by Matthew Cobb

The BBC, together with Science Channel, has just produced an excellent five-part series, The Wonders of the Solar System, fronted by my colleague from the University of Manchester, physicist Professor Brian Cox (no, I haven’t met him). Cox is an extremely pleasant presenter who gets a lot of press because he is young (ish – 42), good looking (well, he has a lot of nice hair) and he used to be a pop star (he played keyboards in a band called D:Ream which had a 1994 hit with “Things can only get better”, which was notoriously played at the early morning celebration of the New Labour electoral victory in 1997).

His popularity is justified and undeniable – only three hours ago, one of my ex-students posted on Facebook “loves bryan cox. pop star and a physicist. amazing.” You can find an amusing profile of Cox here.

The series has used some fantastic astronomical images to show how studies of terrestrial geological phenomena can inform us about what’s happening on other planets in the solar system. The last episode in the series, which I have just watched, was on the possibility of extraterrestrial life. [There’s a BBC page about this episode here.] Cox’s focus being the solar system, he didn’t even mention the Fermi paradox (summed up in his question “where are they?” – given the size and age of the universe, the place should be heaving with bug-eyed monsters in flying saucers, but it clearly isn’t). Rather, he was interested in where there might be life in the solar system.

There are two current candidates, apart from our Goldilocks planet (not too hot, not too cold, just right) – the planet Mars and Europa, Jupiter’s moon. There’s a lot of speculation involved, but it’s still fascinating stuff. Europa is covered with ice, but it is continually fractured and shifting, and measurements indicate that there is a massive ocean of salt water underneath the surface – an ocean that may be 100km deep. This is an awful lot of liquid water (more than twice the amount on Earth), and Cox made the case that because we can find bacteria living and reproducing within ice on Earth, it may also be the case that similar organisms live in Europa’s ice-shell.

One problem, however, is that the very size of the ocean may exclude Europa as a source for genuinely alien life, for the simple reason that for life to evolve, it would require a very stable, static, tightly controlled environment for those fragile molecules to come together. And that will be absent in the swirling black depths of Europa’s ocean.

My feeling is that on Earth the evolution of the first self-replicating molecules – probably RNA – did not take place in “some warm little pond” as Darwin put it, but rather in some tiny bubbles in the mud on the edges of such a warm pond, that would be stable and secure enough, for long enough (perhaps hundreds of years or even more). In other words, something like a cell was required before those amazing reactions that produce life could evolve. In Europa’s case, my guess would be that something similar would be necessary (perhaps tiny bubbles in the ice) for replicant molecules to evolve.

The last time I suggested to Jerry that something like a cell (non-organic, of course) came before its contents, he was rather rude, but what does he know? Or me? Or anyone? It is the case that spherical “protobionts” made out fats occur spontaneously, “reproduce” and have semi-permeable membranes that can see various metabolic processes occur, as shown in this first-level undergraduate textbook:

Even more intriguing for me was the section that dealt with something I knew nothing about, and about which other views have tweeted their disbelief about: snottites. These are slimy structures found in some caves, which are formed by archea – simple bacteria – that are able to metabolise hydrogen sulphide (in a dramatic scene, Cox went deep into one of these caves, where the atmosphere was virtually unbreathable, his personal hydrogen sulphide alarm bleeping away), and they excrete sulphuric acid. When these organisms live in limestone caves, they actually help etch away the caves through their respiration.

The fact that I didn’t know about snottites is merely my ignorance (and shame). You can find a great NASA page about them here.

These are not only great extremophile organisms – they look like snot! they crap out acid! –  it also reinforces the idea that even if all the conditions currently found on Earth are not met, life may still evolve. Including on Mars and Europa.

This is hardly surprising in a way – when life evolved here 3.5 billion years ago, Earth wasn’t like it is now. In particular, atmospheric oxygen levels were at about 0.0007% of what they are now. It took life itself to change that, in two vitally important events – the Great Oxidation Event (2.5 billion years ago which saw levels shoot up to around 8% of current, followed by another massive surge, up to present-day levels, around 650 million years ago, “shortly” before the Cambrian Explosion. But that’s another story.

Here’s a trailer for the ET episode of The Wonders of the Solar System (may not work outside UK…)

There’s also a great spoof of both Cox and the mind-bending amazingness of the solar system here. The success of the spoof owes much to the imitator getting Cox’s Oldham accent more or less spot on, and folk memories of the drug-crazed ramblings of Madchester bands like the Happy Mondays and the Stone Roses. Warning: contains rude words.

“I can live with doubt and uncertainty, and not knowing. I think it’s much more interesting to live not knowing than to have answers that might be wrong.”

“I don’t feel frightened by not knowing things—by being lost in a mysterious universe without having any purpose, which is the way it really is, as far as I can tell, possibly.  It doesn’t frighten me.”

Today’s New York Times Magazine has a long article by Jon Mooallem, “Can Animals Be Gay?,” that discusses recent observations of same-sex sexual behavior in animals.  It’s a pretty good piece, showing the minefield that is animal research on homosexuality.  On one hand you have researchers with a more ideological agenda, studying or describing phenomena in the hopes that they’ll somehow vindicate gay behavior in humans (see my review of Joan Roughgarden’s Evolution’s Rainbow); on the other hand are researchers who explicitly disavow any connection between their studies of same-sex sexual behavior in animals and gay behavior in humans.

The polarization around this work is equally strong among laypeople.  Mooallem describes one study of a mutation that produces same-sex courtship in Drosophila males:

In 2007, for instance, the University of Illinois neurobiologist David Featherstone and several colleagues, while searching for new drug treatments for Lou Gehrig’s disease, happened upon a discovery: a specific protein mutation in the brain of male fruit flies made the flies try to have sex with other males. What the mutation did, more specifically, was tweak the fruit flies’ sense of smell, making them attracted to male pheromones — mounting other males was the end result. To Featherstone, how fruit flies smell doesn’t seem to have anything to do with human sexuality. “We didn’t think about the societal implications — we’re just a bunch of dorky biologists,” he told me recently. Still, after publishing a paper describing this mutation, he received a flood of phone calls and e-mail messages presuming that he could, and would, translate this new knowledge into a way of changing people’s sexual orientations. One e-mail message compared him with Dr. Josef Mengele, noting “the direct line that leads from studies like this to compulsory eradication of gay sexuality . . . whether [by] burnings at the stake or injections with chemical suppressants. You,” the writer added, “just placed a log on the pyre.” (Earlier that year, PETA and the former tennis star Martina Navratilova, among others, were waging similar attacks on a scientific study of gay sheep, presuming it was a precursor to developing a “treatment” for shutting off homosexuality in human fetuses.)

And, in talking to gay people, I find some who would prefer that human homosexuality be shown to be genetic, so that they won’t be derided for making a supposedly immoral “choice” and can impute their behavior to a genetic imperative.  Other gays would prefer a more “nurture-ist” finding, since they envision a kind of pogrom or eugenics program if gay behavior were found to be genetic.  And there are those, myself included, who think that the question is irrelevant, since the morality seeing gays as having equal rights does not depend on any genetic or evolutionary basis. (Or, if you take a Sam-Harris-an approach to the question, you can say that our well being is best served if we don’t discriminate against gay people or legally regulate the sexual behavior of consenting adults).

Can animal studies really inform work on human homosexuality? I’m not an expert in this area, but Mooallem doesn’t paint an optimistic picture.  He shows, and I had guessed this, that “gay” behavior in animals (by this I mean “same-sex” sexual behavior) is a grab-bag of diverse phenomena that don’t support a single evolutionary explanation.  Some same-sex behavior, such as the occasional tendency of males to mount other males, could simply be a byproduct of a general tendency for males to copulate with anything moving, which is itself adaptive since sperm is cheap. (Some flies, for example, will try to copulate with balls of wax, and some orchids, to gain pollination, have flowers mimicking female bees, with which overstimulated males try to mate).  In other cases  same-sex behavior may have evolutionary roots, reflecting specific adaptations.  Mooallem describes “lesbian” behavior in albatrosses in Hawaii, for instance, in which pairs of females will nest together (sans males) to incubate a single egg.  While this behavior isn’t yet understood, it may reflect the advantage of brooding an egg even when you’re not sure it’s yours, just because there’s a dearth of males in the population and it’s better to have half a chance of producing an offspring than no chance at all.  In other cases, like the polymorphous sexuality in bonobo chimps, sexual behavior may have been co-opted into forms of social bonding. I wouldn’t expect, for instance, that same-sex mounting in Drosophila would have an evolutionary explanation similar to that of male mammals fellating each other.

So we shouldn’t hold out a lot of hope that these kinds of studies will shed much illumination on human homosexuality.  It may, but I’m not hopeful.  For one things, humans have a rich and mercurial culture that is unlike anything seen in animals.  Social stigma or conventions can change quite quickly, and this can affect the propensity of same-sex behavior.  Was prolific gay behavior in ancient Athens the same thing, biologically, as the behavior of gays in 1930s Chicago? Who knows?

The controversy about the roots of gay behavior in our culture is often couched as a dichotomy: is it genetic or is it a “choice”?  Because I’m a physical determinist who believes that there’s no such thing as true free will or a genuine “choice”, I prefer to couch the dichotomy as one of nature versus nurture: are there genes whose presence results in gay behavior, or is that behavior entirely due to environmental influences, including social pressures and the behavior of one’s peers?  The most likely answer is “both.”  There is some evidence that homosexual behavior in our species has a genetic basis, but we don’t know much about this, and of course how genes produce traits depends, with few exceptions, on the relevant environments. “Gay” genes may show environmental effects on expressivity (the degree to which gay behavior actually appears when one has “gay genes”) and penetrance (is such behavior even seen at all when one has the genes?).

If one is making an argument that gay behavior has an adaptive evolutionary basis, as do some evolutionary psychologists, then one must answer at least three questions.  These questions, while crucial for any argument about the evolution of human behaviors, are almost never addressed in any work of evolutionary psychology, and the second two aren’t touched by Mooallem.

1.  Does gay behavior have a genetic basis? As I said above, we don’t know much about this, but there are indications that there is some genetic basis in some people.  That doesn’t mean, however, that all gay behavior stems from “gay genes.”  Even if there’s a genetic basis, there is likely a strong interaction with the environment, too, so that one may not be able to impute gay behavior to simply “genes” or “environment.” Complicating this is the additional possibility that some same-sex behaviors may reflect genes or gene-environment interaction, while others  could entirely reflect differences in the environment, perhaps based on neurological or hormonal factors not produced by mutations in the DNA.

If the answer to this first question is “no,” then there is no need to go further with explaining an adaptive basis for homosexuality. Without genes there couldn’t be an adaptive basis for the trait.  If it’s “yes”—that is, there is at least a partial genetic basis for some gay behavior, you can proceed to question #2.

2. If the behavior is “adaptive,” how is it adaptive? That is, how, exactly, do gay people leave more copies of their “gay genes” than non-gay people?  For that is what is implied by saying that the behavior is “adaptive.” Since homosexuality seems patently maladaptive from an evolutionary point of view—presumably gay people don’t leave as many offspring as their non-gay confreres—how come those genes are hanging around in the population?  We’d expect natural selection to eliminate them.

Mooallem notes two possibilities.  One, originally suggested by E. O. Wilson, is kin selection.  As Mooallem notes:

In a paper published earlier this year, Vasey and one of his graduate students at the University of Lethbridge, Doug P. VanderLaan, report that fa’afafine [this is a group of males in Samoa who engage in same-sex behavior] are markedly more willing to help raise their nieces and nephews than typical Samoan uncles: they’re more willing to baby-sit, help pay school and medical expenses and so on. Furthermore, this heightened altruism and affection is focused only on the fa’afafine’s nieces and nephews. They don’t just love kids in general. They are a kind of superuncle. This offers support for a hypothesis that has been toyed around with speculatively since the ’70s, when E. O. Wilson raised it: If a key perspective of evolutionary biology urges us to understand homosexuality in any species as a beneficial adaptation — if the point of life is to pass on one’s genes — then maybe the role of gay individuals is to somehow help their family members generate more offspring. Those family members will, after all, share a lot of the same genes.

This would seem to be the prediction of “adaptive homosexuality” that is most easily tested.  It’s not hard to determine whether gay people have more brothers and sisters (or nieces and nephews) than non-gay people, a finding necessary to support the “kin selection” theory.  And it has to be more than just a one-for-one replacement with you because, according to kin selection theory, related individuals are devalued by their degree of genetic relationship to the gay person.  If a gay person is, as Wilson posited, the human equivalent of a bird “helper at the nest” (birds like Florida scrub jays who forgo reproduction for a while to help their parents raise brothers and sisters), one can make calculations about whether the outcome is “adaptive.”  If I become gay and have no offspring, for example, I’d have to help mom and pop raise produce at least two more brothers and sisters than non-gay people, because each brother or sister carries only half my genes.  I suspect the “kin selection” idea is wrong, but it would be relatively easy to get the data.

Complicating this explanation, however, is the evolutionary-psychology idea that whatever evolutionary forces promoted the evolution of “gay genes” occurred in the distant past, on the African savanna where most of our evolution took place.  Measuring current evolutionary advantages and disadvantages of homosexuality might having nothing to say about why it evolved (if it did evolve) in the first place.  This evocation of an unrecoverable past, while it might be true, makes much of the speculation in evolutionary psychology untestable.  Can’t find an adaptive advantage in modern society? That’s ok—there was probably an advantage several million years ago.

Mooallem raises a different possibility for how “gay genes” might be selected for:

Vasey and VanderLaan have also shown that mothers of fa’afafine have more kids than other Samoan women. And this fact supports a separate, existing hypothesis: maybe there’s a collection of genes that, when expressed in a male, make him gay but when expressed in a woman, make her more fertile. Like Wilson’s theory, this idea was also meant to explain how homosexuality is maintained in a species and not pushed out by the invisible hand of Darwinian evolution. But unlike Wilson’s hypothesis, it doesn’t try to find a sneaky way to explain homosexuality as an evolutionary adaptation; instead, it imagines homosexuality as a byproduct of an adaptation. It’s not too different from how Vasey explains why his female macaques insistently mount one another.

This may also be true, but it doesn’t necessarily solve the problem.  That’s because of question #3, to wit:

3. Are the genes for gay behavior supposed to be fixed in populations or are they polymorphic? That is, do we all have genes that, under the right circumstances, cause us to have same-sex sexual behavior, or are those genes polymorphic—that is, do some individuals have them while others don’t?  This latter possibility is what evolutionary psychologists often suggest; and this possibility is required for studies that purport to show that gay behavior has a genetic basis. After all, if we all have gay genes, there’s no genetic variation among people to study and thus no way of demonstrating a genetic basis to gay-ness!  And if gay genes are polymorphic, why are they polymorphic?  Population-genetic studies show that only under very restricted circumstances can natural selection itself promote the existence of genetic polymorphisms in natural populations.  Just showing that gay behavior is sometimes adaptive, or has adaptive side effects, is not enough to explain the persistence of “gay genes” in populations.

Mooallem’s idea that gay genes are maladaptive in males but adaptive in females doesn’t fully answer this question.  Genes that are adaptive in one sex but not in the other don’t automatically become polymorphic in a population.  In most cases, they’ll either be wiped out of a population (if the disadvantage in males is larger than the advantage in females), or be fixed in a population, so that everyone has them (advantage in females much stronger than disadvantage in males).  To explain a polymorphism, the balance between male and female fitness has to be of a very specific character so that, for example, “heterozygotes” (individuals carrying one gay gene and one non-gay gene) have a net advantage in the population.  This is by no means the inexorable result if gay genes are maladaptive in males and adaptive in females (or vice versa).

***

Answering these three questions is a tall order.  Question 1, whether homosexuality has a genetic basis, is perhaps the easiest to answer.  The other two questions, involving the so-called “adaptive” basis for homosexuality, will be very difficult to answer. In fact, I don’t think—given the difficulties of studying a socially-conditioned behavior in a population on which you can’t do experiments—that they’ll ever be answered to our satisfaction.

In the end, I suppose I’m not much interested in the evolutionary roots of gay behavior.  Yes, it would be nice to know, but, given the problems I’ve described above, we’ll likely never know for sure, and perhaps should spend our time studying more tractable questions.  The data at hand already show that same-sex behavior in animals is a mixed bag of heterogeneous stuff, and may not illuminate homosexuality in humans.  Most of the researchers described in Mooallem’s article seem to recognize this.

And of course, no matter what the evolutionary roots of homosexual behavior are, those are irrelevant (apologies to Sam Harris here) to how we regard gays.  Infanticide is “normal” in some species like lions and langurs, but we condemn it and punish it in humans.   What is “natural,” “genetic,” or “adaptive” has little relevance, to me at least, to the question of what is right.  It’s simply the moral thing to do to ensure that gays have equal rights, regardless of whether same-sex behavior rests on genes, the environment, or both.  Perhaps finding a genetic basis for homosexuality would make some Christians and Mulims stop condemning gays as immoral, but what if homosexuality turns out to be largely a product of environments?  Making your morality depend on such answers is simply a bad way to proceed.

Anyway, read Mooallem’s article. It’s a remarkably good piece of science reporting.

Last week I wrote about the British neurobiologist Colin Blakemore’s assertion that human brain size suddenly increased by 30% about 200,000 years ago, and his idea that this increase was due to the fixation of a single macromutation.  While I questioned this mechanism, John Hawks also questioned the data, claiming that brain size increase over time had been pretty steady, with no leap at the proposed time.

Well, an alert reader, anthropologist Ciarán Brewster from University College Cork, has done the proper statistical analysis of the brain-size data.  Over at his website, Ad Hominin, Brewster shows that there is indeed an inhomogeneity in brain evolution, and that the pace of brain-size increase did indeed pick up about 200,000 years ago.

So Blakemore’s assertion about the acceleration was correct.  But of course this says nothing about whether that acceleration reflected the fixation of a macromutation, which I consider very unlikely for reasons I’ve already mentioned.  And Blakemore’s theory that any brain-size “macromutation” was initially neutral, and became advantageous only after it had already been fixed in our lineage by random processes (e.g., genetic drift), is pretty outlandish.

One thing that Brewster doesn’t discuss is whether that accelerated brain-size evolution was correlated with accelerated body-size evolution.  If brains got bigger simply because bigger bodies produce bigger brains as a byproduct (this is what we geneticists call a “pleiotropic effect”), and if for some reason bodies were selected to get bigger around 200,000 years ago, then it’s not necessary to posit that there was something selecting for bigger brains per se. (Of course, increased body size could also be a byproduct of increased brain size!)  I don’t know if this is likely given the data, but it’s something to consider.

I’ll be in the City of Light for a week starting tomorrow, enjoying a well-deserved break.  All the restaurant reservations were made weeks ago, which, in light of Adam Gopnik’s favorable comments on L’Ami Jean in this week’s New Yorker (see also his article on “Le Fooding”), was a judicious thing to do.

I’ll be back next Sunday, and in the meantime your reliable pinch-bloggers, Drs. Matthew Cobb and Greg Mayer, will be filling in.

Fig. 1. Riz au lait at L’Ami Jean: the world’s best rice pudding, served with either cherry confit or praline.

p.s. If you’re gonna comment that this food is unhealthy, don’t bother. As Julia Child once said, “Food is not medicine.”

Over at HuffPo, Michael Ruse mounts “A Scientific Defense of the Templeton Foundation,” and doesn’t miss an opportunity blast P. Z. (“evolution’s answer to Rush Limbaugh”) and me.  What a thin skin that man has!  But there are many lolz:

Having said this, it seems to me that it was perfectly open to Sir John Templeton to have put his money into a foundation that seeks to reconcile science and religion. The money was earned honorably, even though one might have some questions about Sir John’s decampment to the Bahamas and its tax-free economy. But so long as America is daft enough to let people get away with this, who am I to object? Speaking as one who has probably no more religious beliefs than Richard Dawkins, I don’t see anything morally wrong with someone trying to reconcile science and religion. Clarifying that a little, I don’t see anything morally wrong with religion as such. These days I don’t much care for the Catholic Church, whether it be abusing small children, covering up the crimes of the priests involved, or leading the charge against universal health care because the restrictions on abortion were not sufficiently stringent. But I care for the work that the Church does among the poor and the sick, and I care also about the work that many Evangelicals are doing in Africa.

Who ever said it was “morally wrong” to reconcile science and religion? It’s philosophically and logically wrong!

Oh, and just when you thought that the Catholic Church couldn’t get more clueless, listen to this.  The BBC reports that the  Pope’s personal preacher, Reverend Raniero Cantalamessa, has compared criticism of the Pope and the Church’s handling of the child-abuse scandal to anti-Semitism:

The Rev Raniero Cantalamessa was speaking at Good Friday prayers in St Peter’s Basilica, attended by the Pope.

In his sermon, he quoted a Jewish friend as saying the accusations reminded him of the “more shameful aspects of anti-Semitism”.

His comments angered Jewish groups and those representing abuse victims.

Father Cantalamessa said Jews throughout history had been the victims of “collective violence” and drew a comparison with recent attacks on the Roman Catholic Church.

He read the congregation part of a letter from a Jewish friend who said he was “following with disgust the violent and concentric attacks against the Church, the Pope…

“The use of stereotypes, the shifting of personal responsibility and guilt to a collective guilt remind me of the most shameful aspects of anti-Semitism,” he quoted from the letter.

On the upside, over at Metamagician Russell Blackford, feeling feisty, says that “Some speech needs to be marginalized.” That includes a lot of religious speech:

But some ideas, though not censored, should be given only a marginal place in our society. In every generation, we continue to debate which those are. I am hopeful that future generations will include not only the examples I’ve given, such as the ideas of reinstituting slavery or punishing homosexuals, but also such examples as the ludicrous idea that the Earth is only 6000 years old (contrary to all conclusions from rational investigation). Likewise for the idea that there is something even “sinful” about (as opposed to grounds for banning) consenting homosexual conduct between sufficiently mature people, or that “sin” attaches to the use of contraceptives or to masturbation. Like the advocacy of slavery, these foolish ideas no longer deserve a level playing field in our society. Let them be freely derided, ridiculed, and driven to the margins. The sooner, the better.

As for religious leaders, they certainly do not deserve the kind of deference they currently receive, or the megaphones they are provided by the news media for their pronouncements. They do not deserve to be looked upon as moral or community leaders, or to be given a privileged voice in public debate. Some – such as those Protestant fundamentalists who claim the Earth is only 6000 years old or the celibate, white-haired dinosaurs of the Vatican who think that the use of contraception is a sin – deserve to be accorded little more intellectual credibility than would be given, in a modern city such as Melbourne, to a slavery advocate.

Not all ideas deserve to be taken seriously and considered respectfully, and not all people deserve to be accorded intellectual legitimacy. We can argue about who and what falls into which category, but there is no doubt that some speech deserves to be marginalised … and that certainly applies to a lot of religious speech. There’s no need to be backward about saying so.