Interview With an Author – Joel Adamson

Yesterday, we published “Evolution of male life histories and age-dependent sexual signals under female choice”. We were really interested in hearing from the author, the soon-to-be Dr. Adamson.


Joel J. Adamson is a Ph.D. student studying with Maria Servedio in the Evolution, Ecology and Organismal Biology program at UNC Chapel Hill. Mr. Adamson graduated from the University of Colorado in Boulder in 2002 with a double-degree in Population Biology and Mathematics. From 2005 to 2008, he worked as a biostatistician in the Pediatric Psychopharmacology Research Unit at Massachusetts General Hospital, conducting research on bipolar disorder, ADHD and the genetics of psychiatric disorders. He lives in Durham, North Carolina with “five other primates and a carnivore”.

PJ: Tell us a bit about the research you published with us, and what is the take home message of your article?

The general focus of my dissertation is sexual selection on traits that change over the lifetime. Sexual selection studies typically use simplified life histories and do not account for how an individual’s phenotype might change due to maturation or aging. This is perfectly justified in most cases where the interest is very general. If we just want to know if a preference can evolve we can leave out a lot of details of phenotype. However, long-term studies of birds and mammals in particular are producing a lot of interest in how female preferences and male traits might change over the lifetime of individuals. The studies of Collared Flycatchers, Bighorn Sheep, Soay Sheep (feral sheep living on islands north of Scotland), Elephant Seals and humans really focused me on this topic. Hanna Kokko’s theoretical studies of the nature of handicap traits also brought this to my attention. Reading her papers I really started to think about male attractiveness as a life-history trait, i.e. a component of fitness that might have trade-offs or simply change over a male’s lifetime.

The study published in PeerJ is a numerical simulation of populations with age dependent traits. I used a C program to simulate the changes of allele frequencies over time, and looked at the sizes of traits that tended to be favored by selection when the trait depended on age or not. I also did simulations where both kinds of traits appeared in the same population.

The take-home message is that when sexual signals depend on age, they are basically “easier” to evolve. A sexual signal that depends on age can get past a difficult early period in evolution where it might be eliminated by natural selection. They’re not big enough to be attractive, but they’re big enough to incur selection. Traits that do not depend on age must be a lot bigger to survive this same period, but since age-dependent individuals produce small traits at young ages, selection is not as tough on them. Natural selection just doesn’t have the power to get rid of such traits, since due to demographic effects, selection is weaker on older ages than on younger ones. Therefore mating success becomes a stronger component of fitness later in life, whereas survival is more crucial earlier in life. The overall thesis of my dissertation is that reducing adult mortality facilitates sexual selection. Everything else being equal, organisms with longer lifetimes should be more likely to develop elaborate male signals than related species with shorter lifetimes.

The simulation software, including a library with a recombination algorithm, are all available as free software. The library can be found at and the simulation itself is on figshare. I used all free software in the development of the model and the production of the article, including project management (

PJ: In theory, does your model apply to Humans?

Yes, actually it does. The most likely candidates for sexually selected traits in humans are body size and social connectivity, both of which tend to increase (to a point) with age. Virpi Lummaa’s studies of human populations show exactly the pattern of fitness component changeover predicted by my models. The most critical component early in life is survival to maturity, and after that sexual selection becomes more important.

There are some complicating factors in applying my research to humans, as always.  My study was simplified with only one choosy sex called “female”. Humans probably display mutual mate choice, where both males and females are choosy about whom they mate with. My advisor Maria Servedio’s studies of mutual mate choice show that this does not actually complicate things as much as we might hope, female choice and male choice act fairly independently. However, another complicating factor is that in historical human populations marriage was often arranged without the consent of the people getting married. Mate choice could still have operated, but not in the Baskin-Robbins fashion we typically think of (“Best of 31”). In other words, even if females aren’t the ones doing the choosing, mate choice is still operating as a skewing of the probabilities of particular males mating.

I would definitely be interested in seeing applications of this work to humans and other primates.

PJ: Where do you hope to go from here? What is next in your research?

I have submitted a paper on age-dependent sexual selection with germ-line mutations to another Open Access journal (Ed Note: Is that permitted?).  A preprint is already available on ArXiv. That study uses quantitative genetics to study the evolution of female choice when male sperm carries an age-dependent quantity of deleterious mutations. Basically as males age their sperm carry more mutations. Some authors, particularly Thomas Hansen and Donald Price, suggested back in the twentieth century that this could cut into the adaptive value of mate choice. My basic conclusion (pre-peer-review!) is that age-dependent germ-line mutations actually maintain the adaptive value of sexual selection. I am now working on a project that looks at the evolution of age-dependent female preferences. The first thing people ask me at conferences is “What about when female choice depends on age?” so that’s what I’m doing next.

As so often happens, I’ve been working on this for a few years and would like to get into some new questions. I am really getting interested in the origins of sex and the evolution of lifespan. There’s some interesting mathematics there that I would love to learn. Over the past year and a half I’ve been a TA in cell biology, genetics and molecular biology. That’s given me a perspective on major transitions in evolution that I never had before. All my prior work has been at the organismal level: I barely thought about cells and chromosomes until last year.

PJ: How did you first hear about PeerJ, and what persuaded you to submit to us?

I heard about PeerJ on Twitter. I follow several people who are interested in the state of academic publishing, and this even led to a collaboration published in PLOS Biology encouraging the use of preprints. I am always interested in new ideas, and PeerJ built on the ideas of Open Access and preprints, so I was listening right away. Right before the announcement of PeerJ I did a talk/discussion about Open Access in the UNC biology department. I included PeerJ in a blog posting about developments in publishing. So pretty soon after the announcement people were coming up and asking me what I thought of PeerJ. I had wanted to try submitting a paper but thought “too bad my paper’s in review at that other journal.”

I have spent over two years trying to get this paper published. All the while I have been giving talks on it, presenting posters at conferences and putting it on ArXiv. Naturally I had been seduced by the prestigious, subscription-based journals of our field and submitted this work there first. It took forever to come back each of three times, and was rejected for what seemed like fairly superficial reasons. At least once reviewers said the paper was unoriginal, saying “this has been done already,” but not saying by whom. I had become an expert in this literature over the past few years, and I was fairly confident that the work was, at least in some way, original. The last time the manuscript was rejected mostly on the grounds that the single reviewer did not like my writing, but did not offer any suggestions for clearing it up. The journal also invoked a poorly known rule that published manuscripts must include empirical content. This rule did not apply to many other papers published last year in the same journal.

After that, I rapidly decided on submitting to PeerJ. I emailed a couple of friends, chatted with my advisor and they all said everyone was having a great experience submitting to PeerJ. I thought that the provisions about originality would at least get my paper a better chance of publication.

So you could say that I submitted to PeerJ out of frustration with other journals, paired with the tantalizing prospect of doing something new and interesting.

PJ: As a PeerJ Author, how would you describe your overall experience with us, in terms of submission, review, and production?

Helpful. The peer review and editing I received from PeerJ was actually helpful. This was surprising because it’s not part of the mission statement, or in the rules for reviewers, as far as I know! The reviews I got were actually about how to make the paper more readable. They were not about how it had been done already, nor about how it didn’t contribute anything new to the field. There was no picking on the writing, any more than helpful, concrete suggestions for how to make things clearer.

The other thing I was really happy about was the typesetting of the paper. When I received the page proofs I almost cried, seeing that something I’d worked on was so beautifully prepared. I had tried over the past few years to produce a good piece of work both in scientific and aesthetic quality, and I was glad to see the people at PeerJ had the same goals. I really felt like the production staff was looking out for me. They were really taking great care with my work: they seemed to know the value and hard work that I put into it.

PJ: PeerJ encourages Authors to make their review comments visible. Why did you choose to reproduce the complete peer-review history of your article?

Because it’s part of the article. One of the things that we strive to teach undergraduate students is the process of how an article gets published. As of now, for most articles, this is not something we can really show them. They have to take our word for it. I would also like people to see the effort that I went to in improving the article.

Another aspect is the convenience and total transparency allowed by the Internet.  With journals like PeerJ, the information is there if people want it. It doesn’t need to clutter up the main article. Also, since people can see the whole process, we can be honest in peer reviewing. I doubt reviewers would say the kinds of things I’ve seen if they knew that people would be able to read it on the Internet, with their names attached.

PJ:  What are your thoughts about the value of Open Access publishing?

I don’t see anything immoral about most subscription-based journals (most good ones, that is). There’s nothing inherently bad about paying for access to a journal. However, Open Access is just a great idea on so many fronts that I think it’s the way of the future. I could say I have a more pragmatic approach than some people who think Open Access is The Right Thing To Do. Many proponents I see on the Internet will invoke the taxpayer argument, the developing country argument and many others. I do want students and the general public to be able to see primary research.

Outweighing all of these arguments, however, is that print for scientific articles is pretty much obsolete. I say this as a huge fan of paper—I don’t read eBooks and I am a typography geek—but trying to use print-like format to convey the information we can convey over the Internet is just impractical. It wasn’t impractical in the twentieth century, when everybody was still using modems. Paper journals were still superior then. But now we can have the article, figures, code, data and everything available with a web-browser (it’s there when you want it, it’s not when you don’t). Putting all that convenience behind a paywalls and telling people not to share seems impractical and contrived.

PeerJ has added other innovations over Open Access that are facilitating this kind of future, and I’m really glad to be a part of it.

PJ: What do you see as wrong with the current system of publication?

The lack of transparency in reviewing leads to a lot of funny business. I was the main point person for publishing papers when I was a statistician at Massachusetts General Hospital. The lab I worked in was one of the leading psychiatry research labs in the world. We got away with a lot of stuff. We once had an Endnote glitch and submitted a paper without any references in it—it was still accepted for some reason. I had plenty of rejections in that lab, but it showed me the weight that certain names carry. Transparency in reviewing would put a damper on this. It would make things more obvious to the general public, but also to young scientists.

PJ: What would an ideal publishing venue look like?

A lot like PeerJ or F1000Research. I think preprints, i.e. getting the research out as fast as possible, is really important. Peer review is really valuable, but having it transparent and helpful is most important. I would rather just have a preprint server than an open access journal with terrible reviewing.

PJ: What do you feel makes PeerJ relevant to scientists?

I haven’t mentioned the quality of articles I’ve seen in PeerJ. I’m really glad to see a journal that has paleontology articles next to clinical studies and molecular biology.  That’s pretty cool. I think PeerJ is innovative on the author’s end, but it’s also just great to browse.

PJ: Anything else you would like to talk about?

Tea. The Genmaicha I had with lunch was just excellent.

Oh, and I’m really glad to see PeerJ using MathJax. I suggested this during a Twitter conversation and was glad to see a new journal taking up a new technology.

PJ: In conclusion, how would you describe PeerJ in three words?

Helpful. Fast. Beautiful.

 PJ: Many thanks for your time and your great feedback!

You can follow Joel on his blog and on Twitter.

Dont forget that from now until end-March 2014, we are running a special offer for free PeerJ Publications.

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