The Meat in the Hunter-Gathering Discussion

I was reading Sear's & Mace's 2008 meta-study of the effect of kinship on offspring. I noticed that they were talking about calories rather than nutrition, in reference to the work by Hawkes. That surprised me, given the role that meat nutrients play in chimpanzees and in the rise of hominids, especially the expansion of the human brain.

Claude Sonnet 4.6 agreed:

What's striking is that the nutritional anthropology literature on hunter-gatherer diets (Cordain, Eaton, etc.) does engage seriously with micronutrients — the argument that animal matter satisfies requirements for protein and many essential micronutrients while freeing gut space for carbohydrate-rich plant foods AJCN is well established in that parallel literature. But this reasoning seems not to have been systematically imported into the behavioral ecology debate about paternal provisioning versus signaling. The two literatures appear to be operating largely independently of each other, which may explain why the Hawkes critique lands so cleanly in the provisioning debate: it's aiming at a caloric target that was never the strongest version of the provisioning argument anyway.

And

Meat, and particularly organ meat and marrow, provides bioavailable iron (heme iron, with absorption rates several times higher than plant-sourced non-heme iron), zinc, vitamin B12, and phospholipids in forms that are simply not substitutable by gathered plant foods in most environments. The question "does big-game hunting feed the family?" gets a very different answer if you're asking about preventing iron-deficiency anemia in reproductive-age women and weaned toddlers than if you're asking about raw caloric adequacy. Gathered tubers and seeds can cover calories; they can't easily substitute for heme iron. 

If the nutritional story is about micronutrients rather than calories, then the grandmother's contribution (gathered carbohydrates, caloric buffer for weaned children) and the male hunter's contribution (intermittent but micronutrient-dense meat) are actually complementary rather than competing explanations for offspring survival. Hawkes sets them up as competing — either dad is provisioning or he's showing off — but if the provisioning is micronutrient-specific and the grandmother covers caloric provisioning, both can be true simultaneously and the "show-off" framing becomes less necessary to explain observed hunting patterns. 

Further investigation with Claude's assistence revealed that Hawkes in 2022 admitted as much, while continuing to look mostly at the calory-sharing aspect.

Moreover, as meat provides important nutrients not easily obtained from other sources (see, Milton, 2003; Tennie, Gilby, & Mundry, 2009; Watts, 2020), small quantities of meat may provide benefits to the procurer even when widely shared.

 After all, the paper is called "A cost for signaling: do Hadza hunter-gatherers forgo calories to show-off in an experimental context?" -- which is probably asking the wrong question.

Thin Slice evaluation in Social Settings

This is the abstract for Ambady, Nalini, and Robert Rosenthal. "Half a Minute: Predicting Teacher Evaluations From Thin Slices of Nonverbal Behavior and Physical Attractiveness." Journal of Personality and Social Psychology 64, no. 3 (1993): 431–441. https://doi.org/10.1037/0022-3514.64.3.431.

The accuracy of strangers' consensual judgments of personality based on "thin slices" of targets' nonverbal behavior were examined in relation to an ecologically valid criterion variable. In the 1st study, consensual judgments of college teachers' molar nonverbal behavior based on very brief (under 30 s) silent video clips significantly predicted global end-of-semester student evaluations of teachers. In the 2nd study, similar judgments predicted a principal's ratings of high school teachers. In the 3rd study, ratings of even thinner slices (6-s and 15-s clips) were strongly related to the criterion variables. Ratings of specific micrononverbal behaviors and ratings of teachers' physical attractiveness were not as strongly related to the criterion variable. These findings have important implications for the areas of personality judgment, impression formation, and nonverbal behavior.

The paper is accessible in multiple places on the web, e.g. here. The paper extended NaliniAmbady's dissertation research at Harvard, where Rosenthal was her advisor.

The careful study design is resistant to many of the criticisms that "thin slice" research has been submitted to since the work of Todorov and the "Blink!" popularization. The work builds in three incremental studies, it specifically checks for the attractiveness bias, and it used not only student but also principal evaluation to check for comparability. It did not work on thinning the slices until the third study.

Ambady was bitten, however by the assumption that student evaluations were an informative signal.

The criterion was end-of-the-semester student evaluations. Although student achievement (adjusted for student ability) might be the best possible criterion of effective teaching, it is very difficult to obtain such data. Teacher effectiveness in the real world is often evaluated solely on the basis of ratings of supervisors and students. Therefore, we used end-of-the-semester student ratings of teachers as a measure of teacher effectiveness. Considerable evidence supports the validity of student evaluations: Student ratings are consistent over time and across raters; correlate positively with expert, colleague, and administrator ratings; are independent of extraneous characteristics or characteristics of the students themselves; correlate significantly with how much students actually learn; and, last, do not change appreciably with greater age of the student rater and reflection by the student (Abrami, d'Apollonia, & Cohen, 1990; Centra, 1979; Cohen, 1981; Feldman, 1989a, 1989b; Howard, Conway, & Maxwell, 1985; Kulik & Kulik, 1974; Leventhal, Perry, & Abrami, 1977; Marsh, 1984; McKeachie, 1979; Trent & Cohen, 1973). Thus, student evaluations seem to be a valid means of evaluating teacher effectiveness. (432)

That stance was substantially challenged by the research of Boring, Ottoboni & Stark (2016), which used substantial data sets to argue that

Student evaluations of teaching (SET) are widely used in academic personnel decisions as a measure of teaching effectiveness. We [i.e. Boring, Ottoboni & Stark] show:

• SET are biased against female instructors by an amount that is large and statistically significant.

• The bias affects how students rate even putatively objective aspects of teaching, such as how promptly assignments are graded.

• The bias varies by discipline and by student gender, among other things.

• It is not possible to adjust for the bias, because it depends on so many factors.

• SET are more sensitive to students’ gender bias and grade expectations than they are to teaching effectiveness.

• Gender biases can be large enough to cause more effective instructors to get lower SET than less effective instructors.

These findings are based on nonparametric statistical tests applied to two datasets: 23,001 SET of 379 instructors by 4,423 students in six mandatory first-year courses in a five-year natural experiment at a French university, and 43 SET for four sections of an online course in a randomized, controlled, blind experiment at a US university.

This research appeared three years after Ambady's passing away in 2013.

Ambady's & Rosenthal's work was also hampered by the winner's curse, which their three-times repetition of their study could not fully escape from. (Notice that only some of the concerns that Ioannidis expresses in his 2005 paper apply to Ambady's work, and that the suggestion to use larger studies is silly for a PhD undertaking altogether.)