Gini Coefficients for Inequality in Locke's State of Nature and Lockean Liberal Orders

In various posts (here and here), I have argued that the Darwinian science of human evolutionary history largely confirms John Locke's view of the state of nature as the natural condition of equal liberty, while also confirming (here) that Lockean liberal social orders can approximate that equal liberty that human beings enjoyed in the state of nature.

Over the past 10 years, Darwinian social scientists have brought more precision to the empirical study of the evolutionary history of inequality by finding ways to calculate the Gini coefficients for inequality in human societies over the past 10,000 years; and this new research supports the Lockean liberal account of human history.

The Gini coefficient is a statistical measure of the distribution of income or wealth in a society that ranges from 0 (every individual or household has exactly the same amount) to 1 (one individual or household owns all of the income or wealth, and others have nothing).  (The Wikipedia article on the Gini coefficient is a good survey.)  Gini coefficients below 0.30 are considered indicators of extremely low inequality.  Gini numbers above 0.50 are indicators of extremely high inequality.  So, for example, if the richest 20% have 80% of all income, that would count as an income Gini coefficient of 0.60.  That's the income Gini number for Haiti, which is one of the highest in the world.  The number for the U.S.A is in the middle--0.40.  The lowest numbers are usually for the Nordic social democracies--such as Denmark, Norway, and Finland--which are around 0.24.

Monique Borgerhoff Mulder and her colleagues (2009) have calculated Gini coefficients for 21 historical and contemporary small-scale populations based on ethnographic data.  Timothy Kohler and his colleagues (2017) have calculated Gini coefficients for 63 archaeological sites based on archaeological data.

The 21 societies studied by Borgerhoff Mulder and her coauthors included hunter-gatherer, horticultural, pastoral, and agricultural societies.  They calculated the intergenerational transfer of three kinds of wealth--material (such as household goods, land, and livestock), embodied (such as strength, knowledge, and skills), and relational (such as the individual's position in social networks). They found that material wealth was more easily transmitted across generations, as compared with embodied or relational wealth.  And therefore there was more inequality in pastoral and agricultural societies where material wealth (such as livestock and land) was important, as opposed to foraging and horticultural societies, where material wealth was less important, and consequently there was less inequality.

They estimated Gini coefficients for wealth at 0.25 for hunter-gatherers, 0.27 for horticuluralists, 0.42 for herders, and 0.48 for farmers.  Hunter-gatherers typically have a strong egalitarian ethos, and they found that indeed their level of inequality is much lower than for other societies.  But, still, hunter-gatherers have never achieved absolute equality.  They found that among the foraging societies they examined, a child born into a family in the top 10% of wealth is 3-5 times as likely on average to remain at the top than is a child born into a family in the bottom 10%.

Locke recognized this because while he saw the American Indians in the state of nature as showing relative equality compared with other societies, he also saw that all human societies will have some inequality due to individual differences in age, birth, talents, social networks, and luck, which will make some individuals more highly ranked than others.  So, for example, among hunter-gatherers, some individuals would inevitably distinguish themselves as skillful hunters or as leaders of their groups.  Borgerhoff Mulder and her colleagues confirmed this, and concluded that those Marxist anthropologists who wanted to find "primitive communism" in foraging societies were mistaken (Smith et al. 2010, 31).

Nevertheless, the reputation of hunter-gatherers for being egalitarian is warranted when they are compared with herding and farming societies that have much higher Gini numbers.  And yet, among modern nation-states, those that have Lockean liberal social orders have lower inequality.  The United States has a slightly lower Gini number than the small-scale herding and farming societies.  And the Nordic capitalist welfare states have Gini numbers about the same as the foraging societies.  (I have written about the Nordic social democracies as liberal regimes here.)  This suggests that modern Lockean liberal social orders approximate the equal liberty of human beings in the state of nature.

There are, however, some difficulties in the research of Borgerhoff et al. that have been pointed out by critics.  First, their sample of foraging societies does not include those high-density sedentary coastal foragers with Chiefdoms--such as the Northwest Coast Indians, the Chumash, and the Calusa--who were known to have hereditary nobility and even slavery.

The second difficulty is that their ethnographic sample of foraging societies includes those like the Ache of Paraguay and the Hadza of Tanzania whose foraging life has been altered by contact with modern herding and farming societies.  For that reason, it might not be clear that these foraging societies are really representative of our original evolutionary ancestors (Caldararo 2011; Kelly 2010).  One can respond to this difficulty by pointing out that the Ache and the Hadza have not been completely assimilated into modern societies, and that ethnographers have been able to compile a record of their history before contact (Smith et al. 2011; Hill and Hurtado 1996; Marlowe 2010).  While it is true that people like the Ache and the Hadza are not "living fossils" who have been "frozen in time," it is also true that they at least resemble the societies of our ancient foraging ancestors.

Instead of relying on ethnographic studies of inequality in historical and contemporary populations, Kohler and his colleagues (2017) have gathered archaeological evidence from a sample of 63 sites or groups of sites on four continents dating from around 11,000 to about 2,000 years ago.  For their evidence of inequality, they use house size as a proxy for household wealth.  Measuring the relative sizes of houses as distributed over an archaeological site, they can measure the inequality manifested in the relative wealth of households with large houses versus households with smaller houses (Kohler and Smith 2018).

                             An excavated house at the El Palmillo archaeological site, Mexico

As expected, they found that hunter-gatherers had the lowest Gini coefficients (median = 0.17), the horticulturalists had higher numbers (median = 0.27), and farmers had the highest (median = 0.35).  They were surprised, however, to see that the wealth inequality tended to be higher in the Eurasian sites than in North America and Mesoamerica.  To explain this, they suggested that Eurasia had a greater availability of large mammals that could become domesticated draft animals that could be used for increasing agricultural production and extending the area of land in cultivation, which could have created greater concentrations of wealth in those who controlled this production.

Another possible explanation is that their sample of sites in the New World is slanted towards more egalitarian societies.  For example, they did not include any sites in South America, which could have included the Incan empire centered in Peru, which was probably one of the most unequal agrarian societies, in which llamas and alpacas were domesticated.

And while their Mesoamerican sample included the Mayan city of Tikal with a remarkably high Gini number of 0.62, it also included some cities with surprisingly low Gini numbers, such as Teotihuacan with a Gini of 0.12--lower even than that for the hunter-gatherers!  The archeology of Teotihuacan (AD 400-500) is hard to interpret.  It shows signs of autocratic rule--with its grand avenue and pyramids--but it also shows some signs of broad sharing of power--with a grid of roads, no very large royal palace, and many medium-sized houses.  Thus, pre-Hispanic Mesoamerica seems to exhibit two very different strategies for structuring power--either concentrating and centralizing power in the hands of a few kings and nobles or allowing for a collective holding of power by many individuals, including commoners (Blanton et al. 1996).

Until recent decades, it was common for archaeologists and anthropologists studying ancient Mesoamerica to assume that the prevailing model was the autocratic centralization of power, which ignored the fact that there was evidence in at least some archaeological sites for wide dispersal of power, and perhaps even in some cities something like republican or democratic rule.

I thought about this a few years ago when I was touring the ruins of Tikal, which show a palace facing onto a plaza with pyramids on the side.  It's easy to see the evidence of an hierarchical society ruled by kings, priests, and nobles exploiting the commoners.  Tikal reached the peak of its power in 200-900 AD as the capital of a conquest state.  But believing that human beings have an evolved disposition for freedom and resistance to dominance, I had to wonder whether there was any sign of free societies in Mesoamerica.

                                 Tikal the Capital of a State that Conquered Tributary Regions

I was intrigued, therefore, to learn about Tlaxcallan, which has been identified by some archaeologists as an ancient republic in Mesoamerica.  When Hernan Cortes first landed on the coast of Mexico in 1519, he heard about the powerful Aztec Empire under the rule of Moctezuma.  Marching his soldiers toward Tenochtitlan, the capital city of the Empire, located where Mexico City is today, Cortes met resistance from some of the indigenous peoples, particularly the Tlaxcaltecas.  He learned that Tlaxcallan was a small polity not far from Tenochtitlan that had successfully resisted the attempts of the Aztecs to conquer them.  He finally persuaded the Tlaxcaltecas to become his allies in his campaign to defeat the Aztecs.  By 1521, the Aztecs were defeated, and Cortes claimed their Empire for Spain.  In his letters to Charles V, the King of Spain and the Holy Roman Emperor, Cortes described the people of Mexico, and he identified the Tlaxcaltecas as a freedom-loving people:

"They had tried with all their forces both by day and by night to avoid being subject to anyone, for this province never had been, nor had they ever had an over-all ruler.  For they had lived in freedom and independence from time immemorial and had always defended themselves against the great power of Mutezuma and against his ancestors, who had subjugated all those lands but had never been able to reduce them to servitude, although they were surrounded on all sides" (Cortes 2001, 66).

He described their government as

"almost like that of the states of Venice or Genoa or Pisa, for they have no overlord.  There are many chiefs, all of whom reside in this city, and the country towns contain peasants who are vassals of these lords and each of whom holds his land independently; some have more than others, and for their wars they join together, and together they plan and direct them" (Cortes 2001, 68).

He also described their market-based economy with a marketplace where over 30,000 people come to buy and sell.

In recent years, archaeologists studying the archaeological sites of Tlaxcallan have seen evidence confirming Cortes's comparison of Tlaxcallan with the Renaissance Italian republics (Fargher et al. 2010a; Fargher et al. 2010b; Wade 2017). In contrast to the political structure of the Aztec Empire--with kingship vested in members of the nobility--the archaeologists have found signs in Tlaxcallan of government by a council with members recruited from the ranks of commoners.  The socioeconomic egalitarianism of the city is manifested in the urban layout of scattered public plazas next to modest houses rather than royal palaces.  The distribution of standardized apartment buildings for common citizens and the fact that the art does not depict individual leaders or dynasties suggest that power was widely shared, and so inequality was low.

I have written about my recent visit to the National Museum of Anthropology in Mexico City (here).  One weakness in that museum's presentation of Mesoamerican history is that it displays the power of Moctezuma's autocratic rule over the Aztec Empire while remaining silent about Tlaxcallan's republican freedom and its denial of imperial rule, which expresses the evolved natural desire to be free from oppressive dominance.

Human nature was originally shaped in the hunter-gatherer state of nature that was a condition of equal liberty.  Consequently, we can expect that social orders that approach that original condition of equality and liberty will arise throughout human history.


REFERENCES

Blanton, Richard E., et al. 1996. "A Dual-Processual Theory for the Evolution of Mesoamerican Civilization." Current Anthropology 37: 1-14.

Borgerhoff Mulder, Monique, et al. 2009. "Intergenerational Wealth Transmission and the Dynamics of Inequality in Small-Scale Societies." Science 326: 682-688.

Caldaro, Niccolo. 2011. "On the Use of Contemporary 'Hunters and Gatherers' as Models for Prehistoric Patterns of Wealth Distribution." Current Anthropology 52: 265.

Cortes, Hernan. 2001. Letters from Mexico. Trans. Anthony Pagden. New Haven, CN: Yale University Press.

Fargher, Lane F., Richard Blanton, and Verenice Heredia Espinoza. 2010a. "Egalitarian Ideology and Political Power in Prehispanic Central Mexico: The Case of Tlaxcallan." Latin American Antiquity 21: 227-251.

Fargher, Lane F., et al. 2010b. "Tlaxcallan: The Archaeology of an Ancient Republic in the New World." Antiquity 84: 1-15.

Hill, Kim, and A. Magdalena Hurtado. 1996. Ache Life History: The Ecology and Demography of a Foraging People. Hawthorne, NY: Aldine de Gruyter.

Kelly, Robert L. 2010. "A Good Start." Current Anthropology 51: 109-110.

Kohler, Timothy A., et al. 2017. "Greater Post-Neolithic Wealth Disparities in Eurasia than in North America and Mesoamerica." Nature 551: 619-622.

Kohler, Timothy A., and Michael E. Smith. 2018. Ten Thousand Years of Inequality: The Archaeology of Wealth Differences.  Tucson, AZ: University of Arizona Press.

Marlow, Frank W. 2010. The Hadza Hunter-Gatherers of Tanzania. Berkeley: University of California Press.

Smith, Eric Alden, et al. 2010a. "Reply." Current Anthropology 51: 119-126.

Smith, Eric Alden, et al. 2010b. "Production Systems, Inheritance, and Inequality in Premodern Societies." Current Anthropology 51: 85-94.

Smith, Eric Alden, et al. 2010c. "Wealth Transmission and Inequality among Hunter-Gatherers." Current Anthropology 51: 19-34.

Smith, Eric Alden, et al. 2011. "Wealth Inequality in Foraging, Horticultural, Pastoral, and Agricultural Populations: A Reply to Caldaro." Current Anthropology 52; 579-580.

Wade, Lizzie. 2017. "Unearthing Democracy's Roots." Science 355: 1114-1118.

Property and Wealth Inequality Among Hermit Crabs

This video shows hermit crabs exchanging shells.  A hermit crab who is too cramped in his shell will move into a larger shell, and then the shell that he has discarded will be taken over by another hermit crab.  Sometimes hermit crabs will line up, and the shells will be passed down the line.  In Darwinian Natural Right, I wrote about this in the section on "The Normative Structure of Animal Movement," because hermit crabs are like human beings and other animals in that their behavior conforms to the same normative structure: they have natural desires, they have natural capacities for gathering information relevant to their desires, and they are naturally inclined to do whatever seems to satisfy their desires according to their evaluation of the information.  Aristotle lays out this normative structure in his biological works--particularly, in On the Movement of Animals and the Nicomachean Ethics.

Hermit crabs are small crustaceans who occupy the empty shells of dead snails.  They are most easily seen in tidal pools along ocean coastlines.  Their shells protect them from predators, reduce their physiological stress from desiccation, and promote their reproductive success.  Some shells are better than others in satisfying these desires, and as the animals grow they need to move to larger shells.  Finding the right shell means the difference between life and death, or at least the difference between being cramped or cozy in one's portable domicile.

A hermit crab will carefully inspect a new shell to assess its weight, size, and structure.  Even after moving into a new shell, the animal will continue to test the shell for suitability, and it will sometimes decide to move back into the old shell (Elwood and Neil 1992).  The process of evaluation becomes even more intricate when hermit crabs fight over shells.  Then they must assess not only the relative value of their shells but also the size, strength, and resoluteness of their opponents.  This competition often displays a hierarchy in which the most dominant crabs gets first choice of a shell.  If the dominant crab moves into a new shell, the old shell is occupied by a less dominant crab, which creats another vacancy for a third crab, and so on down the hierarchy.  Sociologists who study the social structure of "vacancy chains," in which resources are passed from one individual to another down a social hierarchy, have discovered remarkable similarities between hermit crabs occupying vacant shells left behind by more dominant crabs and human beings occupying jobs and houses left vacant by those of higher status (Chase 1991; Chase and DeWitt 1988).

We can see here the evolutionary origins of property.  Like all organisms, hermit crabs have evolved to control, preserve, and invest in their own bodies; and thus, as John Locke saw,. the sense of property begins in the self-ownership of one's own body.  This self-ownership then extends to the ownership of external resources when animals privatize those resources and thereby convert them into property.  For hermit crabs to preserve and protect their bodies, they must privatize a shell by carrying it on their body (Strassmann and Queller 2014).  (I have written about the evolutionary neurobiology of Lockean self-ownership here, here, and here.)

We can also see here the first steps in the evolutionary history of possessive behavior. Hermit crab conflicts over shells show first the priority of power, in which the dispute is settled by relative fighting power.  The second step is for the priority of power to become the priority of dominance, so that individuals can yield to those with higher status without the need for fighting.  The third step would be for hermit crabs to recognize prior possession, so that individuals learn that those with prior possession of a resource generally prevail over raiders (Tibble and Carvalho 2018).

Remarkably, Ivan Chase and his colleagues have recently reported a study that shows a distribution of these shells in one hermit crab population that follows a pattern similar to the wealth inequality in human societies (Chase et al. 2020; Preston 2019).  They collected 297 crabs from a tidal pool on a beach on Long Island, New York.  They removed the crabs from their shells.  They then weighed each crab, and they weighed and measured each shell.  Looking at how shells of different weights were distributed across the group, they saw a distribution curve that peaked around the medium-sized shells and then dropped as the shells got larger, then tapering off through the largest shells into a long tail.

They found that this inequality of wealth was similar to what one sees in small primitive human groups, such as hunting-gathering bands, but not as great as in large modern societies today.  The top 1 percent of hermit crabs owned about 3 percent of the total shell weight.  The top 1 percent of people in large human societies typically own a larger proportion of the wealth.  Among the hermit crabs, Chase and his colleagues observed, "there are no Warren Buffets or Jeff Bezoses."  But still the distributional pattern of inequality is similar.

One might think that the distribution of shell sizes among hermit crabs is determined simply by biological factors such as the survival and growth of either the crabs or the snails whose shells the crabs occupy.  Shell distribution might reflect the size distribution of surviving crabs over their life history or the size distribution of shells from dying snails.  But Chase and his co-authors did not find this to be the case.

It is common today to measure economic inequality in human societies with a number called the Gini coefficient, which ranges from 0 (if everyone in a society had exactly the same level of wealth) to 1 (if one person held all of the wealth, and everyone else had no wealth at all).  Chase and his colleagues estimate that the Gini coefficient for the hermit crabs is 0.32, which is only a little higher than some estimates of human hunter-gatherer societies as showing a Gini around 0.25, but much lower than the 0.41 Gini for the United States, and close to the 0.27 Gini for the Nordic social democracies such as Norway and Sweden (Borgerhoff Mulder et al. 2009).  Amazingly, the Gini for the hermit crabs coincides with what Thomas Piketty has proposed as the "ideal" Gini number for low inequality--0.33 (Piketty 2014, 247-60).

If even hermit crabs show such wealth inequality, does this indicate that inequality is "natural"?  And if so, what exactly are the natural causes of inequality?  Even in Locke's account of the state of nature as a state of natural equality, he recognized that all human beings could never be absolutely equal in all respects, because differences in age, talents, birth, merit, and social relationships would always elevate some above others.  Some researchers today explain inequality as arising from individual differences due to personality, training, education, or the random events of luck.  Others emphasize the importance of the intergenerational transfers of wealth, so that wealth accumulates by inheritance within some families.

Among hermit crabs, there is no intergenerational transfer of the wealth in shells.  Some of the inequality among hermit crabs might be explained by individual differences in size, fighting prowess, and dominance.  But Chase and his colleagues emphasize the transfer of shells through vacancy chains, and they imply that some similar vacancy chain process might explain human inequality.  Surely, however, there must be more than that at work in human wealth inequality.

I will have more to say about the evolution of wealth inequality in human societies in my next post.

I have written about the debates over inequality and the possible argument for "good inequality" here, here, here, here, here, here, and here.


REFERENCES

Borgerhoff Mulder, Monique, et al. 2009. "Intergenerational Wealth Transmission and the Dynamics of Inequality in Small-Scale Societies." Science 326: 682-88.

Chase, Ivan. 1991. "Vacancy Chains." Annual Review of Sociology 17: 133-154.

Chase, Ivan, and Theodore H. DeWitt. 1988. "Vacancy Chains: A Process of Mobility to New Resources in Humans and Other Animals." Social Science Information 27: 83-98.

Chase, Ivan, Raphael Douady, and Dianna K. Padilla. 2020. "A Comparison of Wealth Inequality in Humans and Non-Humans." Physica A 538: 122962.

Ellwood, R. W., and S. J. Neil. 1992. Assessments and Decisions: A Study of Information Gathering by Hermit Crabs. London: Chapman and Hall.

Piketty, Thomas. 2014. Capital in the Twenty-First Century. Cambridge: Harvard University Press.

Preston, Elizabeth. 2019. "Even Hermit Crabs Have Wealth Inequality." The New York Times, December 13.

Strassmann, Joan E., and David C. Queller. 2014. "Privatization and Property in Biology." Animal Behaviour 92: 305-311.

Tibble, Lucy, and Susana Carvalho. 2018. "Rethinking the Evolution of Property and Possession: A Review and Methodological Proposition." Evolutionary Anthropology 27: 285-296.

Six Solutions for the Darwinian Puzzle of Homosexuality

Homosexuality has been seen in hundreds of species of animals, including human animals.  For that reason, it is a mistake to argue--as Thomas Aquinas did--that human homosexuality is "contrary to nature" because no other animals engage in homosexual activity.

I have written about Aquinas and animal homosexuality here, here, here, and here.

Aquinas pointed to birds as manifesting the natural law for monogamous heterosexual mating and parental care of offspring.  Now we have evidence that at least 93 species of birds engage in homosexual behavior; and some of these birds show long-term monogamous pairing of females who jointly raise their offspring, which shows that animal homosexuality can achieve what Aquinas identified as the two natural ends of sexual mating--conjugal bonding and parental care (Bagemihl 1999, 479-655; Kotrschal et al. 2006; MacFarlane et al. 2010).

For example, this female-female Laysan albatross pair at Kaena Point Natural Area Reserve on Oahu, Hawaii, share in the incubation of eggs and feeding chicks.  Over 30% of the Laysan albatross nests from 2003 to 2012 were attended by female-female pairs (Young, Zaun, and VanderWerf 2008; Young and VanderWerf 2014).  The Laysan albatross can lay and incubate only one egg per year.  Most of the female-female pairs that fledged chicks in more than 1 year raised at least one chick from each female, so that both females had opportunities to reproduce.  Most of the chicks were fathered by males paired with other females, and these males had had sneaky copulations with one or both of the females in the same-sex pairing.  The female-female pairs raised fewer offspring on average than male-female pairs.  The annual productivity of females in female-female pairs was 80% lower than that in male-female pairs.  But still this is better than for an unpaired female to try to incubate an egg, rear a chick, and find food without any help.  Apparently, the female same-sex coupling here and with other birds is a response to a shortage of males.  In this colony of albatrosses on Oahu, 60% are female.  In these circumstances, the females who pair with another female are making the best of a bad job.  They probably wouldn't choose to pair with other females if there were enough males to go around.

This suggests that by nature the best conditions for reproducing and rearing offspring are a heterosexual pair of parents caring for their offspring, but that a homosexual pair caring for their young can be successful in circumstances where they imitate or approximate that natural standard, which would be the natural law argument for same-sex marriage and parenting.  Previously, I have argued (here) that that was the ultimate issue in the U.S. Supreme Court's decision in Obergefell v. Hodges (2015).

Even as these females engage in same-sex pairings, it's not clear that they are truly homosexual in the sense of having a durable preference for same-sex sexual behavior.  After all, their reproduction depends on copulating with males.  So they might be better identified as bisexual in being open to either opposite-sex or same-sex behavior depending on their opportunities.

Only two animal species have shown some individuals with an exclusively same-sex preference for life, even when partners of the opposite sex are available--humans and domestic sheep (Ovis aries) (Roselli et al. 2011).  Observations of domestic rams from around the world confirm that as many as 8% show a sexual preference for other rams.  And even when they are free to choose between estrous ewes and sexually active rams, some rams will show a same-sex mate preference.

Such animal homosexuality creates a puzzle or mystery for the Darwinian evolutionary psychologist.  If all animals are descendants of a long line of ancestors who were reproductively successful, and if inherited traits that impede reproductive fitness tend to be eliminated by natural selection, as Darwinian theory requires, then how can we explain the evolution of homosexuality, if homosexual animals do not engage in reproductive behavior?  If evolution by natural selection favors those traits that promote reproduction, then it might seem that homosexuality is indeed "contrary to nature."

The solution to this puzzle is to show how the evolution of homosexuality is compatible with reproductive fitness.  And although evolutionary scientists have not reached a general agreement on any one evolutionary theory of animal homosexuality, at least six such theories have been proposed (Savolainen and Lehmann 2007; Savolainen and Hodgson 2016).

1. Kin altruism selection.  Edward Wilson and some other biologists have applied William Hamilton's theory of kin selection to explain homosexuality as kin altruism (Wilson 1975, 1979; Kirkpatrick 2000).  According to Hamilton, the inclusive fitness of a trait depends on both direct fitness (reproducing through one's direct offspring) and indirect fitness (the reproductive success of one's close relatives).  In some circumstances, evolution might favor a trait that reduces one's direct fitness in order to devote resources to one's collateral kin.  This could apply to homosexuality if homosexuals promote the reproductive success of their relatives, perhaps by helping nephews and nieces.

In many societies, for example, homosexuals have become shamans or priests who could use their privileged status to help their relatives.  The word "nepotism"--from the Latin nepos for "nephew"--arose originally as the term for the Medieval and Renaissance popes and bishops of the Catholic Church who often appointed their nephews to positions of power in the Church.  As I have indicated in a previous post (here), there is a long history of the Catholic priesthood and episcopate being dominated by homosexuals.

This evolutionary theory of homosexuality as kin altruism would require evidence that homosexuals do indeed show an avuncular care for their relatives that increases their indirect reproductive fitness sufficiently to outweigh the loss of direct reproductive behavior.  Survey studies of homosexual men in Western Europe and North America have failed to find that homosexuals extend more care to their relatives than do heterosexual men (Bobrow and Bailey 2001; Rahman and Hull 2005).  By contrast, some studies in Samoa (Vasey et al. 2010; VanderLaan et al. 2013) and in Java (Indonesia) (Nila et al. 2018) have reported greater avuncular tendencies in male homosexuals as compared with male heterosexuals.  So the evidence for this theory is weak at best.

2.  Overdominance selection.  In the case of overdominance, a "gay allele" would result in homosexual behavior in an individual who has received this allele from both parents (homozygous), but an individual receiving this allele from only one parent (heterozygous) would be heterosexual and would have increased fitness over the homosexual.  This would be similar to the famous case of sickle-cell anemia in Africa: those who are homozygous for the sickle-cell allele suffer from this genetically inherited disease, but those who are heterozygous for this allele have some resistance to malaria; and therefore this allele is maintained in human populations exposed to malaria.  Although in principle this theory could explain the evolution of homosexuality, there is no clear evidence for it.

3.  Sexually antagonistic selection.  For sexually antagonistic selection, the idea is that a hypothetical gay allele would result in reduced fitness when expressed in males who become homosexual, but this would be counterbalanced by greater fertility when the allele is expressed in females.  This is one possible explanation for why some domesticated male sheep show a lifelong homosexual preference, but it's not clear whether this is true for wild sheep.  Domestic sheep have been bred by farmers to produce highly fertile females, and it could be that the genetic factors favoring fertile females also favor homosexual males.  However, there is little evidence for this.  In one experiment comparing male offspring from high and low fertility lines of ewes, there was no evidence that selection for high fertility ewes favored same-sex oriented rams (Stellflug and Berardinelli 2002).

4.  Alliance formation theory. Many animals engage in homoerotic behavior--same-sex genital contact that is experienced as pleasurable--and this often seems to strengthen the social bonding of individuals.  Bonobos, for instance, have become famous for how they use polymorphous sexual acrobatics as a social glue for binding individuals in alliances--including female-female alliances that allow the females to dominate the males.  This has led some evolutionary psychologists to speculate that homoerotic behavior could have evolved among human ancestors as a mechanism of affiliation that creates same-sex alliances that had adaptive value (Muscarella 2000).

In many human societies, adolescents and young adults go through a period of sex-segregated social and physical isolation, living on the periphery of their societies; and same-sex friendships reinforced by homoerotic behavior could have helped them move up in social status.  Moreover, these social alliances could have helped males to mate with females for reproductive benefits.  At the same time, female same-sex alliances could have helped females raise their offspring when the fathers were not around to help with parental care.  In ancient Greece and Rome, young men engaged in homoerotic friendships with older men who sponsored their social advancement.  When these young men reached full adulthood, they could marry women and form families.

The evidence for this theory is limited.  Although sometimes in some societies, homoerotic behavior can foster alliance formation, it seems to be more common for same-sex alliances to arise from friendly affection and mutual trust without homoerotic activity.

Another problem for this theory is that it's not clear that it's really about homosexuality in the sense of exclusive homoerotic preference, because it assumes that human beings have evolved to be naturally disposed to both homoerotic and heteroerotic behavior, so that same-sex friendships reinforced by homoerotic activity will lead to social alliances that facilitate success in heterosexual mating and parenting.

5. The bisexual advantage.  Another way to resolve the Darwinian puzzle of homosexuality is to deny that homosexuality really is an evolutionary puzzle.  There would be a puzzle if sexual orientation was a strictly binary trait, so that an animal must be either homosexual with no reproductive fitness or heterosexual with high reproductive fitness.  In that case, it would indeed be puzzling that homosexuality has not been eliminated by natural selection.  But if in fact sexual orientation is a continuously variable quantitative trait influenced by many genes interacting, ranging from exclusively homosexual preference through degrees of bisexuality to exclusively heterosexual preference, then there need be no Darwinian mystery about this (Sell 1997),   Continuously variable traits can have fitness costs at the phenotypic extremes, but such traits will persist because these fitness costs are low on average in evolutionary history (Lande 1976).  After all, throughout most of human history, most homosexuals have chosen to enter heterosexual marriages in which they have produced and reared children.

Defending this bisexual advantage theory, Savolanen and Hodgson (2016) explain this theory as predicting:

"that (i) some degree of bisexual attraction is more common than exclusive homosexual or heterosexual attraction, (ii) sexual attraction is fluid and changes depending upon social context (i.e., the environmental component), (iii) many genetic loci weakly influence sexual attraction, and (iv) there are no genetic loci that strongly influence sexual atrraction. . . ."

"There is some behavioral as well as genetic support for this bisexual advantage hypothesis.  First, good estimates of the frequency of bisexuality do not exist; however, the majority of human and nonhuman animals that participate in homosexual sex also participate in reproductive sex (Kirkpatrick 2000; Vasey 1995).  Second, the expression of homosexual behavior is known to be condition-dependent in humans.  For example, having spent time in the US Navy or in a British boarding school increases the likelihood of having had homosexual experience (Kirkpatrick 2000).  Finally, genomic surveys looking for genes that influence sexual attraction have failed to find any loci that strongly predict homosexuality (Sanders et al. 2014)."

6.  The epigenetic model.  Epigenetic effects are chemical modifications to DNA or to the proteins associated with DNA that don't involve changes to the DNA sequence itself.  These epigenetic markers regulate the expression of genes.  William Rice and his colleagues (2012, 2013) have developed an epigenetic model of how the transmission of epigenetic marks that influence sensitivity to androgen hormones in fetuses could explain homosexual orientation.

Typically, in fetal development, epigenetic marks make chromosomal girls (XX) less sensitive to masculinizing androgens and make chromosomal boys (XY) more sensitive.  Rice and his colleagues theorize that if the epigenetic marks directing the sexual development of the brain are not erased correctly, a mother could pass down to her son the epigenetic marks that direct the female development of the brain, so that her son develops a sexual attraction to men, or a father could pass down to his daughter the epigenetic marks for male development of the brain, so that his daughter is sexually attracted to women.

Although this seems theoretically possible, there is not yet any clear evidence to support it.


REFERENCES

Bagemihl, Bruce. 1999. Biological Exhuberance: Animal Homosexuality and Natural Diversity. New York: St. Martin's Press.

Bobrow, D., and J. M. Bailey. 2001. "Is Male Homosexuality Maintained Via Kin Selection?" Evolution and Human Behavior 22: 361-368.

Kirkpatrick, R. C. 2000. "The Evolution of Human Homosexual Behavior." Current Anthropology 41: 385-413.

Kotrschal, Kurt, J. Hemetsberger, and B. Weiss. 2006. "Making the Best of a Bad Situation: Homosexuality in Male Greylag Geese." In Volker Sommer and Paul L. Vasey, eds., Homosexual Behavior in Animals: An Evolutionary Perspective, 45-76. Cambridge, UK: Cambridge University Press.

Lande, R. 1976. "The Maintenance of Genetic Variability by Mutation in a Polygenic Character with Linked Loci." Genetical Research 26: 221-235.

MacFarlane, G. R., S. P. Blomberg, and Paul L. Vasey. 2010. "Homosexual Behavior in Birds: Frequency of Expression Is Related to Parental Care Disparity Between the Sexes." Animal Behaviour 80: 375-390.

Muscarella, Frank. 2000. "The Evolution of Homoerotic Behavior in Humans." Journal of Homosexuality 40: 51-77.

Nila, Sarah, Julien Barthes, Pierre-Andre Crochet, Bambang Suryobroto, and Michel Raymond. 2018. "Kin Selection and Male Homosexual Preference in Indonesia." Archives of Sexual Behavior 47: 2455-2465.

Rahman, Q., and M. S. Hull. 2005. "An Empirical Test of the Kin Selection Hypothesis of Male Homosexuality." Archives of Sexual Behavior 34: 962-969.

Rice, William R., U. Friberg, and S. Gavrilets. 2012. "Homosexuality as a Consequence of Epigenetically Canalized Sexual Development." The Quarterly Review of Biology 87: 343-368.

Rice, William R., U. Friberg, and S. Gavrilets. 2013. "Homosexuality Via Canalized Sexual Development: A Testing Protocol for a New Epigenetic Model." BioEssays 35: 764-770.

Roselli, C. E., R. C. Reddy, and K. R. Kaufman. 2011. "The Development of Male-Oriented Behavior in Rams." Frontiers in Neuroendocrinology 32: 164-169.

Sanders, A. R., E. R. Martin, G. W. Beechman, S. Guo, K Dawood, G. Rieger, et al. 2014. "Genome-Wide Scan Demonstrates Significant Linkage for Male Sexual Orientation." Psychological Medicine 45: 1379-1388.

Savolainen, Vincent, and Jason A. Hodgson. 2016. "Evolution of Homosexuality." In T. K. Shackelford and V. A. Weekes-Shakelford, eds., Encyclopedia of Evolutionary Psychological Science.  Springer International Publishing.

Savolainen, Vincent, and L. Lehmann. 2007. "Evolutionary Biology: Genetics and Bisexuality." Nature 445: 158-159.

Sell, R. L. 1997. "Defining and Measuring Sexual Orientation: A Review." Archives of Sexual Behavior 26: 643-658.

Stellflug, J. N., and J. G. Berardinelli. 2002. "Ram Mating Behavior After Long-Term Selection for Reproductive Rate in Rambouillet Ewes." Journal of Animal Science 80: 2588-2593.

VanderLaan, D. P., and Paul L. Vasey. 2013. "Birth Order and Avuncular Tendencies in Samoan Men and fa'afafine."  Personal Relationships 19: 326-339.

Vasey, Paul L., and D. P. VanderLaan. 2010. "Monetary Exchanges with Nieces and Nephews: A Comparison of Samoan Men, Women, and fa'afafine." Evolution and Human Behavior 31: 373-380.

Wilson, Edward O. 1975. Sociobiology: The New Synthesis. Cambridge: Harvard University Press.

Wilson, Edward O. 1979. On Human Nature.  Cambridge: Harvard University Press.

Young, Lindsay C., and Eric A. VanderWerf. 2014. "Adaptive Value of Same-Sex Pairing in Laysan Albatross." Proceedings of the Royal Society B 281: 20132473.

Young, Lindsay C., Brenda J. Zaun, and Eric A. VanderWerf. 2008. "Successful Same-Sex Pairing in Laysan Albatross." Biology Letters 4: 323-325.

Pseudocopulation Among the Echinoderms--The Evolutionary Origins of Homosexuality

Let's admit it.  We've all thought about pseudocopulation.  So let's talk about it.

One kind of pseudocopulation is male insects copulating with orchids that look and smell like female insects.  You can see some videos of this here and here.  But I warn you that they contain adult content.

Anne Gaskett at the University of Auckland and her colleagues have shown how orchids mimic female insects in ways that attract bees, wasps, and flies to copulate with them and then serve as polinators.  Most flowers attract and reward insect pollinators with nectar, but orchids attract their pollinators with deceptive signals that imitate those produced by female insects.  Orchids can even stimulate male insects to ejaculation (Gaskett et al. 2008).  This serves the reproductive fitness of the orchids, but it's costly for the insects who waste copious sperm.  Some male insects prefer orchids to real females!  Since this copulation does not actually result in sexual union, it can be called pseudocopulation.

Another kind of pseudocopulation is shown by some starfish and other echinoderms.  Starfish or sea stars are star-shaped marine invertebrates that typically have five arms radiating out from a central disc.  They reproduce both sexually and asexually.  Most species of starfish reproduce sexually, and they have separate male and female individuals that produce gametes.  Through spawning, eggs and sperm are sprayed into the water, and fertilization occurs outside their bodies.  For most species, the offspring develop on their own with no parental care.  But for some species, there is brooding, in which the offspring are attached to the mouth of the female, so that she can keep the eggs clean and healthy and protect them from predation--an amazing display of parental care in an animal that has no brain!  (See Hamel and Mercier 1995.)

Three species of starfish--Archaster typicus, Neosmilaster georgianus, and Archaster angulatus--are known to show pair mating in pseudocopulation, in which one starfish lays on top of another (Keesing et al. 2011).  During spawning events, large numbers of mating individuals mate synchronously.  This is not true copulation, because the male does not inseminate the female.  But it seems that pseudocopulatory mating ensures a high level of fertilization of eggs by sperm floating in the water.

The female is always on the bottom, and usually one male is on top of her.  But sometimes multiple males will be stacked on top of her.  So now we know the answer to a great philosophical question: Who's on top?  The male's on top, the female's on the bottom!  And sometimes the female will be crushed by a pile of males on top of her!

For more on this, you can go to the echinoblog here.

Although copulating pairs of starfish are mostly male on female, sometimes it's male on male.  In one study, a sample of 10 mating pairs were taken from the west coast of Australia, and 8 were male on female pairs, while 2 were male on male (Keesing et al. 2011).  Pairs remain in mating position for up to 24 hours.  So the pseudocopulation of these starfish show both heterosexual and homosexual behavior.

Sea urchins are another kind of echinoderm that form mating pairs.  Sea urchins have spherical bodies covered by moveable spines that make them look like little hedgehogs.  For most of the year, they live separate from one another.  But in the spawning season, they move together into pairs with their spines interlocked.  Forming mating pairs seems to increase the external fertilization of eggs by sperm.

Apparently, sea urchins cannot recognize sex differences, and so their pair mating occurs randomly.  Homosexual and heterosexual pairs occur at frequencies that would be expected by chance.  So in a population with a 1:1 sex ratio, random pairing produces male/female pairs 50% of the time.  Since the density of deep-sea echinoderms is normally low, this pairing increases the chances of successful fertilization.  In one study, 26 pairs were collected, and of these, 12 were female/male, 7 were female/female, and 7 were male/male (McCarthy and Young 2002; Young et al. 1992).  These echinoderms thus show indiscriminate sexual behavior directed towards all sexes, with both homosexual and heterosexual behavior.

Echinoderms arose as an early branching lineage of animals.  While the first vertebrates appeared about 500 million years ago, echinoderms first appeared in the Lower Cambrian geological time period--from 542 to 511 million years ago (Smith and Zamora 2013).  It is likely, therefore, that echinoderms have the traits of the ancestral organisms in which sexual behaviors evolved.  This suggests that indiscriminate sexual behavior with both same-sex and different-sex mating was the original ancestral condition for animals.

Homosexual behavior has been observed in over 1,500 animal species widely distributed across most evolutionary groups of animals (Bagemihl 1999; Poiani 2010; Sommer and Vasey 2006).  For many evolutionary biologists, this creates a "Darwinian puzzle": it seems hard to explain how homosexuality has repeatedly evolved and persisted in many different lines of evolutionary descent despite the fact that it reduces reproductive fitness.  To explain this, some evolutionary theorists have tried to show how homosexuality might have some adaptive benefits that outweigh its maladaptive costs: for example, homosexuality might have some indirect fitness benefits for the relatives of homosexual individuals.  Other theorists argue that homosexuality must be seen as a maladaptive trait that arises by accident:  for example, homosexual mating could be simply a matter of mistaken identity.

But notice the usually unstated assumption that homosexual behavior is an anomaly that requires some special explanation because it departs from an ancestral population that was exclusively heterosexual.  Recently, Julia Monk and her colleagues have challenged this undefended assumption that heterosexuality is the baseline condition for animals as showing a cultural bias for seeing homosexuality as abnormal or unnatural.  Monk and her collaborators identify themselves as "LGBTQ+ scientists," who are free from the "heteronormative bias" of most scientists.  They propose considering an alternative hypothesis that starts with a different baseline: what if ancestral sexual behavior was originally indiscriminate in mixing homosexual and heterosexual behavior, because animals were mating randomly with either same-sex or different-sex individuals?  This hypothesis of indiscriminate sexual behavior from the origin of animal sexuality would seem to be the most parsimonious explanation for what we see today--the widespread mixture of homosexuality and heterosexuality across most animal groups (Monk et al. 2019).  And they point to echinoderms as manifesting this ancestral condition of bisexuality.

Monk and her colleagues have summarized their reasoning in a blog post for Scientific American here.  They have also received a lot of press coverage including an article in The New York Times.

Despite their claim that with their alternative hypothesis homosexuality is not a "Darwinian puzzle," Monk and her collaborators must still solve the puzzle.  Even if we assume that homosexuality arose at the beginning as part of the original condition of animal sexual behavior, we must still find a Darwinian explanation for the persistence of homosexuality despite its costs for reproductive fitness.  To do that, they will have to show either that the fitness costs of homosexuality are not as high as they might seem, or that homosexuality has some indirect fitness benefits that outweigh the costs.  that will be the subject of my next post.

Some of my previous posts on animal homosexuality can be found here and here.


REFERENCES

Bagemihl, Bruce. 1999. Biological Exuberance: Animal Homosexuality and Natural Diversity. New York: St. Martin's Press.

Elbein, Asher. 2019. "Seeking a New Lens to Study Same-Sex Behavior in Animals." New York Times, November 26.

Gaskett, Anne C., et al. 2008. "Orchid Sexual Deceit Provokes Ejaculation." The American Naturalist 171: E206-E212.

Hamel, Jean-Francois, and Annie Mercier. 1995. "Prespawning Behavior, Spawning, and Development of the Brooding Starfish Leptasterias polaris." Biological Bulletin 188: 32-45.

Keesing, John K., et al. 2011. "Synchronous Aggregated Pseudo-copulation of the Sea Star Archaster angulatus Muller & Troschel, 1842 (Echinodermata: Asteroidea) and Its Reproductive Cycle in South-western Australia." Marine Biology 158: 1163-1173.

Karmath, Ambika, et al. 2019. "Why Is Same-Sex Sexual Behavior So Common in Animals?" Scientific American, blog, November 20.

McCarthy, Daniel A., and Craig M. Young. 2002. "Gametogenesis and Reproductive Behavior in the echinoid Lytechinus variegatus."  Marine Ecology Progress Series 233: 157-168.

Monk, Julia D., et al. 2019. "An Alternative Hypothesis for the Evolution of Same-Sex Sexual Behaviour in Animals." Nature Ecology and Evolution 3: 1622-1631.

Smith, Andrew B., and Samuel Zamora. 2013. "Cambrian Spiral-Plated Echinoderms from Gondwana Reveal the Earliest Pentaradial Body Plan." Proceedings of the Royal Society B 280: 20131197.

Young, C. M., et al. 1992. "Seasonal Breeding Aggregations in Low-density Populations of the Bathyal Echinoid Stylocidaris lineata." Marine Biology 113: 603-612.

Why the Rush to Impeachment? Jonathan Turley's Prudent Warning to the House Judiciary Committee

Although I have made it clear on this blog that I believe that there is a plausible case for impeaching Donald Trump for serious abuses of his powers, I have also worried that if the House votes for impeachment without building a strong case that can persuade at least 20 Republican Senators, the Senate will refuse to convict; and thus the House's vote for impeachment will appear to have been driven by a purely partisan hatred of the President rather than a reasonable non-partisan judgment that the President has really committed impeachable acts.

My reasons for worrying that the House Democrats are making a big mistake in their rush to impeachment before Christmas were articulated better than I could ever do by Professor Jonathan Turley on Wednesday, in his testimony before the House Judiciary Committee.  Turley is a law professor at the George Washington University Law School, and he was the one law professor selected by the Republican minority to testify.  The other three professors--Noah Feldman (Harvard Law School), Pamela Karlan (Stanford University Law School), and Michael Gerhardt (University of North Carolina Law School)--were selected by the Democratic majority on the Committee.  I watched all of the hearings.  And I have read Turley's written statement.  I regret that I have not yet read the written statements of the other three professors.

Some of Turley's recent articles on impeachment can be found at his website. Particularly good are three published in November:  "How the Democrats Can Build a Better Case to Impeach President Trump," USA Today, November 25; "Adam Schiff's Capacious Definition of Bribery Was Tried in 1787," The Wall Street Journal, November 28; and "Watergate Line Speaks Volumes about Weak Impeachment Case," The Hill, November 30.  Most of what he wrote in these three articles is included in his written statement for the Judiciary Committee.

Far from being a Trump supporter, Turley openly identifies himself as someone who voted for Hillary Clinton and who has been a staunch critic of Trump and his policies.  Moreover, he agrees that a good case might be developed for impeaching Trump for his abuse of power.  But still, he argues, that persuasive case for impeachment has not yet been made, and therefore the House needs to gather more evidence and hear from more witnesses so that they can slowly build a case for impeachment that could be persuasive enough with some Republicans to win a conviction in the Senate.  If the House rushes to impeachment, and then fails in the Senate trial, Turley warns, the impeachment of Trump will look more like the failed impeachment of Andrew Johnson in 1868 than the threat of impeachment that succeeded in forcing Richard Nixon's resignation in 1974.

In the hearings on Wednesday, the other three law professors all argued in favor of the House quickly impeaching Trump, but they did not respond to Turley's arguments.  Both the Democrats and the Republicans on the committee failed to ask the three law professors to reply to Turley.  They thus failed to set up what should have been a lively debate over what should be the central question in these proceedings: What counts as a sufficiently persuasive case for the House impeaching the President, so that conviction in the Republican-controlled Senate is likely?

Yesterday, Trump tweeted: "if you are going to impeach me, do it now, fast, so that we can have a fair trial in the Senate."  Trump himself wants the Democrats to quickly impeach him without taking the time to build the best case for impeachment--by going after the evidence that Trump is hiding--because then Trump can escape conviction in the Senate, and he can campaign against the Democrats for trying to use impeachment as a partisan weapon.

Turley makes three arguments for the conclusion that the case for impeaching Trump as it stands now is too weak.  The first argument is about the constitutional standard for impeachment as it was originally understood by the constitutional framers.  The second is about the lessons taught by the history of presidential impeachments.  The third is about the failure to prove that Trump has committed impeachable offenses.


(1) THE CONSTITUTIONAL STANDARD
Although the Americans adopted impeachment from the British, Turley indicates, the framers of the Constitution wanted to avoid the use of impeachment for political purposes, as had been done in England and in the American colonies.  They did not want the standards for impeachment to be so broad and vague that they could be used by political partisans to remove from office those they disliked.  They wanted the standards to be very limited and clearly defined.

For Turley, one important piece of evidence for this is an exchange at the Constitutional Convention on September 8, 1787, between George Mason and James Madison.  At that point, impeachment was limited to "treason or bribery."  Mason said this was too limited, and he moved to add "or maladministration."  Madison objected: "So vague a term will be equivalent to a tenure during the pleasure of the Senate."  Mason withdrew "maladministration," and substituted "other high crimes and misdemeanors," which was approved (Records, 2: 550).

[As an aside, I should say that I doubt the wisdom of Turley's reliance on Madison's notes on the Constitutional Convention as a guide to the framers' intention.  Madison's notes were not published until 1840, four years after his death, and over the years he had extensively revised his notes with both deletions and additions.  And as Mary Sarah Bilder has shown--in Madison's Hand: Revising the Constitutional Convention (Harvard University Press, 2015)--his revisions were slanted towards the Jeffersonian ideology that he had developed later in his life.]

Madison's notes show, Turley says, that the Framers did not want impeachment to be equivalent to what the British Parliament does today in a vote of no confidence that removes the Prime Minister for purely political reasons.  Turley observes:

"In the end, the Framers would reject various prior standards including 'corruption,' 'obtaining office by improper means,' betraying his trust to a foreign power, 'negligence,' 'perfidy,' 'peculation,' and 'oppression.' Perfidy (or lying) and peculation (self-dealing) are particularly interesting in the current controversy given similar accusations against President Trump in his Ukrainian comments and conduct" (10).

But then Turley admits that Madison apparently contradicted this position at the convention on July 20, when he said that he

"thought it indispensable that some provision should be made for defending the Community against the incapacity, negligence, or perfidy of the chief Magistrate.  The limitation of the period of his service was not a sufficient security.  He might lose his capacity after his appointment.  He might pervert his administration into a scheme of peculation or oppression.  He might betray his trust to foreign powers. . . . In the case of the Executive Magistracy which was to be administered by a single man, loss of capacity or corruption was more within the compass of probable events, and either of them might be fatal to the Republic" (Records, 2:65-66).

So here Madison suggests that the standards for impeachment should include "negligence," "perfidy," "peculation," and "corruption." As I have said in a previous post here, Madison's ambivalence about the scope of impeachment shows the fundamental dilemma in the congressional power to impeach the President: either the standards for impeachment are so broad that it becomes a partisan weapon for subordinating the President to the Congress, or the standards are so narrow that it cannot protect the country from an incompetent or corrupt President.

This dilemma was manifest in an exchange at the Constitutional Convention on June 2, which is not mentioned by Turley:

"Mr. Sherman contended that the National Legislature should have power to remove the Executive at pleasure."

"Mr. Mason.  Some mode of displacing an unfit magistrate is rendered indispensable by the fallibility of those who choose, as well as by the corruptibility of the man chosen.  He opposed decidedly the making the Executive the mere creature of the Legislature as a violation of the fundamental principle of good Government" (Records, 1:85-86).

As I have said in my previous post, the impeachment of Trump really is an attempt to overturn the presidential election of 2016 because of the fallibility of those who voted for him and the corruptibility of Trump.  But the attempt to do this necessarily provokes partisan passions--or as Turley calls it, "rage over reason."  A partisan vote in the Democrat-controlled House is likey to impeach Trump, and a partisan vote in the Republican-controlled Senate is likely to refuse to remove Trump from office.

To avoid this outcome, Turley argues, the House Democrats need to slow down and take the time to build a better case for impeachment that can persuade some Republicans to rise above their partisan interests.

(2) THE HISTORY OF PRESIDENTIAL IMPEACHMENTS
Turley points out that the history of impeachment shows that this is possible--that politicians in the Congress can sometimes be persuaded to set aside their partisan interests in deciding how to vote on impeachment.

In 1868, President Andrew Johnson was hated by the Republicans who controlled the Congress.  He was ridiculed as incompetent and as the "accidental President," because he ascended to the Presidency as a result of Lincoln's assassination.  He was a mean and crude man who often used inflammatory language, such as suggesting that his political opponents should be hanged.  His racism was shocking, and he opposed black suffrage.  He defended the Southern states against the proposals of the Radical Republicans for Reconstruction of the South.  His widespread firings created chaos in the government.  He was one of the worst presidents in American history.  In other words, he was a lot like the man who holds the presidential office today.

It was surprising, therefore, when the Republicans failed in their effort to remove Johnson from office through impeachment.  The Republicans saw Secretary of War Edwin Stanton as their ally in the Administration, and they anticipated that Johnson would fire him.  So they passed the Tenure of Office Act, which prohibited the President from removing a cabinet officer without the appointment of a successor by the Senate.  The Act declared that any violation of this law would be a "high misdemeanor."  Johnson dismissed Stanton on February 21, 1868.  A resolution of impeachment was passed in the House on February 24.  By the middle of May, the Senate was ready to vote on removing Johnson.  And since 42 of the 54 Senators were Republicans, and 36 votes were required for the 2/3 supermajority to convict Johnson, it should have been easy for the Republicans to win conviction.  Nevertheless, on May 16, 1868, the vote was 35 for conviction and 19 for acquittal, with 7 Republican Senators voting for acquittal, thus falling only one vote short of conviction.  The 7 Republicans voting for acquittal hated Johnson, but they thought that impeaching him for violating what was probably an unconstitutional law was an abuse of the impeachment power.  They knew that this would be the end of their political careers because of the animosity of their party.

Turley rightly sees two lessons in the failure of the Johnson impeachment.  Not only does it show that members of Congress can be persuaded to vote against their partisan interests in favor of higher constitutional principles.  It also shows that "short impeachments are generally not strong impeachments" (17).  The Johnson impeachment proceedings stretched a little over three months.  It now appears that the congressional Democrats want their impeachment of Trump to be completed just as quickly; and like the Johnson impeachment, that means that the leaders of impeachment will not take enough time to develop a case for impeachment likely to persuade 2/3 of the Senate.

By contrast, the Nixon impeachment hearings in the House extended over 14 months, which allowed for the development of the broadest and deepest evidentiary record in any impeachment.  Nearly 70 officials were charged, and 48 of them were found guilty.  Some of the Watergate defendants were sentenced to as long as 35 years.  Nixon himself was not actually impeached, because he resigned in August of 1974 after Republican leaders in Congress told him that he had lost the support of his own party.

Turley rightly argues that the current proceedings for impeaching Trump look too much like the failed Johnson impeachment and not enough like the successful Nixon impeachment proceedings.

(3) IS TRUMP IMPEACHABLE?
At various points in the impeachment inquiries, the Democrats have charged that Trump has committed impeachable crimes such as bribery, extortion, obstruction of justice, and violation of campaign finance laws.  But so far there does not seem to be sufficient evidence to convict Trump of such crimes.

Originally, the Ukraine controversy--as centered on Trump's July 25th telephone call with Ukraine's President--was said to show not criminal conduct but an abuse of power in using the authority of the presidency to advance Trump's personal political interests rather than the national interest.  It's clear that a president can be impeached for abuses of power that are not criminal.  After all, Alexander Hamilton (in Federalist Number 65) identified impeachable offenses as "those offences which proceed from the misconduct of public men, or, in other words, from the abuse or violation of some public trust."

But, still, as Turley points out, no president has ever been impeached purely for abuses of power without any charges of criminal conduct.  And while the Constitution does not require a presidential crime for impeachment, impeaching a president for a non-criminal abuse of power would presumably require clear proof of that abuse of power.  In the case of the Ukraine controversy, we would need convincing evidence of Trump offering a quid pro quo.

The problem here, Turley contends, is that the House Democrats have not yet gathered enough direct evidence of Trump's quid pro quo to be convincing.  A convincing case might be developed if they compelled the White House to release pertinent documents and subpoenaed the testimony of those who have direct knowledge of Trump's conduct in dealing with the Ukraine--people like John Bolton, Rudy Giuliani, Mike Pence, and Mike Pompeo. The White House would likely invoke "executive privilege" in appealing to the courts, and this would take some months to get a final decision from the courts.  But why not do this?

This was done in the Nixon impeachment proceedings.  In U.S. v. Nixon, a unanimous Supreme Court issued its decision on July 24, 1974, ordering Nixon to deliver tape recordings and other subpoenaed materials to a federal distinct court.  This decision came less than three weeks after oral arguments.  The White House released the subpoenaed tapes on August 5, which included the famous "smoking gun" tape in which Nixon indicated that he knew about the Watergate break in shortly after it occurred, and that he plotted to cover it up.  Nixon resigned on August 9, only 16 days after the Court's decision.

If something like this was done by the House Democrats investigating Trump, they might actually build such a persuasive record of impeachable conduct that 20 Republican Senators might vote for conviction.  It's hard to understand why the Democrats have decided not to do this.

The Darwinian Liberal Story of Humanity in Mexico City's National Museum of Anthropology

The National Museum of Anthropology in Mexico City

A Room Devoted to Tenochtitlan, the Aztec Island City with Four Causeways Joining it to the Four Points of the Universe

While travelling in Mexico City recently, I visited the National Museum of Anthropology, which offers a magnificent display of the archaeological and ethnographic history of Mesoamerica.  The concept of Mesoamerica was developed in 1943 in an article written by Paul Kirchhoff, a German anthropologist who lived in Mexico--"Mesoamerica: Sus Limites Geograficos, Composicion Etnica y Caracteres Culturales," Acta Americana 1 (1943): 92-107.  He identified Mesoamerica as a cultural area of pre-Hispanic civilizations that extended from what is now central and southern Mexico to the Central American countries of Guatemala, Belize, El Salvador, and parts of Honduras and Costa Rica, in the time period between 2500 B.C. and 1521 A.D.  1521 was the year that Tenochtitlan, the city of the Mexica (the Aztecs), was conquered by the Spanish.  Tenochtitlan was located in the Central High Plateau of Mexica in the center of what is now Mexico City.

Mesoamerica included many peoples with different languages and ethnic traditions: the Olmecs, the Mayas, the Aztecs, the Nahuas, the Zapotecs, the Mixtecs, and others.  Despite their many differences, they shared an agricultural way of life based on the cultivation of seeds and vegetables such as chia, maguey, cocoa, beans, squash, chili, and--most importantly--corn.  They also shared in the cultural development of calendars, pictographic writing systems, arts such as pottery, distinctive architecture, and some common religious beliefs.

The National Museum of Anthropology was opened in 1964 with the support of the Mexican government to present the cultural history of Mesoamerica as part of the national identity of Mexico.  The success of this enterprise is clear as one moves through the museum and sees the many groups of Mexican school children and adults as well as foreign tourists studying the exhibits and listening to lecturers.

What caught my attention was how the museum tells the story of Mesoamerica within the narrative framework of Darwinian liberalism.  It's Darwinian in the sense that everything is explained through the Darwinian science of the biological and cultural evolution of humanity.  It's liberal in the sense that it teaches a liberal morality of equal liberty and tolerance that respects the diversity and unity of the human species.  I have seen the same theme in other museums around the world--in Scotland, the island of Guernsey, and Ecuador.  I have written about this here, here, and here.

In these museums, one can see how the "Evolutionary Epic" or "Big History" has become the scientific replacement for religious origin stories in shaping the popular understanding of the place of human beings in the universe.  I have written about this here and here.  In the National Museum of Anthropology, one can see some of the religious stories of divine creation told by the Mesoamerican people.  For example, the Mayan text Popol Vuh described how the gods created human beings from a mixture of white and yellow corn.  Later, the Spanish conquerors brought with them Christian priests who taught the biblical creation story of how God formed Adam from the dust of the ground and breathed into his nostrils the breath of life (Genesis 2:7).  But when one enters the first hall of the museum--"Introduction to Anthropology"--the first displays are about the natural evolution of the human species from primate ancestors, which includes this recreation of the fossil hominid named "Lucy"--Australopithecus afarensis:

And thus the visitors to this museum are taught by implication that the Darwinian story of human evolution by natural selection is a scientific truth, while the religious origin stories of the Mayans or the Christians are poetic myths.  A Darwinian anthropology can explain these myths as cultural products of religious imagination, while denying that they have any literal truth.

The Darwinian story of human evolution starts in Africa with the first human ancestors such as Lucy, it then traces the migration of human beings around the world.  The museum tells that story of global migration, including the crossing from Asia to North America, as depicted in this mural:

Iker Larrauri's Mural Depicting Ancestral Humans Crossing from Asia to America Around 50,000 Years Ago

The museum's explanation of this mural includes a quotation from Jose de Acosta's Natural and Moral History of the Indies (1590).  Acosta was a Jesuit priest who had lived in the New World, and who wrote this book as a physical, biological, and cultural history of the New World, which included his speculation that the indigenous people of the Americas were descendants of human beings who had crossed over a land bridge between Asia and North America.  By the 20th century, this had become the generally accepted view of evolutionary anthropologists.  The Americas were initially settled by people from far northeast Asia crossing through Berlingia, the land bridge connecting to northwestern North America during the Pleistocene epoch.  Genomic analyses of ancient human remains from Late Pleistocene Alaska can show how indigenous Americans branched out from the initial founding population of Ancient Beringians (J. Victor Moreno, et al., "Terminal Pleistocene Alaskan Genome Reveals First Founding Population of Native Americans." Nature 553 (2018): 203-207.)

John Locke read Acosta's book and quoted from it in his Second Treatise of Government as an account of human beings in the state of nature--in the original human condition when human beings lived as hunter-gatherers.  "In the beginning," Locke declared, "all the world was America."  I have written about this here.

This shows the significance of the European discovery of the New World.  For the first time in human history, the entire Earth was bound together in a human network of global exchange and communication, which made possible a universal history of humanity.  Darwin's 5 year voyage on the Beagle around the world was part of this global exploration that made such a universal history possible.  

That universal history supported the modern anthropological concept of the unity and diversity of humanity that has been part of the liberal teaching of human equality, liberty, and tolerance.  The museum portrays this liberal teaching at the end of the first hall in a mural by Jorge Gonzalez Camarena:

Jorge Gonzalez Camarena's mural "Las Razas y las Culturas" ("Races and Cultures")

This mural celebrates the beautiful diversity of human races and cultures as products of Darwinian evolutionary history.  At the center of the mural is a female who apparently represents the future of humanity, as a species that is a mixture of all races and cultures.  Just below her is a child not yet born in a glowing womb.

On either side of this central female are 14 females symbolizing--from right to left--a sub-Saharan African, an Egyptian/North African, a Mayan/Mesoamerican, an indigenous South American, an indigenous North American, a Polynesian/Melanesian, a Japanese/East Asian, a Southeast Asian, a South Asian/Indian, an Arabian, a Hellenic/Mediterranean, an Iberian, and Celtic and Northern European peoples.

Beneath these women are artifacts symbolic of the great civilizations of history--including Neolithic megaliths, northern European castle walls, a Viking helmet, a Hellenic Doric column, a Hindu elephant sculpture, a Persian bull column, Assyrian Lamassu, a Roman Corinthian pillar, an ancient Egyptian hieroglyphic tablet, a Chinese dragon, a Celtic horse, a Polynesian Moai, an Incan kancha stonework, and an African Yoruba mask.

At the bottom of the mural are symbols of the domesticated plants of the agricultural way of life, which supports urban civilized life.  These symbols include maize, wheat, barley, rice, cassava, potato, yams, taro, sugar beet, and sugar cane.

Finally, on the far right side of the mural--not easily seen in the reproduction above--are several skulls representing the evolutionary hominid ancestors of human beings--those who lived in the evolutionary state of nature.

Camarena's mural is unsatisfying, however, in so far as it suggests a utopian transformation of human nature that overcomes tribalism in a spiritual unification of humanity.  The viewer is left wondering how this could happen.

As one walks through the museum, one sees opposing themes of conflict and cooperation in Mesoamerican history.  On the one hand, one sees religious warfare and brutal violence--such as human sacrifice to please the gods--that gives supernatural legitimacy to ruling elites exploiting those they rule.  I have written about how moralistic religion in the early states promoted human sacrifice here.

On the other hand, one also sees evidence of long-distance trading networks and marketplaces where people from different societies are brought together through cooperative exchange.

Does this suggest that even if the human propensity to tribalism can never be fully overcome, a liberal social order can promote the expansion of cooperative peaceful exchange through trading relationships and open societies based on pluralism and toleration?