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Ed Hagen Profile picture
Ed Hagen
@ed_hagen
Biological anthropologist. Evolutionary medicine, evolution of cognition. https://t.co/dOAYoR8vST https://t.co/iw2gUixlKw
Nov 9 • 19 tweets • 7 min read
1. I intend to positively cite Eppig et al. (2010) despite its retraction for use of the discredited Lynn and Vanhanen national IQ dataset. 🧵

tl;dr: don't throw the baby out with the bathwater
royalsocietypublishing.org/doi/10.1098/rs…RETRACTED: Parasite prevalence and the worldwide distribution of cognitive ability 2. First, please read this excellent article on the Lynn dataset, which details its racist origins (Lynn: "predominantly white states should declare independence and secede from the Union")... statnews.com/2024/06/20/ric…
Jun 25 • 25 tweets • 8 min read
1. Ethical research in evolutionary psychology (EP) and human genetics (HG): A view from a cynical sociobiologist (me). 🧵 2. Recently @dconroybeam penned an Op-Ed on the harmful use of cherry-picked EP research, citing examples of mass shooters linked to EP-inspired manosphere ideology. He called on EP to do more to "defend our work from misappropriation"
Apr 9 • 23 tweets • 5 min read
1. According to some, this article provides strong empirical evidence for nonbinary biological sex, so I took a look.

tl;dr: ironically, the article reinforces the case for binary biological sex. 🧵
academic.oup.com/icb/article/63… 2. First, a refresher:

Sexual reproduction, the recombination of two parental genomes into one offspring genome, is very widespread in eukaryotes. This 2→1 mode of reproduction has many evolutionary consequences...
Apr 6 • 17 tweets • 7 min read
1. Much human genetic variation is phenotypically meaningless. Why? Cooperative genes are locked in a forever war w/ selfish genes. The cooperative genes have won most battles but now our genomes are littered with the dead & decaying bodies of a million selfish genes. 🧵 AI generated image of cooperative warriors blasting an enemy warrior 2. Genome sizes vary tremendously in ways that do not obviously relate to organism complexity, e.g., many fish and amphibians have huge genomes compared to mammals (note that the number of base pairs on the x-axis is on a log scale):
en.wikipedia.org/wiki/Genome_si…
Plot showing that within and across major taxonomic groups, genome size varies by orders of magnitude
Feb 12 • 15 tweets • 5 min read
1. What do we know about hunter-gatherers (HG)? This is the go-to book, first published in 1995, w/ a 2nd edition in 2013. Here's an overview of the book that I hope will encourage @NPR, @sciam, & others to consult it when reporting on & evaluating the import of new HG studies 🧵 The Lifeways of Hunter-Gatherers: The foraging spectrum by Robert Kelly, Second Edition 2. The key theme is that HGs vary a lot, hence the word *Spectrum* in the subtitle, but in principled ways that are best understood in a human behavioral ecology (HBE) framework: The Lifeways of Hunter-Gatherers. In this book, Robert L. Kelly challenges the preconception that hunter-gatherers should conform to a single type, be that of Paleolithic relics living in a raw state of nature, the original affluent society, or downtrodden proletariat. Instead, he crafts a position that emphasizes diversity in foraging lifeways and efforts to explain that diversity. Kelly reviews the anthropological literature for variation among living foragers in terms of diet, mobility, sharing, land tenure, technology, exchange, male-female relations, division of labor, marriage, descen...
Dec 18, 2023 • 25 tweets • 8 min read
1. The causes and consequences of two biological sexes.

A 🧵 that mostly follows Parker (2014) The sexual cascade: doi.org/10.1101/cshper…
The sexual cascade (succession of evolutionary events leading to Darwinian sexual selection) (pink boxes and arrows) showing main transitions and selective forces (white boxes and black arrows) and alternative stable states (blue boxes and arrows). The transitions (A-F) are explained in the text. 2. Major points:

Binary biological sex is not a system to exhaustively categorize every living thing.

Instead, it plays key causal roles in the evolution of many traits across the eukaryotes.

A preview of our journey [syngamy: fusion of two gametes] (Parker 2014): EVOLUTION OF SEXUAL STRATEGIES: THE SEXUAL CASCADE The various evolutionary adaptations surrounding sexuality have presented a formidable challenge for evolutionary biologists and many, from meiosis to sexual selection and sexual con-flict, continue to generate debate. Here and elsewhere (Parker and Pizzari, in press), a deductive approach is developed that seeks to explain sexuality as a sequence of events within a causal framework. It is important to distinguish between irreversible evolutionary transitions that are ubiquitous and fixed in most extant advanced animal taxa and more labile ...
Nov 26, 2023 • 7 tweets • 3 min read
1. Haas et al. argue that projectile points buried with women indicate they hunted big game in communal hunts:

Or?

In many hunter gatherer societies, the owner of the weapon owns the meat, even if he or she did not participate in the hunt. 🧵 2. In the !Kung, for example, the owner of the arrow owns the meat, and men often use arrows borrowed from many others, including from women, who typically do not hunt. Lee (1979): books.google.com/books?id=9085A…
The ! Kung rule for allocating ownership of the meat from a kill is "the owner of the arrow is the owner of the meat." This holds true even if the owner of the arrow is not the man who shot it. (If two or more arrows hit an animal, the owner of the first arrow shot gets credit for the kill.) Ownership in the !Kung context consists primarily of the right to distrib ute the meat formally. Disputes over ownership are rare; in fact, the man take steps to blur the credits for a kill by circulating their arrows in the traditional haro trading system. A man will say to another, "Giv...
Apr 14, 2023 • 18 tweets • 7 min read
1. In evolutionary psychology (EP), what is genetically coded?

* Behavior? No
* Psychological mechanisms or modules? No
* Developmental programs? Yes!

A brief tweetorial 🧵 Homologous hox genes in suc... 2. Humans start off as a single fertilized cell that, over 9 months, develops into an intricately structured, 2 trillion cell infant, and over 20 years, into a 30 trillion cell adult.
nature.com/articles/s4158…
Aug 26, 2022 • 10 tweets • 3 min read
1. The sex lives of Aka hunter-gatherers of the Central Africa Republic. A 🧵based on these two papers from Barry and Bonnie Hewlett:

repository.kulib.kyoto-u.ac.jp/dspace/bitstre…

anthro.vancouver.wsu.edu/documents/75/2… Image 2. The Aka report having sex about 3 times a night, with some days of rest between (all data are self-reported). Here, these frequencies are converted to weekly for comparison with neighboring Ngandu farmers and the US: Image
Aug 10, 2022 • 10 tweets • 3 min read
1. Social scientists who reference research on hunter-gatherers (but don't study them) might not be aware of the extent to which they've participated in the global economy, and been impacted by it.

A short🧵on Aka foragers of the Congo Basin based on the work of Barry Hewlett. Aka woman. Photo by Ed Hagen 2. Slave trading forced Ngandu horticulturalists into contact w/ the Aka, with whom they live today, exchanging starchy foods for meat, honey & other forest products, which initially included ivory that was exported to global markets, increasing the status of Aka elephant hunters Image
Jun 16, 2022 • 30 tweets • 8 min read
1. Santa Barbara Evolutionary Psychology (SBEP) argues that a universal human psychology evolved in Pleistocene Africa. But there has been surprising pushback from evo scholars arguing for recent behavioral evolution in the Holocene. What's the connection w/ race science?

🧵 2. In the terminal Pleistocene & Holocene, Homo sapiens expanded out of Africa into somewhat genetically isolated populations in W, S, & E Asia, Oceania & the Americas pnas.org/doi/full/10.10…
May 25, 2022 • 9 tweets • 3 min read
This 2018 FBI report on the pre-attack circumstances & behaviors of 63 active shooters found that they were aggrieved, highly stressed men, many of whom were depressed, & almost all of whom were suicidal (30/35 for whom a determination could be made). fbi.gov/file-repositor…
🧵 2. Here are the stressors ("mental health" was mostly apparent depression, anxiety, & paranoia, but not a diagnosis of such):
Apr 22, 2022 • 25 tweets • 9 min read
What's missing in most theories of #depression? Anger and conflict.

Theoretical model w/ @kristensyme: anthro.vancouver.wsu.edu/documents/685/…

* Sadness/grief: adaptive response to adversity without conflict.
* Depression: adaptive response to adversity with conflict.
🧵 Image 1. Conflict is a key concept in evolutionary approaches to behavior. Adaptive responses to conflict often involve costly behaviors, eg, fighting, which are NOT pathological!

What's the evidence that folks suffering depression, which is costly, are angry & enmeshed in conflict?
Apr 3, 2022 • 17 tweets • 6 min read
1. How does suicidality play out in traditional societies where community members are highly interdependent, relying on each other for critical needs like food, protection & care? Anthropologists live in these societies, often for years & see both the lead up & the consequences🧵 2. Anthropological analyses of suicidality link many cases to (1) social conflict, and (2) a motive or goal to influence or rebuke antagonists, or seek redemption. Among the Amazonian Aguaruna, for example (Brown 1986):
Feb 23, 2022 • 11 tweets • 5 min read
1. Grip strength, an index of upper body strength, is highly sexually dimorphic: 90% of men are stronger than 90% of women. Could this help explain sex differences in emotional responses to adversity? A 🧵on a study lead by grad student @_carolinebsmith

academic.oup.com/emph/advance-a… Image 2. Most depression is caused by adversity, and both are strongly linked to *conflict*. Assault is perhaps the most potent risk factor for depression. Other depression risk factors, like marital problems, are also tied to conflict. Table from Kendler et al. 1999: Image
Dec 15, 2021 • 22 tweets • 9 min read
A new pre-print w/ @AaronDBlackwell, @adlightner & Sullivan that weaves together human carnivory, shamanism, & encaphalization.

"We propose that in the story of human evolution, which has long featured hunters, healers had an equal role to play"

🧵 1/n

osf.io/76bka 2. We tackle two mysteries. First, human brain size tripled since the start of the Pleistocene.

Why?
Nov 4, 2021 • 10 tweets • 3 min read
At the press conference this morning, I asked if the research team could exclude the hypothesis that H. sapiens deposited the H. naledi bodies in the Rising Star cave. @LeeRberger dismissed this as the "pet cemetery" hypothesis (clever, I admit!).

What were his reasons? 🧵 1/n 2/n Berger argued that other non-human animals are capable of complex behaviors, so H. naledi probably was too. This is a strong argument. Here, for example, is a puffer fish engaging in complex symbolic signaling to mates:

Oct 3, 2021 • 17 tweets • 3 min read
The "neurotransmitters are drugs" metaphor, which is also applied to "surging" hormones in teenagers and women, has things exactly backwards.

🧵 1/n Your body has about 30 trillion cells, of which about 80 billion are neurons in your brain. All these cells constantly communicate with one another to create the organism that is you.

2/n
May 14, 2021 • 14 tweets • 6 min read
There is gold in "unpublished" dissertations

According to #evopsych, it's not surprising that male tourists pay for sex with locals. What is surprising, as April Gorry found, is that women do the same. Is #evopsych wrong about women's mating psychology? In some ways, yes:

A 🧵 2. White women tourists visiting the Caribbean and other warm-weather locales are stereotyped as sex-starved nymphomaniacs lusting after sexually potent dark-skinned men. Where did this myth come from?
May 3, 2020 • 25 tweets • 9 min read
1. @itsbirdemic recently critiqued evolutionary psychology:

kevinabird.github.io/2020/04/27/Evo…

Bird correctly notes that EP (1) focuses on complex adaptations and (2) holds that these always arise from natural selection. 2. Bird, drawing on Lynch (2007), claims that (2) above is false: "Work from Michael Lynch (2007) directly challenges the view that complexity requires adaptive explanations...."

pnas.org/content/pnas/1…