William Costello
@williamcostello.bsky.social
PhD student of Evolutionary Psychology at the University of Texas at Austin.
MSc Psych: Evolution & Culture Brunel University London ‘21
MSc Psych: Evolution & Culture Brunel University London ‘21
Pinned
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates - Archives of Sexual Behavior
Incels (involuntary celibates) are an online subculture of men who form their identity around a perceived inability to form sexual or romantic relationships. This community operates almost exclusively...
link.springer.com
🚨 New publication 🚨
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
Reposted by William Costello
"An unexpected, but interesting finding was the role of sexism in predicting sexual harassment [H]. For women, hostile sexism [HS] strongly predicted all manifestations of H engagement/experience. In men, HS was only predictive of their H of women." journals.sagepub.com/doi/10.1177/...
November 15, 2025 at 3:00 AM
"An unexpected, but interesting finding was the role of sexism in predicting sexual harassment [H]. For women, hostile sexism [HS] strongly predicted all manifestations of H engagement/experience. In men, HS was only predictive of their H of women." journals.sagepub.com/doi/10.1177/...
Reposted by William Costello
The War on Sex Differences
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com/p/the-war-on...
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com/p/the-war-on...
The War on Sex Differences
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com
November 12, 2025 at 10:41 AM
The War on Sex Differences
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com/p/the-war-on...
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com/p/the-war-on...
Reposted by William Costello
There’s a stereotype out there that women want or need relationships more than men, and that women are more inclined to commit faster to a relationship. However, research finds that men are actually more inclined to escalate a relationship faster. www.cnbc.com/2025/10/18/n...
The stereotype is 'that women want or need relationships more,' but data shows it's men who are more likely to rush down the aisle
A new Kinsey Institute study finds 18.8% of men would rush marriage versus 13.7% of women.
www.cnbc.com
November 12, 2025 at 12:26 PM
There’s a stereotype out there that women want or need relationships more than men, and that women are more inclined to commit faster to a relationship. However, research finds that men are actually more inclined to escalate a relationship faster. www.cnbc.com/2025/10/18/n...
Reposted by William Costello
"the evidence sides with the civilians, making this one area where laypeople have a firmer grasp on reality than many alleged experts – and one area where academia seems to impair people’s understanding of the world rather than improving it"
The War on Sex Differences
The second excerpt from my forthcoming book, A Billion Years of Sex Differences
www.stevestewartwilliams.com
November 12, 2025 at 5:33 PM
"the evidence sides with the civilians, making this one area where laypeople have a firmer grasp on reality than many alleged experts – and one area where academia seems to impair people’s understanding of the world rather than improving it"
Reposted by William Costello
Part 3 is now live 📜
Here, I discuss what we learned about infidelity from our data, and why I think CNM is a better way of having multiple partners than infidelity.
Link and notable excerpts below:
Here, I discuss what we learned about infidelity from our data, and why I think CNM is a better way of having multiple partners than infidelity.
Link and notable excerpts below:
November 12, 2025 at 6:43 PM
Part 3 is now live 📜
Here, I discuss what we learned about infidelity from our data, and why I think CNM is a better way of having multiple partners than infidelity.
Link and notable excerpts below:
Here, I discuss what we learned about infidelity from our data, and why I think CNM is a better way of having multiple partners than infidelity.
Link and notable excerpts below:
Reposted by William Costello
"women employ qualitatively differentiated deception-detection strategies to ensure the veracity of men’s signals"
Women’s Anti-Deception Tactics in Mating: A Preliminary Investigation - Evolutionary Psychological Science
Because of the considerable recurrence of deception throughout evolutionary history that could have been much costlier to women’s reproductive fitness, evolutionary pressures may have favored women wi...
link.springer.com
November 10, 2025 at 6:06 PM
"women employ qualitatively differentiated deception-detection strategies to ensure the veracity of men’s signals"
Reposted by William Costello
Played the role of the research nerd in this discussion of whether it's embarrassing to have a boyfriend. www.bbc.co.uk/programmes/m...
BBC Radio 4 - AntiSocial, Are women better off single?
An article about "embarrassing" boyfriends prompts a debate over women's singledom
www.bbc.co.uk
November 10, 2025 at 2:28 PM
Played the role of the research nerd in this discussion of whether it's embarrassing to have a boyfriend. www.bbc.co.uk/programmes/m...
Reposted by William Costello
Have definitely come across this reviewer: “This manuscript was not worth my time so I did not read it and recommend rejection.” www.nature.com/articles/d41...
‘Lipstick on a pig’: how to fight back against a peer-review bully
Scientific societies, journals, editors and researchers are pushing back against mean-spirited peer reviews.
www.nature.com
November 9, 2025 at 8:41 AM
Have definitely come across this reviewer: “This manuscript was not worth my time so I did not read it and recommend rejection.” www.nature.com/articles/d41...
Reposted by William Costello
"Evolutionary psychologists have been asking—and answering—those questions for decades. Their job, basically, is to reverse-engineer human nature to figure out what kinds of traits helped our ancestors survive and reproduce, and how those selection pressures shaped the way our minds work today."
The Science of Sydney Sweeney’s Sex Appeal
The evolutionary logic behind the curves, contours, and proportions that define female beauty.
www.realityslaststand.com
November 8, 2025 at 6:07 PM
"Evolutionary psychologists have been asking—and answering—those questions for decades. Their job, basically, is to reverse-engineer human nature to figure out what kinds of traits helped our ancestors survive and reproduce, and how those selection pressures shaped the way our minds work today."
Reposted by William Costello
🚨 New publication 🚨
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates - Archives of Sexual Behavior
Incels (involuntary celibates) are an online subculture of men who form their identity around a perceived inability to form sexual or romantic relationships. This community operates almost exclusively...
link.springer.com
May 21, 2025 at 10:12 PM
🚨 New publication 🚨
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
Out now and open access in Archives of Sexual Behavior.
The Dual Pathways Hypothesis of Incel Harm: A Model of Harmful Attitudes and Beliefs Among Involuntary Celibates
🧵
link.springer.com/article/10.1...
Reposted by William Costello
My first paper, out in PsychReview!!
Along with @orbenamy.bsky.social, Nik & @jaeggiadrian.bsky.social, @realadamhunt.bsky.social & I revisit an old theoretical question using concepts from evo psychiatry and anthro:
Why do mixed associations exist b/w social media & mental health?
A 🧵
Along with @orbenamy.bsky.social, Nik & @jaeggiadrian.bsky.social, @realadamhunt.bsky.social & I revisit an old theoretical question using concepts from evo psychiatry and anthro:
Why do mixed associations exist b/w social media & mental health?
A 🧵
November 4, 2025 at 8:04 AM
My first paper, out in PsychReview!!
Along with @orbenamy.bsky.social, Nik & @jaeggiadrian.bsky.social, @realadamhunt.bsky.social & I revisit an old theoretical question using concepts from evo psychiatry and anthro:
Why do mixed associations exist b/w social media & mental health?
A 🧵
Along with @orbenamy.bsky.social, Nik & @jaeggiadrian.bsky.social, @realadamhunt.bsky.social & I revisit an old theoretical question using concepts from evo psychiatry and anthro:
Why do mixed associations exist b/w social media & mental health?
A 🧵
Reposted by William Costello
"feminist studies have increasingly prioritized ideological narratives over empirical inquiry... rather than serving as a neutral academic discipline, feminist studies now functions predominantly as an advocacy platform – one better suited to political settings"
Evolutionary Psychology and the Crisis of Empirical Rigor in Feminist Studies - Sexuality & Culture
This paper critiques core tenets of feminist studies through the lens of evolutionary psychology, arguing that many claims – such as those concerning patriarchy, social constructionism, fat studies, r...
link.springer.com
November 4, 2025 at 5:19 PM
"feminist studies have increasingly prioritized ideological narratives over empirical inquiry... rather than serving as a neutral academic discipline, feminist studies now functions predominantly as an advocacy platform – one better suited to political settings"
Keynotes for NEEPS (Northeastern Evolutionary Psychology Society) conference 2026 looking 🔥😎
November 4, 2025 at 4:17 AM
Keynotes for NEEPS (Northeastern Evolutionary Psychology Society) conference 2026 looking 🔥😎
Reposted by William Costello
"For both men and women, the node with the highest strength (i.e., the most direct connections in the network) is the tactic 'deceptive self-promotion' which was significantly more connected than all other nodes except the tactics 'organize and strategize' and 'impress others.'"
Hierarchy Navigation - Human Nature
Navigating status hierarchies depends on the coordination of traits, abilities, tactics, and strategies. Various components of the nomological net of hierarchy navigation have been examined in relativ...
link.springer.com
November 1, 2025 at 2:00 AM
"For both men and women, the node with the highest strength (i.e., the most direct connections in the network) is the tactic 'deceptive self-promotion' which was significantly more connected than all other nodes except the tactics 'organize and strategize' and 'impress others.'"
Reposted by William Costello
Technology is radically restructuring so many elements of social life, from development and education to dating and politics.
Watch what happens to dating around 2007...
Watch what happens to dating around 2007...
October 30, 2025 at 5:41 PM
Technology is radically restructuring so many elements of social life, from development and education to dating and politics.
Watch what happens to dating around 2007...
Watch what happens to dating around 2007...
Reposted by William Costello
"Precisely because humans possess an evolved responsiveness to the strategic use of sex for resource exchange, this mechanism can be manipulated under conditions of inequality, coercion, or trauma."
The Multiple Perspectives Approach to Understanding Sexual-Economic Exchange - Archives of Sexual Behavior
Sexual-economic exchange is a multifaceted phenomenon shaped by biological, psychological, social, and economic factors. This paper examines sexual-economic exchange—including commercial sex and trans...
link.springer.com
November 3, 2025 at 3:28 AM
"Precisely because humans possess an evolved responsiveness to the strategic use of sex for resource exchange, this mechanism can be manipulated under conditions of inequality, coercion, or trauma."
Reposted by William Costello
Reposted by William Costello
"As expected, there is an overall tendency to ignore and/or downplay sex differences... The textbooks also revealed a tension between the standard preferences of the discipline and the growing influence of evolutionary psychology"
(PDF) Ideological Bias in the Psychology of Sex and Gender
PDF | This chapter discusses the influence of ideological bias in the psychological study of sex and gender, with a focus on academic psychology. After... | Find, read and cite all the research you ne...
www.researchgate.net
October 29, 2025 at 11:04 PM
"As expected, there is an overall tendency to ignore and/or downplay sex differences... The textbooks also revealed a tension between the standard preferences of the discipline and the growing influence of evolutionary psychology"
Reposted by William Costello
"To assert that women do *not* have these values and priorities would be to disregard their stated preferences."
From Worriers to Warriors: The Cultural Rise of Women
For the first time in history, women hold substantial cultural and institutional power. Men and women differ, on average, in their values: women are more harm-averse, equity-oriented, and prone to res...
journalofcontroversialideas.org
October 30, 2025 at 5:53 PM
"To assert that women do *not* have these values and priorities would be to disregard their stated preferences."
Reposted by William Costello
From hazardous professions to the daily sacrifice of fatherhood, men continue to accept risk as part of serving and protecting others.
@richardreeves.bsky.social examines how this enduring pattern shapes our understanding of masculinity today.
Read here:
@richardreeves.bsky.social examines how this enduring pattern shapes our understanding of masculinity today.
Read here:
Even today, men put their lives on the line to protect the vulnerable
This is an excerpt of a response to The Dignity of Dependence: A Feminist Manifesto originally published by Fairer Disputations.
aibm.org
October 30, 2025 at 7:40 PM
From hazardous professions to the daily sacrifice of fatherhood, men continue to accept risk as part of serving and protecting others.
@richardreeves.bsky.social examines how this enduring pattern shapes our understanding of masculinity today.
Read here:
@richardreeves.bsky.social examines how this enduring pattern shapes our understanding of masculinity today.
Read here:
Reposted by William Costello
Among Gen Z adults, 15% of men and 18% of women consider themselves to be voluntarily celibate. The single most common reason reported for taking a break from sex and dating was to focus on one's self for a while. www.yahoo.com/lifestyle/fa...
They're young, they're single — and they're not having sex: Meet the Gen Z celibates
A third of Gen Z-ers are celibate, according to recent surveys. Not all of them forego sex by choice — but some who are willingly celibate say it's about self-improvement and empowerment.
www.yahoo.com
October 30, 2025 at 1:56 PM
Among Gen Z adults, 15% of men and 18% of women consider themselves to be voluntarily celibate. The single most common reason reported for taking a break from sex and dating was to focus on one's self for a while. www.yahoo.com/lifestyle/fa...
Reposted by William Costello
Why do women spend so much more on cosmetics than men? Jun-Hong Kim (2025) argues that the answer lies in male choice, paternal investment, and economic inequality. 🧵👇
www.hbes.com/paternal-inv...
www.hbes.com/paternal-inv...
Paternal investment and economic inequality predict cross-cultural variation in male choice - HBES
— by Jun-Hong Kim Over 95% of placental mammals are polygynous, with females bearing sole responsibility for rearing offspring. This stems from the reproductive characteristics of placental mammals. F...
www.hbes.com
October 27, 2025 at 5:46 PM
Why do women spend so much more on cosmetics than men? Jun-Hong Kim (2025) argues that the answer lies in male choice, paternal investment, and economic inequality. 🧵👇
www.hbes.com/paternal-inv...
www.hbes.com/paternal-inv...
Reposted by William Costello
Social media users adopt the toxic behaviors of ingroup members
An analysis of 7 million tweets from over 700,000 accounts finds that exposures to toxic behavior by ingroup members is the primary driver of contagious toxicity online academic.oup.com/jcmc/article...
An analysis of 7 million tweets from over 700,000 accounts finds that exposures to toxic behavior by ingroup members is the primary driver of contagious toxicity online academic.oup.com/jcmc/article...
October 22, 2025 at 1:16 PM
Social media users adopt the toxic behaviors of ingroup members
An analysis of 7 million tweets from over 700,000 accounts finds that exposures to toxic behavior by ingroup members is the primary driver of contagious toxicity online academic.oup.com/jcmc/article...
An analysis of 7 million tweets from over 700,000 accounts finds that exposures to toxic behavior by ingroup members is the primary driver of contagious toxicity online academic.oup.com/jcmc/article...
Reposted by William Costello
This week, we discuss the evolved logic of shame, guilt, and other self-conscious emotions with Daniel Sznycer
youtu.be/OkCBaBSvSzs?...
podcasts.apple.com/us/podcast/e...
www.podbean.com/eas/pb-xyz24...
youtu.be/OkCBaBSvSzs?...
podcasts.apple.com/us/podcast/e...
www.podbean.com/eas/pb-xyz24...
Shame, Pride, and Guilt with Daniel Sznycer
YouTube video by Evolutionary Psychology (The Podcast)
youtu.be
October 21, 2025 at 1:32 PM
This week, we discuss the evolved logic of shame, guilt, and other self-conscious emotions with Daniel Sznycer
youtu.be/OkCBaBSvSzs?...
podcasts.apple.com/us/podcast/e...
www.podbean.com/eas/pb-xyz24...
youtu.be/OkCBaBSvSzs?...
podcasts.apple.com/us/podcast/e...
www.podbean.com/eas/pb-xyz24...
Reposted by William Costello
"findings may help explain why differences...so consistent across time and cultures...humans conform well to general mammalian trend of female advantage in [life expectancy], demonstrating, at least in terms of sex differences in survival, our species is not unique" www.science.org/doi/full/10....
Sexual selection drives sex difference in adult life expectancy across mammals and birds
Sexual size dimorphism and mating system contribute to male and female life-span differences across wild and zoo populations.
www.science.org
October 21, 2025 at 1:03 AM
"findings may help explain why differences...so consistent across time and cultures...humans conform well to general mammalian trend of female advantage in [life expectancy], demonstrating, at least in terms of sex differences in survival, our species is not unique" www.science.org/doi/full/10....