Saturday, February 18, 2017

Thinking About Galapagos (3): The Evolution of Iguanas, Finches, and Humans by Hybridization

Marine Iguana

                                                                   Land Iguana

Hybrid Iguana from Breeding of a Male Marine Iguana and Female Land Iguana
Video of Marine Iguana Feeding Underwater
South Plaza Island, Looking Towards North Plaza Island

                                                       A Video on the Hybrid Iguana

On Day 3 (January 30), I began the day before sunrise, sitting on the balcony of our stateroom, reading and writing in my journal.  As the sun came up, I saw South Plaza Island, a small island (measuring one tenth of a square mile), near the even smaller island of North Plaza, which are off the east coast of Santa Cruz island.  From my reading, I knew that one of the unique features of South Plaza is that it is the only place where hybrid iguanas have been found. 

Both marine iguanas and land iguanas are unique to Galapagos.  The marine iguana is the lizard in the world that swims and forages for food underwater.  DNA analysis has shown that hybrid iguanas have a marine iguana father and a land iguana mother.  This is surprising because not only are marine iguanas (Amblyrhynchus cristatus) and land iguanas (Conolophus subcristatus) separate species, they even belong to separate genera.

Marine iguanas have sharp claws that help them grip the rocky seafloor, and they have flat faces that allow them to eat up algae off the rocks.  Hybrid iguanas also have sharp claws and flat faces, but they have never been observed foraging in the sea.  Instead, they forage for food on land like the land iguanas, but unlike the land iguanas, the hybrid iguanas can use their sharp claws to climb trees and cactus in search of food.

Hybrid iguanas show no defects that would impede their survival, but they do not seem to be capable of reproducing, although some scientists think they might turn out to be fertile.  In fact, many hybrid animals have proven to be capable of reproducing.

Howard Snell, a biologist at the University of New Mexico, was the first person to notice the hybrid iguana on South Plaza in 1977, and he saw that the hybrid iguana had features that were intermediate between the marine iguana and land iguana.  From 1977 to 2000, Snell has seen as many as 16 hybrids.  They are so rare that many naturalist guides who have visited South Plaza many times have never seen one.

Luckily, our group saw one hybrid iguana shortly after we had landed on the small wooden dock on South Plaza and then climbed up the lava rocks.  Snell has identified one hybrid individual who was often near the wooden dock.  And since iguanas can live long lives (30  years or more), it's possible that we saw the same individual.

So here's another example of how the evolution of life forms can depend on the unique natural history of a small island.  South Plaza provides the "Goldilocks conditions" that are "just right" for producing hybrid iguanas.  First, the island is so tiny that there is not enough room for land iguanas and marine iguanas to live in separate habitats.  Since their territories overlap, they frequently come into contact, and thus  they have many opportunities for interbreeding.  The second condition is that on South Plaza the breeding seasons of land iguanas and marine iguanas overlap: when male marine iguanas are ready to mate, the female land iguanas are at the end of their breeding season.

If animals from different species can crossbreed to produce hybrids, and if some of these hybrid animals can be fertile, this challenges the traditional belief of Biblical creationists that the Creator created all species to be eternally separate and fixed.  For example, in Jean-Jacques Rousseau's Emile, the Savoyard Vicar argues that the complex order in living nature proves the existence of God as the intelligent designer of that order, and part of that order is the existence of species that are eternally separate.  The Vicar insists: "The generation of living and organized bodies is by itself an abyss for the human mind.  The insurmountable barrier that nature set between the various species, so that they would not be confounded, shows its intentions with the utmost clarity.  It was not satisfied with establishing order.  It took certain measures so that nothing could disturb that order" (Bloom trans., p. 276).

Early in his life, the naturalist taxonomist Carolus Linnaeus (1707-1788) agreed with this traditional belief that the natural order of created species could never be disturbed: "there are as many species as the Infinite Being created in the beginning."  But as he worked more in the classification of species, he discovered plants that were hybrids, some of which were capable of reproducing, and thus becoming a new species.  He concluded: "it is impossible to doubt that there are new species produced by hybrid generation."  For this, he was denounced by clergy who accused him of blasphemy in denying the Biblical account of God's special creation of species.

Later, creationist naturalists like Joseph Gottlieb Kolreuter (1733-1806) and Carl Friedrich von Gartner (1772-1850) studied hybrids to try to prove that Linnaeus was wrong, arguing that the hybridization of two species could not produce a new species, because God had specially endowed hybrids with sterility. 

In his chapter on "Hybridism" in The Origin of Species, Darwin argued against "the view commonly entertained by naturalists . . . that species, when intercrossed, have been specially endowed with sterility, in order to prevent their confusion."  He pointed out that the degree of sterility was innately variable in individuals of the same species, and that some species could cross with other species and produce fertile hybrids.  Darwin did not explore, however, the possibility that hybridization could be a means for the evolution of new species.

Over the past 150 years, most biologists have recognized the evolution of new plant species through hybridization, but they have generally assumed that this is uncommon for plants, and that it never happens for animals.  And yet, in recent decades, the evidence for the evolution of hybrid animals has  become too extensive to ignore.  Biologists like Matthew Arnold of the University of Georgia and James Mallet of the University College London has led the intellectual movement for recognizing the evolution of animal species by hybridization (Mallet 2007; Pennisi 2016).

This new evidence for evolutionary speciation through hybridization subverts the once long-accepted "biological species concept" of Ernst Mayr, which assumes that reproductive isolation is the critical element of any species, so that members of a species breed only with other members of their species.  The evidence for hybridization shows that the barrier to interspecies reproduction is much weaker than Mayr believed.

Once two species mate and produce fertile hybrid offspring, evolution can occur in two ways.  If the hybrid mates back with a member of the parent species, new DNA is introduced into the genome of the parent species, which is called introgression.  If hybrids mate among themselves and reproduce, this creates a new species.  Introgression introduces much more genetic variation more quickly than is possible through random mutation, which means that hybridization can help organisms adapt better and more quickly to changing environments.

Darwin introduced the image of the evolution of species as a tree of life, as in this famous page in his notebooks, where he drew a tree of life and wrote "I think."


Some devoted Darwinians have even had this tattooed onto their bodies!  But if the idea of the evolution of new species by the hybridization of old species is correct, then we need to draw connections between the branches of this tree, so that the tree of life would become more like a web of life.

The Galapagos hybrid iguana is not a clear example of this, insofar as there is doubt as to whether it can be fertile.  A better example is the Galapagos finches as studied by the Grants on Daphne Major.  In 1981, the Grants noticed the arrival of an unusual male finch that they called "Big Bird."

            "Big Bird," a Hybrid Darwin's Finch on the Galapagos Island of Daphne Major

He had a big head.  He weighed 28 grams, instead of the 18 grams typical for male finches.  And he sang an unusual song.  He probably originated on Santa Cruz Island from the mating of a cactus finch and a medium ground finch.

At first, Big Bird and his offspring consorted with the medium ground finches on Daphne Major.  But then after a severe drought from 2003 to 2005 killed 90% of the finches on the island, the two surviving Big Bird descendants and their 26 offspring crowded together in one corner of the island, and they breed just among themselves, which suggests that they are becoming a separate species.  Because of their intermediate-size beaks, they can crack certain seeds that other birds can't.  The unusual song that they sing also separates them from other birds.  So the effect of hybridization on evolution here is partly cultural--the social learning of song.

Recently, the Grants have been cooperating with geneticists to identify the genes responsible for the size and shape of finch beaks, which explains the genetic basis for beak variations and for the evolution of the intermediate-size beaks of the hybrid finches (Lamichhaney et al. 2015).

So the descendants of Big Bird are beginning to look like a new species that evolved through hybridization, although the Grants are unwilling to say that this really is a new species.

Hybridization has occurred not only among iguanas, finches, and many other animals, but also among human beings.  In 2010, analyses of the nuclear DNA of ancient and living humans showed that they carried traces of DNA from Neandertals and from archaic humans from Denisova Cave in Siberia.  It seems that Europeans and Asians have inherited 2% to 6% of their nuclear DNA from Neandertals.  And people living in Southeast Asia have inherited about 5% of their DNA from the Denisovans.

If this evolution by hybridization is true, this refutes the traditional creationist claim that all species have been created by God to be eternally separated.  It also subverts the argument of people like Leon Kass that genetic engineering--moving genes from one species to another--should elicit moral repugnance as an unnatural act of "playing God."  After all, it appears now that nature has been engaged in genetic engineering for millions of years.  And we can still see that evolutionary genetic engineering in action in the island laboratories of Galapagos.


Lamichhaney, Sangeet, et al.  2015.  "Evolution of Darwin's Finches and their Beaks Revealed by Genome Sequencing." Nature 518 (19 February): 371-75.

Mallet, James. 2007. "Hybrid Speciation." Nature 446 (15 March): 279-83.

Pennisi, Elizabeth. 2016. "Shaking Up the Tree of Life." Science 354 (18 November): 817-21.

Thursday, February 16, 2017

Thinking About Galapagos (2): Islands of Life

                              A Panoramic View of Pinnacle Point on Bartholomew Island

On Day 1 (January 28), my wife and I landed at the Baltra airport.  There we met the five other passengers for our cruise on the Cormorant (a German couple from Switzerland, a Canadian couple from Montreal, and an American living in Ecuador) and our naturalist guide (Xavier).  On the boat, we had lunch, and then we navigated to our first site for hiking--Bachas Beach on Santa Cruz island, where we saw sea turtle nesting sites and American Flamingoes in the lagoons behind the beaches.

On Day 2 (January 29), we navigated to Bartholomew Island in the morning for hiking to the top of the island, and then snorkeling at the foot of Pinnacle Point to see sharks, rays, and the Galapagos penguins.  In the afternoon, we moved to Sullivan Bay on Santiago Island for hiking on a lava field.

I soon found myself thinking about one idea that stayed with me throughout this trip--every one of these islands is a world unto itself that is geologically, biologically, and culturally unique because of its unique natural history, and thus the Galapagos Islands make it easier to see how all of life could have evolved on islands. 

This idea was nicely stated by Loren Eiseley in an essay on the Galapagos: "It is the working of such mysterious principles as adaptive radiation and selection which binds this assemblage of extraordinary plants and animals together and relates even the story of man to island tortoises and flightless birds. We are all, in fact, the product of islands, visible or invisible. At some point in the fossil past, isolation and mutation have diverted each bit of life down some solitary road from which there is no turning back."

After all, the Earth itself is an island in the Cosmos, with a unique natural history that has made it the only place, as far as we know, in which life has emerged.  And even if we do someday discover life on another island planet in the universe, we can expect that it will have forms of life unlike those on Earth, because it will have its own unique history shaped by contingent events and circumstances.

An example of the unique geological and biological history of Santiago Island is a large lava flow at Sullivan Bay created by a volcanic eruption in 1889.  There have been more recent lava flows--the most recent was in May of 2015 from Wolf volcano on Isabela Island.  But this lava field on Sullivan Bay is the most recent lava flow in Galapagos that is open to visitors.  So it's an opportunity to see how these islands originate from volcanic eruptions and also to see how life originates on barren lava.

Galapagos Pahoehoe or Ropy Lava

Mollugo crockeri Plant on Lava


                                                                        Lava Cactus

Looking over the massive expanse of bare lava, it's hard to imagine how life could ever take root here.  And yet after about 45 minutes of hiking, we saw Mollugo crockeri, which is the first plant colonizer on this lava, and this species is found only on Santiago Island and no where else in the world.  Then, after an hour of hiking, we saw a Lava Cactus, which is also endemic to Galapagos, and found only on barren lava flows.  Mollugo is a perennial herb.  It's flowers are white with five petals.  As the leaves die, they eventually create soil, although it takes over 5,000 years to build a layer of soil on lava.

So here we see the origins of plant life on the volcanic islands of Galapagos.  We must assume, however, that these plants unique to Galapagos--and in the case of Mollugo crockeri, unique to Santiago Island--evolved from ancient ancestral species that found their way to Galapagos from the South American continent.  Critics of Darwinian science might object that this is only a speculative assumption--a "just-so story" unsupported by empirical evidence.

And yet Darwin treated this as a testable theory.  First, we can predict that there must be plant species on the mainland that are similar enough to these species endemic to Galapagos as to be plausible candidates for the evolutionary ancestors of these plants.  Second, we can predict that there must be some way for the seeds of these ancestral plants to reach the Galapagos Islands, which are 600 miles from the mainland--either by being blown through the air, by floating on the ocean currents, or by being carried through the air by birds, or by being brought to the islands by humans.

In his Origin of Species, Darwin has two chapters on "Geographical Distribution," in which he reports the results of many years of experimentation at his home in Down to test the possible ways that seeds might have travelled from a mainland continent to distant oceanic islands like Galapagos.  He put the seeds of eighty-seven different plant species in salt-water for weeks at a time, and then he planted them to see if they would germinate.  Most of them did germinate.  He noted that many seeds sank in water.  But when plants were dried, some of them would float.  He then checked the average speed of currents in the Atlantic Ocean (from A. K. Johnson's Physical Atlas), and he calculated that the seeds of 14 out of every 100 plant species belonging to one country could float across 924 miles of sea to another country.  He also tested the possibility that seeds could be carried across an ocean in the carcass of a dead animal.  He fed a pigeon on seeds, killed the pigeon, and then floated its body on salty water for a month.  He then dissected the body, planted the seeds, and discovered that most of them germinated.

This illustrates how evolutionary theory can be experimentally tested.  By contrast, the proponents of "scientific creationism" and "intelligent design theory" never engage in the experimental testing of their theories.  Thousands of scientists have gone to Galapagos to empirically study the evolution of species in the islands.  Much of this research has been supported by the Charles Darwin Research Station in Puerto Ayora on Santa Cruz island.  But there is no Creationist (or Intelligent Design) Research Station supporting empirical research in Galapagos, because Creationism and Intelligent Design Theory are not empirically testable theories.

And yet, while Creationism and Intelligent Design Theory have no positive content as testable theories of the origin of species, they do have some negative content insofar as they criticize evolutionary science for its intellectual weaknesses, which forces evolutionary scientists to strengthened their reasoning.

So, for example, creationists and intelligent design proponents have criticized evolutionary theory for failing to become an empirically proven science, because no scientist has ever directly observed the evolution of new species from ancestral species.  We can directly observe the Mollugo plant and the Lava Cactus growing on the lava field in Sullivan Bay.  We can see that these plants are endemic to Galapagos.  We can see that they are similar to plants on the mainland of South America.  And we can test the possibility that seeds from the mainland could find their way to Galapagos.  But we cannot see the evolution of one plant species into a new plant species on Galapagos.

Now, of course, there is at least one evolutionary research project on Galapagos that has become famous as showing "evolution in action"--the study of the history of finches on the Daphne Major island by Peter and Rosemary Grant.  And yet, despite the way their work is reported in high school and college biology textbooks, there is some dispute as to whether they have really seen the macroevolution of one species into another.  I will return to this in a later post.

As I indicated in my previous posts on my first trip to Galapagos in 2013, I have been surprised that all of the ecotourists and the naturalist guides that I have met in Galapagos assume that the truth of evolutionary science has been proven, and that much of the proof is found in Galapagos.  And consequently, Creationism and Intelligent Design Theory seem ridiculous to them.

That impression was confirmed the night of our second day, while the Cormorant was anchored in Sullivan Bay, when all of the passengers stayed up late drinking some good wine and talking about the evolution debate.  The conversation included Kjetil Haugan, the Norwegian businessman who owns Haugan Cruises, which operates the Cormorant and two other yachts cruising Galapagos.  He travelled with us for a few days, on his way to a business meeting in the islands.  The Europeans and the Canadians were completely baffled that Americans were still debating evolution.  I explained my debates with creationists and intelligent design proponents (particularly those at the Discovery Institute).  And I also explained that many American politicians (like Vice President Pence and Ben Carson) were vocal opponents of evolutionary science.  All of these people on the boat thought that the Galapagos Islands provided irrefutable evidence for the origin of species through Darwinian evolution.  Moreover, this commitment to evolutionary science as a way to explain the universe was part of their global liberal culture as cosmopolitan ecotourists.  As you might expect, we also talked about Donald Trump, who was just as baffling to these global liberal Europeans as the religious opponents of evolution.

I will have more to say about this in future posts.

Sunday, February 12, 2017

February 12: Darwin Day, Lincoln Day, and Galapagos Day

Today is the birthday of Charles Darwin and Abraham Lincoln, who were born on this day in 1809.  It is also "Galapagos Day," because on February 12, 1832, there was a formal ceremony to mark Ecuador's formal acquisition of the Galapagos Islands.

For this day, I have written an essay on Darwin and Lincoln for the Starting Points journal, which is edited by Adam Seagrave at the University of Missouri for the Kinder Institute on Constitutional Democracy.

Wednesday, February 08, 2017

Thinking About Galapagos: Divine Creation? Intelligent Design? Darwinian Evolution?

Having completed my second cruise around the Galapagos Islands on board the Cormorant, I have spent a total of 24 days in the Galapagos.  Of the 14 notably large islands, I have been to 11.  I have also been to some of the dozen or more small islets.  I have been there both in the hot and wet season (January to May) and the cool and dry season (June to December). 

My first trip, in June of 2013, included a week on the island of San Cristobal, in the town of Puerto Baquerizo Moreno, where I participated in a special meeting of the Mont Pelerin Society, cosponsored by the Universidad San Francisco de Quito, on "Evolution, the Human Sciences, and Liberty."  In July of 2013, I wrote a series of blog posts on my cruise around the islands and on the lectures and discussions at the MPS conference.

On board the Beagle, Charles Darwin anchored near the northwest end of San Cristobal on September 16, 1835.  On October 20, the Beagle sailed away from the Galapagos.  During his time there, Darwin walked on four islands--San Cristobal, Floreana, Isabela, and Santiago.

Like Darwin, I have found that Galapagos is good for thinking--particularly, for thinking about the origins and history of life on Earth. 

So, for example, consider the Galapagos tortoise--the animal from which the name Galapagos is derived.  The giant tortoise is one of the many species that are endemic to Galapagos--that is, found naturally only in Galapagos.  It is also one of the many species that varies across the islands.  When Darwin was on Floreana, he was told by Nicholas Lawson, the Ecuadorian Vice-Governor of Galapagos, that he could tell which island a tortoise came from by the shape of its shell.  For example, some of the tortoise shells are dome-shaped (as in the first picture above), and others are saddleback-shaped (as in the third picture).  The saddleback tortoises live predominantly on the low islands--like Pinta, Pinzon, and Espanola.  The dome-shaped tortoises live predominantly on the larger and higher islands with highland areas that get more moisture and thus have denser vegetation.  It is generally assumed that saddleback shells allow tortoises to stretch their necks to reach vegetation that is high up, while dome-shaped shells are more adapted for feeding on dense vegetation near the ground.  It is believed that there are at least 10 existing species of Galapagos tortoise and at least 2 extinct species, although there is disagreement as to whether these are really distinct species or sub-species or varieties of one species.

This raises lots of questions.  Why is the Galapagos tortoise unique to Galapagos?  Where did it come from?  If it came from an ancestral species on the mainland of South America, how did the ancestor make the trip across 600 miles of ocean?  And once it arrived, how and why did it radiate out over the islands and become different on the different islands?  How could it survive and reproduce on such inhospitable volcanic islands?  Does this show the macroevolution of new species from ancestral species?  Or does it only show the microevolution of varieties within a single species?

The Galapagos tortoise has been driven to the edge of extinction by competition with invasive species, such as black rats that eat tortoise eggs and goats that eat up the vegetation that tortoises need.  Is this an example of Darwinian survival of the fittest?  Or is this an unnatural disruption by human beings of the balance of nature?  Does Darwinian science suggest that there is no such thing as a fixed balance of nature, but only a constant evolutionary flux?  Should we intervene to restore the conditions for the survival and reproduction of Galapagos tortoises?  If so, what would motivate us to do that?

There are at least three general kinds of answers to these questions.  Galapagos tortoises arose either by divine creation, by intelligent design, or by Darwinian evolution.

There are various ways in which God could have created them.  If one is a young-earth Biblical creationist who accepts Bishop James Ussher's chronology, then one believes that God created the Earth and all species of life, including the Galapagos tortoise, in 6 days 6,000 years ago.  If one is an old-earth creationist, then one believes that God could have taken millions of years to create all the species of life.  A creationist who reads the Bible as literal scientific history will believe that all the species were on Noah's Ark, and that after the great flood subsided, the Galapagos tortoises somehow migrated from Mount Ararat in the Middle East to the Galapagos Islands.  But why did the giant tortoises migrate to Galapagos and no where else on Earth?

The Bible speaks of God creating the "kinds" of life (in the King James translation).  And so some scientific creationists argue that "kinds" might refer not to species but to some higher level of modern taxonomy--maybe "genus," "family," or "order."  This is necessary, they argue, to explain how there could have been enough room on the Ark for two of each "kind" of life, but not for each species.  So God did not have to specially create the Galapagos tortoise.  He could have created "kinds" of reptiles, and then Galapagos tortoises and other species of reptiles could have evolved naturally within these "kinds."  But doesn't this concede a lot to the action of natural evolution rather than divine creation?  Is this theistic evolution?

In 2002, Mike Pence delivered an entire speech in the House of Representatives endorsing creationism and intelligent design and rejecting evolution. “I believe that God created the known universe, the earth and everything in it, including man,” Pence said.  “And I also believe that someday scientists will come to see that only the theory of intelligent design provides even a remotely rational explanation for the known universe.”  He also argued that the signers of the Declaration of Independence affirmed this in declaring that human beings were created in God's image and thereby endowed with inalienable rights.  So Darwinism contradicts the American creed.  We can expect that as Vice President, Pence will continue to promote this position, which he shares with other members of the Trump administration.

In the early 1800s, the great French naturalist George Cuvier proposed a new form of creationism that he thought conformed to the fossil record, which shows a long history of species emerging and going extinct.  There could be a series of creation events and extinctions over a long time, and these could be explained as miraculous interventions by God or by creative forces within nature. 

This latter view was taken by David Porter, commander of the U.S. frigate Essex, who cruised the Galapagos from April to September in 1813, and wrote about this in his Journal of a Cruise Made to the Pacific Ocean.  (The drawing above of the Galapagos tortoise is from Porter's book.)  "I shall leave others to account for the manner in which all those islands obtained their supply of tortoises and iguanas, and other animals of the reptile kind," he wrote.  "I shall merely state, that those lands have every appearance of being newly created, and that those perhaps are the only part of the animal creation that could subsist on them."  Porter asked, "Nature has created them elsewhere, and why could she not do it as well at those islands?"  But if this creative force is natural, is there any need for divine creation?

Another alternative, favored by the folks at the Discovery Institute in Seattle, is Intelligent Design Theory.  Instead of looking to the Bible as a literal scientific history of creation, we can infer that all forms of life, including the Galapagos tortoise, were created by an Intelligent Designer, regardless of whether we identify that Designer as the God of the Bible.  But as I have indicated in my posts on Intelligent Design, the proponents of Intelligent Design Theory rely on a sophistical rhetoric of negative argumentation--arguing that Darwinian scientists have not yet explained the step-by-step process by which every species has evolved--without themselves explaining where, when, how, and why the Intelligent Designer created the Galapagos tortoise and all other species of life.

Darwinian evolution can be understood as a radical alternative to both divine creation and intelligent design in explaining the origins of Galapagos tortoises and all other forms of life.  But as Darwin himself suggested, natural evolution can also be understood as compatible with some forms of divine creation or intelligent design.  One can see natural evolution as showing the "secondary causes" of life, while the Creator or Intelligent Designer can be seen as the "primary cause" of those laws of nature that make evolution possible.  This is the theistic evolutionism adopted by a long line of thinkers from Asa Gray to C. S. Lewis to Francis Collins.

When Darwin was in the Galapagos Islands, he was not yet a Darwinian evolutionist.  Contrary to the common legend, Darwin did not have a "eureka" experience when he saw the Galapagos tortoises or finches.  It was not until he returned to England in 1836, and began to study his notebooks and the specimens he had collected during his voyage, that he slowly began to move towards his theory of evolution by natural selection.

While he was on the Beagle, Darwin was reading Charles Lyell's new book The Principles of Geology, Lyell revived and extended the evolutionary geology of James Hutton's Theory of the Earth, which argued that the Earth was not permanently fixed in its form by God at the beginning, but was rather in flux, with "no vestige of a beginning--no prospect of an end."  Over millions of years, volcanic mountains could be pushed up from beneath the ocean's floor to become islands that could be weathered back down to create soil to become inhabitable by human beings, but then it could eventually be resubmerged under the sea.  Darwin saw evidence for this in the Galapagos.

In his Voyage of the Beagle, published first in 1839, Darwin indicated that he was also astonished by the "creative force" that he saw in Galapagos.  And then in the second edition of this book, published in 1845, Darwin gave his first published hint of his new theory of the transmutation of species: "Hence, both in space and time, we seem to be brought somewhat near to that great fact--that mystery of mysteries--the first appearance of new beings on this earth."

While he was voyaging on the Beagle, Darwin seemed to be a creationist like Cuvier and Lyell, who believed there were "centers of creation" in places like Galapagos.  The giant tortoise and other species unique to Galapagos could be understood as created there.  But then by 1837 and 1838, he was considering a purely natural process of the evolution of new species.  In 1842, he used the term "natural selection."

Eventually, in The Origin of Species (first published in 1859), and later publications, Darwin defended his "theory of natural selection" as better than the "theory of special creation" in explaining the emergence of giant tortoises and other new species in Galapagos and elsewhere.

Galapagos provided three kinds of evidence for his new theory.  First, oceanic islands like the Galapagos have many species unique to them, and this is best explained by the migration of plants and animals from the mainland of a nearby continent, which then must undergo modification to be adapted to their new circumstances.

Second, isolated places like Galapagos lack some types of plants and animals, and their places will be filled by others.  So, for example, in Galapagos, reptiles rather than mammals are dominant, because it was easier for reptiles to reach the islands and then evolve to fill the niches available there.

Third, the distinctive plants and animals of islands like Galapagos resemble the plants and animals of the nearest mainland.  "Why should the species which are supposed to have been created in the Galapagos Archipelago, and nowhere else, bear so plain a stamp of affinity to those created in America?" Darwin asked.  "I believe this grand fact can receive no sort of explanation on the ordinary
view of independent creation; whereas on the view here maintained, it is obvious that the Galapagos Islands would be likely to receive colonists, whether by occasional means of transport or by formerly continuous land, from America."

Of course, the creationist or intelligent design theorist can always say that the Creator or the Intelligent Designer just liked to create species unique to the Galapagos that resembled those on the South American mainland.  But this is nothing more than an unsubstantiated assertion unless there is some scientific explanation of exactly where, when, how, and why the Creator or Intelligent Designer did this.

And so it is that the Galapagos tortoise and the other unique forms of life in Galapagos provoke deep questions about the origins of life.

But not only is the Galapagos tortoise good for thinking, it is also good for eating!  Darwin testified to the good taste of tortoises.  And indeed hundreds of thousands of Galapagos tortoises were taken away from the islands by whalers who stored them on their ships as a ready supply of food, because tortoises can survive for six months or more without food or water.  Even as late as the 1970s, local people in Galapagos were eating tortoises as tasty food for special occasions. 

Galapagos conservationists have had to try to persuade the local people that it's better to preserve tortoises for the pleasures of observing and studying them, and for attracting tourists, than to kill them for food.  The second picture above, showing a naturalist guide hugging a tortoise, illustrates this.

Darwinian scientists and conservationists have to persuade us that preserving or restoring the original conditions of Galapagos before human settlement and the arrival of invasive species is good for us, because it satisfies our evolved human desire for intellectual understanding of the natural world, the desire that sustains the philosophic or scientific life.  That's the argument for Darwinian liberal ecotourism.

Over the next few weeks, I will be writing a series of posts about my most recent tour of Galapagos.

Wednesday, January 25, 2017

Back to the Galapagos!

                                                                 The Cormorant

Today, my wife and I leave for our second cruise on The Cormorant around the Galapagos Islands (January 28 to February 4).  As I did for the first cruise in 2013, I will write a series of posts on our tour after we return.  The posts on the first cruise begin here.  The Cormorant is a yacht that is about the same size as the Beagle on which Darwin sailed.

After our 8-day cruise in 2013, we spent a week in Puerto Baquerizo Moreno, on the island of San Cristobal, where I participated in a special meeting of the Mont Pelerin Society at the Galapagos campus of the Universidad San Francisco de Quito.  The theme of the meeting was "Evolution, the Human Sciences, and Liberty."  I was one of the speakers--speaking on "The Evolution of Darwinian Liberalism."  I wrote a series of posts on all of the lectures and discussions, which begins here. 

This was a wonderful way to think about Darwinian evolution--first following Darwin's steps through the Galapagos as the natural laboratory of evolution, and then thinking about the implications of evolutionary science for classical liberalism at the MPS conference.  On this second trip, I want to continue thinking about how evolutionary science might support liberal social thought.

I realized that one 8-day cruise was not enough time to see the full range of life in the Galapagos.  That first cruise took us to the central, western, and northern islands (Santa Cruz, Isabela, Fernandina, Marchena, and Genovesa) during the cool and dry season of the year.  This second cruise will take us to the central and southern islands (Santa Cruz, Santiago, Santa Fe, San Cristobal, Espanola, and Floreana) during the warm and wet season of the year.

The ecological circumstances of the Galapagos are fundamentally shaped by the geological and climactic conditions.  The geological features of the Galapagos arise fundamentally from the islands being products of volcanic eruptions.  The volcanoes on the western islands of Fernandina and Isabela remain active.  The Wolf volcano in northern Isabela erupted as recently as May 25, 2015.  The volcanoes on the eastern and southern islands are inactive.

Darwin noticed that the volcanoes seem to lie along parallel straight lines.  He inferred that there were rifts on the ocean floor from which lava had been blurted and formed the islands. He spoke of "fissures of eruption."  Today, geologists agree with this, but their story is a bit more complicated.  They see the western islands as sitting on a deep-seated "hotspot" of volcanic activity that periodically sends volcanoes bubbling to the surface of the Nazca plate, which is moving to the south-east. As the Nazca plate moves, it carries each island away from the hotspot like a conveyor belt.

                                             Wolf Volcano Erupting in May of 2015

                                              Plate Tectonics of the Galapagos Islands

The Creation and Movement of Volcanoes in the Galapagos

As the islands move away from the hotspot over millions of years, they eventually sink under the sea.  The newest islands--Fernandina and Isabela--are rugged and inhospitable to life.  The older islands have had time for soil and vegetation to grow on what originally was pure lava, and thus they are somewhat more hospitable to life.

The other fundamental ecological factor for the Galapagos is climactic fluctuations due to ocean currents.

Between June and November, the cold Humboldt Current flowing up from the south lowers the temperature in the islands and causes some moisture in the warmer air to condense into a drizzling mist.  Beginning in December, the warm Panama Current flowing down from the northeast becomes more powerful, which raises the temperature of the water, creates a hot season, and with evaporation from the warmer water, clouds form and rain falls.  During an El Nino year, the Panama Current is particularly warm, which creates heavy rains.

So while in my first tour, I saw the youngest and most volcanically active islands during the cool and dry season of the year; in this tour, I will see the older and volcanically inactive islands during the warm and wet season.  Even in the wet season, however, the rain is confined mostly to the higher elevations, and so those of us who are hiking mostly at lower levels can be comfortable.

For anyone who is thinking about touring the Galapagos, I can recommend The Cormorant and the other two yachts of Haugan Cruises.  It's a luxury cruise with 16 passengers and 11 crew members.  Each stateroom has a balcony.  The food is good. The experienced naturalist guides are intelligent and engaging.  And as I indicated in my previous series of posts on the first trip, the guides offer a well-informed commentary on the evolutionary science of the Galapagos.

Of course, to speak of the evolutionary science of the Galapagos points to the deepest questions raised by any visit to the Galapagos: Does the variety of wildlife in the Galapagos provide evidence for the evolution of species by natural selection and other Darwinian mechanisms?  Or does it rather show the work of a Divine Creator or Intelligent Designer?

How do we explain the origin of those many species of life that are endemic to the Galapagos--species found here and nowhere else in the world?  There are over 4,000 species that are native to the Galapagos.  And of these about 1,600 species (40%) are endemic.  How exactly were so many species produced in these islands?

Those Biblical believers who read the first chapters of Genesis as a textbook of science say that God specially created these 1,600 species for the Galapagos, just as He created all other species.  The proponents of Intelligent Design Theory don't follow this literal reading of Genesis, but they do argue that all species must have been originally designed by some intelligent mind.

Doesn't it seem a little strange that the Creator chose to specially create these 1,600 species for the Galapagos and no where else?

Both the Creationists and the Intelligent Design proponents argue that the failure of Darwinian biologists to explain exactly when, where, and how a process of evolution created these species shows that we must assume that this requires a Divine Creator or Intelligent Designer.

But notice the rhetoric of negative argumentation here.  The Creationists and Intelligent Design proponents challenge the Darwinians to explain the step-by-step pathway by which the species endemic to Galapagos evolved by purely natural causes.  If the Darwinians cannot do this, then it's assumed that this failure proves the truth of Creationism or Intelligent Design. 

The sophistical fallacy in such argumentation becomes clear as soon as one notices that the Creationists and Intelligent Design proponents do not explain exactly when, where, and how the Creator or Intelligent Designer created the species for the Galapagos.  So they don't satisfy the standards of proof that they apply to the Darwinians.

So, for  example, the Creationists and Intelligent Design proponents have conceded that Peter and Rosemary Grant have observed evolutionary change in Darwin's finches in the Galapagos, particularly in the size and shape of their beaks.  But they argue that this is only microevolution--evolutionary change within a species--and not macroevolution--the evolutionary emergence of new species from ancestral species.  And yet, these proponents of Creationism and Intelligent Design have not provided any explanation of exactly when, where, and how God or the Intelligent Designer created the finches and other species endemic to the Galapagos.

The Grants have spent over 40 years of their life carefully studying the finches in the Galapagos as they empirically test hypotheses about evolution.  Have any creationist scientists made the same effort to test their hypotheses about how the Creator did His work in the Galapagos?

There is  another possibility--theistic evolution.  In the beginning, God might have created the laws of nature, but then allowed the natural laws of evolution to create all the species of life, including those endemic to the Galapagos. 

Darwin suggests this in the last paragraph of The Origin of Species:
"It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us.  These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms.  Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows.  There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved."
The Galapagos  Islands are perhaps the best place in the world to feel the grandeur in this view of life.

Saturday, January 21, 2017

Is Monogamy for the Birds?


If monogamy is the pairing of a single male and a single female to cooperate in the generation and rearing of offspring, this looks like monogamy.  A male and a female penguin have given birth to a chick that they are now rearing.

If this is so, then it might seem that Thomas Aquinas was right in arguing that birds show that monogamy is natural, and thus part of natural law, for those animals who require the cooperative parental care of both mother and father to secure the generation, feeding, and education of their offspring.  Thus, natural law dictates monogamous marriage for human beings insofar as they are like these birds in needing biparental care for children.  I have written previously about Aquinas's biological argument for the natural law of monogamy (here and here).

Across most groups of animals, monogamy is rare.  But over 90% of birds are monogamous, in that pairs of males and females form partnerships in the breeding season to generate and rear offspring.  The male can contribute in many ways--by helping to build and maintain the nest, by helping to incubate the eggs, by feeding the chicks and the mother, by guarding the nest, and by protecting the offspring from predators.  The importance of male parental care has been demonstrated experimentally: if male parental care is reduced or eliminated, reproductive success (measured as the number of fledged young per brood) is reduced (Alcock 2013, 224-25).  This seems to confirm Aquinas's argument.

The emperor penguins show the intense devotion that bird parents can have for their offspring.  They nest on the ice in Antarctica in the middle of the winter, caring for one egg, and then chick, in total darkness with temperatures down to minus 80 degrees Fahrenheit and wind of up to 100 miles an hour.  Here is how biologist Bernd Heinrich describes it:
"The eggs are laid in May and June after the birds have walked far enough onto the ice so that the spring ice breakup will not reach the young until they are old enough to handle life in the water.  After the female has laid her egg, it is carefully transferred onto the male's feet and tucked up into his brood pouch.  he is then stuck with the egg (or vice versa) as she returns to the sea.  During his continuous care of the egg during her over two-month absence, he loses about 40 percent of h is body weight.  It is pitch black most of the time, except possibly for the southern lights shimmering in the skies.  He sleeps a great deal, but during the howling blizzards at the deep subzero temperatures the whole colony of thousands of males of which he is a part contracts and presses against each other to conserve heat.  Other penguins are highly territorial, but the emperors cannot be, or they would not survive the cold.  Without each other for protection against the lements, they would too quickly use up their fat reserves and then starve; they need to huddle during their long fast in the cold to conserve calories.  By July, when the eggs start to hatch, the males may feed the chicks with milklike secretions produced by glands in the esophagus.  But then the females start to return from the sea to bring predigested food that they can regurgitate.  In the crowds of hundreds, they all call for their mates, and somehow the mated pairs recognize each other, are attracted only to each other, and unite, transferring their young chick from the male's feet onto the female's and providing it with food that she has brought.  He, by now emaciated, then heads to the sea to feed himself and also collect food for his chick.  His return journey is made shorter by the receding ice edge, melting in the spring warmth." (Heinrich 2010, 83-84)
This story is now well-known from the hit documentary film of 2005--March of the Penguins, narrated by Morgan Freeman, who spoke of this as "a heartwarming story about family and the power of love."  Like Aquinas, some religious conservatives pointed to this film as showing that these birds could teach human beings about the virtues of monogamous love and parental care.

But some people protested that to speak of these birds as showing "love" was crudely anthropomorphizing these animals.  Similarly, some people have complained about Aquinas's "biologizing" of natural law as failing to see that nonhuman animals cannot provide any moral standards for human beings, because human morality has nothing to do with animal biology.

Heinrich was asked by the New York Times to write an article about this controversy as to whether it was proper for Freeman to speak of these penguins as showing "love."  Heinrich wrote:
"The unspoken rule is that this four-letter word is to be applied only to one creature on earth, Homo sapiens.  But why?  A look at the larger picture shows this presumption of exclusivity is utterly unproved.  In a broad physiological sense, we are practically identical not only with other mammals but also with birds--muscle for muscle, eye for eye, nerve for nerve, lung for lung, brain for brain, hormone for hormone--except for difference of detail of particular design specifications.  Functionally, I suspect love is an often temporary chemical imbalance of the brain induced by sensory stimuli that causes us to maintain focus on something that carries an adaptive agenda. Love is an adaptive feeling or emotion--like hate, jealousy, hunger, thirst--necessary where rationality alone would not suffice to carry the day.  Could rationality alone induce a penguin to trek 70 miles over the ice in order to mate and then balance an egg on his toes while fasting for four months in total darkness and enduring temperatures of minus 80 degrees Fahrenheit and gusts of wind of up to 100 miles an hour?  And bear in mind that this 5-year-old penguin has just returned to the place of its birth from the open sea, and thus has never seen an egg in his life, and could not possibly have any idea what it is or why it must be kept warm.  Any rational penguin would eventually say, 'To heck with this thing, I'm going back for a swim and eat my fill of fish.'" (Heinrich 2010, 80-81)
Although Heinrich was expecting criticism from his fellow biologists, those who wrote to him praised him for recognizing the evolutionary biology of emotions.  The criticism came from everyone else, who said that it was degrading to human dignity to speak of love as a chemically induced state of mind serving the same reproductive function as it does for other animals.

While Aquinas insisted on the uniqueness of human beings as the only animals capable of conceptual thought and speech and of morality in the strict sense, he would have agreed with Henrich that nonhuman animals do have emotions, that these emotions are what motivate animal movement, and that they do have "a certain likeness of moral good [similitudo boni moralis] in them, in regard to the soul's passions" (ST, I-II, q. 24, a. 4, ad 3).  We can know that they have such emotions, because "the internal passions of animals can be gathered from their outward movements: from which it is clear that hope is in dumb animals" (I-II, q. 40, a. 3).

It is not clear, however, that the modern evolutionary understanding of mating among penguins and other birds fully supports Aquinas's claim that birds show a monogamous bonding of male and female in the generation and care of offspring that manifests the natural law of monogamy for human beings.

For Aquinas, natural monogamy requires a pair-bonding of male and female over their entire life that excludes any sexual mating with anyone else outside the pair.  What scientists now know about birds suggests that they depart from this standard in three ways.  First, the monogamous pair-bonding of birds almost never lasts longer than one or two breeding seasons.  Second, even while the pair-bond lasts, there is often copulation with others outside the pair.  Third, the pair-bonding is sometimes between birds of the same sex.

While many people found the March of the Penguins to be an endearing display of "family values," some people pointed out that the bonding between the mated pair of penguin parents and the bonding of the parents with their offspring almost never last beyond one breeding season.  Emperor penguins can live up to 50 years.  And once a mated pair has reared one chick, the male and the female must forage independently for several years; and when they return to the colony for another breeding season, they find different mates.  So once the kid is out of the nest, the parents are free to divorce and find new mates. 

This is true for most birds, although a few, such as ravens, seem to pair for life.  Ravens form a lifelong attachment to their mates.  This has various benefits for them.  Raven young require a longer period of rearing than is the case for other birds.  If a raven pair holds a territory throughout the year, they don't have to look for a new nesting site every spring.  A raven pair also hunts and forages together, so that their strong and enduring bond makes them a coordinated team.

But even with raven couples, it is unclear as to whether they might occasionally engage in sexual mating with birds outside the pair.  In the 1980s, new techniques in molecular genetics allowed scientists for the first time to determine the genetic parentage of birds, and they were surprised to discover that many of the offspring being reared by pair-living individuals were genetically related to the female but not the male, and thus they were products of what came to be called extra-pair copulations (EPCs) (Reichard 2003; Alcock 2013, 224-41).  Ornithologists had always assumed that monogamous male birds were advancing their reproductive success by helping their female partners in caring for their genetic offspring.  But now it seemed that some monogamous males were being cuckolded, because they were caring for the offspring of another male.

So it seems that social monogamy is not necessarily the same as genetic monogamy or sexual monogamy.  Pair-living birds who cooperate in caring for offspring are in a monogamous social partnership.  But if some of the offspring are genetically related to the female but not the male, then we could say that the mating system here is not genetic monogamy, but either genetic polyandry (a female mating with multiple males) or genetic polygyny (a male mating with multiple females), although the system for caring for offspring is socially monogamous. 

This creates two puzzling questions for the Darwinian scientist.  What do males gain from being socially monogamous but genetically polygynous, when this means that some males will be cuckolded?  And what do females gain from being socially monogamous but genetically polyandrous, when this means that they have to trick their social partner into caring for another male's offspring?  Evolutionary biologists have offered various hypotheses as to how the benefits of these mating strategies outweigh the costs, with costs and benefits measured in terms of reproductive fitness.  But there is no general agreement on which hypothesis is correct.

This is a similar puzzle in explaining human monogamy.  Through much of human history and in some societies today, polygyny (men with multiple wives) has been permitted or even preferred.  This makes sense from an evolutionary perspective, because, as Robert Trivers (1972) argued, polygynous mating manifests the difference in mating effort and parental investment between males and females.  The most reproductively successful men have many more children than the most fertile women, because while a man can potentially impregnate thousands of women, a woman can give birth to no more than about 20 to 25 children at the outer limit.  So it seems that a man's reproductive fitness is promoted by investing his time and energy in mating with as many women as possible and investing very little in the parental care of his many offspring, while a woman's reproductive fitness is promoted by investing a little in mating and investing a lot in the parental care of her few offspring. 

If the successful rearing of human offspring typically requires parental care from both parents, then we might expect that women would want to mate with men who seem likely to be caregiving fathers.  A polygynous father will have to divide his paternal caregiving among his many offspring, and we can expect that the wives will have to compete with one another for the father's parental investment in their children.  But if the father controls great social resources (high status and great wealth), he can possibly provide those resources to his wives for the successful rearing of the children.

Aquinas says that polygyny is partly natural and partly unnatural (ST, suppl., q. 65, a. 1).  It is natural insofar as it is possible for one man with great resources to mate with multiple wives and provide for the successful generation, feeding, and education of their children.  But it is unnatural insofar as the jealousy of the multiple wives will drive them to fight amongst themselves in competing for the husband's attention and resources, and thus the conjugal bonding of husband and wife will not achieve the sort of marital friendship that is possible in a monogamous marriage.  In fact, the wives in polygynous marriages are often treated as almost the slaves of the husband.  The conflict among the co-wives can be softened somewhat by sororal polygyny--one man marrying sisters--because then each woman will be related to the children of the other women as t heir nieces or nephews.

By contrast, polyandry (one wife with multiple husbands), Aquinas says, is totally contrary to nature, because the wife can be impregnated by only one man at a time, and the men will be reluctant to invest parental care in children if they are uncertain as to whether the children are theirs (ST, suppl., q. 65, a. 1, ad 8).  The sexual jealousy of men is stronger than that of women, so that it is much harder for men to share a wife than it is for women to share a husband.  And yet the conflict among the co-husbands can  be softened somewhat by fraternal polyandry--one woman marrying brothers--because then each man will be related to the children of the other men as their nieces or nephews. 

Aquinas thought human polyandry was impossible, but actually there have been a few rare cases of polyandry, particularly in Tibet, Nepal, and adjacent areas.  And often these have been cases of brothers marrying one woman.  This seems to have been an adaptation to a harsh mountainous environment where farming is difficult, and arable land is scarce, and so brothers marry a single wife so that their land is held together rather than divided between the brothers, and this also maximizes the number of males for working the land (Durham 1991; Levine 1988; Sanderson 2014, 175-80).  The brothers often fight over this arrangement.  Clearly, they are making the best of a bad situation.  In showing the instability of polyandrous marriages, they confirm Aquinas's observation that polyandry is unnatural (Levine and Silk 1997).

So should we agree with Aquinas that we are left with monogamous marriage as the most natural form of marriage?  By the time Aquinas was born in the 13th century, the Catholic Church had abolished polygyny and made monogamy the only legal form of marriage across Europe.  Aquinas saw this as the fulfillment of natural law, because monogamous marriage best satisfies the two natural ends of marriage--the parental care of children and the marital friendship of men and women.

Notably, however, Aquinas admitted that there were exceptions to this norm of monogamy.  A wealthy woman might provide for the successful rearing of her children without need for the father's help (SCG, III, chap. 122, sec. 7).  And a wealthy man might generate a child through fornication and then help the unmarried mother in the rearing of their child (ST, II-II, q. 154, a. 2) .  But Aquinas claimed that marriage law must conform to what is generally best and not what works only in exceptional cases.

Even if we agree with Aquinas about monogamous marriage as naturally normative, however, we might wonder whether his ignorance of how to trace genetic lineage blinded him to the distinction between social monogamy and genetic monogamy, or between marriage systems and mating systems.  Beginning in medieval Europe, monogamous marriage has spread around the world as the legal norm; and thus it seems that as Aquinas argued, human beings have followed the example of the monogamous birds.  But now that we see that even most of those monogamous birds are engaging in extra-pair copulations, we have to doubt that social monogamy coincides with genetic monogamy.  And isn't this often as true for human beings as for birds--that human beings who are socially monogamous are often genetically or sexually polygamous?  Or, in other words, monogamous marriage systems are not necessarily monogamous mating systems?  (See Low 2003.)  Doesn't this suggest that human beings are by nature a mildly polygamous species, and consequently that genetic monogamy is almost never fully attained across a society, although socially-imposed monogamous marriage systems are common?

If this is true, then perhaps Aquinas was unrealistic in upholding life-long heterosexual monogamy with extensive biparental care and absolutely no extra-pair copulation as the natural standard.  He might have been right that by nature this satisfies the fullest range of natural human desires--including sexual mating, parental care, conjugal bonding, familial bonding, and friendship.  But predictably many human beings will fail to achieve this.  It might, therefore, be prudent for marriage law to tolerate these human imperfections--by, for example, legalizing no-fault divorce and remarriage and by not punishing adultery and fornication as crimes.

This seems to follow from Aquinas's prudent observation that it does not rightly belong to human law to punish all vices:
"Human law is established for the collectivity of human beings, most of whom have imperfect virtue.  And so human law does not prohibit every kind of vice, from which the virtuous abstain.  Rather, human law prohibits only the more serious kinds of vice, from which most people can abstain, and especially those vices that inflict harm on others, without the prohibition of which human society could not be preserved.  For example, human laws prohibit murders, thefts, and the like" (ST, I-II, q. 96, a. 2).
Therefore, Aquinas argues, human law "permits some things because it is unable to direct them, not because it approves them" (ST,  I-II, q. 93, a. 3, ad 3; q. 96, a. 2).  If human law permits without approving what we know by nature to be vices, we can rely on social pressure in civil society to disapprove of those vices, but without the coercive punishment of law.  This is what some scholars have identified as the "permissive natural law" that supports the modern idea of natural rights (Tierney 1997, 2014).

Moreover, as I have argued (here), there is some empirical evidence that Aquinas was correct in claiming that by nature monogamous marriage supporting sexual partnership and parental care promotes human happiness

"Permissive natural law" might also permit without approving homosexuality.  Aquinas condemns homosexuality as clearly "contrary to nature" for two reasons.  First, nonhuman animals do not engage in homosexual conduct.  Second, homosexuality does not lead to procreation and parental care of children (Summa Theologica, I-II, q. 30, a. 3; q. 31, a. 7; q. 94, a. 3, ad 2, q. 94, a. 6; II-II, q. 154, aa. 11-12).. We now know, however, that Thomas was mistaken about both of these points (as I have argued in a previous post here).

Scientists have observed homosexual behavior in 471 animal species--167 species of mammals, 132 species of birds, 32 species of reptiles and amphibians, 15 species of fishes, and 125 species of insects and other invertebrates.  Scientists have also observed that same-sex pairs have successfully reared young in at least 20 species.  In some cases, one or both partners are the biological parent(s) of the young they raise together.  In other cases, the partners adopt and care for young without being the biological parents.  Moreover, in some cases, the same-sex couples seem to be more successful in their parenting than opposite-sex parents.

We also now know that homosexuality is biologically natural in that it arises through the interaction of many biological factors in the early development of fetuses and children--genes and sex hormones shape the body and the brain in early life so that people are naturally predisposed to become heterosexual, bisexual, or homosexual (LeVay 2011; Sanderson 2014, 144-52). 

Penguins are one of the birds that show homosexuality.  Penguins can mate with a same-sex partner, incubate a fertile egg, and then raise their chick for three months.  If Aquinas is right about birds providing us with models of the natural law of monogamy and parental care, does this show that homosexual monogamy and parental care is natural?  If so, does this suggest a Thomistic natural law argument for the Supreme Court's decision in Obergefell v. Hodges (2015) upholding the constitutionality of same-sex marriage (as I have argued here, and here,).


Alcock, John. 2013. Animal Behavior, 10th ed. Sunderland, MA: Sinauer Associates.

Durham, William H. 1991. Coevolution: Genes, Culture, and Human Diversity. Stanford, CA: Stanford University Press.

Heinrich, Bernd. 2010. The Nesting Season: Cuckoos, Cuckolds, and the Invention of Monogamy. Cambridge, MA: Harvard University Press.

LeVay, Simon. 2011. Gay, Straight, and the Reason Why: The Science of Sexual Orientation. New York: Oxford University Press.

Levine, Nancy. 1988. The Dynamics of Polyandry: Kinship, Domesticity, and Population on the Tibetan Border.  Chicago: University of Chicago Press.

Levine, Nancy, and Joan Silk. 1997. "Why Polyandry Fails: Sources of Instability in Polyandrous Marriages." Current Anthropology 38: 375-98.

Low, Bobbi S. 2003. "Ecological and Social Complexities in Human Monogamy." In Ulrich H. Reichard and Christophe Boesch, eds., Monogamy: Mating Strategies and Partnerships in Birds, Humans, and Other Mammals, 161-76. Cambridge: Cambridge University Press.

Reichard, Ulrich H. 2003. "Monogamy: Past and Present." In Reichard and Boesch, Monogamy, 3-25.

Sanderson, Stephen K. 2014. Human Nature and the Evolution of Society. Boulder, CO: Westview Press.

Tierney, Brian. 1997. The Idea of Natural Rights. Grand Rapids, MI: Eerdmans.

Tierney, Brian. 2014. Liberty & Law: The Idea of Permissive Natural Law, 1100-1800. Washington, DC: Catholic University of America Press.

Trivers, Robert. 1972. "Parental Investment and Sexual Selection." In Bernard Campbell, ed., Sexual Selection and the Descent of Man, 1871-1971. Chicago: Aldine.

Saturday, January 14, 2017

Does Ethnic Nationalism Have Greater Genetic Fitness than Classical Liberalism?

Both Friedrich Hayek and Paul Rubin have argued that the liberal social order has emerged through a process of evolution as more adaptive than any other social order.  Both Hayek and Rubin have been challenged by some critics who argue that classical liberalism is actually maladaptive in reducing genetic fitness, and that ethnic nationalism is more adaptive in maximizing genetic fitness.  This argument has become part of the new wave of ethnic nationalism that has recently been rising in various parts of the world.

Hayek’s argument is that through a process of selective cultural group evolution, the market order has shown its evolutionary superiority to the alternatives by producing the explosive growth in population and wealth of the past 200 years.  Some of his critics do not dispute the growth in wealth coming from the market order of expanding global trade and specialization.  But they do dispute the claim that market liberalism shows its adaptive superiority in producing growth in population.

The demographic transition—the drop in fertility rates among wealthy people in liberal societies that began to appear at the end of the 19th century—is said by Hayek's critics to show that market liberalism is maladaptive because it reduces reproductive fitness relative to those illiberal groups with higher fertility rates.

Hayek recognized that the demographic transition could slow the growth in population among wealthy people in liberal societies (The Fatal Conceit, 125, 128).  But he did not see this as weakening his argument for the adaptive superiority of market orders in producing population growth.  After all, population can still grow even if the rate of growth has slowed.  And even if the fertility rate of wealthy people in liberal societies declines, the population of those societies could still grow because those societies will attract immigrants (Law, Legislation, and Liberty, vol. 3, p. 159).

The response of the critics has been to argue that there are two reasons why the mass immigration of outside groups into liberal societies is evolutionarily harmful to those liberal societies:

One is that, as ethologist Frank Salter (2004, 2007) explained, in his critique of Rubin, the mass migration from groups into other groups reduces the relative fitness of the receiving population.  Second, differential birth rates potentially biased in favour of newcomers can itself constitute a form of group selection against the original group. Ultimately, if reproductive fitness is the measure of success in the evolutionary process, there is no equally suitable replacement for sheer reproduction.

According to ethnic nationalists like Salter, market liberalism is maladaptive for two reasons.  People in liberal societies tend to have low fertility rates, and liberal societies tend to have open borders that allow the immigration of outside groups with high fertility rates.  If this continues into the future, eventually the native ethnic groups in liberal societies will become small minority groups, or they will go completely extinct. 

So, for example, Salter warns that liberal globalism is not adaptive for Americans, because if unrestrained immigration of non-European people continues, America’s majority white population will eventually become a minority, and America will change from being a nation state to being an ethnically plural state.  This shows that liberal globalism is maladaptive, because liberal ethnic groups have lower reproductive fitness than illiberal ethnic groups. 

The alternative, Salter argues, is “universal nationalism”: every ethnic group should have a right to its own national homeland in which it practices ethnic nepotism—discriminating in favor of its own ethnic identity, so that each ethnic group would pass on its genes to the next generation of people living in its homeland.  The success of ethnic nationalism would depend on two policies: promoting high fertility in the native ethnic group and restricting the immigration of outside ethnic groups. 

Salter has elaborated his reasoning in his book On Genetic Interests (2003), which has become one of the most influential books among ethnic nationalists today, particularly the “alt-right” white supremacists in the United States.  In his review of Salter’s book, American white supremacist Jared Taylor claimed that Salter provides “a scientific justification for racial consciousness and activism.” 

Rubin has responded to Salter.  Like Hayek, Rubin makes an evolutionary argument for classical liberalism.  He claims that modern liberal societies satisfy the preferences or desires of their citizens better than any other social order that has appeared in human history, and that evolutionary science can show that those desires belong to the evolved human nature that evolved to maximize fitness in the environments of evolutionary adaptation that prevailed among our Paleolithic foraging ancestors.  Thus, Rubin starts with the standard assumption of economists that human beings desire to maximize utility.  But his novelty is in arguing that human utility functions have evolved by natural selection, and therefore evolutionary science can explain and clarify the formation of those utility functions.

But while our natural human desires originally evolved to maximize reproductive fitness in the environments of evolutionary adaptation, Rubin argues, there is no reason to believe that those desires will always maximize fitness in the circumstances of modern life.  So, for example, we can assume that the desires for sexual mating and parental care originally evolved as part of the human nature of our evolutionary ancestors because those desires tended to maximize fitness in ancient environments.  But in modern environments, those desires might not maximize fitness. 

Like all animals, human beings must decide how many offspring to produce and how much to invest in each offspring, and that decision requires trade-offs that depend upon the socioecological circumstances in which they live.  Throughout most of human history, most human beings lived in a world of poverty and high infant mortality, in which it was adaptive for parents to produce many offspring, while investing few resources in each, so that the quantity of offspring was favored over quality.  But in a modern world of wealth and low infant mortality, and a world where high levels of education and training are important for social success, parents might want to produce few children in which they can invest a lot in the education and training of those children; and those parents might also want to delay reproduction in order to have more time to invest in their careers. 

By the beginning of the twentieth century, almost all adults in the liberal societies had learned to read, which had never happened in human history.  Now, increasing numbers of people are going to college and professional schools for the education necessary to be successful in societies where social and economic success requires high levels of training and cognitive talent.  This makes children very costly for parents who want to invest heavily in the education of their children, and as the cost of children rises, the demand for children declines. This can produce small families with low fertility rates that can fall below the levels necessary for replacement. 

People desire to increase the likelihood that they and their children will be socially and economically successful, even when this results in low fertility rates that do not maximize reproductive fitness.  In other words, people desire sexual mating, parental care, wealth, social status, and other goods; but they don’t desire reproductive fitness.  A liberal social order is better than any other social order in allowing people to satisfy their natural desires, but in doing that, it does not necessarily maximize reproductive fitness.

Salter seems to agree with Rubin that modern liberal societies largely succeed in satisfying the natural desires of their citizens.  But Salter believes that these desires are mistaken, and that people are incorrect in not desiring reproductive fitness.  Salter concedes this point when he laments that ethnic nepotism is not instinctive, and therefore serving ethnic genetic interests requires artificial cultural strategies devised by modern scientific reasoning, and that no ethnic state has ever succeeded in securing an adaptive ethnic group strategy.  Salter admits that in protecting their genetic interests in modern states, “humans can no longer rely on their instincts” (On Genetic Interests, 28).

Salter identifies various “ethnic states” in the modern world, but he admits that “no state yet developed has reliably kept its promise as an adaptive ethnic group strategy” (221), which includes “the best known modern ethnic state”—Nazi Germany (231).  None of the ethnic states he mentions have succeeded in raising the total fertility rate of its ethny.  The drop in the total fertility rate for native Germans continued under the Nazis, and the Germans have had one of the lowest fertility rates for any population in the world.  Other modern ethnic states that Salter mentions—such as Malaysia—show the same failure to raise fertility rates.  Malaysia provides special protection for the Malay majority at the expense of the Chinese and Indian minorities, and yet the total fertility rate for Malays has fallen below replacement levels.

It’s not clear what policies ethnic nationalists would have to promote to raise fertility rates.  Should they impose severe tax penalties on those couples who do not produce lots of children?  Is this the kind of illiberal policy that ethnic nationalism would require to maximize the genetic fitness of the ethny?

The success of the multiethnic liberal culture is manifest in the passage by white American legislators of the U.S. Immigration and Nationality Act of 1965, which eliminated the national origin and racial restrictions on immigration, including restrictions on immigration from Africa and Asia.  The American ethnic nationalists would have to overturn this act.

When ethnic nationalists warn that a liberal culture must inevitably lead any ethnic group that adopts that culture to below replacement levels of fertility that will bring the extinction of that group, they assume that steep declines in fertility rates are never reversed.  In fact, that is not true.  Some of the lowest fertility rates appeared in Europe and the United States in the 1930s, but this was followed by the post-World War Two rise in fertility rates (the “baby boom”).  Beginning in the late 1960s, the rates began another steep decline.  But in recent years, there has been some evidence that as societies move into the very highest levels of human development—as measured by long life expectancy, great wealth, and high levels of education—the declining trend in fertility is reverse.  Recently, Sweden and some other highly developed societies have shown this, although the increase in fertility is still not up to replacement levels (see Mikko Myrskyla et al., “Advances in Development Reverse Fertility Declines,” Nature 460 [6 August 2009]: 741-43.)

For me, this shows that the natural human desire for children and parental care will always assert itself, although parents in the socioeconomic circumstances of modern liberal societies will often prefer to invest heavily in fewer children, which can reduce reproductive fitness.
Paul H. Rubin, Darwinian Politics: The Evolutionary Origin of Freedom (New Brunswick, NJ: Rutgers University Press, 2002).
Paul H. Rubin, "Utility, Fitness, and Immigration: Reply to Salter," Journal of Bioeconomics 9 (2007): 53-67.

J. Philippe Rushton, "Ethnic Nationalism, Evolutionary Psychology, and Genetic Similarity Theory," Nations and Nationalism 11 (2005): 489-507.

Frank K. Salter, "Estimating Ethnic Genetic Interests: Is It Adaptive to Resist Replacement Migration," Population and Environment 24 (2002): 111-40.

Frank K. Salter, On Genetic Interests: Family, Ethny, and Humanity in an Age of Mass Migration (New York: Peter Lang, 2003).
Frank K. Salter, "Is Ethnic Globalism Adaptive for Americans?" Population and Environment 25 (2004): 501-527.
Frank K. Salter, "Proximate and Ultimate Utilities: A Rejoinder to Rubin," Journal of Bioeconomics 9 (2007): 69-74.
Other pertinent posts are here, here, here, here, here, here, and here.