Evolution of the 'childfree' culture

In the middle of the last century, Pulitzer Prize winning American author Phyllis McGinley (1956) wrote:  “Women are the fulfilled sex.  Through our children we are able to produce our own immortality, so we lack that divine restlessness which sends men charging off in pursuit of fortune or fame or an imagined Utopia.”  

A similar notion is reflected in Murray’s (2003) commentary on why women comprise such a small percentage of the highly accomplished people in recorded history: “So closely is giving birth linked to the fundamental human goal of giving meaning to one’s life that it has been argued that, ultimately, it is not so much that motherhood keeps women from doing great things outside the home as it is men’s inability to give birth that forces them to look for substitutes.” 

As Sir Francis Bacon (1561-1626) put it:  The perpetuity by generation is common to beasts; but memory, merit, and noble works are proper to men.  And surely a man shall see the noblest works and foundations have proceeded from childless men, which have sought to express the images of their minds, where those of their bodies have failed.  So the care of posterity is most in them who have no posterity" (Bacon 1985). 

But the long history of patriarchal subju-gation of women (Joshi 2006) has surely been at least equally significant in keeping women "from doing great things outside the home." This is evident from a dramatic cultural shift that began to unfold around the middle of the last century:  women worldwide managed, in greater frequencies, to break free from this oppression, and thus became more empowered to decide for themselves whether they will have children, and how many.

With this freedom, many women elected to have no children at all — choosing to abandon the uniquely female opportunity for symbolic immortality through motherhood.

They chose instead to seek 'fulfillment'
from a different domain for legacy —
personal accomplishment — as well as
in domains for leisure.

Both were largely denied to
their oppressed maternal ancestors,
historically controlled mostly by men for men.

Cover of Time magazine, August 2013

These women are the architects of the modern ‘childfree culture’ (Shorto 2008, Frazer 2011, Sandler 2013, Kingston 2014). Their partners of course also play a role. But because women are now, for probably the first time in history, widely and significantly in control of their own fertility, they are principally in charge of the agenda and momentum of the childfree culture.  On the surface, it has all the symp-toms of a Darwinian paradox. But digging deeper reveals that it may actually have evolutionary roots.  In terms of ‘fulfillment’, it may be understood more directly from a historically male perspective.  In other words, it is men who have been the ‘unfulfilled sex’ — possibly in part because of their inability to give birth, but perhaps more because of paternal uncertainty (thus accounting for their "charging off" in pursuit of symbolic immor-tality through "fortune or fame").

Plus, partly in order to minimize paternal uncertainty, many or most women — throughout most of recorded history — were essentially forced, by patriarchal subjugation and/or religious im-peratives (also controlled by men), to bear offspring (often many) regardless of whether they had any intrinsic desire to be hard-working mothers, or mo-thers at all.  Presumably, many didn’t.

Our 'unfulfilled' male ancestors thus coerced female ancestors — many of whom happened not to have a particularly strong, so called, 'maternal instinct' (or any at all) — to (nevertheless) bear offspring, including daughters who inherited their mothers’ weak maternal instincts.  This presents an intriguing evolutionary hypothesis:  women of the ‘childfree’ culture today, or significant numbers of them at least, may be descendants of these daughters (Aarssen and Altman 2012).

Cover of MacLean's magazine, May 28, 2007

The childfree culture, therefore, may be a product of what we might call a ‘failed disfavouring selection’ hypothesis — i.e., unlike many traits that can be interpreted as a consequence of being favoured by natural selection in the ancestral past, attraction to a childfree lifestyle may instead be a consequence of not having been disfavoured.

Importantly, however, things may be about to change dramatically: Choosing to be childfree — as women are increasingly free to do (as they should be) — means zero gene transmis-sion through direct lineage.  Accordingly, selection against weak maternal instinct (or weak 'parenting drive' — see below) may soon be ramping up (Aarssen 2007). If so, then might this selection, within say a generation or two, spell an abrupt end to the childfree culture?

The childfree culture is one of the reasons that world population growth rate started to decline near the end of the last century — a welcoming trend for a crowded planet with “too many people and too much stuff” (Ehrlich and Ehrlich 2008). An important question is whether human birth rate might continue to drop voluntarily and substantially in the coming decades — both in developed countries, where more and more women are embracing small families and the childfree culture, and in less developed countries, where empow-erment for women is gaining more and more momentum (Engelman 2010). But this may be unlikely to unfold so neatly, and maybe not at all — for one fairly obvious reason:  The parents of the future will not be products of the childfree culture. Instead, many of them will be the descendants of women today who are choosing freely and anxiously to raise children, and perhaps especially those who are anxious to raise a lot of them.

Natural selection never limits the reproductive success of resident individuals of any species in order to minimize the collective misery of over-population.  Echoing Charles Galton Darwin (1953), Theodosius Dobzhansky (1962) warned, over half a century ago:

“Reduction of the birth rates is necessary if the population growth is to be contained.  Family planning and limitation are not, however, likely to be undertaken by everybody simultaneously.  Those who practice such controls will contribute to the following generations fewer genes in proportion to their number than those who do not.  Fewer and fewer people will, therefore, be inclined to limit their families as the generations roll by.  The human flood, rising higher and higher, will overwhelm a multitudinous but degenerate mankind.  The assumption implicit in this argument is, of course, that the craving for perpetuation of one’s seed is uncontrollable by reason and education, and that people will go on spawning progeny, even knowing that it is destined to be increasingly miserable.”   

 

There are already signs that this effect may be unfolding now — in part, I suggest, because of selection that has only recently been allowed to favour a strong 'parenting drive' (by disfavouring weak parenting drive).   


‘Parenting drive’ is defined here as an intrinsic attraction (informed in part by genetic inheritance) to memetic legacy through influence on offspring, but one that is also heavily infused with intrinsic attraction to a particular kind of pleasure reward at the same time — triggered specifically (odd as it may seem to some) by the hard work of parenting.  Research has shown that there is often a sense of ‘meaning’ in purposeful toil and mundane routine (Baumeister et al. 2013).  Pre-occupation with hard work (especially when purposeful) leaves little time for worry or depressing thoughts, including those rooted in self-impermanence anxiety.  A distracting pleasure then — like that of leisure — is obtained from just staying busy.  And the ‘busy work’ of parenting is available in greater abundance, of course, with increasing family size (Angeles 2010, Nelson et al. 2013).

A strong ‘parenting drive’ can be seen in recent pro-natalist movements involving attraction to large family size — typically supported by wealth, and combined often with religion (e.g. the ‘Quiverfull’ movement; Joyce 2010), but not in all cases (Brooks 2004, Kaufman 2010, Rowthorn 2011, Caplan 2012).  Importantly, prior to the women's liberation movement of the last century, weak parenting drive (despite it’s obvious disadvantage for evolutionary fitness), probably never had widespread opportunity to be strongly disfavoured by natural selection.  But today this opportunity is growing rapidly and globally, as women everywhere are becoming fully empowered, like never before, to take control of their sexuality and fertility, as well as their livelihood and personal goals.

These freedoms for women are of course cause for great celebration, and are long overdue. Is it possible, however, that without coercive measures to limit the number of births per female, contemporary pro-natalist cultures (e.g. like ‘Quiverfull’) could — because of Darwinian selection — soon displace the childfree culture?  And could this result in rising birth rates in the coming decades?   If so, a collapsing civilization (Ehrlich and Ehrlich 2013, Bradshaw and Brook 2014 ) will undoubtedly look more certain than it already does.

References

Aarssen LW (2007) Some bold evolutionary predictions for the future of mating in humans. Oikos 116: 1768-78.

Aarssen LW, Altman T (2012) Fertility preference inversely related to ‘legacy drive’ in women, but not men: Interpreting the evolutionary roots, and future, of the ‘childfree’ culture.  The Open Behavioral Science Journal 6: 37-43. 

https://benthamopen.com/ABSTRACT/TOBSJ-6-37

Angeles L (2010) Children and life satisfaction. Journal of Happiness Studies 11: 523-538.

Bacon F (1985) Francis Bacon: The Essays. Penguin, London.

Baumeister RF, Vohs KD, Aaker JL, Garbinsky EN (2013) Some key differences between a happy life and a meaningful life.  The Journal of Positive Psychology 8: 505–516.

Bradshaw CJA, Brook BW (2014) Human population reduction is not a quick fix for environmental problems. Proceedings of the National Academy of Science 111: 16610-16615.

http://www.pnas.org/content/111/46/16610.full.pdf

Brooks D (2004) The New Red-Diaper Babies. New York Times.

http://www.nytimes.com/2004/12/07/opinion/07brooks.html?ex=1260162000&en=ebdde83f03fe6d2e&ei=5090

Caplan B (2012) Selfish Reasons to Have More Kids: Why Being a Great Parent is Less Work and More Fun Than You Think. Basic Books, New York.

Dobzhansky T (1962) Mankind Evolving: The Evolution of the Human Species. Yale University Press, New Haven.

Ehrlich P, Ehrlich A (2008) The problem is simple: too many people, too much stuff. http://www.alternet.org/story/94268/the_problem_is_simple%3A_too_many_people%2C_too_much_stuff.

Ehrlich PR, Ehrlich AH (2013) Can a collapse of global civilization be avoided? Proceedings of the Royal Society B  280:  http://dx.doi.org/10.1098/rspb.2012.2845

Engelman R (2010) More: Population, Nature, and What Women Want. Island Press, Washington DC.

Frazer B (2011) The No-Baby Boom: A growing number of couples are choosing to live child-free. And you might be joining their ranks. Details, April 2011. http://www.details.com/culture-trends/critical-eye/201104/no-baby-boom-non-breeders

Joshi ST, ed (2006) In Her Place:A Documentary History of Prejudice Against Women. Prometheus Books, Amherst NY.

Joyce K (2010) Quiverfull: Inside the Christian Patriarchy Movement.  Beacon Press, Boston.

Kaufmann E (2010) Shall the Religious Inherit the Earth?  Demography and Politics in the Twenty-First Century. ProfileBooks, London.

Kingston A (2014) The no-baby boom: Social infertility, baby regret and what it means that shocking numbers of women aren’t having children.  MacLean’s magazine, March, 2014.

http://www.macleans.ca/society/the-no-baby-boom/

McGinley P (1956) Women are wonderful: They like each other for all the sound, sturdy virtues that men do not have. Life magazine, 24 Dec 1956.    

Murray C (2003) Human Accomplishment: The Pursuit of Excellence in the Arts and Sciences, 800 BC to 1950. New York: HarperCollins.

Nelson SK, Kushlev K, English T, Dunn EW, Lyubomirsky S (2013) In defense of parenthood: Children are associated with more joy than misery. Psychological Science 24: 3–10.

Rowthorn R (2011) Religion, fertility and genes: a dual inheritance model. Proceedings of the Royal Society B 278: 2519–2527.

Sandler L (2013) Having It All Without Having Children. Time Magazine, August 2013.

http://time.com/241/having-it-all-without-having-children/

Shorto R (2008) No Babies? New York Times, June 2008. http://www.nytimes.com/2008/06/29/magazine/29Birth-t.html?_r=2&ref=magazine&pagewanted=all&

  

The evolution of cool

For my new book (Aarssen 2015; coming out later this year), I’ve been thinking lately about the culture of ‘cool’, and in particular whether it can be understood in terms of probable evolutionary roots. The term ‘cool’ has assumed several connotations over a long history of social evolution, commonly referring to characteristics of people, but also, in some cases, things or situations. But one version in particular has endured, and remains conspicuous today: the person who is regarded as ‘cool’ because of a distinctive attitude — represented in certain ways of walking or speaking, or certain types of facial expressions or gestures (sometimes with props/accessories like sunglasses or cigarettes) — that evokes a demeanor of composure, self-confidence, and nonchalance towards situations where, normally, excitement or emotional vulnerability would be expected.

This is usually also accompanied by a distinctive appearance or presentation — e.g. reflected in certain styles of dress or grooming (e.g. hair, beard), certain choices for hobbies, or certain 'tastes' (e.g. in music, preferred restaurants, or home furnishings) — that evokes an impression of being impervious to the sway of popular fashions and conventions. These have been the trademarks of the beatniks, bohemians, eclectics, freethinkers, eccentrics, hipsters, and elitists.

The question is: Why are we impressed with this? What interests me is whether it might be rooted in our intrinsic attraction to anything that points to potential for defying inevitable death — an apparent indifference to awareness of self-impermanence.

Do people admire coolness and want to be like cool people because this signals a talent that could be deployed for dismissing or buffering the normally crippling private anxiety of mortality salience?

Did our ancestors want to be around cool people (including as a potential mate) because they thought that this talent might somehow rub off on them?

Perhaps coolness served our distant ancestors by ‘announcing’ truthfully (to potential adver-saries and potential mates), an unflappable superiority: “My talents for poise and emotional control have such high quality that nothing fazes me; I can handle any challenge with dispassionate ease.” The embedded message here is that this includes the challenge of responding effectively to the universal human terror from the ‘curse of consciousness’: “to know that one is food for worms”, as Becker (1973) put it. According to this hypothesis then, potential mates that were authentically cool were not only socially popular; they were sexually attractive and probably also a good bet for being equipped to provide for (and to favourably inspire) one’s offspring — all good things for gene transmission success.

Natural selection (and hence cultural selection shaped in part by natural selection) in our ancestral past, therefore, may have favoured (probably especially in males) dispositions (informed by genetic inheritance) for public mannerisms and styles of many sorts that projected a confident, self-determining, calm, and collective persona, with an elite knowingness — as truthful advertisements of these personifications. This would have also required of course the evolution of capacity to accurately detect and correctly interpret these advertisements in others. And at the same time, therefore, the evolution of strategies for deception would have been inevitable. The latter, much of the time, can reward reproductive success just as well as the ‘real deal’.

Today therefore, the ‘cool guy’, much of the time, is likely to be a fake, a complete scam —

a deliberate deception designed to attract the notice of others, serving only to bolster one’s self-esteem (a handy tool-kit item, of course, for buffering self-impermanence anxiety). Like the mostly female culture of cosmetics, and the largely male culture of conspicuous wasteful consumerism, the culture of ‘cool’, one might expect then, is commonly also a false advertisement. In other words, the cosmetics user is often not really as young as she appears, the young male who buys expensive fast cars (that he can’t afford) is often not really as rich as he appears, and the ‘cool guy’ whose countercultural style screams — “I’m too cool to care about convention or the latest trends that the masses follow” — is often just very concerned about appearing ‘cool’, and very talented (and concerned) about concealing that concern.

The latter is plainly evident in some men whose clothing makes a statement, but not because it is flamboyant or expensive. Just the opposite; instead, it looks understated for the venue relative to the average or ‘standard’ expectation — e.g. because it looks (sometimes ever so subtly) like it is past its best-before date, or because it is minimalist (e.g. a clean but plain undershirt, usually white, grey or black, and untucked or half-tucked), or because it is a style from an earlier decade. On the surface of course, the ‘cool guy’ here — despite obviously being able to afford the latest fashion — looks like he just can’t be bothered to make any significant effort in deciding what should be in his wardrobe. After all, only ‘cool guys’ can get away with that.

But nothing could be further from the truth; the wardrobe was cleverly and carefully chosen — including even with intentional visits to the used clothing store — in order to give the appearance that it was not carefully chosen.

And so, just as with cosmetics and expensive fast cars, contrived ‘coolness’ will fool some of the people some of the time. The interesting and entertaining thing here lies in watching how the contrived ‘cool’ need to continually reinvent themselves, as the masses discover and copy what is ‘cool’ (thus rendering it no longer cool) — and in trying to decipher who these many pretentious fakes are, lurking in our midst. [It’s easier to spot them, when you’ve been one yourself].

References

Aarssen LW (2015) What Are We? Exploring the Evolutionary Roots of Our Future. Queen’s University, Kingston.

Becker E (1973) The Denial of Death. Simon and Schuster, New York.

Wherefore the curse of consciousness?

Around 40—50 thousand years ago, but possibly earlier, our ancestors started to become equipped for profound enlightenment:  they discovered a sense of time, and got a glimpse of self-awareness. With consciousness (variously called, 'theory of mind', the 'human spark', and the 'mind’s big bang'), our species began to interpret self in relation to the passage of time, and in relation to a recognition of self-awareness in others. With this came capacity to plan for the future, and to envisage an existence of unseen others and events from the past that was understood to have been just as ‘real’ as the present. Combined with growing powers of reasoning, computation, curiosity, insight, imagination, and memory, it meant being able to use abstract/symbolic thinking to see beyond the actual to the possible, to anticipate the thoughts and actions of others, and to deliberately control one’s behaviour. With these cognitive skills, Homo sapiens was launched on a trajectory of genetic and cultural evolution unlike any other in the history of life — sometimes called the 'great leap forward'. Our predecessors who lacked them did not become our ancestors. 

But all of this came with an emotional cost: anxiety about one’s imagined, eventual mor-tality at some unknown time in the future. The uniquely human capacity to foresee one’s own eventual death, normally evokes a well-spring of terror — the 'curse of consciousness'. It starts in early childhood and extends cross-culturally. Numerous studies in social psychol-ogy involving 'terror management theory' have shown how death reminders commonly evoke a wide range of behaviours associated with "world-view and esteem defense and striving" (Burke et al. 2010).



Many critical questions, however, remain unanswered:  Where did this terror come from? Why are humans so primed to feel it?  Was 'eventual mortality' anxiety just a by-product of something else favoured by natural selection?   Was it linked to a cost-benefit trade-off? How did our ancestors cope with it?  Did they just put up with it as best they could?  Why did natural selection not eliminate this seemingly maladaptive cognitive domain?  Or was it perhaps never really maladaptive at all?  Did natural selection play a role in shaping motivational and behavioural responses to it, in ways that facilitated deployment of 'anxiety buffers'?  Or did natural selection somehow turn the emotional cost of this anxiety into a fitness benefit?

In my new book, to be published later this year (Aarssen 2015), I explore possible answers to these questions. Below is an excerpt from the book, describing three plausible evolutionary hypotheses, where 'eventual mortality' anxiety can be interpreted — in terms of genetic fitness — as maladaptive, neutral, or adaptive.

(i) 'Eventual mortality' anxiety is just ancient 'survival instinct' gone awry, misemployed by a fitness trade-off cost of consciousness — i.e. maladaptive in terms of genetic fitness. 

According to this hypothesis, time- and self-awareness gave us knowledge of eventual mortality, which automatically deploys our primitive survival instinct, thus triggering its usual emotional response: anxiety.  But this anxiety, and hence the consciousness that caused it, imposed a fitness cost — one that was worth paying, because the fitness benefits of consciousness were greater.  Survival instinct in other mammals is mostly about responding with 'fight, flight, or freeze' (accompanied by fear) to perception of a looming danger (e.g. attack from a predator or a rival) — or responding with frantic (fearful) desperation to an immediate or impending shortage of an essential resource (e.g. starvation). Importantly, these mortality risks all involve physical pain (from injury or hunger), and the above responses of course also characterize expressions of traditional Survival Drive in humans. The crucial question here, however, is this:  Is it possible that deployment of survival instinct in humans (because we can imagine ourselves in the future) need not (as for other mammals) require an immediate or imminent threat to continued existence?  In other words, did humans inherit a survival instinct so overpowering that it also manifests as fear even in response to events that we know will only eventually happen, like death?  The answer, according to this hypothesis, is yes — i.e. humans and humans alone have a survival instinct so acute that it routinely compels us to be anxious about our own death, even though it can only be imagined, as an eventuality, sometime in the future, resulting (if young) even in the distant future from just ordinary old age, and even peacefully without violence, injury or even pain — AND even when all of this resides in the mind only subconsciously.  If this is true, the emotional cost of this anxiety may or may not — as a trade-off of consciousness — also have imposed a genetic fitness cost for our ancestors.  But if it did (i.e. impose  a cost that partially compromised the fitness benefit of time- and self-awareness), then we might expect natural selection to have favoured cognitive domains like Leisure Drive that — through distractions — at least partially mitigated the anxiety.

(ii) 'Eventual mortality' anxiety is/was just a neutral by-product of 'fear of the unknown' — i.e. neutral in terms of genetic fitness. 

In this case, the anxiety had an emotional cost only, without im-posing any significant fitness cost (or benefit). Imagining a non-vio-lent and painless death, happen-ing sometime eventually, in our advancing years is just as much a personal mystery today as it was for our ancestors. We have no idea what the experience will be like, or even whether there will be anything to experience at all.  Eventual mortality then can be considered as just one item in a list of several unknown and unseen things that provide no clue about what they are — like the quiet dark. Behind some of these, however, at least some of the time (but regularly enough in the experience of ancestors), danger was lurking — maybe a predator or an ambush by compet-itors. Accordingly, humans apparently evolved a general all-purpose, hard-wired, instinct-ual caution, and sometimes fear (despite its emotional cost), regarding anything and everything that couldn’t be understood, couldn’t be sensed, or couldn’t be predicted, because this was, on average, good for gene transmission success in ancestors.  Importantly, however, this differs from the survival instinct triggered by known hazards (like lack of food, or an attacker that is in plain view, or that makes a familiar sound revealing its presence nearby). Much or most (and in some cases virtually all) of the time, when ancestors were confronted with a mysterious unknown, there was really no danger 'lurking in the dark' at all.  The latter, according to this hypothesis, was true all of the time with respect to ‘eventual mortality’ anxiety.  In other words, a general anxiety ('just in case') about things unknown was undoubtedly adaptive for our ancestors, but the specific anxiety about one’s imagined eventual death, at some unknown time in the future, never was. And neither was it maladpative [but even if it was, then again, we might expect natural selection to have favoured cognitive domains like Leisure Drive, serving to buffer the anxiety]. This is whimsically captured in the definition of life from Bierce (2011): "LIFE, n. A spiritual pickle preserving the body from decay. We live in daily apprehension of its loss; yet when lost, it is not missed." 

(iii) 'Eventual mortality' anxiety was directly favoured by natural selection — i.e. adaptive in terms of genetic fitness. 

In this case, the anxiety itself directly promoted gene trans-mission success in ancestors. This seems counter-intuitive at first, but according to this hypothesis, the anxiety here is not really associated with the eventual ex-perience of literal death; it is associated more directly with what eventual death imposes: self-impermanence.  Hence, it is not really rooted in what is traditionally understood as a survival instinct, or 'survival drive'.  Self-impermanence anxiety is about worrying that life is absurd — pointless and meaningless — not just because time brings eventual death, but more specifically because (in bringing eventual death) time inevitably annihilates all that we do, and all that we are.  Self-impermanence anxiety then can be buffered by Leisure Drive, but also by Legacy Drive — i.e. a drive to leave (despite knowledge of inevitable mortality) something of oneself — a legacy — for the future. Legacy Drive then essentially 'comes to terms' with mortality salience. And yet, at the same time, it is always just a delusion. Consider that today, for every deceased human that has ever existed (save for a miniscule micro-fraction), it is as though s(he) never did.   Only genes have legacy (Dawkins 1989). But Legacy Drive has a powerful hold on human nature nonetheless, because (according to this hypothesis) it has evolutionary roots in an ancestral attraction to 'memetic legacy' through offspring; i.e. through feeling a sense that one can create a lasting 'carbon-copy' of self by shaping the minds of one's offspring — to instill within them the same things (the ideas, values, beliefs, ego, self-image/esteem, personality, and virtue of character) that define who you are.  This is also mostly a delusion, with parents easily fooled (e.g. see Harris 1998).  But importantly, the reward nevertheless goes to gene transmission because offspring are the very vehicles of genetic legacy, including for genes that might inform Legacy Drive (as well as Leisure Drive) (Aarssen 2007, 2010). As Barash (2012) put it, "Maybe awareness of mortality isn’t merely a tangential consequence of consciousness but its primary adaptive value, if it has the effect of inducing people to seek yet another way of rebelling against mortality: by reproducing."

Humans are not as smart as they often think they are.  We are easily fooled, distracted, and deluded.  Our motivations did not evolve to deliver us truth — only fitness.  

References

Aarssen LW (2007) Some bold evolutionary predictions for the future of mating in humans. Oikos 116: 1768-78.

Aarssen LW (2010) Darwinism and meaning. Biological Theory 5: 296–311.

Aarssen LW (2015) What Are We? Exploring the Evolutionary Roots of Our Future. Queen’s University, Kingston.

Barash DP (2012) Homo Mysterious: Evolutionary Puzzles of Human Nature. Oxford University Press, New York.

Bierce A (1911) The Devil’s Dictionary. http://www.thedevilsdictionary.com

Burke BL, Martens A, Faucher EH (2010) Two decades of terror management theory: A meta-analysis of mortality salience research. Personality and Social Psychology Review 14: 155-195.

Dawkins R (1989) The Selfish Gene, rev. ed. Oxford University Press, Oxford.

Harris JR (1998) The Nurture Assumption: Why Children Turn Out the Way They Do. Simon & Schuster, New York.

Bioscience research needs more valuation branding

I have spent over 30 years in a career that has allowed me to enjoy, on a regular basis, one of the greatest pleasures of childhood: making discoveries by following one’s curiosity.
It has been a great privilege being able to earn a salary from doing what I love — curiosity-driven research, and sharing enthusiasm for it with students. It's what universities have always done.

Looking back on my productivity so far, I am pleased enough with its impact and contribution to fundamental science within my main field of study (plant ecology and evolution).  But I am struck now, in retrospect, by how most of it was pursued (and funded) with very little or nothing in the way of conspicuous goals in mind to address societal needs. This was of interest to me, but it did not drive me. 

Of course I have always paid some lip service to ‘applied implications’ within grant applications.  But it was never expected of me to justify my (mostly lame) claims of ‘relevance’, nor to provide a progress report on these claims, nor to explain to the general public exactly how my research results — funded by taxing the public — had potential to contribute in some way, at least eventually, to human well-being or the betterment of society.  I certainly believe that my research has made contributions in this regard — in terms of a better understanding of how nature works — but probably not as much as it

might have, had I been encouraged and motivated to be more explicit in thinking and communicating about these connections. Importantly, I could have easily done this without weakening my contributions to basic science. But I didn't need to.

I take some of the blame for not showing more initiative on my own in this regard.  But such initiatives have not been a conspicuous part of popular culture within academia.  When I joined it over 30 years ago, there was pressure to fit into the professional ‘mold’, where the mission was defined (and still is) by an expectation to publish in the most prestigious fundamental research journals — journals that the general public did not have access to read from (and largely still don’t), and mostly wouldn't understand if they did.  I was given freedom and encouragement to gorge with exhilaration on the excitement of wonder in the exploration of new ideas, and the joy of discovery in the generation of new knowledge — purely for their own sake, all as part of my job description.  And all without any meaningful accountability to the public.

The temptation to indulge was like candy to a child.

But it is a very different world today, and the tide is turning more and more rapidly. Escalating global-scale crises — antibiotic resistance, terrorism, addiction to consumerism, collapsing economies, depletion of non-renewable resources, frenetic urban expansion, species extinctions, irreversible climate change, and other converging environmental catastrophes — require urgent interdisciplinary focus.  They demand that universities break free of their centuries-old mission to train and inspire the next generation of specialized 'blue skies' researchers and scholars within a series of largely isolated traditional disciplines. Universities love their traditions. But as Behm et al. (2014) put it: “Academics no longer possess the privilege of complacency, of choosing to remain cloistered within the walls of the academy, of engaging only with the members of their disciplines. We must assume our roles as agents of democracy and perform service that promotes the public good. Unfortunately, after numerous calls to action, academics have largely failed to make publicly active scholarship and civic engagement defining parts of their mission.”
I have been as guilty of this as any.

In response to these developments and realities there has been a wave of media buzz in recent years from politicians, journalists and social commentators challenging university research to ‘get with the times’ in making clearer its connection to needs that are important to society at large (e.g. Mervis 2013, Sarewitz 2013).  The Canadian government has responded in kind with determination to channel greater allocation of research funding into ‘innovation needs’, including for partnerships with industry in support of sustainable technologies, commercialization of research, and job creation (Owens 2013, Taylor-Vaisey

2013).  Calls for a stronger alignment with societal needs has also challenged universities to reconsider their roles as educators.  As Behm et al. (2014) put it, there are "… lingering public perceptions that higher education is elitist and unresponsive to contemporary social challenges."  And from Miller (2014): "... as universities have become providers of education for the masses of advanced societies, the narrow goal of disciplinary education is no longer fit for purpose.  The academy does not need thousands of economists or physicists to keep these disciplines going; we need only a small number of brilliant minds.  And yet the academy, because of its conservative disciplinary nature, insists on training legions of economists, religionists and physicists." 

It is important for university researchers to continue to advocate for the support of fundamental research (e.g. Seidman 2014, Carmi and Crago 2014) but not by contrasting it with applied research.  What is needed is a more blended philosophy for defining the purpose of research.  In my view, this requires a new nomenclature to replace the archaic

university research label that we call ‘biology’.  Specifically, we need modern labels that represent valuation branding — i.e. missions for discovery defined by the generation of new knowledge that is contextualized and integrated with problem-solving relevance for human societies. Essentially this means no longer thinking about basic and applied research as a dichotomy or a continuum, but instead regarding them as a blend.

Recently (Aarssen 2013), I identified three distinct research valuation themes that are already evident within most university biology departments, and that could be used for restructuring and naming new administrative units within the biosciences: (1) life health science; (2) life products science; and (3) life conservation science (Fig. 1).  As new departmental branding labels, these could easily be born out of the biological sciences in the same way that several distinct departmental brands for engineering — each representing an integration of problem solving with deep curiosity — were at one time born out of the physical sciences.

Figure 1

These valuation branding labels for university research would not only guide and expand the progress of bioscience.  They would also enable society to better appreciate what university researchers do and why they do it, including with parents seeing more clearly where their graduated daughters and sons might find careers.  Distinct valuation branding for bioscience would also allow researchers to organize themselves into more operational administrative units, in which members of each department overlap significantly in terms of how they define infrastructural needs and how they identify the expertise and skills of departmental colleagues needed for building and maintaining effective local collaborations and centers of excellence.  In addition, the diversification of departmental labels on the basis of valuation branding would strengthen the identification of priorities for university administrators to invest in future growth and increased support for bioscience research and scholarship.

Throughout the history of science, essential progress was made through the generation of

new basic knowledge from curiosity-driven research, without necessarily having any societal need or benefit in mind.  Much of it of course laid the foundation for applications that have given us the tools and technologies of modern civilization. But there was never any reason to worry that incremental and serendipitous advances in science, or the curiosity and creativity behind them, would have been compromised if attention to potential societal value had been blended in with the original research objectives.  It was (and remains) key that research funding be used to support the best scientists with the best ideas, but these great minds are more than talented enough to imagine and communicate how their objectives and efforts have potential to inform future value for society.  And even if an eventual societal value turns out to differ from the potential value that was anticipated, what harm would there be?

Research that includes basic curiosity as a motivation is of course still important today. But much (maybe all) of the ‘low-hanging fruit' has already been plucked.  And so, a culture

that continues to sanctify curiosity-driven, 'blue-skies' research, purely for its own sake — while neglecting or refusing to blend its objectives with application goals for society — runs an increasing risk of becoming an elitist, self-serving, intellectual void of esoteric and largely irrelevant eccentricities, completely disconnected from the practical concerns of humanity.

Researchers can no longer justify this approach by saying things like: “Well, it might lead to a discovery, someday, that might inspire an important unexpected application for society, and since we can't be sure whether a particular project will do that, we need to fund it anyway and just carry on with it, in case it does”.  If this was ever true, it has become much less so; today it is largely mythical, as Sarewitz (2013) put it (with sarcasm): "After all, the outcomes of basic research are unpredictable and therefore politicians need only pour in the money and stand aside as the scientists make the world a better place."
The general public and research funding agencies today are no longer convinced by this — because the average citizen is now too educated to be fooled by it.  In a 2013 Globe and Mail interview, the then federal Minister of State for Science and Technology said, “The day is past when a researcher could hit a home run simply by publishing a paper on some new discovery; the home run is when somebody utilizes the knowledge that was discovered for social or economic gain.”  It seems this is probably true according to a list of the top-50 "game-changing" research discoveries published recently by the Ontario Council of Universities; every one of them is lauded for it's public value.

If you have a hard time explaining the potential value of your research to society, there’s a good chance that it doesn't have any.  Sadly, this seems likely to be the case for the majority of published research, which apparently remains uncited in the literature — or virtually so, attracting only a small handful of citations, many (or most) of which are self-citations (Bauerlein et al. 2010, Remler 2014).

Maybe it's time some changes were made.


References

Aarssen, L.W. 2013. Valuation branding for bioscience research in the twenty-first century. BioScience 63 (6): 417-418. http://hdl.handle.net/1974/13048

Behm, N., Rankins-Robertson, S. and Roen D. 2014. The Case for Academics as Public Intellectuals. Academe (American Association of University Professors). http://www.aaup.org/article/case-academics-public-intellectuals#.VUP2biFVhBd

Bauerlein, M., Gad-el-Hak, M., Grody, W., McKelvey, B., and Trimble, S.W. 2010.
We Must Stop the Avalanche of Low-Quality Research.  The Chronicle of Higher Education. http://chronicle.com/article/We-Must-Stop-the-Avalanche-of/65890/

Carmi R., and Crago, M. 2014. This is the path of innovation.  Globe and Mail. http://www.theglobeandmail.com/globe-debate/this-is-the-path-of-innovation/article21300489/

Mervis, J. 2013. U.S. Lawmaker Proposes New Criteria for Choosing NSF Grants. Science. http://news.sciencemag.org/2013/04/u.s.-lawmaker-proposes-new-criteria-choosing-nsf-grants

Miller, J. 2014. Turning students into citizens. http://religiondispatches.org/turning-students-into-citizens-religious-studies-edition/

Owens, B. 2013. Canada puts commercialization ahead of blue-sky research. Nature. http://www.nature.com/news/canada-puts-commercialization-ahead-of-blue-sky-research-1.12663

Remler, D. 2014. How Few Papers Ever Get Cited? It’s Bad, But Not THAT Bad. http://blogs.lse.ac.uk/impactofsocialsciences/2014/04/23/academic-papers-citation-rates-remler/

Sarewitz, D. 2013. Pure hype of pure research helps no one. Nature. http://www.nature.com/news/pure-hype-of-pure-research-helps-no-one-1.13031?WT.ec_id=NEWS-20130528

Seidman, K. 2014. Academics unimpressed with Ottawa's new research fund. Montreal Gazette. http://montrealgazette.com/news/local-news/academics-unimpressed-with-federal-governments-new-research-fund

Taylor-Vaisey, N. 2013. The Conservative love affair with targeted research. Macleans. http://www.macleans.ca/politics/ottawa/the-conservative-love-affair-with-targeted-research/

Why be a reviewer?

Much concern has been raised in recent years about two related and growing problems with peer review:  willing reviewers are hard to find, and when found, review quality is often mediocre at best.  A few years ago, the managing editor of a reputable journal remarked to me in an email exchange (regarding the difficulty of finding reviewers): “It is getting worse and worse by the day.  Back a few years I sent manuscripts to 2-4 people and I could be sure to have two reports.  Today I need to send it to 10 persons to get 1-2 reports.  It is awful.”

Recently, as editor for a journal, I was forced to make the following unfortunate recommendation to be sent to the author:  “After several invitations, this paper was unable to raise the attention of reviewers; not a single review could be obtained.  Because editorial time is limited with many submissions to process, and because the authors are entitled to a timely assessment of their paper, it is in the best interests of the journal to withdraw further consideration of this paper, and also in the best interests of the authors to have an early opportunity to seek an alternative place for publication.”

In some cases of course, an invitation to review may be declined for unavoidable reasons — e.g. because the reviewer is too busy, has a conflict of interest, or does not feel qualified to review the topic or content of the paper.  Other personal reasons might be based on concern about avoiding bias in cases where the reviewer has already reviewed the paper for another journal, or based on a preference to remain anonymous, with concern that the review might reveal the identity of the reviewer.  In other cases, a reviewer may have none of the above concerns or limitations, but may simply lack sufficient incentive to review — for example because the reviewer finds the topic of the paper uninteresting, and sees no other personal benefit from spending precious time to provide a gratuitous review (especially if it is for a commercial publisher earning big profits).

Some journals have attempted to provide more incentives for reviewers (including for those who are just too busy) by offering things like a free one-year journal subscription, reduced author / article processing fees, more public recognition credit or reputation metrics for reviewing service, and monetary compensation.  I am unaware of any evidence

indicating how successful these are, but none of them so far has had any impact in affecting my own willingness to review.  Everyone however has a price.  [I might be persuaded, for example, by an attractive cash option to work overtime to complete a review that I would otherwise be unable to fit within my regular work schedule].

There is even more to this issue, when we ask the important question the other way around: Why do people agree to review manuscripts for journals, even when they are already busy?

This is a more interesting question because the fact is: virtually everyone is already overworked.  Based on conversations with colleagues, the traditional reasons reported for nevertheless accepting invitations to review are:  reviewing service is an obligation to my profession; reviewing helps me to establish a favourable reputation with journal editors; as a reviewer, I can learn how to be a better author/writer, or I can gain early insight into the latest research ideas and discoveries. Some say that when they agree to review (despite being already busy), it is just because they find the topic of the paper interesting.

The extent to which these alleged benefits are realized is difficult to quantify, but they all sound like very fine and noble reasons for making time to review journal manuscripts —

despite that there are 'never enough hours in the day’.  However, I am skeptical.  I wonder if none of the above reasons, even when added up together, represent the most common reasons for agreeing to review. Could it be that the most common real reasons are those that people are least likely to admit? Would it not be reasonable to predict that many (most?) people (regardless of how busy they were) would agree to review, with eager anticipation, every time they are invited to review a paper that cites one’s own work favourably, or disfavourably? — or a paper that is supportive or critical of one's most favourite theory, or least favourite theory? — or a paper authored by a research rival?

Two important reasons then are evident here in accounting for poor quality peer reviewing: One is because the reviewer really doesn't want to review, and one is because the reviewer really, really does want to review.  In the first case, the reviewer very reluctantly agrees

to review — and it shows.  This results because the reviewer is already overworked or lacks personal incentive to do a good job, but for some reason feels an obligation to review, and so it is completed with resentment and frustration (often manifesting as an overly critical assessment).  In the second case (more common in my view, and much more egregious), a poor quality review results because the reviewer is actually anxious to review, but for the 'wrong' (self-serving) reasons mentioned above.  This generates a peer-review bias problem that may be bigger and more systemic than we will ever be capable of detecting.  It is the grand un-testable hypothesis—and unspeakable for most researchers—thus ensuring that the peer-review system will forever remain far from perfect.

(Whatever you do, don't tell the general public.)

The ‘size-advantage’ hypothesis for plant competition — rejected

  Plants with larger body size generally have lower fitness under severe competition.

  ----------------------------------------------------------------------------------------------------------------------------------
The blue-flowered species has a larger maximum potential body size, but also must reach a larger size before it can reproduce at all — i.e. it has a larger minimum reproductive threshold size. In a severely crowded neighbourhood, therefore (represented here), very few offspring ever reach this minimum size and so they die without sex. In contrast, many offspring produced by the smaller red-flowered species — despite also being strongly suppressed by competition — manage to produce at least some grand-offspring, simply because they have a much smaller minimum reproductive threshold size.

Within most natural vegetation, resources are routinely and strongly contested between near neighbours of both the same and different species. According to conventional theory, the selection consequences of this sustained competition have been interpreted mostly in terms of a ‘size-advantage’ hypothesis — i.e. under severe neighbourhood crowding / competition, natural selection generally favours capacity (through pre-emptive, rapid and/or prolonged resource capture) for growth to a body size that is relatively large (e.g. Grime 1979; Keddy 1989, Grace 1990; Goldberg 1996). The precise physiological and morphological mechanisms of resource competition (particularly below-ground) may not always be size-related (Craine 2009). Nevertheless, since resources (water, soil nutrients, quanta of sunlight, etc) are always spatially (and temporally) distributed, it follows that a plant occupying more space (and over a longer time), both above and below ground, will generally be better equipped to acquire these resources and thus deny them to neighbours. An individual that manages to attain this relatively large body size (while neighbouring plants fail to do so) will thus, inevitably, be expected to achieve greater reproductive output. 

Results from recent empirical research, however, call into question the size-advantage hypothesis. If larger plant species are generally expected to exclude smaller ones when there is persistent crowding/competition, then neighbouring species should generally be more similar in body size than would be expected by random assembly, based on the local species pool. Yet several studies have failed to find evidence for this, including in grasslands (Schamp et al. 2011), old-field vegetation (Schamp, Chau & Aarssen 2008), wetlands (Weiher et al. 1998), temperate forests (Schamp & Aarssen 2009), tropical forests (Swenson & Enquist 2009), and coastal sand-dune succession (Waugh & Aarssen 2012). Larger species in crowded woody vegetation (Keating & Aarssen 2009), as well as in crowded herbaceous vegetation (Schamp et al. 2013, Aarssen et al. 2014), are not more likely than smaller species, to limit the resident species density within their immediate neighbourhoods, nor are they more likely to limit the representation of relatively small resident species. Bonser and Ladd (2011) similarly found that vegetative size was not a strong predictor of success under competition in annuals species; more important was the capacity to reproduce efficiently in the presence of competitors. Finally, a recent survey of published literature (Bonser 2013)—including for both short-lived semelparous and potentially longer-lived iteroparous species—showed that the efficiency of conversion of resources from vegetative tissue to reproductive output is generally higher (not lower) when competition levels increase, contrary to traditional life history theory.

When neighbourhood resources are strongly and persistently contested, therefore, there is apparently no general advantage (in terms of recruitment success or relative abundance within the habitat) for the offspring of species that are capable of (i.e. because they have evolved) relatively large potential body size (relative to the offspring of neighbouring species that have not evolved a large potential body size) (Tracey and Aarssen 2011, 2014). The vast majority of plant species everywhere are in fact relatively small; i.e. plant species body size distributions are right-skewed within every phylogenetic lineage, and for resident species at every spatial scale — from regional floras down to local neighbourhoods (Aarssen & Schamp 2002, Niklas et al. 2003, Aarssen et al. 2006, Poorter et al. 2008, Moles et al. 2009, Schamp & Aarssen 2009, McGlone et al. 2010, Dombroskie & Aarssen 2010, Tracey & Aarssen 2011). And importantly this is also true even within habitat types traditionally characterized as having the strongest competition effects imposed on resident species.

There is sufficient evidence, therefore, to reject the size-advantage hypothesis, and hence a need to replace it with revised model predictions for body size evolution in plants. The latter, I suggest, should begin with a now largely validated generalization: there is a fundamental between-species trade-off between maximum potential body size (MAX) and the capacity to reproduce when forced to remain small, i.e. minimum reproductive threshold size (MIN). This has long been evident anecdotally for woody vegetation (and see Thomas 1996, Davies & Ashton 1999), but has only recently been reported from empirical studies in herbaceous vegetation, including for the resident species within a single community (Tracey & Aarssen 2011, 2014, Nishizawa & Aarssen 2014). This ‘cost’ of relatively large body size likely reflects the need for generally greater investment in structural support tissue, and also structural or chemical defense against consumers — thus enabling the longevity (survival/growth time) needed in order to reach a large body size (Taylor et al 1990). This has implications for the interpretation of body size variation not just between habitat types — but also within a single community of interacting species.

Herein then lies a profound and largely overlooked implication for plant competition theory: if a larger species generally also needs to grow to a larger threshold size before it can reproduce at all, the latter may not be generally attainable in neighbourhoods with severe and persistent crowding / competition. Larger species, therefore, can certainly be successful competitors in terms of denying contested resources to neighbours, but not if they are unable to get large. And there can be no fitness (gene transmission) advantage at all in having a large body size unless the plant can reach, at least, its relatively large MIN. Accordingly, as argued below, it turns out that larger resident species within a plant community are not usually superior competitors when it really matters — in the most severely crowded neighbourhoods.

The 'reproductive economy advantage' hypothesis for plant competition.   

In the illustration above, hypothetical plants (genotypes or species) A, B, and C are represented by differently colored circles (white/gray/black) within three square ‘plots’ showing different neighborhood densities of resident seeds, which is the only stage in which the three plants – as embryos – are all the same size. In each case, the ‘stickplant’ symbols represent the relative body sizes of A, B, and C following emergence and growth to final developmental stage. The maximum potential body sizes (MAX) for A, B, and C can be expressed only when neighborhood density is very low (top row), where A has the largest MAX and hence the highest fecundity (represented by small red circles), and where it is thus favored by natural selection. Plant A therefore also has (as a trade-off) the largest minimum reproductive threshold size (MIN), which is expressed within a higher (intermediate)-density neighborhood (middle row). Here, plant B is favored by natural selection because its smaller MIN permits a higher fecundity than A, and its larger MAX permits a higher fecundity than C. Under very high neighbor density (bottom row), however, where all resident plants are severely suppressed in size, plant C has the highest fecundity because it has the smallest MIN (which imposes, as a trade-off, the smallest MAX) (Tracey and Aarssen 2014). Under these conditions, plants of both A and B die without sex because MIN for both is too large. Selection thus favours plant C because it has greater ‘reproductive economy’ — i.e. capacity to produce offspring that can survive long enough to produce at least some grand-offspring, while nevertheless remaining with a severely suppressed body size, even until death (Aarssen 2008).

Contrary to the ‘size-advantage’ hypothesis, therefore, selection in favor of relatively large MAX (plant A) occurs, not under the most crowded conditions, but only within local neighborhoods where competition effects are relatively weak (top row) — because only here can MAX (and its potential fitness advantage) be realized. The preponderance of relatively small resident species within most natural vegetation, therefore, can be at least partially accounted for by a preponderance there of severely crowded neighborhoods (bottom row).

Importantly here, success under severe competition is defined not just (or even most importantly) by capacity to capture resources and deny them to neighbours, but more fundamentally by the capacity to transmit genes to future generations, despite severe resource deprivation by neighbours. For this latter capacity, a growing body of evidence is pointing to an alternative hypothesis based on ‘reproductive economy advantage’: under conditions of extreme and protracted neighbourhood crowding/competition (where virtually all resident plants are necessarily forced to remain, until death, at only a small fraction of their maximum potential body sizes), it is the relatively small species that are more likely to leave descendants here — simply because they need to reach only a relatively small body size in order to produce at least some offspring. Resident plants of most larger species, however, are more likely to die here producing none at all.


References


Aarssen, L.W. (2008) Death without sex — the ‘problem of the small’ and selection for reproductive economy in flowering plants. Evolutionary Ecology, 22, 279–298.

Aarssen, L.W., Schamp, B.S. (2002) Predicting distributions of species richness and species size in regional floras: applying the species pool hypothesis to the habitat template model. Perspectives in Plant Ecology, Evolution and Systematics, 5, 3–12.

Aarssen, L.W., Schamp, B.S., Pither, J. (2006) Why are there so many small plants? Implications for species coexistence. Journal of Ecology, 94, 569–580.

Aarssen, L.W., Schamp, B.S., Wight, S. (2014) Big plants — do they affect neighbourhood species richness and composition in herbaceous vegetation? Acta Oecologica, 55, 36-42.

Bonser, S.P. (2013) High reproductive efficiency as an adaptive strategy in competitive environments. Functional Ecology, 27, 876–885.

Bonser, S.P., Ladd, B. (2011) The evolution of competitive strategies in annual plants. Plant Ecology, 212, 1441-1449.

Craine, J.M. (2009) Resource Strategies of Wild Plants. Princeton: Princeton University Press.

Davies, S.J., Ashton, P.S. (1999) Phenology and fecundity in 11 sympatric pioneer species of Macaranga (Euphorbiaceae) in Borneo. American Journal of Botany 86, 1786–95.

Dombroskie, S.L., Aarssen, L.W. (2010) Within-genus size distributions in angiosperms: small is better. Perspectives in Plant Ecology, Evolution and Systematics, 12, 283–293.

Grace, J.B. (1990) On the relationship between plant traits and competitive ability. In: Grace J.B. & Tilman, D. (eds). Perspectives on Plant Competition. San Diego, Texas: Academic Press, pp.384-385.

Goldberg, D.E. (1996) Competitive ability: definitions, contingency and correlated traits. Proceedings of Royal Society B: Biological Sciences, 35, 1377–1385.

Grime, J.P. (1979) Plant Strategies and Vegetation Processes. Wiley, New York.

Keating, L.M., Aarssen, L.W. (2009) Big plants—do they limit species coexistence? Journal of Plant Ecology, 2, 119-124.

Keddy, P.A. (1989) Competition, 2nd Edition. New York: Chapman and Hall, 202 pp.

McGlone, M.S., Richardson, S.J., Jordan, G.J. (2010) Comparative biogeography of New Zealand trees: species richness, height, leaf traits and range sizes. New Zealand Journal of Ecology, 34, 137–151.

Moles, A.T., Warton, D.I., Warman, L., Swenson, N.G., Laffan, S.W., Zanne, A.E., Pitman, A., Hemmings, F.A., Frank, A., Leishman, M.R. (2009) Global patterns in plant height. Journal of Ecology, 97, 923–932.

Niklas, K.J., Midgley, J.J., Rand, R.H. (2003) Size dependent species richness: trends within plant communities and across latitude. Ecology Letters, 6, 631–636.

Nishizawa, T., Aarssen, L.W. (2014) The relationship between individual seed quality and maternal plant body size in crowded herbaceous vegetation. Journal of Plant Ecology, doi:10.1093/jpe/rtt042

Poorter, L., Hawthorne, W., Bongers, F., Sheil, D. (2008) Maximum size distributions in tropical forest communities: relationships with rainfall and disturbance. Journal of Ecology, 96, 495–504.

Schamp, B.S., Aarssen, L.W. (2009) The assembly of forest communities according to maximum species height along resource and disturbance gradients. Oikos, 118, 564–72.

Schamp, B.S., Chau, J., Aarssen, L.W. (2008) Dispersion of traits related to competitive ability in an old-field plant community. Journal of Ecology, 96, 204-212.

Schamp, B.S., Hettenbergerová, H., Hájek, M. (2011) Testing community assembly predictions for nominal and continuous plant traits in species-rich grasslands. Preslia, 83, 329‒346.

Schamp, B.S., Aarssen, L.W., Wight, S. (2013) Effects of ‘target’ plant species body size on neighbourhood species richness and composition in old-field vegetation. PLoS ONE, 8(12), e82036. doi:10.1371/journal.pone.0082036

Swenson, N.G., Enquist, B.J. (2009) Opposing assembly mechanisms in a Neotropical dry forest: implications for phylogenetic and functional community ecology. Ecology, 90, 2161– 2170.

Taylor, D.R., Aarssen, L.W., Loehle, C. (1990) On the relationship between r/K - selection and environmental carrying capacity: A new habitat templet for plant life history strategies. Oikos, 58, 239-250.

Thomas, S.C. (1996) Relative size at onset of maturity in rain forest trees: a comparative analysis of 37 Malaysian species. Oikos, 76, 145–54.

Tracey, A.J., Aarssen, L.W. (2011) Competition and body size in plants: the between-species trade-off in maximum potential versus minimum reproductive threshold size. Journal of Plant Ecology, 4, 115-122.

Tracey, A.J., Aarssen, L.W. (2014) Revising traditional theory on the link between plant body-size and fitness under competition: evidence from old-field vegetation. Ecology and Evolution, 4, 959–967.

Waugh, J.M., Aarssen, L.W. (2012) Size distributions and dispersions along a 485-year chronosequence for sand dune vegetation. Ecology and Evolution, 2, 719–726.

Weiher, E., Clarke, G.D.P., Keddy, P.A. (1998) Community assembly rules, morphological dispersion, and the coexistence of plant species. Oikos, 81, 309‒322.