Salter’s Blank Slate Hypothesis.
Back in my Legion Europa days I discussed Salter’s “Sender Males Carrier Females” “Blank Slate Hypothesis,” also mentioning how underlying issues in that hypothesis illuminate inconsistencies in certain Nordicist paradigms at that time. I will revisit the Salter paper in this post.
See here. Abstract:
The article introduces and elaborates the hypothesis of carrier features, characteristics which in females are attractive to males as mate-choice cues. Female carrier features increase paternal resemblance and are ultimately attractive because they help pair-bonded males distinguish genetic offspring from those conceived by mates in extra-pair copulations. The proposed kin recognition mechanism, whether culturally evolved or innate, facilitates discriminatory paternal investment, and hence male fitness. Carrier features would be attractive to males in monogamous species where paternal investment is high, and cuckoldry represents a significant risk to male fitness. Logical space exists for male sender features, which tend to be expressed in offspring regardless of female characteristics. Conflict of genetic interests between the sexes should favor the evolution of carrier, rather than sender, features in both sexes. The argument centers on humans, for whom candidate carrier features are discussed with regard to physiognomy, behavior, recessive traits, and body odor. Criticisms are discussed, and testable predictions enumerated.
The best summary of the hypothesis is in the opening of Salter’s paper itself:
Imagine an individual possessing a heritable characteristic of such a form that when the individual sexually reproduces, offspring tend to show enhanced resemblance to the other parent in that characteristic. To use the metaphor of radio communication, this hypothetical characteristic could be called a carrier feature, because it acts to transmit a distinctive characteristic of a mate to offspring.
Now, males who find carrier features attractive as mate-choice cues in females should be better able to discriminate their own offspring from offspring conceived by their mates in extra-pair copulations (EPCs). Female EPCs lower paired males' objective confidence of paternity. When paternal investment is significant, the phenomenon is often called cuckoldry and the victim a cuckold (a male who does not invest in his mate's young by provisioning or defending territory cannot be cuckolded, because he has nothing to lose) (Trivers 1972; Alexander 1974). Given these factors, males predisposed to choose as mates females with carrier features should experience an increase in relative reproductive fitness over males who are not so predisposed, so long as some anticuckoldry mechanism exists whose efficiency is improved by enhanced recognition of genetic offspring. Assuming these preconditions, genes and/or knowledge predisposing males to choose carrier-females as mates would tend to spread throughout the whole population. By the same logic, enhanced male characteristics that tend to express themselves in the offspring of any female, would be selected. To continue the radio analogy let us call these sender features, meaning characteristics with forms that tend to be expressed in offspring more than alternate forms.
Possible candidate carrier characteristics would be:
Facial appearance – female beauty (male preference) is typically associated with less distinctive faces with more average proportions; indeed, facial averaging methodologies (e.g., overlaying photos, computer morphing of composites, etc.) result in more attractive female faces than actual individual females, suggesting that individual females that have faces that trend more toward the non-distinctive average look would be considered more attractive. Note that small noses, small chins, etc., are considered attractive in females, while more distinctive and masculine traits like larger noses and chins and the “manjaw” are considered unattractive in females. Symmetrical faces are typically considered attractive, although the data are stronger (as of the time Salter wrote the paper, 1996) for non-distinctive (“average”) features as opposed to symmetry, with respect to female features being more important than that if males.
Note that paternal relatives are typically particularly interested in noticing ostensible father-child resemblance. Further, some researchers have postulated differences in paternal vs. maternal gene expression on offspring, favoring paternal expression and resemblance, as a selected mechanism for assuring paternal investment. Of course, as sender traits spread in a population, a male cannot be sure the sender traits in offspring are from him or another, similar man – there is no definitive proof of paternity other than genetic analysis. There is merely altered probabilities, and given the immense costs and benefits for fitness, probabilities are sufficient to be the target of selective pressure and altered paternal investment in offspring.
Behavior – attractive female behavior is more subdued and demure, and less idiosyncratic, than male behavior.
Recessiveness – eye, hair, and skin color, etc. Of course, as recessive traits spread in a population, paternity detection via sender traits becomes more difficult. When both the male and female are “monozygotic recessive” for a trait this becomes a problem. Also note that if a dark-eyed male is heterozygotic for that trait, it is of course less dependable than is homozygotic for that trait. In the absence of gene sequencing, the male would have to look at his extended family – if everyone has dark eyes, without fail, it is more likely he is homozygous; on the other hand, having some number of light-eyed blood relatives increases the probability that he is heterozygous and hence that trait is a less dependable marker of paternity.
Male vs. female strategies would differ based upon how frequent recessive traits are in a population. In populations that exhibit a high frequency of recessive traits, a female prone to cheat would want a recessive mate and recessive lovers so as to obscure paternity. However, females who want to maximize paternal investment via a “fidelity strategy” would choose a mate with dominant traits to make paternity “less ambiguous.” In populations that exhibit low frequencies of recessive traits, cheating females would want dominant mates (and dominant lovers) to obfuscate paternity; however, here, females choosing fidelity would prefer a recessive mate so the man can be more confident in recessive offspring (given that most potential male lovers for the female would be phenotypically dominant).
Body odor – this has the advantage that it can work subconsciously, without the male needing to even think about paternal investment in a conscious way.
Therefore, males would prefer and select females who have more recessive, more average (less distinctive), and/or less intense physiological (“carrier”) traits so that offspring resulting from mating with such females would reflect the more dominant, distinctive, and intense male (“sender”) traits of the (assumed) father, thus enhancing confidence in paternity (hence, an anti-cuckoldry mechanism). Carrier traits would be selected in females. What about males? Male behavior would select for male sender traits. If females wanted to assure the male of paternity and enhance paternal investment in offspring, females would choose males with more pronounced sender traits. On the other hand, given female hypergamy, the optimal female strategy would be to choose male mates with carrier traits so paternity is obfuscated; alternatively, evolution of sender traits in females would favor female hypergamy interests by also obfuscating paternity (male paternity confidence is typically maximized by more sender traits in males and more carrier traits in females). Thus, there is a divergence of sex-based interests, resulting in competing selective pressures. Of course, offspring are a mix of traits, so a sender male would see his sons be “more carrier” than himself (negative), compensated by daughters who are “more carrier” (positive) – for carrier females the calculation is of course different, more unattractive daughters with more sender traits from the father but compensated with sons with more sender traits. There is constant selection and counter-selection here, and it is not difficult to see how recessive carrier traits can spread in a population, particularly in populations in which paternal investment is high and in which the environment favors the maintenance of recessive traits. On the other hand, in societies in which paternal investment in low and cuckoldry doesn’t impose a large fitness cost to males, then there is less selective pressure for carrier traits – that these societies are often in tropical areas like Africa makes the maintenance of recessive traits more problematical in any case.
Patriarchal societies that enforce proper female behavior and control female hypergamy would have less need of the sender-carrier selective pressures, while more matriarchal and/or “liberated” societies would result in more female hypergamy, more cuckoldry, and increased selective pressure for sender-carrier selection.
Salter answers a number of potential criticisms and then makes predictions via testable hypotheses. These testable hypotheses are:
1. Carrier features should be independent of “health signs.” As we know, many features considered attractive in humans, particularly in females, are markers of health. Of course, the two may be “additive” – but there should be some additional carrier utility above and beyond health. This needs to be determined.
2. Carrier features in females should promote male sexual desire and mate bonding – this seems to be the case.
3. There’s some question as to whether carrier features would peak at a certain age and then diminish – e.g., at the peak of female youthful fertility – or should continue to ensure long-term mate bonding. This needs to be determined.
4. If strategies to control cuckoldry impose costs, then societies that have other mechanisms for controlling cuckoldry would have less need for the sender-carrier distinction. One can consider Middle Eastern societies that are very patriarchal and in which female sexuality is tightly controlled – females tend not have many carrier features compared to the males. More research is needed.
5. If “displays of fidelity” impose costs as well, one would expect populations that have females with many physiological carrier traits would also have females who feel less need to display behavioral cues of fidelity – the carrier traits are enough. One could consider phenotypically recessive Northern European populations with “feminist” “liberated” females who are not pressured to act chaste. Meanwhile, in other, less recessive populations, with fewer female carrier traits, females may be under increased pressure to act chaste to make the man confident in paternity through a (deluded?) perception of female fidelity. More research is needed. On the other hand, Africans have few female carrier traits and also very unchaste female behavior, but there is low paternal investment there (see below), so no need for carrier traits or displays of fidelity.
6. Populations that have more male mate choice of carrier females should exhibit more “paternal discrimination based on resemblance” (behavior that is genetic and/or cultural) than other populations. This needs to be determined.
7. There may be group differences in sender-carrier features. Societies that have more female choice, then males would have more carrier features, since females would tend to pick carrier males who are easier to cheat on (except in populations that have mostly dominant sender characteristics, see above). Are egalitarian Northern European populations with bossy women examples of this – since the males have recessive features as well? On the other hand, in societies with low levels of paternal investment, there is less need for the sender-carrier distinction. Note that sexual dimorphism in facial features is less in low-paternal-investment Africans compared to European and South American populations in which paternal investment is higher (particularly among Europeans); see this:
Sexual selection, including mate choice and intrasexual competition, is responsible for the evolution of some of the most elaborated and sexually dimorphic traits in animals. Although there is sexual dimorphism in the shape of human faces, it is not clear whether this is similarly due to mate choice, or whether mate choice affects only part of the facial shape difference between men and women. Here we explore these questions by investigating patterns of both facial shape and facial preference across a diverse set of human populations. We find evidence that human populations vary substantially and unexpectedly in both the magnitude and direction of facial sexually dimorphic traits. In particular, European and South American populations display larger levels of facial sexual dimorphism than African populations. Neither cross-cultural differences in facial shape variation, sex differences in body height, nor differing preferences for facial femininity and masculinity across countries, explain the observed patterns of facial dimorphism. Altogether, the association between sexual shape dimorphism and attractiveness is moderate for women and weak (or absent) for men. Analysis that distinguishes between allometric and non-allometric components reveals that non-allometric facial dimorphism is preferred in women's faces but not in faces of men. This might be due to different regimes of ongoing sexual selection acting on men, such as stronger intersexual selection for body height and more intense intrasexual physical competition, compared with women.
On the other hand, Asians tend to have low sexual dimorphism with higher paternal investment, which brings up issues of mate choice in those populations. These are complex issues with counter-acting selective pressures.
8. High status males should have more sender features and low status males more carrier – high status males have more choice in mates; the low status males have to be content with females who pick carrier males more prone to cuckoldry. There will be of course ethnic and racial considerations here, as some populations have a very high frequency of certain carrier traits. Prediction number eight would be most appropriate for populations that exhibit a higher degree of carrier traits. More study is required.
America is an interesting laboratory for Salter’s entire thesis, as it contains widely varied populations with a spectrum of sender-carrier traits, genetic and phenotypic differences of all types, evolved behavioral differences, differing levels of sexual dimorphism, etc.
On the whole, Salter’s hypothesis has merit and deserves closer examination and testing. This hypothesis compares favorably to related hypotheses, such as that of Frost, and, likely, these various hypotheses are complimentary, rather than in conflict.
As I wrote long ago, this all puts into question certain Nordicist paradigms. On the one hand, Southern Europeans are said to be phenotypically dark and unassimilable, completely different in appearance from Northern Europeans. On the other hand, Southern European men are said to be (mostly in America, I presume) engaging in mass cuckoldry of Northern European men via extra-pair copulations between Southern European men and Northern European women (who are the long term mates of Northern European men). But where is the evidence of the cuckoldry, even if we accept the alleged large phenotypic differences? How can both be true? If Southern Europeans are so phenotypically different and distinct then the offspring of such cuckoldry would be easily detected and the extent of the cuckoldry would be public knowledge and dealt with in some fashion. Or, if the cuckoldry is hidden, then the phenotypic differences must be so small that the offspring of the cuckoldry cannot be easily distinguished, and, hence, there is essentially full phenotypic assimilability between the two groups. Which is it?
Labels: behold the female, Blank Slate Hypothesis, Legion Europa, Nordicism, phenotype vs. genotype, racial cuckoldry, Salter, sex, sex differences, sexual behavior, White behavior