Marathon mice, enhancement and the will to work out

In his article in the Pacific Standard last week, author Bruce Grierson discusses the emerging scientific evidence that the ‘will to work out’ might be genetically determined. Grierson describes a ‘marathon mouse’, the descendant of a long line of mice bred for their love of exercise, and a 94-year-old woman called Olga, who is an athletic anomaly. Both the mouse and Olga love to work out. The mouse goes straight to his wheel when he wakes up, running kilometers at a time and Olga – a track and field amateur – still competes in 11 different events. Grierson suggests that cracking the code for intrinsic motivation to exercise would lead to the possibility of synthesizing its biochemical signature: ‘Why not a pill that would make us want to work out?’, he asks. Such a possibility adds an interesting dimension to the debate about enhancement in sport, and to enhancement debates more generally.

Those who are opposed to enhancement often argue that taking enhancers devalues achievement because it removes the need for effort. The suggestion is that for achievements to have value, they must have involved an appropriate amount of struggle or sacrifice.  For example, Kass (2003) says:

Yet in those areas of human life in which excellence has until now been achieved only by discipline and effort, the attainment of those achievements by means of drugs, genetic engineering, or implanted devices looks to be “cheating” or “cheap.” We believe – or until only yesterday believed – that people should work hard for their achievements. “Nothing good comes easily.”


A common rebuttal to this type of argument is that, whilst enhancements can make efforts more effective, they do not replace the need for dedicated, sustained training. In the sporting domain, for example, steroids will help athletes increase their muscle bulk, but steroids do not remove the need for many grueling hours in the gym. Muscles don’t build themselves; discipline and effort is still required. In further support of the argument that enhancements do not devalue achievement is the observation that natural abilities are not fairly distributed and so to demand that abilities remain fixed in their ‘given’ state so that they can be judged accordingly is to unfairly seek to reward the lucky. Allowing enhancements that make training or learning more effective opens up the race to those who are willing to put in the effort regardless of or perhaps despite natural endowment. The playing field is supposedly levelled.

But, if we are in favour of enhancements that make natural ability matter less, relative to effort – because putting in effort is what people can control – what about an enhancement that increases the will to work out (or the will to study)? Is there an important difference between enhancement of effectiveness and enhancement of motivation? Physiologically, there does seem to be a difference between effectiveness and motivation. The author draws a distinction between, on the one hand, genes that make some athletes highly ‘trainable’ (acutely responsive to aerobic exercise) and let people lose weight easily on a workout regime and, on the other hand, Olga’s will to work out. Interestingly, Olga apparently does not have either of the aforementioned genetic variants; it is not these natural endowments that make her an athletic superstar – her training is not unusually effective, rather, she spends an unusual amount of time training.

It could be argued that an enhancement that increases motivation still doesn’t remove the need for training so is no more problematic than an enhancement that increases the effectiveness of training. The motions must still be gone through. However, the core of the anti-enhancement concern is not just that achievement must involve time at the gym or the desk, but that it must be in some way hard, or burdensome or unpleasant. ‘Nothing good comes easily’, and it is our working hard for achievements that in part makes them ‘intelligible’ to us (Kass 2003).  There is perhaps cause for concern, then, if an enhancement makes spending one’s time at the gym or desk too easy. Whilst there may be effort in the sense of expended energy, if this energy is a joy to expend then it does not involve the striving or sacrifice that bioconservatives seem to think necessary for achievements to have value.

And the science points to enjoyment being the operant mechanism in those with a strong will to work out. The marathon mouse and people like Olga find exercise uncommonly satisfying. Grierson explains that this is likely due to ‘the neurotransmitter dopamine, which is central to the brain’s reward circuitry. Exercise stimulates dopamine production, which in turn causes a cascade of other molecular effects—a process known as “dopamine signaling.”’ In relation to the marathon mouse, Grierson speculates that something is unusual about his dopamine signaling: ‘when he runs, some as-yet-identified molecule, downstream from the dopamine receptor, gets altered so that it now provides reinforcement that normal mice don’t get.’ So, if working out feels extremely pleasurable – as it does for the mouse and Olga – there is not much striving or sacrifice involved. An enhancement that has this effect therefore does seem qualitatively different from an enhancement that allows the user to reap more benefits from his arduous programme.

However, whilst there does seem to be a difference, the very possibility of a Pill for Will is predicated on the influence of genes on our motivational makeup.  It’s not the case that abilities, on the one hand, are unfairly and undeservedly distributed, whereas it is completely up to us how much effort we put in on the other: rather, how much effort we are inclined to put in is also partly genetically determined – this, after all, is what give legs to the idea of cracking the genetic code for intrinsic motivation to exercise. If our control over how much effort we can put in is less than we tend to imagine, then does this put the will to work out more in line with natural abilities? Just as it seems unfair to require people to put up with whatever level of ability they were given, it might be unfair to require people to put up with their natural motivational drives. Correspondingly, if we think that it is unfair to praise people based purely on their natural abilities, does it make it any fairer to praise people who are genetically disposed to find it fun to use and develop their natural abilities?

It is an empirical question whether natural limits on motivation are any more malleable or defiable than natural limits on abilities. Intuitively, it seems that we have greater capacity to compensate for a naturally weak will than for naturally limited abilities: not enjoying working out doesn’t prevent us from forcing ourselves to do it, but possessing physiology that is unresponsive to aerobic exercise (for example) is not something we can change simply through gritted determination. However, such speculation would need to be scientifically verified before it could have any bearing on the enhancement debate.

The possibility of a Will Pill raises interesting questions for enhancement and the value of achievement. It is up for debate whether there is an important difference between enhancement of motivation and enhancement of effectiveness and, if so, whether this is relevant to the value of resulting achievements. Moreover, regardless of any implications for enhancement, Olga and the marathon mouse demonstrate that how much effort we can and do put in to pursuing achievements is not as controllable as we sometimes imagine; therefore, to venerate or vilify based on the presence or absence of a strong will to pursue achievements is perhaps not much fairer than celebrating or berating people based on their natural levels of ability.


Kass, L (2003), ‘Beyond Therapy: Biotechnology and the Pursuit of Human Improvement’, available online at:

  • Facebook
  • Twitter
  • Reddit

One Response to Marathon mice, enhancement and the will to work out

  • John Scott says:

    It seems to me that there is a difference between the enhancement of effectiveness and the enhancement of motivation. If we enhance our effectiveness we might possibly devalue our determination. It is hard to see how enhancing our motivation could devalue motivation. Devalue our determination to be determined? It seems it would be possible for Kass to endorse artificially enhancing our motivations whilst at the same time maintaining it would be wrong to artificially enhance more general goods such as our strength or intelligence whilst remain consistent. Personally I doubt that Kass would make such an endorsement. I expand on these points in wooler.scottus


Subscribe Via Email