Introduction

Sexual selection is the key theoretical framework for understanding sexual behavior from an evolutionary perspective. It depends on the advantages that certain individuals have over others in relation to reproduction, which lead to differences in reproductive output (Darwin, 1871). The process of sexual selection has overwhelmingly been conceptualized in terms of two interactive mechanisms: intra-sexual competition among males for female reproductive partners and choice of male reproductive partners by females (e.g., Buss & Schmitt, 2019; Jones & Ratterman, 2009; Lidborg et al., 2022; Stewart-Williams & Thomas, 2013).

Other configurations of mate acquisition and retention have, however, been reported, including male choice of female reproductive partners (Smuts, 1987; Stewart-Williams & Thomas, 2013), female–female competition for male mates (Reynolds, 2022; Stockley & Bro‐Jørgensen, 2011), and male sexual coercion of females (Goetz & Shackelford, 2006; Smuts & Smuts, 1993). In addition to these, inter-sexual mate competition occurs when a sexually motivated individual attempts to acquire or maintain exclusive access to a sexual/reproductive partner (the target of competition), while decreasing the likelihood of, or preventing, a sexually motivated opposite-sex conspecific from doing the same (Vasey et al., 2014). Two facets of these interactions occur simultaneously: one reproductive, and the other, non-reproductive.Footnote 1 The competitor who is the opposite-sex of the desired target can be described as the reproductive competitor; whereas, the competitor who is the same-sex as the target of competition can be described as the non-reproductive competitor. Like intra-sexual competition for mates, inter-sexual mate competition involves behaviors that could potentially influence the reproductive competitor’s acquisition and retention of reproductive partners through interactions with conspecifics.

Anecdotal reports of inter-sexual mate competition exist for a variety of avian and mammalian animals (Vasey et al., 2014; Zenchak et al., 1981) and empirical research analyzing these interactions exists for Japanese macaques (Macaca fuscata) (Vasey, 1998). Anecdotal accounts of inter-sexual mate competition also exist across a variety of human cultures (e.g., Devereux, 1937; Dunbar Moodie et al., 1989; Mostow, 2003; Peacock, 1968; Sorenson, 1984), and empirical research has documented these interactions in Samoa and among the Istmo Zapotec (Semenyna et al., 2020, 2022, 2023). Apart from illuminating the distribution of inter-sexual mate competition both phylogenetically and cross-culturally, these data help pinpoint conditions influencing the expression of inter-sexual mate competition and provide a basis for reconstructing its evolutionary history.

In addition to cross-species and cross-cultural investigations, psychological science is strengthened when considering human variation across time (Muthukrishna et al., 2021). Accordingly, the historical record can furnish a temporal depth of knowledge about the existence of inter-sexual mate competition as well as the tactics that competitors employed. Mate competition tactics have been well described in contemporary contexts (Barbaro et al., 2016; Buss, 1988; Buss et al., 2008; Shackelford et al., 2005), providing insight into recurrent adaptive problems faced by humans and plausible behavioral solutions for attracting mates, outcompeting rivals, and defending mates once partnerships are established. Mate acquisition and retention tactics evolved as vital elements of human mating psychology because success in these domains increased ancestral fitness (Buss, 1988). That said, once sexual partners are acquired, the drive to retain them is such a powerful component of human mating psychology that it is even expressed in non-reproductive (i.e., same-sex) contexts (VanderLaan & Vasey, 2008). This drive to competitively acquire and retain sexual partners, be they members of the opposite sex or the same sex, potentiates inter-sexual mate competition. Here, we use insights from the mate competition literature to re-examine a historical event, reassessing the incident as an example of inter-sexual mate competition that illustrates several stereotypic mate competition tactics employed by both the reproductive and non-reproductive competitors.

To this end, we draw upon the work of Mott and Assunção (1989), which presents five remarkable letters written in seventeenth century Portugal. The five letters in question were penned in the Lenten season of 1664 by Francisco Correa Netto, the sacristan of the cathedral of Silves, Portugal, and sent to Manuel Viegas, a guitarist and maker of musical instruments. Originally there were six such letters, but one of these has been lost. Viegas responded to Correa, but these letters were destroyed by Correa. Although the author was never put on trial, the five letters were scrutinized by the Portuguese Inquisition and preserved in Lisbon’s Arquiva da Torre do Tombo, where Mott and Assunção (1989) discovered and translated them.

Four of the letters are highly noteworthy because they describe a prolonged sequence of inter-sexual mate competition, although Mott and Assunção (1989) did not labeled the exchange as such. We build on Mott and Assunção’s (1989) important work by explicitly identifying the interactions described in these letters as inter-sexual mate competition and by analyzing the competitors’ mate competition tactics that are either manifestly illustrated, or justifiably inferred on the basis of the evidence. We then discuss how these tactics compare to contemporary examples of inter-sexual mate competition in humans.

Our approach aligns with others who have used an evolutionary lens to interpret written and visual media. This includes understanding archetypes in literature from the Romantic period (Kruger et al., 2003), sex and sexual orientation differences in the language used by male and female novelists (Luoto, 2021), and interpretation of recent (pop) cultural products such as romance novels and pornography (Salmon & Burch, 2022). In this way we do not test any hypothesis or make formal predictions. Instead, we highlight the ways in which evolutionary thinking, and especially recognition of inter-sexual mate competition, can bring new insights and reinterpretation to historical texts.

Method

Correa’s second to fifth letters recounting inter-sexual mate competition were coded by the two co-authors using a psychometrically validated mate retention inventory taxonomy (Barbaro et al., 2016; Buss, 1988; Buss et al., 2008; Shackelford et al., 2005). A summary of tactics is provided in Table 1, and detailed descriptions of the tactic categories can be found on the Open Science Framework (https://osf.io/ac6rd/). Based on the textual evidence, Viegas was treated as the target of inter-sexual mate competition; whereas, his past male lover (Correa) and his female fiancé (Maria Nunes) were treated as the male and female competitors, respectively. The mate competition tactics employed by both Correa and Nunes were identified. Initial inter-rater reliability for the presence/absence of tactics was high (Cohen’s kappa = 0.73, Percent Agreement = 92.6%), and disagreements were resolved via discussion between the co-authors until consensus was reached. Tactics are capitalized throughout the remainder of the manuscript, and unabridged translations of the letters are reproduced in the Appendix.

Table 1 Taxonomy of mate competition tactics
Full size table

Results

In the first letter, Correa makes a blatant offer of sex to Viegas (Mott & Assunção, 1989). In the second letter, it becomes clear that Viegas accepted Correa’s offer and the two had a sexual/romantic relationship. At some point Viegas promised to be “betrothed” to Correa, but now Viegas is engaged to a woman (Maria Nunes, the female competitor). In response to this revelation, Correa (the male competitor) exhibits five mate competition tactics that all involve attempts to manipulateFootnote 2 Viegas (the target male). Three types of Positive Inducement tactics are evident in Correa’s second letter. First, he emphasizes Love and Caring (e.g., “I desire and love you,” p. 94). Second, he exhibits Submission and Debasement (e.g., “I shall not stop doing what I can to be at your service,” p. 94). Third, he employs Sexual Inducements by reminding Viegas how much he enjoyed their previous sexual interactions (e.g., “There was no Lent for that heart in your loins, when I touched it with my fingers, and instantly it sprang up!” p. 94). Along with Commitment Manipulation (“I would have said that by Easter you would be betrothed to me. You implied it often and gave your word to me,” p. 94), Correa also employs Emotional Manipulation (e.g., “…remembering your arms and the kiss you gave me, that is what torments me most!” p. 94). Both Negative Inducement tactics can be interpreted as attempts to make Viegas feel guilty. In this letter, Correa refers to himself as “Francisquinha,” a feminine nickname that could also represent an attempt to increase his sexual allure vis-à-vis Viegas.

In the third letter, we learn that Viegas has made public statements that Correa should not go to his house (Mott & Assunção, 1989). In response to this public humiliation, Correa continues his attempts to manipulate Viegas using a mixture of Positive and Negative Inducements, as well as attempts to Gain Access to Viegas. Correa opens his third letter by expressing Love and Caring for Viegas (e.g., “Our Lord allow you to live as many happy years as you desire!” p. 96). He then switches tactics by engaging in Emotional Manipulation, expressing anger in a plausible bid to bargain for better treatment (Sell & Sznycer, in press; Sznycer et al., 2022) (e.g., “I was not so black-hearted that you should say publicly that I should not go to your house. If you wished to say that, you should write and tell me privately,” Mott & Assunção, 1989, p. 96). He switches back to using another Positive Inducement in the form of Submission and Debasement (e.g., “…not even for this affront will I become your enemy; and if you need something, advise me in writing,” p. 96). In addition to these tactics, Correa also attempts to Gain Access to Viegas by concocting reasons they should continue to interact (“Make me a guitar (viola) by your own hand, for which I will pay you,” p. 96). Correa also employs a new Positive Inducement—Resource Display (e.g., “I sent your clothes to be washed. Go to the house of Matias Araujo to order some shoes,” p. 96). Correa goes on to make a much more lavish offer when he writes: “I will give you everything I have promised and for the fiancée, thirty alqueires [~ 300 kg] of wheat” (p. 96). Mott and Assunção (1989) note that this substantial gift of wheat would feed a family of four for a year, which is made all the more significant given that wheat was frequently imported from afar to this arid region of Portugal. They argue plausibly that Correas’ offer seems to be an attempt to outbid the dowry provided by Viegas’ fiancée, Maria Nunes. If accepted, such a copious gift might serve as a signal to Nunes that Correa continues to enjoy a special relationship with Viegas.

Throughout the fourth letter, Correa attempts to further manipulate Viegas’ emotions (“My Grace has left my heart besieged, with my sentiments manifested in my tears; and when I see the person I desire, I am sad and jealous, and so Your Grace grows happier,” p. 97). We learn that Viegas had recently visited Correa, so some of the mate competition tactics Correa employed in the previous two letters must have been successful in promoting continued interactions between the two, at least temporarily. We also learn that Maria Nunes and Correa have interacted directly in the streets of Silves. Correa writes to Viegas:

After Your Grace left, news came to me that Your Grace intended to possess Maria Nunes, who does not conceal this from anyone, not even me, saying Your Grace gave her some beads and pin money, saying that you desired her much. And en route to the shoemaker’s to repair some shoes, we talked about biscuits, and she said that Your Grace gave her some, and she said there were none so perfect. So it seems that Your Grace has a great love for her, because she says that you come from your lovers, bringing her their gifts. (p. 97)

Thus, it appears plausible that Maria Nunes (the female competitor) made a concerted effort to manipulate Correa (the male competitor) by Verbally Signaling Possession of Viegas (the target male) as her intimate partner. Nunes emphasized the intensity of this relationship by reiterating to Correa that Viegas gives her various luxury items including beads, pin money and biscuits. In addition, Nunes tells Correa that Viegas turns over to her the gifts that his lovers give him. This information serves to elevate Nunes’ status with Viegas compared to his other lovers. The repeated specificity of Nunes’ comments suggests that she was fully aware of Correa’s infatuation with her fiancé, which appears to have become public knowledge, making this exchange a Direct Action intended to confront her (inter-sexual) rival and portray his relationship with Viegas as inconsequential.

We also learn that during this exchange, Correa was wearing a ring given to him by Viegas, a Possessive Ornamentation that could publicly indicate their connection. Nunes recognized the ring as having belonged to Viegas, but Correa obscures the truth by telling her that he purchased it from Viegas. In this way, Correa is able to emphasize to Viegas that he loves him so much, he is willing to lie in order to protect him from the consequences that would ensue should the truth about the ring become known. His lie notwithstanding, Correa was still able to signal that he and Viegas had interacted in the recent past. Thus, Correa’s decision to adorn himself with Viegas’ ring in public may have created uncertainty in Nunes about the true state of Correa’s relationship with Viegas, as well as that of her own.

The fifth and final letter concludes with Correa’s one-sided attempts to inflict parting wounds (Emotional Manipulation) on his former lover, and the return of the ring mentioned previously. Once again, Correa’s bids to Gain Access to Viegas appear to have been at least partly successful, with Correa asking, “why do you dine with your women friends rather than with me, and why do you send me notes that are lies?” (p. 98). This implies that Viegas continued to correspond with Correa, although the spurned lover yearned for more. The fifth letter marks the termination of the relationship, with Correa presumably losing the inter-sexual competition to his female rival.

Discussion

Mott and Assunção (1989) described five letters that were written in 1664 by Francisco Correa Netto, the sacristan of Silves cathedral in the Algarve region of Portugal. Correa sent these letters to Manuel Viegas, a guitarist and maker of musical instruments. Viegas and Correa had been involved in a romantic/sexual relationship, but by the time Correa wrote his second letter, Viegas was engaged to a woman named Maria Nunes. The second and third letters present details pertaining to Correa’s attempts to retain Viegas as his sexual partner in the face of Nunes, whom he learns has become engaged to Viegas. It is unclear whether Nunes was aware of Correa’s existence at this time, and Correa’s tactics seem to have been at least somewhat successful given that his interactions with Viegas continued. By the time Correa wrote his fourth letter, however, there is little doubt that Nunes was aware of his infatuation with her fiancée, which seems to have become publicly known, and the evidence suggests that direct inter-sexual mate competition ensued in the streets of Silves. Viegas’ mate switching (Buss et al., 2017) from Correa to Nunes appears more definitive at this point, leaving Correa in a position whereby he was attempting to poach Viegas away from Nunes and back to himself. Correa’s final letter makes clear that these attempts were unsuccessful.

In more widely recognized and understood intra-sexual mate competition, competitors direct most tactics toward the object of their desire, with less focus on their rival(s) (Barbaro et al., 2016; Buss, 1988; Buss et al., 2008). Indeed, some competitors, such as mate poachers, may behave surreptitiously so that their rivals are unaware of their existence, thus underscoring that rivals need not interact directly for mate competition to occur. Semenyna et al.’s (2020, 2022, 2023) cross-cultural research indicates that most inter-sexual mate competition similarly involves the male and female competitors trying to manipulate the target of competition, rather than each other. Correa’s letters reveal the same. First, he tries to manipulate Viegas using a variety of Positive Inducements including: (1) Love and Caring, (2) Submission and Debasement, (3) Sexual Inducements, and (4) Resource Display. Second, in Correa’s attempt to maintain his relationship with Viegas, he makes extensive use of Emotional Manipulation—a Negative Inducement directed at the target of competition. Third, Correa attempts to Gain Access to the target of competition, Viegas, by devising reasons they should continue to interact.

Interestingly, Correa’s willingness to do anything for Viegas, even if it required putting his own interests aside (e.g., Submission and Debasement) is a mate retention tactic that Semenyna et al. (2020) found was rarely, if ever, employed among the Istmo Zapotec or Samoans, despite the routine occurrence of inter-sexual mate competition in both those cultures. This difference may have emerged because Semenyna et al. (2020) collected narratives only from female participants. Most of these narratives involved female participants describing attempts by androphilicFootnote 3 males to poach their husbands or boyfriends. As such, Semenyna et al.’s (2020) data did not include intimate access to male competitors’ perspectives, as was the case with the letters penned by Correa to his former lover.

Although the target male, Viegas, was the main focus of Correa’s efforts, in his fourth letter we learn that he had interacted directly with the female competitor, Nunes. Correa describes how Nunes pointedly reiterated the degree to which Viegas loves her, while holding his other lovers in disregard. In this way, she was able to verbally signal to Correa that it was she who possessed Viegas’ heart. The repeated specificity of her comments suggest that Nunes was trying to drum home her point to Correa, and this has not been lost on other researchers. Indeed, as Mott and Assunção (1989) stated, “Maria Nunes’ comments were surely made with the intention of wounding Correa and making him jealous” (p. 89). This conjecture seems entirely plausible given that, Correa’s infatuation with Viegas seems to have become publicly known by this point, and Nunes appears to have confronted her rival to weaken his competitive resolve. Correa’s decision to wear a ring Viegas had given him could be interpreted as his desire to physically signal the existence of their relationship in public. His chance meeting with Nunes, and her observation of the ring, may have helped to create uncertainty in her mind regarding the true nature of Correa’s relationship with her fiancée, as well as that of her own. Thus, the interaction between Correa and Nunes involved aspects of Competitor Manipulation by Nunes, and perhaps Correa as well.

The subtle and indirect confrontation between Nunes and Correa is akin to female-typical tactics documented in contemporary contexts (Reynolds, 2022). Female social competition tends to be more indirect than male social competition, with the use of relational aggression, social tactics, gossip, and exclusion (Krems et al., 2020; Reynolds & Palmer-Hague, 2022; Stockley & Campbell, 2013). These same approaches appear in female–female mate competition (Fisher & Cox, 2011; Reynolds, 2022). Readers will note that inter-sexual mate competition between Correa and Nunes bears a striking resemblance to many instances of intra-sexual mate competition between females. This same parallel was found in Samoa and among the Istmo Zapotec, where women reported similar tactics employed by themselves and their rivals during both intra- and inter-sexual mate competition (Semenyna et al., 2022).

The research conducted by Semenyna et al. (2020, 2022, 2023) on inter-sexual mate competition in Samoa and among the Istmo Zapotec reported a number of other mate competition tactics that were not evident in Correa’s letters. For example, there was no evidence of Mate Guarding, use of Coalitional Strategies, or Competitor Manipulation via Negative Inducements such as derogation, threats, or violence. It is possible that the competitors employed these tactics, but that they were not mentioned by Correa in his letters. For example, Nunes could have attempted to prevent Viegas from interacting with Correa, but Correa may have been unaware, and thus unable to mention it in his writing. We have necessarily made certain measured assumptions about the nature of the relationships and interactions that ultimately led to Correa’s letters, and most details are lost to history. Nonetheless, the letters paint a clear enough picture for us to discern an instance of inter-sexual mate competition in the early-modern historical record.

In sum, four of the existing five letters written by Correa to Viegas provide valuable evidence of inter-sexual mate competition that occurred in seventeenth century Portugal, and the final letter conveys the anguish accompanying Correa’s unrequited love. We suspect that other examples of inter-sexual mate competition remain to be uncovered in the historical record, and many tactics will be discernible to modern readers. With inter-sexual mate competition acknowledged as a real possibility in the mating landscape, we hope that readers recognize this style of mate competition wherever it is likely to exist.

Because inter-sexual mate competition inherently involves a reproductive and a non-reproductive competitor, evolutionary theory leads us to predict that many non-reproductive competitors will ultimately leave these competitions bitterly disappointed when the desirable target chooses an opposite-sex mate. The existence of men’s bisexual behavior may, for example, create conditions conducive to inter-sexual mate competition, but sexual selection has nonetheless ensured most men (even those who sometimes behave bisexually) prefer reproductively viable female partners when given a choice (Rahman et al., 2020). It seems likely that many androphilic males throughout history and across cultures have pined after masculine men in a manner similar to Francisco Correa, whose parting words to his lover included, “for me there were only tears, tears caused by you and by so many skirts” (Mott & Assunção, 1989, p. 98).

The rich detail provided in Correa’s letters allows for a rare and remarkably thorough glimpse into the inter-sexual mate competition tactics that the competitors employed over three and a half centuries ago. As Correa’s letters make clear, whenever individuals are attracted to sexual partners who behave in bisexual manner, then inter-sexual mate competition can ensue with members of the other sex. This principle appears to hold across species, cultures, and historical time.