Giving Guys Get the Girls: Men Appear More Desirable to the Opposite Sex When Displaying Costly Donations to the Homeless

Round 1

Reviewer 1 Report

This study assesses an interesting theory with regards to sexual selection being a partial explanation of why humans are altruistic to non-kin. This has been examined previously, but this study speaks to a valuable insight in terms of the nature of what altruistic displays in mate choice might be signalling, and why it is important. The relative costs involved in altruistic displays is relevant here, and it is good to see the authors address this. Furthermore, the authors offer a simple yet effective methodology to control for the baseline levels of resources in individuals, which is a weakness of previous research.

This is a clearly structured and focused manuscript, well-written and thorough as well as offering findings that will be of interest, I feel, to the more general reader. As such I would recommend this manuscript is accepted for publication with a couple of minor amendments that I outline below:

• The authors make the distinction between their findings and that of Bhogal et al. (2020), who found the opposite to the current findings (i.e. they found lower altruistic costs were more desirable). The authors rightly discuss how the size of offers differed between the studies and this may explain the difference in results. The authors discuss here how the high costs (£30) may explain their findings and how varying this may help triangulate on how relative cost can play a role, however I would also like to see some discussion of how the ‘trivial’ low costs (£1) may also affect the results – to me this is as excessively low as the high cost was excessively high! Perhaps participants viewed a £1 offer as derisory, particular as the actor had just withdrawn £30?
• The authors discuss social desirability in explaining the ratings between ST and LT, but it might also be worth mentioning that in general women rate LT desirability higher for all traits.
• The authors cite Brown & Sacco (2019) who looked at morality, and I would like to see the authors expand on this link to the ratings they used in their study. Do they think this suggests an overall personality type that is desirable (e.g. ‘kindness’)?

Author Response

Many thanks for reading our paper ‘Giving guys get the girls: Men appear more desirable to the opposite sex when displaying costly donations to the homeless’ and for giving clear and helpful feedback. We have tried to address the comments below:

1. The authors make the distinction between their findings and that of Bhogal et al. (2020), who found the opposite to the current findings (i.e. they found lower altruistic costs were more desirable). The authors rightly discuss how the size of offers differed between the studies and this may explain the difference in results. The authors discuss here how the high costs (£30) may explain their findings and how varying this may help triangulate on how relative cost can play a role, however I would also like to see some discussion of how the ‘trivial’ low costs (£1) may also affect the results – to me this is as excessively low as the high cost was excessively high! Perhaps participants viewed a £1 offer as derisory, particular as the actor had just withdrawn £30?

Thank you, hopefully we have addressed the differences in the size of offers between our paper and Bhogal et al.’s (2020) study. Bhogal et al’s (2020) paper raises the importance of relative percentage donations.

We selected £30 as high cost because it was higher than the average monthly donations to charity, and £1 because it was significantly lower - and therefore the majority of people would be capable of signalling this (Charities Aid Foundation, 2019) [see lines 118-122]. I hope we have been able to address the question of why low cost £1 may affect the results here:

Line 284: “Since giving away £1 was considered within most people’s capabilities (Charities Aid Foundation, 2019), we argue it was not found to be an attractive trait because it is not an honest signal of quality. Indeed, the participants may have considered £1 as derisory, especially after seeing the actor withdraw £30 from a cash machine.”

2. The authors discuss social desirability in explaining the ratings between ST and LT, but it might also be worth mentioning that in general women rate LT desirability higher for all traits.

Line 307: “Overall, females tend to place greater value in long-term mating over short-term mating, and this may explain why they place more attention on altruism cues here (Buss 1989; Farrelly 2013).”

3. The authors cite Brown & Sacco (2019) who looked at morality, and I would like to see the authors expand on this link to the ratings they used in their study. Do they think this suggests an overall personality type that is desirable (e.g. ‘kindness’)?

Thank you for this comment, it is really helpful. We have addressed this in the following comment:

Line 351: “Showing willingness to donate to strangers, however, may not only signal willingness to share resources, but also signal underlying personality qualities (such as human kindness and sympathy), that are important in good long-term partners. Palmer and Tackett (2018) for example, found that those who score high on a Dark Triad personality scale expressed less empathy and were significantly less likely to engage in stranger based altruism. Women may therefore be picking up on cues that avoid potentially unwanted personality traits in mates.”

Reviewer 2 Report

The present manuscript presents findings from 285 women evaluators of an experimentally-framed video clip manipulation of a young man's altruistic behavior (giving no, a small amount, a large amount to a putative homeless man). The project is placed well within the literature concerning the evolution of human altruistic behavior, signaling, and kindness. The paper is very well written and structured, making it easy to follow. The methodological approach relying on videos serves as a nice complement to a few other papers within the topical scope but that relied on other methods such as vignettes. I believe this strongly warrants publication, and with few edits warranted. A few comments are:

The primary concern I had was the age and other characteristics of the female sample. Their ages ranged up to 70 years with an average of 31 years, and about 2/3 reported being in a sexual relationship. Why does this matter? Other work suggests that women tend to prefer mates slightly older than themselves. Actual patterns of human mating suggest statistically it's not common for say a 45 or 60 year old to be considering a 21-year-old man as a long-term mate, and yet effectively the research design and sample yielded this sort of scenario. Please touch on this issue as a limitation in the Discussion.

Could you also touch on how female age, sexual relationship status and ethnicity (with the assumption that many female raters were non-white) were related to findings? I don't know that all analyses using these latter three variables need to be incorporated throughout the Results, but at least some attention to these as key covariates and how they related to findings could be helpful. 

How long were the videos? Any other details on these videos that could be provided in the Methods, given that the illustrative photos are helpful but static.

I only see one minor typo: line 111, in which though should be those; this speaks to how polished the manuscript was.

A few references and concepts could be added to the Discussion to further situate the findings. One idea is that the signaling context operationalized here is ecologically relevant and valid for a globalized contemporary world, but from an evolutionary perspective the context of seeing a stranger give resources to a homeless individual doesn't fit the EEA envisioned in some hunter-gatherer world; in the latter, a man's capacity for signaling his kindness and parenting might be visible from day-to-day behavior in a small social world of largely familiar individuals, and potentially with older individuals (who themselves know individuals/families often well: see Apostolou work, for example) helping arrange first marriages. Among the !Kung San, as another hunter-gatherer ethnographic example, young men provided brideservice early in a relationship to establish their capacity for providing resources. The bottom line here is that the signaling context investigated in the present manuscript differs from some earlier hominin contexts to mate evaluation.

A few other papers provide further dimensions in which men might signal parenting capacity, from physical features to personality to perhaps even how then tend to a pet like a pet dog. Gueguen is a social psychologist who has done some interesting real-world experiments including a few that speak to similar altruistic capacities (like how a man treats a child in public), though there has also been some controversy (I don't know the final arbitration of these controversies and in turn whether his work could be referenced or not) in related studies too. This all said, here are a few papers to consider incorporating in the Discussion.

Roney, J. R., Hanson, K. N., Durante, K. M., & Maestripieri, D. (2006). Reading men's faces: Women's mate attractiveness judgments track men's testosterone and interest in infants. Proceedings of the Royal Society B: Biological Sciences, 273(1598), 2169-2175.

Gray, P. B., Volsche, S. L., Garcia, J. R., & Fisher, H. E. (2015). The roles of pet dogs and cats in human courtship and dating. Anthrozoös, 28(4), 673-683.

Brase, G. L. (2006). Cues of parental investment as a factor in attractiveness. Evolution and Human Behavior, 27(2), 145-157.

Guéguen, N. (2014). Cues of men's parental investment and attractiveness for women: A field experiment. Journal of human behavior in the social environment, 24(3), 296-300.

Author Response

Many thanks for reading our paper ‘Giving guys get the girls: Men appear more desirable to the opposite sex when displaying costly donations to the homeless’ and for giving clear and helpful feedback. We have tried to address the comments below:

1. The primary concern I had was the age and other characteristics of the female sample. Their ages ranged up to 70 years with an average of 31 years, and about 2/3 reported being in a sexual relationship. Why does this matter? Other work suggests that women tend to prefer mates slightly older than themselves. Actual patterns of human mating suggest statistically it's not common for say a 45- or 60-year old to be considering a 21-year old man as a long-term mate, and yet effectively the research design and sample yielded this sort of scenario. Please touch on this issue as a limitation in the Discussion.

Thank you, this is a very good point. We have addressed this now in the discussion (and the results – see reply to comment 2):

Line 317: “Future research could also test whether the age of the male altruist has an impact on female mating preferences. Women tend to report preferences for males older, rather than younger, than themselves (Buss 1989). Whilst in our sample we found no significant relationship between age of female observer and rating of the male’s attractiveness, we do acknowledge that the male actor (who was 21 years old) was younger than the median age of the female sample (28 years old). It would be interesting to explore whether older or younger altruists, relative to females’ age, have an impact on mate preference.”

Given the issue of age, we thought it would also helpful to report the median age in the Participants section. The range may have given the impression there were a higher number of older participants in the sample than there actually were. For example, the median age was 28 years old, 86.1% of the participants were 45 years or younger and 90% were younger than 50:

Line 375: “The data from a total of 285 women (age range 18-70, M_age = 31.07 years, SD = 11.35, Median age = 28, 90% were under 50 years old) were analysed”

2. Could you also touch on how female age, sexual relationship status and ethnicity (with the assumption that many female raters were non-white) were related to findings? I don't know that all analyses using these latter three variables need to be incorporated throughout the Results, but at least some attention to these as key covariates and how they related to findings could be helpful. 

Please see how we have tried to address these each in turn:

2a). Age: To explore whether the age of the participants was related to their ratings of attractiveness towards the male we performed a correlation between the two but did not find a relationship. However, it is a very valid point given our wide age range in the sample and we were glad to be able to address and comment on this in the paper.  

Line 188: “Due to the wide age range in our sample, we checked whether the age of the participant correlated with the ratings of the actor’s attractiveness. No relationship was found between age and attractive ratings, r(279) = 0.05, p = 0.43.”

2b). Relationship status: Thank you, again this was a very valid point to test and to report. We found in our sample no significant difference in attractive ratings between those who reported being single to those who reported being in a relationship:

Line 190: “We also checked whether there was a difference in participants’ ratings of attractiveness depending on whether they reported being in a relationship or not but no significant difference was found between those in a relationship (M = 4.08 , SD = 1.43) and those who were not (M = 3.76 , SD = 1.53), ), t (160.77) = 1.63. p = 0.11. Therefore, neither age nor relationship status were included in any further analyses.”

2c). Ethnicity: Because the majority (77.9%) of our sample identified as Caucasian, we felt it was not appropriate to test the difference between ethnicities in the results. We have, however included information about participant ethnicity in the Participant section:

Line 377: “Four of the participants described themselves as African (1.4%), five as African American (1.8%), 23 as Asian (8.1%), 11 as Black British (3.9%), 222 as Caucasian (77.9%), one as Chinese (0.4%) 10 as Hispanic (3.5%), seven as mixed race (2.5%) and two left this question blank (0.7%).”

3. How long were the videos? Any other details on these videos that could be provided in the Methods, given that the illustrative photos are helpful but static.

Each video lasted 40 seconds. We have added this detail now under Materials and Procedure

Line 391: “Participants were asked to read a vignette about a man (describing him as either ‘rich’ or ‘poor’) and then watch a short (40 seconds) video clip of him”

4. I only see one minor typo: line 111, in which ‘though’ should be ‘those’; this speaks to how polished the manuscript was.

Thank-you for spotting that:

Line 111: The word ‘though’ has been changed to the correct word ‘those’

5. A few references and concepts could be added to the Discussion to further situate the findings. One idea is that the signaling context operationalized here is ecologically relevant and valid for a globalized contemporary world, but from an evolutionary perspective the context of seeing a stranger give resources to a homeless individual doesn't fit the EEA envisioned in some hunter-gatherer world; in the latter, a man's capacity for signaling his kindness and parenting might be visible from day-to-day behavior in a small social world of largely familiar individuals, and potentially with older individuals (who themselves know individuals/families often well: see Apostolos’ work, for example) helping arrange first marriages. Among the !Kung San, as another hunter-gatherer ethnographic example, young men provided brideservice early in a relationship to establish their capacity for providing resources. The bottom line here is that the signaling context investigated in the present manuscript differs from some earlier hominin contexts to mate evaluation.

Thank you for this helpful suggestion. We think the reviewer raises a good point here. One-off altruism towards a non-reciprocal genetic stranger differs from anthropological hunter-gather data which shows that altruism may be signalled in more daily occurrences and towards kin (who may also make choices in mating pairs). Whilst we touch upon the anthropological work by Hawkes (1993) and Hawkes and Bliege Bird (2002) in our introduction, we have not addressed this fully in our discussion. Please see now the addition in our Discussion addressing the reviewer’s point:

Line 297: “Whilst this research highlights that help towards non-reciprocal strangers may signal mate qualities to women, it is important to note that in hunter gatherer societies, kin also play an important role in mate selection (Apostolou 2007). Therefore, further research could explore whether altruistic signals by males are important for women’s kin as they are for the women themselves.”

We also tried to clarify the evolutionary adaptive explanation in one of our closing sentences:

Line 358: “One of the challenges of explaining the evolutionary adaptive benefits as to why we might help non-reciprocal genetic strangers is that it cannot be explained by the traditional methods of Kin or Reciprocal altruism (Hamilton 1964; Maynard Smith 1964; Trivers 1971). Here we argue that there may be indirect benefits of displaying costly helping behaviour to strangers, as it may increase the altruist’s attraction as a potential mate.”

6. A few other papers provide further dimensions in which men might signal parenting capacity, from physical features to personality to perhaps even how then tend to a pet like a pet dog. Gueguen is a social psychologist who has done some interesting real-world experiments including a few that speak to similar altruistic capacities (like how a man treats a child in public), though there has also been some controversy (I don't know the final arbitration of these controversies and in turn whether his work could be referenced or not) in related studies too. This all said, here are a few papers to consider incorporating in the Discussion.

Roney, J. R., Hanson, K. N., Durante, K. M., & Maestripieri, D. (2006). Reading men's faces: Women's mate attractiveness judgments track men's testosterone and interest in infants. Proceedings of the Royal Society B: Biological Sciences, 273(1598), 2169-2175.

Gray, P. B., Volsche, S. L., Garcia, J. R., & Fisher, H. E. (2015). The roles of pet dogs and cats in human courtship and dating. Anthrozoös, 28(4), 673-683.

Brase, G. L. (2006). Cues of parental investment as a factor in attractiveness. Evolution and Human Behavior, 27(2), 145-157.

Guéguen, N. (2014). Cues of men's parental investment and attractiveness for women: A field experiment. Journal of human behavior in the social environment, 24(3), 296-300.

Thank you for these references, we have introduced the topic of good parental qualities in a short paragraph that includes these studies (and therefore also added these references to our reference section).

Line 324: “The fourth and final hypothesis related to parenting skills. Because men can signal good parental qualities through the care and protection of others, for example positive interactions towards children (Brase 2006; Guéguen 2014; Roney et al. 2006;) or ownership of a pet (Gray et al. 2015), it was predicted that displays of altruism would be associated with good parenting skills.”