Means,variances, and ranges in reproductive success: comparative evidence

Data on reproductive success in traditional cultures suggest that for men, but not for women, range and variance rise as subsistence intensifies. For hunter–gatherers, ranges and variances tend to cluster in single digits: they reach 15 or 16, at the high end. For herder-gardeners, ranges and variances are more consistently in double digits: they get as high as 80 or 85. And for full-time agriculturalists in the first civilizations, ranges consistently ran to triple digits: emperors from Mesopotamia to Peru were the fathers of hundreds of children. In human societies, as in other animal societies, reproductive skew goes up with a more sedentary life.     

Forever Slaves? Inequality,Uncleanliness and Vigilance about Origins in the Southern Highlands of Madagascar

ABSTRACT

In the southern highlands of Madagascar, Betsileo free descendants strictly avoid marrying descendants of slaves, whom they regard as ‘unclean people’. A close examination of the history of a slave descent group shows that the most serious difficulty faced by former slaves after abolition was not access to land but ritual uncleanliness, which prevented intermarriage with free people and led to the essentialisation of the now pervasive hierarchical distinction between clean and unclean people. Today, free descendants actively maintain a social memory of ‘origins’ and remain extremely vigilant about not marrying the slave descendants, who are ‘locked’ into an unequal and unclean status that they cannot easily escape.     

The age-sex structure of the slave population in Harris County, Texas: 1850 and 1860

The effect of the slave system on demography can be revealed by examining the age-sex structure of slave populations. The age-sex structure of slaves in Harris County, Texas is investigated using the 1850 and 1860 slave schedules. Median ages for black and mulatto slaves suggest that the population was young. Population pyramids exhibit a narrow base and top with a broad middle. The high proportion of slaves between 10 and 30 years of age and the increase in population size between 1850 and 1860 were mainly related to the importation of slaves and only partly due to natural increase. The data also show that black slaves were older on small plantations while mulattoes were older on larger farms. It is suggested that differential treatment in terms of purchase practices, assignment of tasks, food allocation, and/or differential susceptibility to infectious diseases may account for this pattern.     

Women's mating strategies

What does a woman want? The traditional evolutionist's answer to Freud's famous query is that a woman's extensive investment in each of her children implies that she can maximize her fitness by restricting her sexual activity to one, or at most, a few high-quality males. Because acquiring resources for her offspring is of paramount importance, a woman will try to attract wealthy, high-status men who are willing and able to help her. She must be coy and choosy, limiting her attentions to men who are worthy of her and emphasizing her chastity so as not to threaten the paternity confidence of her mate. The lady has been getting more complicated of late, however. As Sarah Hrdy¹ predicted, we now have evidence that women, like other female primates, are also competitive, randy creatures. Women have been seen competing with their rivals using both physical aggression^2,3 and more subtle derogation of competitors.⁴ While they are still sometimes coy and chaste, women have also been described recently as sexy and sometimes promiscuous creatures, manipulating fatherhood by the timing of orgasm^5,6 and using their sexuality to garner resources from men. The real answer to Freud's query, of course, is that a woman wants it all; a man with the resources and inclination to invest, and with genes that make him attractive to other women so that her sons will inherit his success. Her strategies for attaining these somewhat conflicting aims, and her success in doing so, are shaped by her own resources and options and by conflicts of interest with men and other women.     

Voice pitch predicts reproductive success in male hunter-gatherers

The validity of evolutionary explanations of vocal sexual dimorphism hinges upon whether or not individuals with more sexually dimorphic voices have higher reproductive success than individuals with less dimorphic voices. However, due to modern birth control methods, these data are rarely described, and mating success is often used as a second-rate proxy. Here, we test whether voice pitch predicts reproductive success, number of children born and child mortality in an evolutionarily relevant population of hunter-gatherers. While we find that voice pitch is not related to reproductive outcomes in women, we find that men with low voice pitch have higher reproductive success and more children born to them. However, voice pitch in men does not predict child mortality. These findings suggest that the association between voice pitch and reproductive success in men is mediated by differential access to fecund women. Furthermore, they show that there is currently selection pressure for low-pitch voices in men.     

Genetic relatedness to sisters' children has been underestimated

Males of many species help in the care and provisioning of offspring, and these investments often correlate with genetic relatedness. For example, many human males invest in the children of sisters, and this is especially so where men are less likely to share genes with children of wives. Although this makes qualitative sense, it has been difficult to support quantitatively. The prevailing model predicts investment in children of sisters only when paternity confidence falls below 0.268. This value is often seen as too low to be credible; so investment in sisters'' children represents an unsolved problem. I show here that the prevailing model rests on a series of restrictive assumptions that underestimate relatedness to sisters'' children. For this reason, it understates the fitness payoff to men who invest in these children. This effect can be substantial, especially in societies with low confidence in paternity. But this effect cannot be estimated solely from confidence in paternity. One must also estimate the probability that two siblings share the same father.     

The temporal ‘structure’ and function of the insect photoperiodic clock: a tribute to Colin S. Pittendrigh

In 1936, Erwin Bünning suggested that photoperiodic time measurement was a function of the circadian system. Colin Pittendrigh became an ardent supporter of Bünning's hypothesis, drawing parallels between photoperiodism and his own group's investigations of adult eclosion rhythmicity in the fruit fly Drosophila pseudoobscura. They developed several more modern versions of Bünning's general hypothesis based on the entrainment of circadian oscillations to the light cycle, including ‘external coincidence’, which is a derivation of Bünning's original model, and ‘internal coincidence’, which relied upon seasonal changes in the mutual phase relationship of oscillators within a multi‐oscillator circadian system. This review considers the experimental evidence for the central role of the circadian system in photoperiodic timing and, in some species, for both external and internal coincidence. Pittendrigh, however, pursued the idea of internal coincidence further with his analysis of the pacemaker–slave organization of eclosion rhythmicity in D. pseudoobscura and proposed a similar theoretical model for photoperiodism comprising a group of slave oscillators driven by a light‐sensitive pacemaker. In this model, the phase relationships of the slaves to the pacemaker were affected by (i) the relative periods of the pacemaker and slave(s); (ii) the strength(s) of the coupling between the two; and (iii) the dampening coefficients of the various slaves. Manipulation of these variables showed that the slaves adopted different internal phase relationships (both to each other and to the pacemaker) under the influence of changes in daily photophase, the period of the Zeitgeber and phase shifts of the entraining light cycle.     

Birds Do It. Bees Do It. So Why Not Single Women and Lesbians?

Infertile couples have come to take assisted reproductive technologies (ART) for granted. An increasing number of single women and lesbian couples also desire to have children and turn to ART, especially donor insemination, to fulfill this desire. While most married couples find that access to ART is limited primarily by the ability to pay, for single women and lesbian couples, the story may be much different. In the United States, they may find that doctors and infertility clinics view their desires as immoral and refuse to accept them as patients, although other doctors and clinics readily accept them. In most other countries, however, it is against the law for single women and lesbian couples to make use of ART, including donor insemination.
In this paper I will argue that marital status and sexual orientation should not serve as a barrier to accessing the world of reproductive medicine. I will base this conclusion on two arguments. First, that justice requires that we treat like cases alike. Just as we would not accept or reject patients for cardiac rehabilitation programs based on factors such as a history of poor eating habits, so too we should not look at nonmedical factors such as marital status when deciding whether to treat infertility. For the second justification for the conclusion of equal access to ART, I will examine the concept of the family. I will argue that it is morally acceptable for single women and lesbian couples to have children and to head families.     

Birds do it. Bees do it. So why not single women and lesbians?

Infertile couples have come to take assisted reproductive technologies (ART) for granted. An increasing number of single women and lesbian couples also desire to have children and turn to ART, especially donor insemination, to fulfill this desire. While most married couples find that access to ART is limited primarily by the ability to pay, for single women and lesbian couples, the story may be much different. In the United States, they may find that doctors and infertility clinics view their desires as immoral and refuse to accept them as patients, although other doctors and clinics readily accept them. In most other countries, however, it is against the law for single women and lesbian couples to make use of ART, including donor insemination.
In this paper I will argue that marital status and sexual orientation should not serve as a barrier to accessing the world of reproductive medicine. I will base this conclusion on two arguments. First, that justice requires that we treat like cases alike. Just as we would not accept or reject patients for cardiac rehabilitation programs based on factors such as a history of poor eating habits, so too we should not look at nonmedical factors such as marital status when deciding whether to treat infertility. For the second justification for the conclusion of equal access to ART, I will examine the concept of the family. I will argue that it is morally acceptable for single women and lesbian couples to have children and to head families.     

Eusociality: From the First Foragers to the First States

People have always been social. Ethnographic evidence suggests that transfers of food and labor are common among contemporary hunter-gatherers, and they probably were common in Paleolithic groups. Archaeological evidence suggests that cooperative breeding went up as we settled down: as territory defenders became more successful breeders, their helpers’ fertility would have been delayed or depressed. And written evidence from the Neolithic suggests that the first civilizations were often eusocial; emperors fathered hundreds of children, who were provided for and protected by workers in sterile castes. Papers in this issue of Human Nature look at helpers and workers across the eusociality continuum—from hardworking grandmothers and grandfathers, to celibate sisters and brothers, to castrated civil servants—from the first foragers to the first states.     

Dilemmas in conservation for applied biologists

Prevention of the use of DDT has been made the target of a powerful propaganda drive in certain prosperous countries because, it is stated, DDT is a danger to man and harms wild life. On the other hand, DDT is by far the most economical, effective and safe insecticide for many uses, particularly for protecting men from certain insect-borne diseases and for enabling cotton to be grown in poor countries. Some risks can be reduced by eliminating those uses of DDT for which adequately safe, economical and effective substitutes exist, whether chemical or not; other risks can be reduced in other ways. The known risks to men are trivial, except when DDT concentrate is deliberately drunk, and the scare is made up of unknown risks -which could equally exist with any object or material, new or old. Risks to wild life have been greatly exaggerated and scares depending on falsehoods have become current. The postulated threat of progressive accumulation of DDT along a long food chain is not adequately supported by evidence, much of which has been misinterpreted. Thus the main dilemma is how to balance the great and undoubted benefits of DDT to millions of men, women and children against harm to wild life, sometimes genuine and remediable and sometimes dubious. People who campaign for banning have possibly failed to recognize this dilemma. On the other hand, they may have made a deliberate choice in favour of wild life. In that case, to be logical, they should also oppose all other means of preventing premature death of other people, which they might justify as a means of postponing over-population. The use or abuse of DDT is a minor component in the rise of the worl's population.     

Serum ferritin and the iron status of Canadians.

Serum ferritin concentration was determined in 1105 Canadians aged 1 to 90 years. Geometric mean values (ng/ml) were as follows: children 1 to 4 years old, 12; children 5 to 9 years old, 15; adolescent girls, 17; adolescent boys, 18; women 20 to 39 years, 23; women 65 years and older, 52; men 20 to 39 years, 93; and men 40 and older, 92. Ranges were side in all age groups, reflecting variations in size of body iron stores. From analysis of the ferritin values it is highly probably that iron stores were greatly reduced in approximately 25% of children, 30% of adolescents, 30% of menstruating women, 60% of pregnant women and 3% of men. Iron-deficiency anemia was noted in only 2% of subjects. If "normality" requires more than small amounts of storage iron to meet physiologic demands, the study results suggest a high probability of iron deficiency in 60% of the pregnant women and in 19% of the other subjects; but if normality is defined as maintenance of adequate iron stores for erythropoiesis, the prevalence of iron deficiency was zero in the pregnant women and 2% in the other subjects.     

Joan Heath interviews Suzanne Cory and Joan Steitz: a female perspective of science in the swinging ‘60s

Prompted by the occasion of International Women''s Day, Joan Heath and DMM reunited Professors Suzanne Cory and Joan Steitz via Zoom to discuss their extraordinary careers and joint experiences in science. They also delve into past and present challenges for women in science, and discuss the role of scientists in a post-pandemic world.

Suzanne Cory, Joan Steitz and Joan Heath (from left to right) As one of Australia''s most eminent molecular biologists, with a school in Melbourne bearing her name, Professor Suzanne Cory has been both Director of The Walter and Eliza Hall Institute of Medical Research in Australia (WEHI) and President of the Australian Academy of Science. She earned her PhD at the Medical Research Council (MRC) Laboratory of Molecular Biology (LMB) in Cambridge, UK, with postdoctoral training at the University of Geneva. She continues her research at WEHI as an honorary distinguished research fellow, investigating the genetics of the immune system in the development of blood cancers and the effects of chemotherapeutic drugs on cancer cells.Joan Steitz – currently Sterling Professor of Molecular Biophysics and Biochemistry at Yale University, and for 35 years the recipient of a Howard Hughes fellowship – is best known for her seminal work in RNA biology. She was the first female graduate student to join the laboratory of James Watson at Harvard University and proceeded with her postdoctoral training at the MRC LMB in Cambridge. Her pioneering research delved into the fundamental mechanisms of ribosome and messenger RNA interactions, as well as RNA splicing, heralding the phenomenon of alternative RNA splicing. A recipient of many awards and honours, she is also involved in international projects aimed at supporting women in science.Host Joan Heath heads a laboratory at WEHI in Australia. She received her undergraduate degree from the University of Cambridge, followed by her PhD at the Strangeways Research Laboratory also in Cambridge, then just across the road from the MRC LMB. After postdoctoral positions in bone biology and osteoporosis research, Joan joined the Ludwig Institute for Cancer Research where she became a laboratory head, and changed her focus to cancer research using zebrafish to identify genes that are indispensable for the rapid growth and proliferation of cells during development. She joined the WEHI in 2012. There she showed that the same developmental genes are also required by highly proliferative, difficult-to-treat cancers, including lung, liver and stomach cancer, paving the way for translational research targeting these genes in novel cancer therapies. Joan H: How long have you two known each other? Suzanne: I was calculating that this morning and I was astonished because it seems like only yesterday, but it has been 55 years since we met in Cambridge. It has been a voyage in science and a voyage in the world because we have always made a point to meet up in beautiful places and go hiking. That is how we''ve been able to renew our friendship over all these years. Joan H: Where were you when you first met? Joan S: We both were working at the MRC LMB in Cambridge, England. Suzanne was doing her PhD and I arrived slightly later for a postdoc.Suzanne: We had a pre-meeting in the sense that Joan, Jerry Adams (my future husband) and Tom Steitz (Joan''s husband), were all graduate students together in Harvard. So, when Joan and Tom came to Cambridge, it was natural that we would all start doing things together. And Joan and I ended up sharing a lab bench.Joan S: The reason that I did a postdoc in the mecca of X-ray crystallography was that I had married a crystallographer – and there was no other place that he could possibly go. They very much wanted to have my husband at the Cambridge MRC lab, but there wasn''t a clear plan for me. Francis Crick suggested that I do a literature project in the library, but I knew that theory was not my forte in comparison to experiments. I started talking to the many people working in the lab and found a project that no one wanted, because it was so challenging. But it was a very interesting problem, so I decided to take it on – and it turned out to be a great project.Joan H: That''s amazing. You were obviously determined to overturn other people''s expectations of you.Suzanne, even now, it''s extremely unusual for a young person to leave their home country to do their PhD. It''s still a brave thing to do but all those years ago it was really courageous. You told me that you ended up there because you wrote a simple letter, which was a complete shot in the dark.Suzanne: It certainly was. During my master''s degree at the University of Melbourne, I became more and more interested in doing science and decided I would do a PhD. But I had a counteracting desire to travel and see Europe. So I decided that I would do my PhD overseas to give myself the opportunity of travelling. I had fallen in love with DNA during my undergraduate studies. So, I wrote a letter to Francis Crick in Cambridge, and asked if he would take me on as a PhD student. Much to my amazement, I eventually got a letter back saying yes. I think that my professor of biochemistry might have also visited Cambridge while he was travelling and spoken up for me. However, I was still extraordinarily fortunate that Francis had agreed because there weren''t many PhD students in the LMB at that time. It made such a difference to my entire life. I look back on that letter and think, “How did you have the audacity to write that letter and aim to go to that laboratory?”. I think it was partly naivety.Joan H: That''s a lesson for everyone, to go for your dreams, and don''t assume people won''t take notice of you. It is more difficult now, when scientists receive hundreds of e-mail applications from prospective PhD students in their inbox. You would have written a letter with a stamp on it that probably took three weeks to arrive, but it just shows you that you should be audacious. Did you have a different experience to Joan when you arrived? Was there a proper project already lined up for you?Suzanne: I was interviewed by Francis Crick and Sydney Brenner, who were the joint directors of the department. They decided that I would work on the structure of the methionyl-tRNA that puts methionine into internal positions in polypeptides. After they described the project – which involved doing counter-current distribution fractionation of bulk tRNAs, in which I had no experience whatsoever – Sydney in his very characteristic monotone said, “Do you think you''re up to it?”. I sort of gulped to myself and said, “Yes, I think I could do that”. I then went to Brian Clark''s laboratory, who was going to be my PhD supervisor, and started the project. Like always in life, if you learn from people and just go from one day to the next, you actually get there in the end.Joan H: So, persistence was key. Were there many other women at the LMB at the time?Suzanne: I don''t remember any female scientists who had official senior positions. There were certainly some strong female scientists there, but I don''t think they were given the recognition or the status that they actually deserved.Joan S: Later, some were given more recognition, crystallographers in particular, but not so much the molecular biologists.Suzanne: I think, as women, we both pioneered in that department.Joan H: Given the fact that you both agreed to take on projects you had very little previous experience with and that the male supervisors thought you weren''t going to have the mettle to carry it through, once you were there, did you feel that you had to work the whole time? Or did you still manage to have lots of fun and partake in opportunities that Cambridge had to offer at the time?Joan S: We certainly partook in a lot of those things. My husband and I got interested in antique furniture, antique paintings, and used to scour the countryside for little antique shops. We saw lots of England, then a little bit of Scotland and Wales. It was wonderful. A real adventure.Suzanne: I worked really hard most of the time that I was in Cambridge, as the work was very exciting. But I would take holiday periods, camping and youth hostelling all over Europe with a girlfriend from Melbourne and later, travelling with Jerry. We also would go to London for the opera and looking for amazing clothes on Carnaby Street and Chelsea Road (this was the Beatles era, late 60s). Jerry once came back with a purple velvet suit, which was his prized possession for many years. There was lots of fun but also lots of work.Open in a separate windowJoan Steitz, Tom Steitz, Jerry Adams and Suzanne Cory (from left to right) in the Swiss Alps, 1970. Image courtesy of Mark Bretscher. This image in not reproduced under the terms of the Creative Commons Attribution 2.0 Generic license. For permission to reproduce, contact the DMM Editorial office. Joan H: Can you remember the first moment in that part of your career that gave you the most pleasure? Joan S: I worked on a project for about a year, and it turned out that I was doing the wrong fractionation method to get the material that I needed to analyse. Then I had a conversation with Sydney Brenner telling him that I was going to give this one more try with a new method, and then I was going to give up. I remember Sydney saying, “Sometimes, like with a bad marriage, you have to give experiments one last try before you give them up.” Then I tried again, and it worked. This is often the case in science, that you try something new, that''s a little bit different, and it makes all the difference. Then you''re running.Suzanne: The same thing happened to me. I was labouring away on the counter current distribution machines fractionating methionine tRNA, with the goal of sequencing it by the laborious procedure recently published by Robert Holley. However, Fred Sanger, in the department upstairs, had invented a totally new method for sequencing using ³²P-labelled RNA. I desperately wanted to try this, so I managed to persuade my supervisor that we should change techniques. That change was key to my future because the approach was successful. I still remember to this day exactly where I was in Cambridge, walking on a Sunday afternoon, when the last piece of the puzzle dropped into place in my mind, and I had the entire sequence. In that moment, I was extremely joyful, because I knew I had my PhD and that I had succeeded. So that was my eureka moment.Joan H: Obviously, these were extremely productive years, and you''ve mentioned several Nobel Prize winners in your midst. It must have been the most inspiring environment, which I''m sure had a big impact on what you did next. By this stage in your career, were you already feeling ambitious or was it still your scientific curiosity that was driving your path?

“I expected that I would go back to the United States and be a research associate in some man''s lab […]. Then it turned out that people were more impressed than I thought and started offering me junior faculty jobs.”

Joan S: I had gotten a lot of recognition for having sequenced a piece of mRNA, using the same methods that Suzanne used to sequence tRNA. However, I had no expectations, because I had never seen a woman as a science professor, or head of a lab. I expected that I would go back to the United States and be a research associate in some man''s lab, and maybe they''d let me guide a graduate student. Then it turned out that people were more impressed than I thought and started offering me junior faculty jobs.My husband had already secured a junior faculty job in Berkeley before we even went to England, so we went back there after two years. My husband went to the chair of the department in Berkeley and put down letters on his desk of job offers that both of us had received for independent, junior faculty positions from several universities. The Chairman then said to Tom, “But all of our wives are research associates in our labs, and they love it”. This tore at my pride, as there had been a couple of universities that offered us both faculty jobs, and Berkeley was only offering one. So, we didn''t stay at Berkeley, and we came to Yale, which was wonderful.Suzanne: It''s really amazing to think that they gave you up. How foolish they were.Joan H: They''ve lived to regret it a million times over. Suzanne, at that point were you ready to climb this very difficult ladder?Suzanne: Like Joan, I didn''t have any expectations. For me, it was a matter of being able to continue discovering things in science. Jerry had already arranged to start a postdoc in Geneva. So, I applied for a postdoctoral fellowship, and obtained one. We went off together to Geneva to start our married life, and that was the beginning of us doing science together, which we''ve done ever since. I think without Jerry guiding me at that stage in my life, I would have probably drifted out of science. I don''t think I had the scientific confidence to ever think that I would be running a lab. For me, it was just continuing a voyage of discovery; and being lucky to end up in a wonderful scientific partnership and, through that partnership, my confidence grew over the years. Joan H: How many years after your postdoctoral training was it before you looked around your environment and had the confidence to think that you could be a lab or department head or could run an Institute? Joan S: I would say that confidence just grew. Tom and I were part of a departmental overhaul that involved hiring about six new people at Yale. We all stuck together, supported each other and were very collegial even though we worked in different areas. I think the collegial nature of the department in Yale helped me gain confidence. It was very scary at first because I didn''t know if I could write grants or direct people.Suzanne: Cambridge had an incredible influence, certainly over me, and I''m sure over Joan, Tom and Jerry, too. We looked around and saw all these amazing Nobel laureates, but also all these very ambitious, talented postdocs from around the world. I don''t think anyone thought about being the head of a department at that stage. We were simply striving to make discoveries and we gave each other mutual confidence, and stiff competition, too.The other thing that Cambridge gave us, was a new technology. For Joan and me, it was RNA sequencing. Being able to do that technology opened doors all around the world. I now always advise young people to go to the best place in the world to train in your chosen subject and acquire a new technology, because that will open the door to many opportunities in the future.Jerry and I made some excellent discoveries in Geneva, which were published in front-rank journals. Then it was time to move to full independence. I really wanted to go back to Australia but, as Jerry is an American, it was not at all obvious that he should take the big leap of moving to the bottom of the world and starting a lab there. I owe him a tremendous debt because he decided that he would take that risk.Earlier, whilst on our honeymoon, we had visited various labs in Australia. Although WEHI was an institute for immunology, a field we knew little about at that stage, it had the same atmosphere as the LMB in the sense that everyone was striving at the frontiers of science and competing with the rest of the world. We decided this was the only place in Australia that we would work at and that we would attempt to persuade the new director Gus Nossal that he needed molecular biologists. We had an interview with him in Switzerland and he offered us jobs as postdocs. Again, we were probably very naive and audacious but we told him we didn''t want to be postdocs – we wanted to run our own lab. And he agreed and we launched our fledgling lab together in 1971. What drove us was always discovery, rather than career ambitions.Joan H: You''ve both described these amazing sets of circumstances that were challenging but, nevertheless, very satisfying. However, a lot of things have since changed. What do you think are the main remaining barriers to women in science?Joan S: There is an important phenomenon called social identity threat, or stereotype threat, that I think still impedes women in proceeding in their careers. The phenomenon is described by cognitive psychologists as a reaction that all people experience if they feel that they are part of an undervalued minority. And so, by definition, since there are fewer women in science than there are men, women are being subjected to stereotype threat. Cognitive psychologists have studied the physiological manifestations of this, including increased heart rate and perspiration but, psychologically, they''ve also documented that cognitive learning and memory are impaired when one has these feelings.I first learned about this in 2007 and I looked back and realized why, for 30 years, when I''d been on committees as the only woman amongst ten men, I wouldn''t dare say anything – because I was frightened stiff. Men undergo this response, too, if they''re put into the situation of being undervalued. If you understand why you''re reacting the way you''re reacting and know that this is a normal human response, I think it helps you to overcome your own feelings of insecurity and allows you to go ahead. I always tell young women who I''m rooting for in science about this, because I want them to know that they will very likely end up feeling this way, and it''s a normal human response.

“One thing I sometimes get frustrated about is that we often need men to change things […] but what we really need are women in those high-level positions, so that they can be the champions of change.”

Joan H: There are other terms describing other relevant phenomena, such as unconscious bias, imposter syndrome and champions of change. One thing I really relate to is imposter syndrome. I''ve listened to webinars on this topic and they all reach a similar conclusion that we all feel the same. On the one hand, at the end of the webinar, you do feel somewhat elated to know that it''s not just you, and that it''s normal. But, on the other hand, it doesn''t really change things. It''s a recognition of what we feel, and we all get some help from that, but you really need opportunities to change things at a higher level. One thing I sometimes get frustrated about is that we often need men to change things, leading to this concept of male champions of change. I admire those men; but what we really need are women in those high-level positions, so that they can be the champions of change. Not having 50% of university departments and medical research institutes run by women still limits our full potential.Joan S: I certainly agree with you, Joan. It''s very important to have realistic role models. Suzanne being head of the WEHI for all those years has engendered all sorts of admiration.Joan H: During that period, Suzanne not only did fantastic science but our Institute doubled in size.It''s transformative when you have women making up 50% of people around the table. It''s no help just having a token female because that poor person''s not going to be able to change everything on her own. In American scientific institutions, are there any firm quotas for female scientists and other people that are underrepresented in science?Joan S: In recent years there has been a push in that direction. Sometimes it''s successful and sometimes it''s not. It is very different now compared to when there was no consciousness that this was unfair or that things could be better if we had real representation.Suzanne: I agree with both of you in everything that''s been said. While reflecting at this moment, what it says to me is that what''s really needed is societal change, and that we need to give courage to girls from the very earliest age. It should come naturally, they shouldn''t feel inferior, and others should not look at them as inferior. They should expect to have careers as well as families, be able to manage both and have somebody alongside them who helps them manage both.I think that affirmative action for women in science is necessary because the pace of change has been so slow. However, I also think quotas can be detrimental to the cause of women, in the sense that it''s then possible for people to say you only made it because there was a quota – which is very destructive. If I look back on our careers in science, it is clear that things have changed tremendously. Today there are more opportunities for women because many universities and institutes are bending over backwards to equalise things. The downside of this is that talented men may miss out on positions because of this policy and the pendulum could swing back.Joan H: The evidence shows that when more women are involved in things, those things go better. For instance, boards that have more women on them are more productive. Obviously, what you alluded to is there are lots of fantastic male scientists as well. The real issue here is there''s not enough funding to go round to support all the great men and women. But there are clearly enough good women around to be represented at the 50% level, without disproportionately disadvantaging male scientists.Joan S: Men and women are now operating on a more even playing field, which doesn''t mean that the men are missing out. They''re just in a more-competitive situation – as they should be. Joan H: Suzanne previously covered the specific advice she would give to young female researchers. Joan, do you have any other suggestions? Joan S: I encourage them to try lots of different things in science, and when they find something that really grabs them, then go for it and be persistent. We all know that science is very up and down. But if you keep pushing when you''re in a trough, it will always go back up again and you will succeed. That''s harder for a young person, who hasn''t experienced these troughs, to understand.Joan H: Yes, and the period when women scientists start having children is the hardest part. It''s still a choice that some women make, to take some years off and come back with a less ambitious plan for their career. Obviously, things like maternity leave payments and so on are improving but there''s no question that, in most circumstances, the research will slow down during that period.Suzanne: What I say to young women at that stage of their careers is that you have to be very focused, you must spend the time that you do have in a very focused manner, so that you can be the most productive you can be. But you have to be supported at home by your partner. If you''re both scientists it''s easier because you can appreciate why the other person is rushing into the lab late at night, for example, but for most people, that''s not true. So, what is really important is equal sharing of responsibilities from both partners when young families are around. And I think employers need to give both of those partners a longer time to achieve the kind of papers that they need to progress in their careers. That''s a period when it is much harder to be productive, and we need to continue to support people during that difficult phase of their careers because we''ve invested so much in them. They have so much to offer to science and to society, so to let them slip out at that stage is a great waste.Joan H: Let''s change tack a little bit and think about some of the broader challenges in science. What do you think the COVID-19 pandemic has taught us about the importance of clear scientific communication and real engagement with the community?Joan S: Whenever I talk to people about this, I very clearly make the point that it was decades of fundamental research that led to the development of the COVID-19 vaccine. If it hadn''t been for those fundamental discoveries in how cells and mRNA work, it would never have only taken 63 days from sequencing the virus to phase one clinical trials at Moderna. I try to point out to people that all the different discoveries coming in from different angles made that possible. I personally find it absolutely remarkable that all that knowledge could be harnessed, so very quickly. I''ve been doing fundamental research my entire life and I never expected to see it materialise in the way it has. It''s a wonderful reward. Joan H: Do you think this has resulted in the community appreciating scientists more? Joan S: I don''t think we''re far enough downstream to know that. In the US, there has been a congressional vote to abandon our maintenance of vigilance and preparedness for future pandemics – which seems ridiculous. Now we have all these procedures set up, all we have to do is maintain them for the next one. Whereas, if we just let go of these procedures, we''ll have to start over again for future pandemics. I guess we''re not good enough at communicating some of these things at this point.Joan H: Millions of people died from the virus and yet, if we hadn''t had the vaccines, the scale would have been even more horrific. If we were able to convey this information effectively to the public, then, hopefully, people would recognise that – as well as spending a fixed percentage of the gross domestic product on defence, for example – we should spend at least the same amount on science. Not only for pandemics but for tackling climate change and other pressing issues. I like to think this is an auspicious time but I don''t know whether we are really taking advantage of it.Suzanne: The pandemic has brought science and scientists to the forefront, and there has been a period of great respect for scientists having developed the vaccine. It''s an absolute miracle that it was done so fast and effectively. We''re very fortunate but, as Joan said, that was not luck. It was through investment in basic science for decades. We have to keep conveying this message, to our politicians in particular, so that they will keep supporting all kinds of scientists, because we never know what''s around the corner.Joan H: Certainly, people like Anthony Fauci in the US and Catherine Bennett in Melbourne, spoke eloquently and had a real talent for communicating things clearly and in a nutshell. That''s not something we''re all good at and it''s not something that is easy to train into people either. I think we all need to try to capture the attention of the community at large, by speaking plainly. I don''t think people understand that scientists are underfunded and could do so much more if funding was more generous.

“All I can say to young people is, if you really love science and have a passion for it, keep trying – because you will succeed if you put your whole heart and soul into this career path.”

Suzanne: I think the general public has no appreciation of how tenuous the life of a scientist can be, and how we are losing so many great minds entering the field because young people just finishing their PhDs look with dismay at how hard it is to support a career in science and get enough funding. There''s a tremendous waste of talent. All I can say to young people is, if you really love science and have a passion for it, keep trying – because you will succeed if you put your whole heart and soul into this career path.Joan H: This has been an absolutely fantastic discussion and it''s such a delight to talk to women who, after all these years, are still as passionate as ever and are pursuing their scientific subjects with the same vigour as they have all along.Suzanne: It''s been wonderful to talk with you, Joan, and I hope that we see each other soon, no matter what continent. And thank you, Joan Heath for getting us together and giving us this opportunity.     

Qualitative interview study of communication between parents and children about maternal breast cancer

Objective To examine parents'' communication with their children about the diagnosis and initial treatment of breast cancer in the mother. Design Qualitative interview study within a cross-sectional cohort. Setting Two breast cancer treatment centers. Participants 32 women with stage I or stage II breast cancer with 56 school-aged children. Main outcome measures Semistructured interview regarding timing and extent of communication with children about the diagnosis and initial treatment of the mother''s illness, reasons for talking to children or withholding information, and help available and requested from health professionals. Results Women were most likely to begin talking to their children after their diagnosis had been confirmed by biopsy, but a few waited until after surgery or said nothing at all. Family discussion did not necessarily include mention of cancer. There was considerable consistency in the reasons given for either discussing or not discussing the diagnosis. The most common reason for not communicating was to avoid children''s questions, particularly those about death. Although most women had helpful discussion with a physician concerning their illness, few were offered help with talking to their children; many would have liked help, particularly the opportunity for both parents to talk to a health professional with experience in understanding and talking to children. Conclusion Parents diagnosed with cancer or other serious illnesses should be offered help to think about whether, what, and how to tell their children and about what children can understand, especially as they may well be struggling themselves to come to terms with their illness.     

Parasite scouting and host defence behaviours are influenced by colony size in the slave-making ant Protomognathus americanus

In the slave-making ant Protomognathus americanus, scout workers leave their colony, discover host colonies, and initiate slave raids. Captured host pupae subsequently emerge in the slavemaker colony and replenish the slave workforce. The course of these antagonistic encounters can be influenced by the species, aggressivity, or size of the host colony. We asked how the demography of parasite and host colonies influences the initial raiding phase by observing the scouting behaviour of P. americanus slavemakers during 48 raiding attempts. Experiments were performed under controlled laboratory conditions in a Y-shaped experimental arena. The number of active scouts increased with increasing slavemaker worker numbers, but was unaffected by the slave to slavemaker ratio, showing that slavemaker worker numbers are a good indicator for the scouting workforce. Colonies with fewer slaves discovered host colonies faster (colonies with 15 or less slaves: median 9:53 min, colonies with 42 or more slaves: median 18:55 min), suggesting that small slave workforces lead to intensified scouting behaviour. The more scouts were active, the faster a host colony was discovered, but the time between discovery and trial completion was unaffected by slavemaker colony demography. Host colonies were successfully attacked in 79.2 % of the trials, and they fought off an intruding scout only once. Yet host aggression towards slavemaker scouts increased with host colony size, and higher aggression rates delayed a subsequent attack. Our study demonstrates that colony size influences the behaviour and the course of crucial interspecific interactions of a social parasite and its host.     

Intersexual conflict across women's ovulatory cycle

A growing literature shows that the features women find particularly attractive in men vary across the ovulatory cycle. Women furthermore appear to more frequently report attraction to men other than primary partners when they are fertile in their cycle than in the infertile luteal phase. Previous studies have shown that men are more vigilant of or attentive to their primary partners during the fertile phase compared to the luteal phase. This study had several aims: First, to replicate and extend previous findings concerning men's vigilance of partners using male as well as female reports of men's behavior; second, to examine changes in women's behavior toward partners across the cycle; third, to examine ways in which women resist men's attempts to mate-guard across the cycle. Results indicate that (a) men are particularly self-assertive toward partners when their partners are fertile; (b) similarly, women are especially self-assertive toward partners when they are fertile; (c) women report engaging in more behaviors that resist male vigilance and mate guarding when they are fertile, especially in ways that are unobservable to male partners; and (d) these effects are especially strong when women themselves report greater attraction to men other than partners when they are fertile, compared to the luteal phase.     

Women and telomeres

Last year''s Nobel Prizes for Carol Greider and Elizabeth Blackburn should be encouraging for all female scientists with childrenCarol Greider, a molecular biologist at Johns Hopkins University (Baltimore, MD, USA), recalled that when she received a phone call from the Nobel Foundation early in October last year, she was staring down a large pile of laundry. The caller informed her that she had won the 2009 Nobel Prize in Physiology or Medicine along with Elizabeth Blackburn, her mentor and co-discoverer of the enzyme telomerase, and Jack Szostak. The Prize was not only the ultimate reward for her own achievements, but it also highlighted a research field in biology that, unlike most others, is renowned for attracting a significant number of women.Indeed, the 2009 awards stood out in particular, as five women received Nobel prizes. In addition to the Prize for Greider and Blackburn, Ada E. Yonath received one in chemistry, Elinor Ostrom became the first female Prize-winner in economics, and Herta Müller won for literature (Fig 1).Open in a separate windowFigure 1The 2009 Nobel Laureates assembled for a photo during their visit to the Nobel Foundation on 12 December 2009. Back row, left to right: Nobel Laureates in Chemistry Ada E. Yonath and Venkatraman Ramakrishnan, Nobel Laureates in Physiology or Medicine Jack W. Szostak and Carol W. Greider, Nobel Laureate in Chemistry Thomas A. Steitz, Nobel Laureate in Physiology or Medicine Elizabeth H. Blackburn, and Nobel Laureate in Physics George E. Smith. Front row, left to right: Nobel Laureate in Physics Willard S. Boyle, Nobel Laureate in Economic Sciences Elinor Ostrom, Nobel Laureate in Literature Herta Müller, and Nobel Laureate in Economic Sciences Oliver E. Williamson. © The Nobel Foundation 2009. Photo: Orasis.Greider, the daughter of scientists, has overcome many obstacles during her career. She had dyslexia that placed her in remedial classes; “I thought I was stupid,” she told The New York Times (Dreifus, 2009). Yet, by far the biggest challenge she has tackled is being a woman with children in a man''s world. When she attended a press conference at Johns Hopkins to announce the Prize, she brought her children Gwendolyn and Charles with her (Fig 2). “How many men have won the Nobel in the last few years, and they have kids the same age as mine, and their kids aren''t in the picture? That''s a big difference, right? And that makes a statement,” she said.The Prize […] highlighted a research field in biology that, unlike most others, is renowned for attracting a significant number of womenOpen in a separate windowFigure 2Mother, scientist and Nobel Prize-winner: Carol Greider is greeted by her lab and her children. © Johns Hopkins Medicine 2009. Photo: Keith Weller.Marie Curie (1867–1934), the Polish–French physicist and chemist, was the first woman to win the Prize in 1903 for physics, together with her husband Pierre, and again for chemistry in 1911—the only woman to twice achieve such recognition. Curie''s daughter Irène Joliot-Curie (1897–1956), a French chemist, also won the Prize with her husband Frédéric in 1935. Since Curie''s 1911 prize, 347 Nobel Prizes in Physiology or Medicine and Chemistry (the fields in which biologists are recognized) have been awarded, but only 14—just 4%—have gone to women, with 9 of these awarded since 1979. That is a far cry from women holding up half the sky.Yet, despite the dominance of men in biology and the other natural sciences, telomere research has a reputation as a field dominated by women. Daniela Rhodes, a structural biologist and senior scientist at the MRC Laboratory of Molecular Biology (Cambridge, UK) recalls joining the field in 1993. “When I went to my first meeting, my world changed because I was used to being one of the few female speakers,” she said. “Most of the speakers there were female.” She estimated that 80% of the speakers at meetings at Cold Spring Harbour Laboratory in those early days were women, while the ratio in the audience was more balanced.Since Curie''s 1911 prize, 347 Nobel Prizes in Physiology or Medicine and Chemistry […] have been awarded, but only 14—just 4%—have gone to women…“There''s nothing particularly interesting about telomeres to women,” Rhodes explained. “[The] field covers some people like me who do structural biology, to cell biology, to people interested in cancers […] It could be any other field in biology. I think it''s [a result of] having women start it and [including] other women.” Greider comes to a similar conclusion: “I really see it as a founder effect. It started with Joe Gall [who originally recruited Blackburn to work in his lab].”Gall, a cell biologist, […] welcomed women to his lab at a time when the overall situation for women in science was “reasonably glum”…Gall, a cell biologist, earned a reputation for being gender neutral while working at Yale University in the 1950s and 1960s; he welcomed women to his lab at a time when the overall situation for women in science was “reasonably glum,” as he put it. “It wasn''t that women were not accepted into PhD programs. It''s just that the opportunities for them afterwards were pretty slim,” he explained.“Very early on he was very supportive to a number of women who went on and then had their own labs and […] many of those women [went] out in the world [to] train other women,” Greider commented. “A whole tree that then grows up that in the end there are many more women in that particular field simply because of that historical event.Thomas Cech, who won the Nobel Prize for Chemistry in 1989 and who worked in Gall''s lab with Blackburn, agreed: “In biochemistry and metabolism, we talk about positive feedback loops. This was a positive feedback loop. Joe Gall''s lab at Yale was an environment that was free of bias against women, and it was scientifically supportive.”Gall, now 81 and working at the Carnegie Institution of Washington (Baltimore, MD, USA), is somewhat dismissive about his positive role. “It never occurred to me that I was doing anything unusual. It literally, really did not. And it''s only been in the last 10 or 20 years that anyone made much of it,” he said. “If you look back, […] my laboratory [was] very close to [half] men and [half] women.”During the 1970s and 1980s; “[w]hen I entered graduate school,” Greider recalled, “it was a time when the number of graduate students [who] were women was about 50%. And it wasn''t unusual at all.” What has changed, though, is the number of women choosing to pursue a scientific career further. According to the US National Science Foundation (Arlington, VA, USA), women received 51.8% of doctorates in the life sciences in 2006, compared with 43.8% in 1996, 34.6% in 1986, 20.7% in 1976 and 11.9% in 1966 (www.nsf.gov/statistics).In fact, Gall suspects that biology tends to attract more women than the other sciences. “I think if you look in biology departments that you would find a higher percentage [of women] than you would in physics and chemistry,” he said. “I think […] it''s hard to dissociate societal effects from specific effects, but probably fewer women are inclined to go into chemistry [or] physics. Certainly, there is no lack of women going into biology.” However, the representation of women falls off at each level, from postdoc to assistant professor and tenured professor. Cech estimated that only about 20% of the biology faculty in the USA are women.“[It] is a leaky pipeline,” Greider explained. “People exit the system. Women exit at a much higher proportion than do men. I don''t see it as a [supply] pipeline issue at all, getting the trainees in, because for 25 years there have been a great number of women trainees.“We all thought that with civil rights and affirmative action you''d open the doors and women would come in and everything would just follow. And it turned out that was not true.”Nancy Hopkins, a molecular biologist and long-time advocate on issues affecting women faculty members at the Massachusetts Institute of Technology (Cambridge, MA, USA), said that the situation in the USA has improved because of civil rights laws and affirmative action. “I was hired—almost every woman of my generation was hired—as a result of affirmative action. Without it, there wouldn''t have been any women on the faculty,” she said, but added that: “We all thought that with civil rights and affirmative action you''d open the doors and women would come in and everything would just follow. And it turned out that was not true.”Indeed, in a speech at an academic conference in 2005, Harvard President Lawrence Summers said that innate differences between males and females might be one reason why fewer women than men succeeded in science and mathematics. The economist, who served as Secretary of Treasury under President William Clinton, told The Boston Globe that “[r]esearch in behavioural genetics is showing that things people previously attributed to socialization weren''t [due to socialization after all]” (Bombardieri, 2005).Some attendees of the meeting were angered by Summers''s remarks that women do not have the same ‘innate ability'' as men in some fields. Hopkins said she left the meeting as a protest and in “a state of shock and rage”. “It isn''t a question of political correctness, it''s about making unscientific, unfounded and damaging comments. It''s what discrimination is,” she said, adding that Summers''s views reflect the problems women face in moving up the ladder in academia. “To have the president of Harvard say that the second most important reason for their not being equal was really their intrinsic genetic inferiority is so shocking that no matter how many times I think back to his comments, I''m still shocked. These women were not asking to be considered better or special. They were just asking to have their gender be invisible.”Nonetheless, women are making inroads into academia, despite lingering prejudice and discrimination. One field of biology that counts a relatively high number of successful women among its upper ranks is developmental biology. Christiane Nüsslein-Volhard, for example, is Director of the Max Planck Institute for Developmental Biology in Tübingen, Germany, and won the Nobel Prize for Physiology or Medicine in 1995 for her work on the development of Drosophila embryos. She estimated that about 30% of speakers at conferences in her field are women.…for many women, the recent Nobel Prize for Greider […] and Blackburn […] therefore comes as much needed reassurance that it is possible to combine family life and a career in scienceHowever, she also noted that women have never been the majority in her own lab owing to the social constraints of German society. She explained that in Germany, Switzerland and Austria, family issues pose barriers for many women who want to have children and advance professionally because the pressure for women to not use day care is extremely strong. As such, “[w]omen want to stay home because they want to be an ideal mother, and then at the same time they want to go to work and do an ideal job and somehow this is really very difficult,” she said. “I don''t know a single case where the husband stays at home and takes care of the kids and the household. This doesn''t happen. So women are now in an unequal situation because if they want to do the job, they cannot; they don''t have a chance to find someone to do the work for them. […] The wives need wives.” In response to this situation, Nüsslein-Volhard has established the CNV Foundation to financially support young women scientists with children in Germany, to help pay for assistance with household chores and child care.Rhodes, an Italian native who grew up in Sweden, agreed with Nüsslein-Volhard''s assessment of the situation for many European female scientists with children. “Some European countries are very old-fashioned. If you look at the Protestant countries like Holland, women still do not really go out and have a career. It tends to be the man,” she said. “What I find depressing is [that in] a country like Sweden where I grew up, which is a very liberated country, there has been equality between men and women for a couple of generations, and if you look at the percentage of female professors at the universities, it''s still only 10%.” In fact, studies both from Europe and the USA show that academic science is not a welcoming environment for women with children; less so than for childless women and fathers, who are more likely to succeed in academic research (Ledin et al, 2007; Martinez et al, 2007).For Hopkins, her divorce at the age of 30 made a choice between children or a career unavoidable. Offered a position at MIT, she recalled that she very deliberately chose science. She said that she thought to herself: “Okay, I''m going to take the job, not have children and not even get married again because I couldn''t imagine combining that career with any kind of decent family life.” As such, for many women, the recent Nobel Prize for Greider, who raised two children, and Blackburn (Fig 3), who raised one, therefore comes as much needed reassurance that it is possible to combine family life and a career in science. Hopkins said the appearance of Greider and her children at the press conference sent “the message to young women that they can do it, even though very few women in my generation could do it. The ways in which some women are managing to do it are going to become the role models for the women who follow them.”Open in a separate windowFigure 3Elizabeth Blackburn greets colleagues and the media at a reception held in Genentech Hall at UCSF Mission Bay to celebrate her award of the Nobel Prize in Physiology or Medicine. © University of California, San Francisco 2009. Photo: Susan Merrell.     

Ecological demography: A synthetic focus in evolutionary anthropology

The interests of evolutionary anthropologists, behavioral ecologists, and demographers converge on the ecology of human fertility. Ecological conditions influence the optimum pattern of maternal effort. Patterns of abortion, neglect, and infanticide vary with mothers' ability to invest in their children and children's ability to use that investment. As in most other mammals, the ecology of human fertility varies between the sexes: status and resource control are important for males, whereas reproductive value is crucial for females. In pre-industrial societies, and even in monogamous societies in demographic transition, wealthy men had more children than did poorer men. This correlation, often assumed to have disappeared, persists today, with richer men still having more sexual access than others. Sex differences in the ecology of fertility mean that sex of the offspring, as well as birth order, influences parental investment. Because individual fertility varies with environment, it is not surprising that “natural” (uncontrolled) fertility varies across societies or that demographic transitions proceed locally, with occasional reverses, as individuals strive to maximize their lifetime reproductive success in changing, competitive, conditions.     

Confidence of paternity,divorce, and investment in children by Albuquerque men

Using a sample of men living in Albuquerque, NM, we examined the relationship between paternity confidence and men's investment in children. In humans, men may reduce their investment in a child in two ways: indirectly, by ending their relationship with the child's mother and ceasing to cohabit with the child (e.g., divorce), and directly, by allocating less time and fewer resources to the child. In this article, we tested two hypotheses regarding the effect of paternity confidence on investment in children: (1) men will be more likely to divorce women if they suspect or are sure that they are not the father of their wife's child, and (2) controlling for divorce, men will reduce direct investments in low paternity confidence children relative to high paternity confidence children. The first hypothesis was supported by the data. The second hypothesis was supported for two out of three measures of paternal investment we examined; low paternity confidence reduces the time men spend with a child in a group with other children or adults, and it reduces extensive involvement with the child's educational progress; there was no effect of paternity confidence on the amount of time men spend with children in one-on-one interactions. We also examined the effects of unstated paternity confidence (e.g., when men decline to answer the question) on divorce and paternal investment. Overall, the results suggested that paternity confidence plays an important role in shaping men's relationships with women and with their putative genetic children.     

The life histories of American stepfathers in evolutionary perspective

This paper presents an analysis of the characteristics of men who become stepfathers, and their subsequent fertility patterns and lifetime reproductive success. Because women who already have children are ranked lower in the marriage market than women without children, men who marry women with children (e.g., stepfathers) are likely to have lower rankings in the marriage market as well. Using retrospective fertility and marital histories from the Panel Study of Income Dynamics (PSID), I show that men who become stepfathers have lower levels of education, less income, and are more likely to have been divorced before and to already have children, all characteristics that lower their rankings in the marriage market. Men with one or two stepchildren are just as likely to have children within a marriage as non-stepfathers, although men with three stepchildren show decreased fertility. Among men age 45 and older, stepfathers have lower lifetime fertility than non-stepfathers, although the difference disappears when men’s age at first marriage is controlled for. Additionally, stepfathers have significantly higher fertility than men who never marry. The results suggest that some men become stepfathers to procure mates and fertility benefits that they would otherwise have been unlikely to obtain; for these men, raising other men’s children serves as a form of mating effort. Preliminary versions of this paper were presented at the Evolution and Human Adaptation Program at the University of Michigan, and the Human Behavior and Evolution Society’s annual meeting at Amherst. Kermyt G. Anderson received his Ph.D. in anthropology from the University of New Mexico in 1999. He is currently a Mellon Postdoctoral Research Fellow at the Population Studies Center of the Institute for Social Research at the University of Michigan. His current research examines the relationship between family structure, parental investment, and children’s educational and employment outcomes in South Africa.