The big bird that takes away water

 

The constellation of the Southern Cross has inspired similar myths among indigenous peoples as far apart as Australia and South America. Why?

Southern Cross (Wikipedia – Yulanlu97). 

 

 

Did people cross the Pacific in pre-Columbian times? This question has aroused renewed interest with the discovery of sweet potato remains at Polynesian sites dated to A.D. 1000. There also seem to be loan-words of Polynesian origin in some Amerindian languages (Jones et al. 2011). Finally, we have strong evidence that Polynesians introduced chickens to the west coast of South America in prehistoric times, probably A.D. 1300-1420 (Fitzpatrick and Callaghan 2009).

 

A new piece of evidence is the similarity between a myth told by Aboriginal Australians, particularly those of southeast Australia, and a myth told by indigenous peoples in Argentina and central Brazil. In both cases, one finds the same two elements:

 

- A large flightless bird that can cause the land to dry up.

- The constellation of the Southern Cross and two adjacent regions of the sky: the Southern Pointers (Alpha and Beta Centauri) and the Coalsack Nebula

 

These similarities are mentioned by Gullberg et al. (2020) in a cross-cultural study of beliefs about the 'Dark Constellations':

 

Wiradjuri, Kamilaroi, Euahlayi, and others (Australia)

 

The Emu in the Sky is perhaps the best-known Aboriginal dark constellation (Figure 2). It is the silhouette of an emu traced out by the dark nebulae within the plane of the Milky Way and is featured in the traditions of Aboriginal people across Australia. The Coalsack Nebula, near the Southern Cross, forms the head, and the body extends along the dust lanes through Centaurus in the Milky Way, to the body as outlined by the galactic bulge in Scorpius and Sagittarius (Gullberg et al. 2020, p. 392)

 

When the celestial emu swings to where it is low on the horizon in October and November, the galactic bulge is now seen as the backside of an emu sitting in a waterhole, displacing the water and causing the land to dry up as the hot summer months approach. (Gullberg et al. 2020, p. 393)

 

Moqoit (Argentina)

 

Due to this crucial role of the Milky Way and the fact that it is a huge area of diffuse brightness interrupted by dark spots, it is not surprising that the Moqoit pay attention to dark patterns on it. The most important of all of them is the Mañic, the master of the South American rheas, a large flightless bird similar to an emu or ostrich shown in (Figure 5)

 

[…] We know many Moqoit stories mention that in the time of the origins, the master of Mañic used to shelter in a number of burrows, under the roots of an ombú (a very big tree, seen as the world tree—the Milky Way), and eat humans. Lapilalaxachi, a powerful human ancestor of the Moqoit people identified with the Pleiades, decided to face the Mañic. He chased the Mañic throughout the world and the cornered Mañic climbed up the ombú trunk to the sky.

 

Today, the shadow-soul (la 'al) of the Mañic can be seen in the Milky Way's dark clouds, with its head in what we know as the Coalsack (around -59° 50' galactic longitude). Alpha and Beta Centauri are the dogs of the man chasing the Mañic and bite at its neck (López and Giménez-Benítez, 2008). The Mañic's head is the Coalsack.

(Gullberg et al. 2020, p. 396)

 

Tupi (central Brazil)

 

In a similar view, the Tupi people of central Brazil also perceive a rhea in the sky, making essentially the same shape as the Aboriginal emu. The rhea and the emu are both large, flightless birds with a similar appearance and breeding cycle. Just as in Moqoit traditions, the head of the rhea is the Coalsack, and the body is traced out by dust lanes in Centaurus and Scorpius. The Tupi associate the rhea with the end of the world. The stars of Crux are holding the head of this animal. If it escapes, it will drink all the water of the world (Alencar, 2011)

(Gullberg et al. 2020, p. 397)

 

 

Why is this myth found only in Australia and South America? Why is it absent in-between? Actually, a version does exist on the Polynesian island of Tonga, except that the large flightless bird is a giant duck and it simply keeps people from getting access to water:

 

Tongans (Polynesia)

 

Polynesians of the Pacific recognise dark spaces in the Milky Way, focusing on the Coalsack Nebula and relating it to fish or fishing. Polynesian traditions of Tonga describe it as Humu (a giant triggerfish). In their traditions (Gifford, 1924), a Tongan chief named Ma'afu took a lizard wife and had twin sons, which they wanted gone as the chief's subjects were afraid of the pair. Ma'afu sneakily instructed the brothers to collect water from a waterhole containing a giant duck that would kill and consume anyone who came too close. The boys were attacked by the duck but grabbed it by the neck and killed it. When the boys returned unharmed, the father instructed them to obtain water from a more distant waterhole, inhabited by Humu, a triggerfish (these are large aggressive animals with powerful teeth designed for crushing shellfish). The boys killed the triggerfish and in anger at this, the father blurted out his secret to have the boys killed. The boys walked away and ascended to the stars, each carrying one of the two animals they killed. The twins became the Magellanic Clouds, the duck became the Southern Cross (with the duck's bill as γ Crucis), and Humu became the Coalsack Nebula

(Gullberg et al. 2020, p. 398)

 

 

My thoughts

 

This myth seems to have begun in one of three areas (Australia, Polynesia, South America) and then spread to the other two. If it began among Aboriginal Australians, the myth could be very old, going back perhaps 65,000 years. If it began among the Amerindian peoples of South America, it may go back 10,000 years. Finally, if it began among the Polynesians, the time depth would be no more than 3,500 years. The first and last scenarios seem most likely, given that oceanic travel was much easier from Polynesia to South America than the reverse (Fitzpatrick and Callaghan 2009).

 

Nonetheless, all of the scenarios run into a big problem: the myth is known to South American groups on the east side of the continent but not to those on the west side (which would be more consistent with trans-Pacific contact). I can think of only one other scenario. Given that the Americas were once inhabited by a population related to Aboriginal Australians and similar groups in Southeast Asia (Frost 2015), the myth may have originated in Asia more than 65,000 years ago and then spread in two directions: to Australia via Southeast Asia and to the Americas via the Bering Strait. But could a myth survive intact for that long?

 

Two other things leave me wondering. Why would the sky around the Southern Cross be seen as a large flightless bird? Gullberg et al. (2020) provide several pictures of that part of the sky and trace the outline of a bird on them. To my eyes, one could just as easily trace the outline of many other animals.

 

Finally, is this evidence, à la Von Däniken, of extraterrestrial contact? Keep in mind that the region of the Southern Cross includes the closest star system to ours. And if that system does have intelligent life, should we be reaching out to them and inviting them over? The last time around they didn’t leave a good impression.

 

Enough! I shouldn’t let myself get carried away. Extraordinary claims require extraordinary evidence, and a single myth hardly qualifies as extraordinary.

 

 

References

 

Fitzpatrick, S.M. and R. Callaghan. (2009). Examining dispersal mechanisms for the translocation of chicken (Gallus gallus) from Polynesia to South America. Journal of Archaeological Science 36(2): 214-223.

https://doi.org/10.1016/j.jas.2008.09.002

 

Frost, P. (2015). Guess who first came to America? Evo and Proud. August 1

http://evoandproud.blogspot.com/2015/08/guess-who-first-came-to-america.html

 

Gullberg, S.R., D.W. Hamacher, A. Martin-Lopez, J. Mejuto, A.M. Munro, and W. Orchiston. (2020). A Cultural Comparison of the 'Dark Constellations' in the Milky Way. Journal of Astronomical History and Heritage 23(2): 390-404.

http://www.narit.or.th/files/JAHH/2020JAHHvol23/2020JAHH...23..390G.pdf

 

Jones, T.L., A.A. Storey, E.A. Matisoo-Smith, and J.M. Ramirez-Altamira (eds). (2011). Polynesians in America: Pre-Columbian Contacts with the New World. Rowman Altamira.

Nigerians, Scrabble, and the GCSE

 

Exam hall at Hull Collegiate School (Wikicommons – Robin S. Taylor). The GCSE exam is a poor measure of raw cognitive ability. If some students get tutored and others do not, there will be more environmental variance in IQ, and the exam results will say less about the genetic potential for cognitive ability.

 

 

Chanda Chisala has written more about cognitive ability in sub-Saharan Africa. His argument is straightforward:

 

[…] if it is true that on average black Africans in Africa score extremely low on scholastic/intelligence tests because they grow up with much less educational and other modern cultural resources (as Flynn would agree), then they should perform "extremely well" (by comparison) in those "g-loaded" cognitive contests that do not require too much of such quality cultural exposure (as Jensen would agree). (Chisala 2021)

 

Chanda argues that raw cognitive ability is better measured in Africa by a Scrabble championship than by an IQ test, since most Africans lack "access to well-trained teachers, big libraries, computers or even TVs" (Chisala 2021). Africans are good at Scrabble:

 

Nigeria happens to be the world's top performing nation in English Scrabble, while francophone African countries are also the most dominant in French Scrabble, despite the fact that the top players in Western countries are super-high-IQ nerds with visibly exceptional mathematical talents (Chisala 2021)

 

Correlation isn't causation. Is a high IQ needed to do well at Scrabble? Not according to this study:

 

Forty tournament-rated SCRABBLE players (20 elite, 20 average) and 40 unrated novice players completed a battery of domain-representative laboratory tasks and standardized verbal ability tests. The analyses revealed that elite- and average-level rated players only significantly differed from each other on tasks representative of SCRABBLE performance. Furthermore, domain-relevant practice mediated the effects of SCRABBLE tournament ratings on representative task performance, suggesting that SCRABBLE players can acquire some of the knowledge necessary for success at the highest levels of competition by engaging in activities deliberately designed to maximize adaptation to SCRABBLE-specific task constraints. (Tuffiash, Roring, and Ericsson 2007)

 

Success at Scrabble seems to be due largely to practice and is thus a poor measure of raw cognitive ability.

 

A curious detail: Nigeria's top performers come overwhelmingly from one part of the country: the Niger Delta, which is home to the Igbo and related tribes. Since the peoples of the Niger Delta used to dominate trade between the coast and the interior, and since trade selects for cognitive ability, mean IQ should be higher in those populations that have long practiced it, like the Igbo (Frost 2015).

 

Young Nigerians in the UK - Academic achievement on the GCSE

 

Although many African immigrants do poorly in British schools, some actually do well. A study of six secondary schools in inner London found that results on the General Certificate of Secondary Education (GCSE) were higher for African students who spoke Igbo, Yoruba, Luganda, and Ga than for White British students who spoke only English (Demie 2013, p. 9). Chanda sees the GCSE as a proxy for IQ and argues that IQ differences between African immigrants and White British must be highly malleable:

 

Africans speaking Luganda and Krio did better than the Chinese students in 2011. The igbo were even more impressive given their much bigger numbers (and their consistently high performance over the years, gaining a 100 percent pass rate in 2009!). The superior Igbo achievement on GCSEs is not new and has been noted in studies that came before the recent media discovery of African performance. A 2007 report on "case study" model schools in Lambeth also included a rare disclosure of specified Igbo performance (recorded as Ibo in the table below) and it confirms that Igbos have been performing exceptionally well for a long time (5 + A*-C GCSEs); in fact, it is difficult to find a time when they ever performed below British whites. (Chanda 2015)

 

Igbo students stood out as high achievers on the GCSE, as did Yoruba students to a lesser extent. In both groups, however, the mean results were highly variable from one year to the next:

 

2009: Igbo - 100%, Yoruba - 39%

2010: Igbo - 80%, Yoruba - 68%

2011: Igbo - 76%, Yoruba - 75% 

(Demie 2013, p. 9)

 

Chanda attributes this variability to statistical noise caused by small sample size. If so, there should be an inverse correlation between sample size and variability. GCSE scores should be more variable for smaller groups than for larger ones. Yet the reverse seems to be true for the years 2009 to 2011:

 

Yoruba: 90 students / gain of 36 percentage points

Somali: 53 students / gain of 13 percentage points

Twi-Fante: 37 students / loss of 3 percentage points

Igbo: 16 students / loss of 24 percentage points

Krio: 12 students / gain of 4 percentage points

Tigrinya: 12 students / loss of 8 percentage points

Lingala: 12 students / loss of 5 percentage points

Ga: 8 students / gain of 9 percentage points

Swahili: 8 students / gain of 10 percentage points 

(Demie 2013, pp. 7, 9)

 

The two largest gains were made by the two largest groups: the Yoruba and the Somali. If the differences between 2009 and 2011 are statistical noise, why are the largest ones associated with the largest groups? Shouldn't we see the reverse? Shouldn't the smallest groups show the most variability?

 

Something seems to be causing those impressive GCSE gains. Since the students are not the same from one year to the next, and since the gains differ considerably from one ethnic community to another, the "something" must be the community itself. Over time, the Yoruba community became better at assisting its students, and this kind of assistance was available only in larger communities like the Yoruba.

 

The most obvious forms of assistance are tutoring and coaching. Such assistance is mentioned by parents in interviews for the above study:

 

Parent A: Father of daughter in Year 9. Generally supportive of the school which was not his first choice but is supplementing his daughter's education with a home tutor. He also calls on his extended family, his oldest son who is a graduate is also expected to help. (Demie 2013, p. 14)

 

Although tutoring and coaching are perfectly legitimate, they invalidate the GCSE as a means to measure IQ, particularly its genetic component. If some students get tutored and others do not, there will be more environmental variance in IQ, and the exam results will say less about the genetic potential for cognitive ability. Therefore, GCSE results tell us what we already know: if you get tutored and coached before an exam, you'll do better.

 

Are tutoring and coaching the only forms of community assistance? There is another one: impersonation. In other words, the parents hire a smart student from their community to take the exam in their child's place. This strategy is feasible only if the community has enough individuals who are (1) intelligent and (2) similar in age and appearance to the student in question. Such individuals are lacking in a small community, as are the middlemen who can refer an anxious parent to a suitable source of assistance.

 

How common is this strategy? Adebayo (2013) studied cheating behavior among Nigerian university students and British university students. He found that impersonation services were used or provided by 20% of the former and 1% of the latter. In general, cheating took non-collaborative forms among British students and collaborative forms among Nigerian students:

 

These include behaviours like writing somebody's coursework, colluding with others to communicate answers to one another, over marking one another's course work etc. This is quite different from plagiarism and non-collaborative cheating characteristic of the British sample reported by Newstead et al (1996). Reasons for these differences may be attributable to differences in population, differences in cultural ethnic, differences in emphasis placed on examination as part of educational assessment (Adebayo 2013, p. 146)

 

Adebayo (2013, p. 148) found high rates of collaborative cheating among Nigerian students:

 

Permitting own coursework to be copied - 72.6%

Copying another student's coursework with consent - 47.3%

Collaborative generous marking of coursework - 64.6%

Submitting joint work as an individual's - 49.3%

Doing another student's coursework for them - 77.3%

Collusion with another student to communicate answers - 83%

 

We live in a world that has low-trust and high-trust societies. In a high-trust society, like the UK, cheating is considered shameful and disreputable, regardless of whom you cheat. In a low-trust society, like Nigeria, cheating is wrong only when you do it to friends and relatives.

 

What happens when individuals from a low-trust society migrate to a high-trust one? If they come in sufficient numbers, their opportunities for collaborative cheating are greatly increased. Imagine you're supervising an exam in an English school, and you suspect an African student is filling in for another. He shows you his school card and another piece of ID. Both are correct. So what do you do now? Do you really want to make a fuss and risk being accused of racial profiling? No you don't.

 

Future research

 

The GCSE study by Demie (2013) leaves much to be desired. It does not provides the number of students who had to retake that exam (which must be a large number); nor does it provide a breakdown of the number of students taking it per year.

 

In any case, the GCSE is a poor substitute for an IQ test. Even if we exclude cheating, the results are distorted by legitimate activities like tutoring and coaching. The latter are more available to some students than to others. Consequently, GCSE results tell us nothing about differences in raw cognitive ability, either between individuals or between communities.

 

Chanda promises to write an article that will rule out cheating as an explanation for Nigerian success on the GCSE. Again, the issue isn't just cheating. It's any assistance that goes to some students and not to others. If you want to measure raw cognitive ability, you need a level playing field. In particular, you need a test that does not offer high achievers the lure of personal gain, which may push test-takers to do well by hook or by crook. In the UK, an African with good GCSE results has access to a wide range of good-paying jobs, in large part because of "diversity quotas" of one sort or another.

 

This motive comes out in interviews with the parents of African students:

 

● 'Without an education you cannot earn a decent salary, without qualifications you cannot get a good job. The best thing is to push your children as hard as you can.'

● 'Being a Black woman if you don't have education in this country, what job will you have to do, clean people's toilets?'  (Demie 2013, p. 13)

 

This subject should definitely be a research priority. We need IQ data on Nigerians, and not inadequate substitutes like GCSE scores. We also need data on alleles associated with educational attainment (i.e., polygenic scores). Furthermore, we need data on each of Nigeria's ethnic groups, particularly the Igbo. It's hard to fake intelligence in the real world, and the Igbo have a long history of doing better at business and other endeavors. Unfortunately, intelligent people are also better at cheating, so there is some confounding between real intelligence and the fake kind.

 

References

 

Adebayo, S.O. (2011). Common Cheating Behaviour among Nigerian University Students: A Case Study of University of Ado-Ekiti, Nigeria. World Journal of Education 1(1): 144-149.

https://files.eric.ed.gov/fulltext/EJ1159043.pdf

 

Chisala, C. (2015). The IQ Gap Is No Longer a Black and White Issue. The Unz Review, June 25

https://www.unz.com/article/the-iq-gap-is-no-longer-a-black-and-white-issue/

 

Chisala, C. (2020). Nigerians, Jews and Scrabble: An Update on the IQ Debate. The Unz Review, February 27

https://www.unz.com/article/nigerians-jews-and-scrabble-an-update-on-the-iq-debate/#comment-4520966

 

Demie, F. (2013). Raising Achievement of Black African Pupils. Good Practice in Schools. London: Lambeth Research and Statistics Unit, Lambeth Council.

https://www.lambeth.gov.uk/rsu/sites/www.lambeth.gov.uk.rsu/files/Raising_the_Achievement_of_Black_African_Pupils-Good_Practice_in_Schools_2013.pdf

 

Frost, P. (2015). The Jews of West Africa. The Unz Review, July 4

https://www.unz.com/pfrost/the-jews-of-west-africa/

 

Tuffiash, M., R.W. Roring, and K.A. Ericsson. (2007). Expert performance in SCRABBLE: Implications for the study of the structure and acquisition of complex skills. Journal of Experimental Psychology: Applied, 13(3), 124-134. https://doi.org/10.1037/1076-898X.13.3.124

Not getting the concept

 

In selling mass immigration to the public, Japan’s government is faced with a semantic problem. Many have trouble understanding the concept, i.e., foreigners can come in large numbers, receive citizenship, and be treated as if they really are Japanese. (Wikicommons – Maya-Anaïs Yataghène)

 

 

An ideology will spread more easily among people who already understand its concepts, and such understanding is made easier by a common language. Conversely, an ideology will spread less easily across a language boundary. The problem is not simply one of translating the words but also one of reformulating the concepts, which may seem less familiar in another language and culture.

 

For that reason, globalism has spread unevenly around the world. It has penetrated the thinking of nations that widely use English as a first language, especially their chattering classes. It has less easily penetrated where English is poorly understood. This has been the case in East Asia, especially Japan.

 

The Japanese exception

 

That country is linguistically isolated from the English-speaking world to a high degree, despite close economic ties. In 2019, Japan ranked 53rd in English proficiency out of a hundred non-English-speaking countries, down from 49th the year before. Even China had a better ranking (Nippon.com, 2019).

 

Japan’s linguistic isolation is part of a tendency toward cultural isolation that goes back to the two-century-long period of sakoku ("closed country"), when the government forbade Japanese nationals to go abroad and severely limited trade with other countries. That policy didn't fully end when Japan opened up to the world in the mid-nineteenth century. There has continued to be an unwritten policy of protecting Japanese culture and identity.

 

This isolationist tendency is now viewed as a problem by the ruling Liberal Democratic Party. Because of a very low birth rate, the population shrank by about 1.7 million between 2010 and 2018 and is projected to lose another 20 million by 2045 (Davison and Peng 2021). Stopping this demographic decline will require radical changes to the economy, particularly the balance between work and home life. There is also a deeper problem with consumer culture: advertising tends to promote the lifestyle of singles, since they have the most disposable income. Corporate advertising thus projects images of happy carefree singles, and such images influence how ordinary people see themselves.

 

While some moves have been made to improve work/life balance in Japan, fertility will not immediately return to replacement levels, even with generous incentives. We’re dealing with ingrained attitudes, as well as an uncooperative consumer culture. Policy makers are thus tempted by a seemingly easier solution—mass immigration—and that seems to be where they’re heading:

 

[…] some scholars and policymakers have called for a vigorous increase in the number of immigrants admitted to the country. [...] Sakanaka (2015), for example, argues that Japan would need to accept 10 million immigrants over the next 50 years (an average of 200,000 per year) to sustain its population and economy. (Davison and Peng 2021)

 

In 2014, a government commission came out in favor of increased immigration: "With the falling birthrate, in order to raise productivity, we will strategically bring in foreign talent (gaikoku jinzai) as we encourage a national debate, and we will design the development of our interactions with them" (Roberts 2018, 90).

 

A matter of semantics

 

In selling mass immigration to the public, the government is faced with a semantic problem. Many have trouble understanding the concept, i.e., foreigners can come in large numbers, receive citizenship, and be treated as if they really are Japanese. This was a finding from in-depth interviews with people from all walks of life:

 

An unexpected finding of our research was that the notion of immigration as we know it in the West — migration to a foreign country with the intention to settle as a permanent resident or naturalised citizen — was somewhat foreign to many of our interview participants. When asked for their opinions on immigration, many participants assumed the term 'immigrant' (imin) was synonymous with 'temporary foreign worker' (gaikokujin rodosha) and that 'immigration policy' (imin seisaku) was inclusive of temporary worker programmes like the Economic Partnership Agreements (EPAs) that bring in up to 1000 nursing and care work interns from the Philippines, Indonesia, and Vietnam each year. (Davison and Peng 2021)

 

This misunderstanding can be seen in the following exchange between the interviewer (Davison) and nurses at a hospital:

 

Participant:

There's one thing I don't get. When you say immigration ... if someone likes Japan and wants to live here ... Is that the kind of person you have in mind? Or someone who just wants to come here for a short time to make some money ... Is there a difference between those kind of people? When you say immigrants ... I don't understand the concept.

 

Davison:

I mean people who come here and get citizenship, Japanese citizenship.

 

Participant:

Get Japanese citizenship? So they're Japanese?

 

Most of the interviewees were initially neutral or favorable toward immigration. They often changed their minds when told that immigrants are "people who come to Japan with the intention to settle in the country and perhaps naturalise as Japanese citizens" (Davison 2021). This confusion may be due to government discourse on the subject:

 

For example, 'immigration policy' is frequently presented as 'acceptance of foreign workers policy' (gaikokujin rodosha ukeire seisaku) and, in official messaging, the implication of permanent settlement is often left unstated. (Davison 2021)

 

To some degree, the confusion may be deliberate. The government may realize that immigration is more acceptable to the public if presented as a temporary worker program, even if it provides a path to permanent residency and citizenship.

 

 

References

 

Davison, J. and I. Peng. (2021). Views on immigration in Japan: identities, interests, and pragmatic divergence. Journal of Ethnic and Migration Studies. January 8

https://doi.org/10.1080/1369183X.2020.1862645

 

Nippon.com (2019). Japan's English Proficiency Drops among Non-English-Speaking Countries. December 4

https://www.nippon.com/en/japan-data/h00594/japan%E2%80%99s-english-proficiency-drops-among-non-english-speaking-countries.html#:~:text=Japan%27s%20English%20Proficiency%20Drops%20Among%20Non%2DEnglish%2DSpeaking%20Countries,-Culture%20Language%20Dec&text=A%20survey%20has%20revealed%20that,both%20South%20Korea%20and%20China.

 

Roberts, G.S. (2018). An Immigration Policy by Any Other Name: Semantics of Immigration to Japan. Social Science Japan Journal 21 (1): 89-102. https://doi.org/10.1093/ssjj/jyx033

White Skin Privilege: Modern Myth, Forgotten Past

 

Cairo Slave Market, Maurycy Gottlieb, 1877 (Wikicommons)

 

I've published a paper "White Skin Privilege: Modern Myth, Forgotten Past" in the journal Evolutionary Studies in Imaginative Culture. Here is the abstract:

 

European women dominate images of beauty, presumably because Europe has dominated the world for the past few centuries. Yet this presumed cause poorly explains "white slavery"—the commodification of European women for export at a time when their continent was much less dominant. Actually, there has long been a cross-cultural preference for lighter-skinned women, with the notable exception of modern Western culture. This cultural norm mirrors a physical norm: skin sexually differentiates at puberty, becoming fairer in girls, and browner and ruddier in boys. Europeans are also distinguished by a palette of hair and eye colors that likewise differs between the sexes, with women more often having the brighter hues. In general, the European phenotype, especially its brightly colored features, seems to be due to a selection pressure that targeted women, apparently sexual selection. Female beauty is thus a product of social relations, but not solely those of recent times.

 

Please feel free to comment.

 

Reference

 

Frost, P. (2020). White Skin Privilege: Modern Myth, Forgotten Past. Evolutionary Studies in Imaginative Culture 4(2): 63-82.

https://doi.org/10.26613/esic/4.2.190

https://www.jstor.org/stable/10.26613/esic.4.2.190

Sex differences in human eye morphology

 

Women have rounder-looking eyes with narrower fissures, but only in Europeans. Eyes are not sexually dimorphic in other human populations. (Petr Novak, Wikicommons)

 

 

The exposed white of the eye is larger in men than in women among Europeans but not in other human groups. This sexual dimorphism is due to the white of the eye being more horizontally exposed in men, with the result that female eyes look rounder. In addition, eye fissures are narrower and less rectangular in women (Danel et al. 2018; Danel et al. 2020).

 

This is analogous to what we see with eye color and hair color. Eyes are brown in most humans with the exception of Europeans, whose eyes may also be blue, gray, or green. Hair is black in most humans with the exception of Europeans, whose hair may also be blonde, red, or brown. In both cases, the palette of colors is more evenly balanced in women than in men. Women are less likely to have the more common hues, like blue or brown eyes and black hair. Conversely, they are more likely to have the less common hues, like green eyes and red hair.

 

There is no common genetic cause of these sex differences in eye morphology, eye color, and hair color. The genes are different in each case. The common cause seems to be some kind of selection among ancestral Europeans. Something favored the reproduction of women with rounder-looking eyes and less common eye and hair colors.

 

Was that "something" a someone? Were men selecting women through a process of sexual selection? That has been my explanation: in northern Eurasia until the end of the last ice age, women outnumbered men and had to compete for them, as a result of high male mortality and the high cost of polygyny. There was thus strong selection for women with an eye-catching appearance, and this selection ultimately changed the appearance of both sexes. The new phenotype eventually died out in northern Asia but survived in parts of Europe, which had a larger and more continuous human presence. It then spread throughout the rest of Europe almost at the dawn of history (Frost 2006; Frost 2014; Frost et al. 2017).

 

Danel et al. (2020) consider this explanation but reject it because female eye morphology does not correlate with two other aspects of female attractiveness: face shape and facial averageness. That lack of correlation, however, simply shows that each of these aspects has different constraints on the direction of sexual selection:

 

Eye morphology - the direction of sexual selection seems open-ended. Women are more attractive if they have rounder eyes.

 

Face shape - the direction of sexual selection goes into reverse beyond a certain point. Women are more attractive if they have smaller chins and smaller noses, but only up to a certain point. Excessively small chins and noses are not attractive either.

 

Facial averageness - the constraints are again different. Women become less attractive on each side of a narrow median.

 

References

 

Danel, D.P., S. Wacewicz, Z. Lewandowski, P. Zywiczynski, and J.O. Perea-Garcia. (2018). Humans do not perceive conspecifics with a greater exposed sclera as more trustworthy: a preliminary cross-ethnic study of the function of the overexposed human sclera. Acta Ethologica 21: 203-208.

https://doi.org/10.1007/s10211-018-0296-5

 

Danel, D.P., S. Wacewicz, K. Kleisner, Z. Lewandowski, M.E. Kret, P. Zywiczynski, and J.O. Perea-Garcia. (2020). Sex differences in ocular morphology in Caucasian people: a dubious role of sexual selection in the evolution of sexual dimorphism of the human eye. Behavioral Ecology and Sociobiology 74(115)

https://doi.org/10.1007/s00265-020-02894-1

 

Frost, P. (2006). European hair and eye color - A case of frequency-dependent sexual selection? Evolution and Human Behavior 27(2): 85-103.

https://doi.org/10.1016/j.evolhumbehav.2005.07.002

 

Frost, P. (2014). The puzzle of European hair, eye, and skin color. Advances in Anthropology 4(2): 78-88.

https://doi.org/10.4236/aa.2014.42011

 

Frost, P., K. Kleisner, and J. Flegr. (2017). Health status by gender, hair color, and eye color: Red-haired women are the most divergent. PLoS One 12(12): e0190238.

https://doi.org/10.1371/journal.pone.0190238

 

Are identical twins really identical?

 

Sibling similarity in personality for monozygotic twins, dizygotic twins, and adoptees (Wikicommons)

 

 

Monozygotic and dizygotic twins who were separated early in life and reared apart (MZA and DZA twin pairs) are a fascinating experiment of nature. They also provide the simplest and most powerful method for disentangling the influence of environmental and genetic factors on human characteristics. (Bouchard et al. 1990)

 

Monozygotic twins are identical twins. They develop from a single fertilized egg and are assumed to be genetically identical. Any differences between them in mind or behavior must therefore have an environmental cause. Of course, "environmental cause" does not mean only things like diet, upbringing, education, or parental help with homework. It can also mean accidents during pregnancy or childbirth.

 

But are monozygotic twins really identical? Monozygotic twins begin to go their own ways long after the zygote has made its first division. It's actually around a week later that they begin to develop separately, when the zygote has already divided several times to form a mass of about sixteen cells. During that time, mutations may have occurred in one cell lineage or another, and not all of those mutations will be inherited by both twins. A twin may in fact develop from a single lineage or several lineages within the cell mass. The two twins may thus be genetically different.

 

Jónsson et al. (2021) have quantified these genetic differences between twins. They examined the body tissues of adult twins, specifically one sample from adipose tissue, 204 samples from buccal tissue, and 563 blood samples.  On average, one of the twins had 14 postzygotic mutations that were not present in the other. There was, however, considerable variability: 39 twin pairs differed at more than 100 loci, whereas 38 pairs did not differ at all.

 

Germ cells develop from a subset of cell lineages very early in embryonic development, and it is possible to see how twins differ genetically in their germ lines by looking at their offspring. In this case, there was a difference of 5.2 mutations between twins. Again, there was considerable variability, ranging from a minimum of no mutations at all in 207 offspring to a maximum of 8 mutations in 3 offspring.

 

If monozygotic twins are not genetically identical, we will have to revise upwards our estimates of the relative importance of nature versus nurture in different human traits:

 

Phenotypic discordance between monozygotic twins has generally been attributed to the environment. This assumes that the contribution of mutations that separate monozygotic twins is negligible; however, for some diseases such as autism and other developmental disorders, a substantial component is due to de novo mutations. Our analysis demonstrates that in 15% of monozygotic twins a substantial number of mutations are specific to one twin but not the other. This discordance suggests that in most heritability models the contribution of sequence variation to the pathogenesis of diseases with an appreciable mutational component is underestimated. (Jónsson et al. 2021)

 

In particular, we will have to revise upwards our estimates of the genetic component of intelligence, such as the 70% estimate offered by Bouchard et al. (1990):

 

Since 1979, a continuing study of monozygotic and dizygotic twins, separated in infancy and reared apart, has subjected more than 100 sets of reared-apart twins or triplets to a week of intensive psychological and physiological assessment. Like the prior, smaller studies of monozygotic twins reared apart, about 70% of the variance in IQ was found to be associated with genetic variation. On multiple measures of personality and temperament, occupational and leisure-time interests, and social attitudes, monozygotic twins reared apart are about as similar as are monozygotic twins reared together.

 

Or the 41% to 66% estimate offered by Haworth et al. (2020):

 

Although common sense suggests that environmental influences increasingly account for individual differences in behavior as experiences accumulate during the course of life, this hypothesis has not previously been tested, in part because of the large sample sizes needed for an adequately powered analysis. Here we show for general cognitive ability that, to the contrary, genetic influence increases with age. The heritability of general cognitive ability increases significantly and linearly from 41% in childhood (9 years) to 55% in adolescence (12 years) and to 66% in young adulthood (17 years) in a sample of 11 000 pairs of twins from four countries, a larger sample than all previous studies combined.

 

My criticisms

 

Why focus on germline differences?

 

I have two criticisms of the study by Jónsson et al. (2020). First, their abstract highlights the median of 5.2 mutational differences in the germline, and not the larger median of 14 mutational differences in somatic tissues.

 

Here we show that monozygotic twins differ on average by 5.2 early developmental mutations and that approximately 15% of monozygotic twins have a substantial number of these early developmental mutations specific to one of them. (Jónsson et al. 2021)

 

Yes, "heritability" refers to genes that are passed on to the next generation, but most twin studies don't include the offspring of twins. The researchers simply examine pairs of monozygotic twins and see how they differ. Any differences would therefore reflect differences in somatic tissues and not the germline, or at least not solely the germline.

 

Undoubtedly, some of the somatic mutations occurred later in development, but they would still be relevant for any study on adult monozygotic twins.

 

Do these differences really make a difference?

 

We estimate the genetic component of a mental or behavioral trait by comparing monozygotic and dizygotic twins, i.e., identical and fraternal twins. A difference between monozygotic twins is assumed to be 100% environmental, and a difference between dizygotic twins is assumed to be partly environmental and partly genetic. Therefore, we can estimate the genetic component by subtracting one from the other, right?

 

This is where the study by Jónsson et al. (2021) comes in. They argue that the genetic component is always underestimated because some of the difference between monozygotic twins is also genetic. But is that additional genetic difference large enough to make a difference? If monozygotic twins differ from each other, on average, at 14 loci, and dizygotic twins differ from each other, on average, at 1400 loci, we might as well assume that monozygotic twins are genetically identical. Any upward revision of the heritability estimate would be slight.

 

Of course, the key lies in the words "on average." Some of the twins in this study differed at more than 100 loci. More importantly, around 15% of the twins had a substantial number of "near-constitutional" mutations, i.e., absent from one twin and present in almost all the tissues of the other. In those cases, we could see big differences in development between the two.

 

It's difficult to say without a point of comparison. In other words, the same kind of study should be done on dizygotic twins. How much more variable are they genetically?

 

 

References

 

Bouchard Jr., T.J., D.T. Lykken, M. McGue, N.L. Segal, and A. Tellegen. (1990). Sources of human psychological differences: the Minnesota Study of Twins Reared Apart. Science 250(4978): 223-228. https://doi.org/10.1126/science.2218526

 

Haworth, C.M.A., M. J. Wright, M. Luciano, N.G. Martin, E.J.C. de Geus, et al. (2010). The heritability of general cognitive ability increases linearly from childhood to young adulthood. Molecular Psychiatry 15: 1112-1120. https://doi.org/10.1038/mp.2009.55

 

Jónsson, H., E. Magnusdottir, H.P. Eggertsson, O.A. Stefansson, G.A. Arnadottir, et al. (2021). Differences between germline genomes of monozygotic twins. Nature Genetics 53: 27-34 (2021). https://doi.org/10.1038/s41588-020-00755-1

Are fungal pathogens manipulating human behavior?

 

Fungal infection of brain tissue (Wikicommons, CDC). Some fungi persist in the human brain for years and begin to harm their host only in old age. What were they doing previously?

 

 

I've published a paper on manipulation of human behavior by fungal pathogens. Here's the abstract:

 

Many pathogens, especially fungi, have evolved the capacity to manipulate host behavior, usually to improve their chances of spreading to other hosts. Such manipulation is difficult to observe in long-lived hosts, like humans. First, much time may separate cause from effect in the case of an infection that develops over a human life span. Second, the host-pathogen relationship may initially be commensal: the host becomes a vector for infection of other humans, and in exchange the pathogen remains discreet and does as little harm as possible. Commensalism breaks down with increasing age because the host is no longer a useful vector, being less socially active and at higher risk of death. Certain neurodegenerative diseases may therefore be the terminal stage of a longer-lasting relationship in which the host helps the pathogen infect other hosts, largely via sexual relations. Strains from the Candida genus are particularly suspect. Such pathogens seem to have co-evolved not only with their host population but also with the local social environment. Different social environments may have thus favored different pathogenic strategies for manipulation of human behavior.

 

Please feel free to comment.

 

Reference

 

Frost, P. (2020). Are Fungal Pathogens Manipulating Human Behavior? Perspectives in Biology and Medicine 63(4): 591-601. https://doi.org/10.1353/pbm.2020.0059