the research seems to support the notion that risk aversion can be maximized in safe environments with no cost to growth prospects.

 

One factor that supports that kind of evolution is that survival through reproduction goes through phases with different kinds of vulnerability and survival of the species and the gene pool depends on survival of each individual throughout different life phases. Before maturity the most important goal are both sheer survival of the day and a growth rate that will reduce vulnerability. With maturity the priorities are changed from growth to reproduction and parental investment, that is to ensuring the survival and growth of the next generation.

 

Parental investment is defined as any time, energy, resources, and risk that a parent uses for the benefit of their offspring. Every expenditure of this sort carries a cost along with it, and an element in this cost is a reduction in the ability of the investing parent to rear additional successful offspring” (Barash 1981, pg. 56).

 

The king penguin is a prime example on this kind of behavior: While breeding king penguin males remain in a fasting-period at the breeding site for five weeks, waiting for the female to return for her own incubation shift. The males’ sacrifice of their body weight and possible survivorship, in order to increase their offspring’s chance of survival is a trade-off between current reproductive success and the parents’ future survival.

 

The labeling of this kind of behavior and the genetic dispositions that promote the behavior as “altruistic” is really a misnomer: It is only altruistic from the point of view of the individual, not from the point of view of the evolutionary process – the species – that  “owns” the gene pool and is the sole beneficiary of evolutionary progress. As there is no point in a one generation species, there is a inherent long term view in the way that the interest of the species is maintained. Evolution that is based on survival and reproduction necessarily adapts in a way that promotes long time survival.

 

As we shall focus on later, this survival is in part promoted by instincts that tend to favor short term solutions. These solutions have their value in the fact that all long term interests are worth nothing if the organism does not survive the day. There is thus a delicate balance between short term and long term interest, that for humans in some cases are skewed towards a short term focus. And while this balance can promote short term survival it will most often also lead to suffering, misery and ill health. But the fact remains that the evolution of the genetic basis for a species cannot only take a short term view as it depends on the turnout of reproduction from one generation to the next. Survival in absence of reproduction is not sufficient for the evolution of a species. Survival is a necessary cause of evolutionary progress, not a sufficient one.

 

Even when instincts serve a long term  interest, it is always balanced against the need for short term survival. In the case of the King Penguins the male and potential father will wait – and fast – for up to five weeks for the female to return while he cares for the eggs. But if she does not return, there is a limit to how long he will remain invested in the offspring. At some point he will abandon the eggs in order to seek food. But this limit however is not fixed: with experience, after fathering offspring successfully in one or more seasons the period he is prepared to stay with the eggs gets prolonged. In other words his time horizon seems to get prolonged by positive experience of investing and having success. Experienced males that abandoned the egg weighed significantly less (9.49 kg) at departure than relieved males (10.43 kg), but inexperienced males abandoned the egg at a nearly significantly higher body mass (10.27 kg) than experienced males  (Olof Olsson, 1997).

 

This is a pattern that seems relevant and central to how humans react to challenges as well, something that we will touch upon in later chapters. Olsson suggest that the difference in experience is relevant because of experience means better hunting skills and faster post-fasting recovery. But given what we now know about risk management in the deeper structures of the brain, this change in parental investment might just as well hinge on a slight change in expectations of outcome of the investment for the experience Penguin, ie. stronger expectations of seeing live offspring soon after.  This perspective would assume that the uncertainty and/or experience regarding outcome of the investment plays a role in determining the balance point between short term and long term interests, just as trust in hunting abilities would play a role in the alternative view of Olsson.