The Biological Basis of Boys loving Boys: Part I

Part I of a three part article I've written for GayNZ on homosexuality and biology...

News that gay men can be sperm donors must be welcome to couples requiring assisted reproductive technology. However, evidence is accumulating that sexual orientation is the result of gene-environment interaction; sexual orientation has a heritable component.

Thus, using sperm from gay donors may have the potential of passing the gay gene(s) to the next generation. Patients requiring such service should be informed of such potential.

--Assoc. Prof. Frank Sin, The Press, 13 March 2006.

66 words, two paragraphs. It's hard to imagine that Sin's almost non-existent letter to the editor would have prompted the response that it did. Albeit brief, the ensuing attention in the news media, on talkback radio and its internet equivalent the blogs, seemed surreally disproportionate to what essentially was an innocuous letter...

Of course, the topic itself served merely as a catalyst to open up the ubiquitous can of worms (or indeed several cans) around not only the 'genetic' basis of homosexuality, but also the broader issues of personal liberties, rights to privacy, and the ominous spectre of 'designer babies' and neo-eugenics.

The issue is, naturally, an incredibly complex one. Like all issues that meet at the common vertex of science, ethics and the individual, it paradoxically becomes more complex, more troublesome, as our so-called 'knowledge' increases. As we gradually accumulate what we think we know, the boundaries become fuzzier, the grey areas become greyer, and our ability to make scientifically and ethically sound decisions becomes harder. It's not unique to the homosexuality debate; we see it in the euthanasia and abortion clashes that pop up like clockwork.

It is unfortunate that the public domain is not always well suited to complex debate. Instead of granting space for real discourse, a robust korero, everything is a soundbite, a simplistically absurd reduction of arguments, ideas and narratives to their most basic precepts. Suddenly everyone has an opinion, some more reasonable than others.

Sin didn't do himself any favours. Given he's an expert in genetics, I was surprised that he wrote the letter in the first place. Until of course one considers that Sin's field of expertise is human male infertility. Perhaps he could be forgiven for wanting to flag a warning about something that he perceived could undo the work to which he has devoted much of his research career. The response from Allan-John Marsh of the Wellington based Gay Association of Professionals (GAP) wasn't particularly helpful, or even correct either, implying that homosexuality was innate but neither inherited or heritable.

As could be expected, the mainstream media had a field day, frantically calling whoever they could to milk whatever controversy they could. Much huffing and puffing ensued, redneck opinions were aired, agendas were either pushed or defended, whichever 'side' of the debate you happened to be on. Somewhere in the middle of all this, the potential for the greater public to gain some understanding was lost.

So how then do we approach this topic? It appears that this issue has two distinct components: the biological basis of sexual orientation, and the ethical implications of 'choosing' a child's sexual orientation. Obviously the two are interrelated, but it is a good idea to work out what we think we know, and what we know we don't know about the first part, before trying to understand the basis for the second.

We need to be careful about this term ‘biological’. All too often it is confused with related but distinct terms like ‘genetic’, ‘innate’, or ‘inherited’, but the word biological also encompasses that which is ‘environmental’, ‘learned’ or ‘aquired’. Most, though not all, characteristics that make us human are a combination of many of these factors. When we enter the realm of behaviour, be it social or sexual, these interactions become even more complex and subtle. There are very few behaviours that are either genetic or environmental, innate or learned. Of those that are, it doesn't mean that one is more 'biological' than the other; at its very fundamental level, all behaviour is in some way biological, given that it involves the neurochemical processes of the brain - an essentially biological phenomenon.

A useful analogy is blinking and winking. Blinking is an entirely genetically, neurologically, innately controlled behaviour. It is universal across all human populations; we can all do it from birth without learning how to. Contrast this with winking, which is an entirely learned behaviour; there have been no studies which suggest that certain people have a predisposition to winking. We can often recall the period of our lives when we learned to do it. Winking isn't a human universal: not all cultures wink, and in the ones that do, it has different meanings, different contexts and different social responses. Both blinking and winking, however, are fundamentally biological. Although not innate, winking relies on our ability to learn, our behavioural flexibility, and our responses to environmental (social and cultural) stimuli, factors that do have strong biological, genetic and developmental bases.

Admittedly this is a simplistic analogy, and most behaviours are far more complex than blinking or winking. But it serves its purpose in our understanding of the fallacy of the false 'nature versus nurture' dichotomy which has seriously handicapped our ability to understand what it means to be human. As the author Matt Ridley points out, a more valid phrase would be 'nature via nurture', or possibly even 'nurture = nature'. Remember that in all of these discussions we do not assume any of these biological factors to be in some way immutable or deterministic (except perhaps blinking!). We can only talk, at most, about predispositions, about relative potentials to be inherited, about probabilities and trends. The very fact that there are individuals that break these trends, the fact that we can only work with statistical probabilities, means that these factors, social and non-social, are by their very nature not deterministic.

We must similarly exercise caution about what we mean by the terms 'sexual orientation', 'homosexuality', 'heterosexuality' and 'sexual identity'. The terms are very deeply embedded in our socialised classical Judaeo-Christian ideas and Victorian Protestant moral constructs, with a healthy dollop of modern pyschological, feminist and queer theories, not to mention theories of gender, thrown in for good measure. Everything that we 'learn' about sexual behaviour is constrained by the labels that we come up with, our classification system du jour. Our concepts of 'sexual orientation' are a product of current and historical cultural norms, which means that any 'answers' we gain are contingent on those norms. Our answers may not be very accurate, or even valid, but in this point in time it's the best we've got.

Given the variation we observe in sexual orientation, the hodge podge of behaviours, attractions and identities that we call human sexuality, we ask the question: are there any non-social biological factors that can be identified as playing a role in sexual orientation? The simple answer is yes: there are no 'gay genes', but there are factors, unrelated to social experience, that correlate with sexual orientation. Broadly these factors can be grouped into two categories: pre-natal developmental processes and genetic factors.

Raging hormones

There is substantial evidence that homosexuality is associated with 'atypical' pre-natal hormone levels, resulting in sex-atypical brain formation. We can hypothesise that foetal action of hormones (specifically testosterone) in laying down the brain structures which will play a role in sexual orientation is atypical in homosexuals. Specifically, lesbians are thought to be subjected to higher than average testosterone levels than straight women, while gay men experience lower levels than straight men.

Part of the evidence for this comes from the study of biological females, who through genetic mutation, express either massive or very little amounts of testosterone as foetuses (Congenital Adrenal Hyperplasia and Adrenal Insensitivity Syndrome/CAH and AIS respectively). As adult women, CAH individuals show a greater level of attraction towards other women than the population average, despite having received 'corrective' hormonal treatment, being raised as gendered females, and identifying as gendered females. By contrast, AIS individuals show a much lower level of attraction towards other women average. This suggests that the action of sex hormones in the womb is related to adult sexual orientation.

The problems with this are of course numerous. The vast majority of lesbians and gay men of course do not have these specific or identifiable genetic conditions resulting in increased/decreased testosterone levels; a mechanism by which they would be subjected to atypically high or low hormone levels is then unclear. Further, the specific markers which we know are the result of higher or lower testosterone levels, such as brain differentiation patterns, differences in the size of certain brain structures etc, are not consistently correlated with homosexuality in males or females. Some do show trends that we would expect, others do not.

The patterns of sexual orientation differ between males and females: males show a bimodal distribution, with the vast majority identifying as either entirely gay or entirely straight. In women it's the opposite: most identify somewhere in between, although not necessarily in the middle. There are also differences within homosexual groups. Gay men who identify as having 'feminine' childhoods exhibit some different markers than those with more 'masculine' childhoods. But then, is childhood gender non-conformity even a valid characteristic of sexual orientation? Similarly, there are differences between 'butch' and 'femme' lesbians in some of the neurological, hormonal and body markers that indicate differences in pre-natal testosterone levels.

So are we dealing here not only with different mechanistic 'causes' of homosexuality between men and women, but also between different types of homosexual men and women – types we've conveniently thrown together for labelling purposes? And where the hell do bisexual men and women fit into the picture?

Next Week: Part II - What is it with gay men and their mothers?

Use your noggin, Sonic

What is it with developmental biologists?

Most biologists like to name the proteins that they identify in metabolic pathways by their function. For this reason, we have the sensibly named Epidermal Growth Factor, or the Glyceraldehyde-3-Phosphate dehydrogenase, or Phosphofructokinase. Sure, they look complicated, but if you know what the words mean, you can generally figure out what the protein does

Then you have the developmental biologists. These smart arses decided their goal in life wasn't the pursuit of higher knowledge, but rather the thwarting of confused university undergraduates.

There are actually proteins called Hedgehog, Noggin, Goosecoid, Nodal, Dickkopf (german for 'fathead' = stubborn) Sonic Hedgehog, Frazzled, Siamois, Cerberus, Bicoid, Hunchback, Smaug, Swallow, Engrailed and Fushi Taruzu.

Sure. The names are cute. But when you're hunched over a text book trying to remember what protein does what, they are totallly utterly useless.

Take this email 'clarification' from my lecturer to the class:

In lectures, I mentioned that the Siamois protein was expressed in the Niewkoop centre and from there it activates goosecoid in the organiser, which activates organiser-specific genes (Gilbert). Of course, it would be difficult for Siamois (a transcription factor) to directly activate goosecoid if it were not expressed in same cells. In fact, Moon and Kimelman, (1998) describe Siamois expression not only in vegetal cells on the dorsal side, but also in equatorial cells of the dorsal side - presumably the cells that are fated become the organiser.

You are as confused as I am. And I've been doing this for four years.

Winning the war on terror

Reduction to the Absurd

This week will see the first reading of a Bill that promises major change. Barbara Stewart's Electoral (Reduction in Number of Members of Parliament) Amendment Bill seeks to do what it says on the label: reduce the number of MPs in Parliament from 120 to 100 by amending the Electoral Act 1993

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This Bill will come as much-needed relief to the millions of ordinary hard-working New Zealanders, Kiwi battlers, mums and dads, who lives are blighted by the burden of supporting twenty MPs. It will also help reduce the colossal impact these MPs have on the infrastructure of Wellington, where the roads are frequently blocked by MP jams, cafes and bars are filled to overflowing with MPs, and power and water supplies are under constant threat from MP overloads.

Or something like that. It is very difficult to find out what this Bill will achieve. Ms Stewart does not seem to know, as this illuminating interview with Scoop shows. One hundred is a nice round number, which will no doubt be of comfort to members of the anal-retentive community. Passing the Bill will also respond to the People's Voice, which spoke in the referendum of 1999 and demanded a reduction in the number of Parliamentarians. Political scientists will remember 1999 as the annus idioticus, in which two stupid referenda were put before the electorate: this one and the other one, which demanded that the problem of crime be stamped out by combining retribution, restitution and restoration, or something along those lines. I was one of the tiny handful of people who voted against these measures, as well as casting Labour's vote in Remuera; I felt very alone that day.

Still, they were passed and by Albanian-sized majorities. Perhaps Parliament should respond and send some of its members home at the next election; or perhaps not. Ms Stewart thinks that twenty fewer MPs will be more representative. One can see what we rhetoricians call a reductio ad absurdum looming on the horizon here: if 100 is more representative than 120, then Fifty will be more representative still and One would be the perfect state of representation.

What Ms Stewart does not seem to understand is our MMP system. She wants to reduce the number of List MPs rather than redrawing the electoral boundaries and removing constituency seats. We have the List MPs so that Parliament will be representative: any party which passes the threshold of five percent of the votes cast will be proportionately represented in Parliament: for example a party that gets twenty percent of the votes has twenty percent of the seats, made up of the constituency seats it wins in its own right and List seats added to make the proportions representative. It's not that difficult to grasp. Contrast this with bad old Britain, where the charming and cuddly Liberal Democrats never get the representation they deserve, because all that counts is winning constituency seats. Labour and the Tories get most of these and all the Lib Dem votes in those constituencies are wasted.

Consider also that New Zealand, unlike most democracies, has only one chamber, the House of Representatives. Most have two and many have federal systems with state assemblies, like Australia and the USA. We are hardly over-represented.

If Ms Stewart's explanations of her Bill are not unconvincing enough, consider as well that she intends to retain the Maori seats, thus gaining the support of the Maori-Tory Party. Leaving aside all concerns of fairness, history and avoiding blood on the streets, the Maori seats surely are the ones that should go first in any reduction. They are effectively a duplication of mainstream seats, since voters can choose to be on either the General or Maori electoral rolls. You don't have to be Maori, but it helps. If a management consultant were in charge of a parliamentary restructuring exercise, the Maori seats would be gone by lunchtime.

It is List seats that will suffer. Which is all very rum. As the aptly-named Kevin List points out in the Scoop interview, Ms Stewart's party, New Zealand First, is a beneficiary of the List system. Her party doesn't have enough support concentrated in any one area to get a regular seat, not since Tauranga was lost. However, the elderly and bigoted still have a voice in Parliament, thanks to new and improved MMP.

So, if the Bill's proposer cannot justify it with any reasoned arguments and if it goes against the apparent interest of her own party, what can be the reasoning behind this measure? Ms Stewart gave the game away when talking to Scoop: it has had a good response from talkback callers. This is Talkback Politics at its finest. Under the thin surface of Ms Stewart's great idea lie the murky depths of muttered discontent, the domain of the Angry White Male. All those seething resentments mouthed by the sad gits who waste time calling some of the country's worst radio shows are encapsulated in this Bill. It probably won't get passed but that only goes to show how corrupt that lot in the Beehive are, doesn't it? They are only concerned about their perks and their pensions; and they would take the shirts of the backs of ordinary hard-working Kiwi battlers to feather their own nests.

Perhaps they have a point. If Parliament really can find the time to hear this sort of nonsense, then maybe it is over-staffed. On the other hand, maybe it will just hold up more important and better thought-out legislation which might just do some good.

Perhaps someone should table a Parliament (Wasting Everyone's Time) Amendment Act.

But you’d hardly know it

The world wide web of fallacies, or: It doesn't logically follow, Ian.

Moxie has written a number of posts so far about the issue of abortion law, both within New Zealand and overseas. As a modern feminist, it is easy to see why she is becoming increasingly frazzled with the current state of the law: the 'pro-choice' side is steadily losing. We're not just talking about the march of the unnatural neo-conservative/neo-liberal hybrids, insidiously encroaching throughout the United States like some bizarre bible-wielding zombies; in our own country the heretofore-assumed-moderate-liberal George Hawkins has been calling for changes to our abortion laws, much to the chagrin of those within his own party (including Moxie)...

Over at Sir Humphrey's the usual debate has started on a number of posts, with stock-standard visceral name-calling and stock-standard stretched analogies of Bush and Iraq, Al Qaeda, Hitler and The Jews et cetera (they should make a song called "Hitler and The Jews" to the tune of "Pinky and The Brain", and just pull it out as a stock standard argument whenever tired and intractable moral flame-wars arise; it might just save a little more bandwidth.). It's not very helpful in the abortion debate, and even less relevant or logically justified.

I'm not particularly qualified to talk about abortion. I'm not biologically female, and I don't have sex with females (even if I did, I still don't think it would be a good qualifier). I will never to have to consider having an embryo or foetus removed from my uterus, I will never have to make the decision. I don't believe that any man has the right to tell a woman, either by personal force or through legislation, what they can do with their bodies. In fact, another woman justifiably has no right to tell a woman what to do with their own body. I am not 'pro-choice'. I am 'pro-butt-the-hell-out-of-my-business'.

As an interesting aside, it is profoundly ironic that those creatures who normally occupy the 'less government meddling' part of the socio-political landscape are just so keen to make an exception in the instance of abortion law. These are the people who, in many states, have 'reformed' welfare systems to ensure that people exhibit personal responsibility to lift themselves out of the situation that are, of course, entirely of the person's own making. These are the people who advocate personal responsibility when it comes to raising a number of children on a single income, who advocate choice when it comes to whether state funds are poured into religious education programs, who advocate choice when it comes to employers' rights to discriminate on the basis of gender or sexual orientation. There is a great espousal of an individual owning his or her life, and choices about that life, without 'big government meddling'

Should, however, an individual choose to exercise personal responsibility, or choice, when it comes to owning her own reproductive life, it is entirely consistent and justified for these moralisers to advocate full and invasive state regulation into that person's life. We're not just talking abortion law here either, but also access to contraception, or even just good sexual education that would, in many cases, make the issue of abortion almost irrelevant. The hypocrisy is breathtaking, but seems to slip out of these people's mouths without them appearing to even take one. The great neo-con/neo-lib chimera, a walking ideological contradiction, positively oozes hypocrisy. It would be funny if it didn't ruin lives.

Anyway, back to the web based fallacies, rather than the living breathing life-ruining ones. One of the debates over at SH, specifically this one entitled "When do you BELIEVE a fetus/child gains full rights to life?", appeared to be going relatively well, in that it was on-topic and marginally cogent, until Ian Wishart turned up with with some real doozies:

I argue Conception for the following reason.

Science, despite billions of dollars in effort, has been unable to grow life from inanimate matter.

It therefore follows that until such time as it can be proven otherwise, it should be assumed that life begins at conception, it doesn't magically grow at some point of fetal development.

It may not bear physical resemblance that early to the human form, but in sharp contrast to a slab of meat those cells are alive, not dead. The life force in a fertilised egg is the same life force that will drive that person for the rest of their lives.

What Ian is essentially arguing is that because we haven't yet replicated, in the laboratory, how life first arose on earth some 3.5-4 billion years ago, a woman does not have the right to an abortion.

Oh Dear. Oh Dear, indeed.

Lets lay this out logically.

1. According to Ian, a human being gains full rights to life at conception. This is because, at conception, that is fertilisation, the particular cellular phenomenon occuring in utero becomes "alive".

2. Ipso facto, Ian is arguing that before fertilisation occurs, both sperm and egg are unequivocally not alive.

3. Ipso facto, it follows that Ian is arguing that the process of fertilisation is equivalent to either or both of abiogenesis, the process of primeval earth in which 'non-living' organic molecules developed into 'living' ancestral cells or spontaneous generation, the archaic belief that held that rotting meat produces maggots.

What basis does Ian have for arguing that sperm and eggs are not 'life'?

Is it because they are haploid, that is, only contain one set of genetic material? In that case, almost all life on earth, that is, Bacteria and Archaea, are in fact not life, because they too are haploid. Or indeed some worker castes of some species of ants or wasps, which are also haploid.

Is it because, by themselves, sperm or eggs are not enough to produce a living, breathing, organism, because they require another equal partner to produce life? If we were to apply that standard to its absurdly logical conclusion, then any adult human being is not alive either, because by ourselves we are not capable of producing 'life', without another equal partner, only haploid gametes. Conversely, those organisms that can produce life from gametes without a sexual partner via parthenogenesis are more alive than we are. That's right, ladies and gentlemen: the aphid has more of a right to live than you do.

There are three blatantly obvious logical and scientific absurdities here.

Firstly, fertilisation is not equivalent to either abiogenesis or spontaneous generation. This is because sperm and egg cells are living. Sure, they do not represent individual organisms, but they are living, respiring cells, just as much as (admittedly diploid) liver, muscle or nerve cells are living.

Secondly a lack of understanding about the development of living systems on earth 3.5-4 billion years ago does not provide any moral imperative to prevent the abortion of a foetus. Nor does it convey on a zygote the rights of an individual. This last one just boggles the mind, it simply does not follow.

Thirdly, Ian argues that fertilisation itself somehow 'creates' a life force that then drives the organism throughout it's life. This is argued without any real evidence for such a force (in earlier years called the 'protoplasm') or understanding of development or reproductive biology. Actually, it's argued without any real understanding of basic biological principles at all.

If Ian did know some basic things about developmental biology, he would know that the first stages of development of the embryo are not guided by the zygote's own genes at all, but rather by maternal mRNA left in the egg during its genesis in the womb. This mRNA, once translated into protein, directs the first few cleavages of the cell, as well as setting up spatial polarity within the embryo, upon which only later (4-8 cell stage) does the embryonic genome begin to lay down the body plan.

Next, Ian stumbles further down the development-of-life-on-primordial-earth-somehow-relating-to-abortion-law tangent even further, this time exposing hints of a great conspiracy to 'create life' by mad modern scientists:

The Miller-Urey experiments were a failure: the mere creation of amino acids (bricks) does not lead to the Empire State building without intervention and there's been enormous work to try and get the so-called building blocks of life to do something. Nothing happens no matter how you shake the mixture or put sparks through it.

As one of the former doyens of chemical evolution, Professor Dean Kenyon puts it: the field of chemical evolution is effectively dead.

You are being disingenuous Danyl, if you expect people to believe that science has no interest in creating life. If you can't see the "point" of experiments in that vein, then you may be lacking the genuine inquiring mind necessary for scientific advancement.

The first scientist to figure out how to create life has a commercial mortgage on the future of the planet. But it is precisely because creating the real thing is impossible that work has opened up on genetic modification instead...

Ian is right, of course, in that the formation of amino acids does not lead to the formation of life without some kind of intermediate processes. Those processes are, of course, the formation of precursor replicating molecules, most likely ancestral versions of RNA, and the process of natural selection whereby molecules which are statistically 'better' at more faithful self-replication and oligopeptide synthesis are more likely to continue propagating. Those processes are not a divine hand, but rather an artefact of physical, chemical and statistical laws acting over an early, angry tumultuous earth.

The field of abiogenesis is a young and developing one, hindered by the fact that it is very difficult to 'know' what the early earth looked like. What I can safely say is that the scientists in the field no longer run electricity through little flasks (the Miller-Urey experiments); it has progressed somewhat. We may not know a huge amount, but we have some pretty sound ideas about it.

What does all of this have to do with abortion, or the right's of the foetus?

Very little. But then, that's Ian's rhetorical style. Rather than logical substance, it focuses more on wild red herrings that beg the question, irrelevant tangents that throw the reader off and conspiratorial undertones that call on the reader to suspend their incredulity. Although this suits the hysterical tabloid media to a T, it contributes very little to reasoned, humane debate.

Squishy things, or a new post not about education

My first semester of University involved taking BIOSCI 103: Comparative Animal Biology. It was a great course, and really piqued my interest in pursuing an animal-based biology degree, rather than a biochemistry one, which had been my initial intention. Hell, my initial intial intention had been to do law (until I worked for lawyers), so it's not like changing my mind as often as I change my underwear isn't particularly out of the ordinary...

Nonetheless, I digress. The course itself contained laboratories which essentially involved hacking all manner of animals up and looking at their innards. My initial uneasiness wore off in about 3 minutes into the first lab, as I realised how cool chopping animals up can be. Ok, sure, it's probably not very ethical to assign one rat per person, rats that had been specifically bred to be slaughtered, congealed blood staining their nostrils from the poison-induced respiratory haemorrhaging that ultimately led to their demise. But hey. I had just bought my new leather bound dissection kit, and like I wasn't going to let that go to waste, right?

Oh dear. Another digression.

ANYway. One of our labs involved observation of Amphioxus, or the lancelet 'worm', under the microscope. These critters are only very small, about 2-3cm maximum in length, and look a lot like anchovies. Amphioxus, otherwise called Branchiostoma has long been lauded as a key model species for understanding the development of the vertebrates from from an invertebrate world sometime during the Ordovician period of the Paleozoic era, some 470 million years ago.

Our little corner of the tree of life is called the Deuterostomia (which means "second mouth"), as opposed to Protostomia (which means "first mouth"). These names refer to the period of development where the gut forms: in protostomes, the first opening eventually forms the mouth, whereas in deuterostomes (us), the first opening forms the anus, and the second opening forms the mouth - hence 'second mouth'. Comprising this set are the echinoderms (star fish, kina et cetera), the hemichordates (a random and obscure group of worms) and the 'chordates'. The chordates themselves split into the urochordates - things like sea squirts and other tunicates, the cephalochordates, where our little lancelet friend fits in, and the vertebrates - us.

The textbook view of these groups holds that echinoderms are the most 'primitive', or basal member of the deuterostomes. This is mainly due to the fact that they are unlike any other deuterostome - they are the odd ones out in terms of their symmetry, their locomotion, internal organisation et cetera. The next group up are the hemichordates, so called because they do have some of the characteristics which are normally associated with the chordates, in particular the presence of first signs of gill (pharyngeal) slits. The classical view argues that the urochordates (tunicates) are the most basal member of the chordate clade - they possess a hollow 'notochord' and dorsal nerve cord, but don't exhibit the body complexity, particularly body segmentation, seen in the remaining cephalochordates (lancelets) and vertebrates, which together comprise the Euchordata or 'true chordates'. This classical view is shown in the image below.

[Click to enlarge]

All of this is based on an apparent increase in complexity throughout the lineages - almost as if the principles behind that iconic 'ape to man' idea had been transplanted to explain the development from 'squishy' to 'us'. Those more like us are more advanced, those more squishy are, well, primitive. Of course, we're only dealing here with complexity in a morphological sense - the appearance of new and improved features on organisms over time. If we were to look at biochemical or intracellular physiological complexity, the earliest forms of life (bacteria) would kick our proverbial arse. This idea of a supposed correlation between being 'complex' and being 'advanced' isn't completely arrogant or conceited. The earliest forms of animal life at least were simple and squishy, and there is, overall, a general trend towards "complexity". But many squishy lineages developed incredible complexity - you only need to look at the cephalopods (octopuses, squid and cuttlefish) who are most closely related to snails and slugs, as well as the more 'complex' forms that have rediscovered the joys of a simple squishy lifestyle.

This view on the deuterostome phylogeny has been challenged before, with some success. However, the most significant recent change to the phylogeny really only focussed on the origins of the hemichordates (shown below), shifting them from being basal to the chordates, to being a more closely related sister taxon of the echinoderms. As you can see, that still maintains that nice, convenient transition from the more primitive and squishy sea squirts, through Amphioxus, up to us and the other vertebrates.

[Click to enlarge]

Not anymore.

A paper published in this last week's Nature throws some quite serious spanners into the classical works of deuterostome phylogeny. The researchers, Delsuc et al. (Delsuc interestingly held a post-doctoral position in Massey Univerity's Allan wilson Centre for Ecology and Evolution) used 146 common genes from 14 different deuterostomes to really hammer out the relationships between the groups. The results below are quite profound (ignore the black bits, just focus on the bottom coloured bits).

[Click to enlarge]

Essentially this provides two fundamental shifts:

Firstly, the urochordates are placed as the sister group to the Vertebrates, supporting a previously hypothesised clade called Olfactores. What this phylogeny implies is that we are more closely related to the sea squirt we are desperately trying to get rid of in Auckland Harbour than we are to Amphioxus. Now, this may not sound very important to some of you, but for anyone who has done even some basic evolutionary study, it means everything that we assume about the evolution and appearance of the vertebtrates, this gradual appearance of more 'vertebrate' features via the cephalochordates could quite possibly be absolute shite. Ipso facto, our (perhaps conceited) grouping "Euchordata" or "True chordates" could also be absolute shite.

Secondly, The cephalochordates are not only not directly basal to the vertebrates, they are actually placed as the sister group to the echinoderms in their own clade. Although the authors point out that this particular grouping doesn't have the statistical robustness as the urochordate-vertebrate grouping, it is nonetheless a rational interpretation of their data. This completely disrupts the "Chordata" group. From a systematics point of view, a lineage name applies to a common ancestor and all it's living and non-living descendants. Given that the chordates are now distributed all over the show (that is, they are polyphyletic) the term "chordate" may not, evolutionarily speaking, mean a hell of a lot. Unless of course we lowered the bar, if you will, and classified echinoderms (and by default hemichordates) as chordates. This naturally, is not likely to happen, because then basically we would be renaming all of the living deuterostomes as chordates. And that just won't do. No it won't. These two shifts can be seen in the simplified cladogram below.

[Click to enlarge]

This is the beauty of the tension that often arises between traditional morphological cladistics, or grouping organism relatedness based on overall similarity of body form and the sharing of structures, and that of molecular systematics - using genes to work out the same thing. Often they do come out with the same answer, but many times they don't. It's incredibly exciting when a study like this comes out, and challenges our assumptions about our 'knowledge' of morphological systems.

Perhaps more exciting than the actual repositioning of taxa within the deuterostome phylogeny is the implication for what this repositioning means for the evolutionary history of the deuterostomes themselves. The classical view suggests a steady aquisition and appearance of more 'vertebrate' like features through the lineages, with the cephalochordates representing the penultimate innovation before the appearance of the first vertebrate fish about 470 million years ago. Conversely, the echinoderms are seen (along with their sister group the hemichordates) as some bygone era of deuterstome evolution, a weird and wacky cousin that doesn't quite fit. Similarly, the urochordates, with their sessile habit and (apparently) simple body plan are seen as the primitive precursors to the euchordates.

According to the new study, however, both of these taxa can be viewed as highly advanced and derived lineages, which extensively modified the ancestral deuterostome body plan to become the forms that we see today. In the echinoderms an internal calcitic skeleton developed, along with radial symmetry and a particularly unique mode of locomotion, in the urochordates, the complete loss of the notochord in at least one sublineage, unique genetic simplicity and a lazy, squishy way of life.

And what of that ancestral body plan? The researchers suggest that the last common ancestor of the living deuterostomes may be far closer to Amphioxus than previously imagined - free living, bilateral symmetry, well developed metamerism (segmentation), distinct gill slits, and a pretty well organised brain and dorsal central nervous system. Essentially, all of these features that we assumed appeared just before we did may actually be the most ancestral, the most basic condition, Further those forms we assumed to be 'primitive' and distantly related are in fact extreme modifications of that basic body plan, bizarre yet equisite examples of evolution and adaptation, and in the case of the urochordates, closer to us in evolutionary time than we had ever imagined.