A paper discussed in an earlier post (Alford et al., 2005) relies for much of its justification on a series of papers by Thomas J. Bouchard and coauthors. An expansive claim for genetic heritability of all sorts of behavior and attitudes is found in Bouchard and McGue (2003). Frankly, the arguments made are even more disturbing in this paper.

Why disturbing? What is truly the harm in scientifically separating out the genetic and environmental influences on everything from social attitudes to "vocational interests"? The harm is that such papers serve no function other than to fan the flames of bigotry.

We are likely not yet at the crest of the pro-genetics wave. There are more and more studies being published which claim genetic bases for all sorts of traits (e.g. politics, aversion to new foods, obesity). One walks a precarious path interpreting the actual significance of this work for the general public, who is under the mistaken impression that scientists know far more about human genetics than they actually do. The mainstream media certainly tends to work more as a blunt instrument than as a nuanced filter of published scientific studies, happily being used by authors and journals who have a strong self-promotion agenda.

The straw man constructed by the pro-genetics crowd is that obviously genetic variation exists or we would all be the same. But of course it is biological significance of genetic traits that matters, not whether or not the variation actually exists. Even the most rigorous study that shows valid statistical significance for variation in a trait does not necessarily demonstrate biological significance - in fact, the huge sample sizes often used in these studies, which has the intended effect of increasing the chance of reaching statistical significance, undermine arguments for biological significance (see figs. 1 and 2). If it takes a survey of 10,000 people to detect a difference, then there is clearly so much overlap in the groups being compared that the authors should be hard-pressed to convince anyone that it matters. A slight fluctuation about the mean is much more likely to be amplified into statistical significance, although the direction it is significant is determined randomly. This was brilliantly demonstrated in a pair of papers about birth order and IQ.



Where do all the heritability estimates come from? For example, Bouchard and McGue report "heritability of IQ is about 50%." This of course is based on twin studies. But the logic used by all of these authors (none of whom I have encountered so far are actual geneticists) to produce such an exact value of genetic heritability is flawed. They make the assumption that if you compare differences in scores on surveys between fraternal twins with the differences between identical twins, that difference is the genetic component of the trait. This assumes that the environment in which fraternal twins are reared is as similar as the environment for identical twins. This assumption has naturally been both challenged and defended, but for the moment, let us concede it as valid. That leaves us with the corollary assumption that the difference between fraternal differences and identical differences is therefore entirely genetic. This is where the problems with these studies lie (discounting the obvious problems with using tests or surveys - which are biased by authors, affected by mood of the taker, etc. - to make sweeping statements about genetics).

Identical twins not only share a genotype, but also a phenotype - they look the same. As explained in the previous post on this topic, how you look is going to affect your social attitudes, not to mention self image, mostly because of your interactions with other people, who clearly behave differently to people who look different. Until a study is conducted in which one half of 30 identical twin pairs has a dramatically altered appearance (e.g. is in a wheelchair or has had major facial reconstructive surgery), all the twin studies (even those in which the identical twins were reared apart, long a mainstay of the pro-genetics camp) declaring the percent genetic contribution for any subjective phenotypic trait will be meaningless.

These papers harken back to the dark days of phrenology and craniometry - the methods employed are no more scientific, because we know no more about how genetics affects these traits now (more than mere speculation) than we did back then about how the brain functioned. But, the results are used by those who are racist or sexist to defend their views. All traits are a unique combination of usually complex genetics and environment. There is no way to establish that a person a particular "genotype" for intelligence or social attitudes, and even if there were, the expression of that trait will be dependent on the environment in complex ways that are not easily measured. Most important, because of the huge overlap in any trait associated with the brain across all types of people, for any given individual, there is no way to determine what part of their intelligence, personality, or skills are based on their appearance, even if there actually is a true statistical difference in these traits for different races or sexes (Fig 2.). But studies such as these are used by people who wish to have their stereotypes confirmed "scientifically," and frankly one has to wonder if the authors are not such people themselves.


References

Alford, J.R., C.L. Funk, and J.R. Hibbing, 2005. Are political orientations genetically transmitted? American Political Science Review, 99:153-167.

Bouchard, T.J., and M. McGue 2003. Genetic and environmental influences on human psychological differences. Journal of Neurobiology 54: 4–45.

Labels: environment, genetics, humans, statistics

The coqui frog Eleutherdactylus coqui, a native of Puerto Rico, gets its species name from the shrill call produced by males seeking mates, which is surprisingly loud for a beast the size of a quarter. Anyone from a part of the world with native tree frogs generally appreciates the lovely sound of calling peepers in the spring. Unfortunately, when the coqui was introduced to lands without its native predators to keep its populations in check, the lovely peeping sound in the distance was transformed into an overwhelming, piercing cacophony, which can be heard here at the site for Hawaiian Ecosystems at Risk (HEAR), where there is bountiful information on the hundreds of alien invasive species devastating Hawai`i's ecosystems. Listen to the recording. Then imagine playing it through your surround sound system at full wattage, and you will begin to get the idea of one of the problems caused by this species. After dusk, one literally has to yell to carry on a conversation at one house I have visited in Kurtistown (which lies between Hilo and Volcano on the Big Island).

Here is a youtube video of a single calling male. Well, puppies are cute too, but no one wants to live next to a kennel, do they? Even from a purely anthropocentric perspective, this invasive has much more direct effects on property values than any other. Control efforts are detailed at the University of Hawai`i College of Tropical Agriculture site.

While the attempted control of a tiny frog meets with far less opposition than previous plans to kill destructive feral cats in Volcanoes National Park, some PETA-types of course object. But even if you can tolerate the highly unnatural, deafening noise, anyone who cares about the ecological integrity of the Hawaiian Islands understands that coquis are a destructive pest that is incompatible with efforts to conserve endemic Hawaiian species (many of which are of course are living animals also).

Although predators in its native land clearly make an impact on coqui populations, it is remarkable how difficult it is, for humans at least, to localize a single calling frog. Apparently this is what the recent producers of smoke alarms were trying to emulate when they designed the system in which a dying battery causes the alarm to beep at long intervals. If your spouse, like mine, believes him- or herself to be the household's safety police, then you have about a dozen of these things littering your home, in every room. So, being able to find the one whose battery is dying is no trivial task. These contraptions strive to imitate the behavior of chirping frogs: as one attempts to hone in on the sound, they fall silent, in order to confuse and frustrate you, their predator.

As I have stalked around the second floor of the house, frozen for 30 seconds or more at a time, waiting for the next beep, my sympathies fall more into line with my father, who was decidedly not the Safety Monitor of our family. When smoke alarms first became available, my mother, whose very natural fear of house fires was grounded in personal experience, installed a single one in our split-level house. The first time it went off (the usual false alarm, of course, caused by kitchen smoke or whatnot) my father brandished a hatchet at the alarm, threatening over the excruciating whine to chop it to bits. Somehow my mother got the alarm away from him and turned off before he was able to make good.

My patience with the smoke alarms has run thin as well, every time I have to hurl one out the back door because my spouse insists on placing it in the kitchen, in defiance the manufacturer's instructions. "Ever heard of the smoke alarm that cried wolf?!!" I bellow.

But the Chinese-beeping-torture is the worst. I cannot move on with my life until I have ripped the innards from every alarm in the house, looking for the culprit, which is always the sixth or eighth one I've checked. My poor mother though, has seen the karma in her early support of smoke alarms. The Einstein who built the house she moved into several years ago placed a wired-in smoke alarm near the peak on the wall of their two-story living room, with only a narrow stair landing about ten feet below. Wired smoke alarms would seem like a better solution if they too did not have back-up batteries - after all, the power could be out when a fire starts. A note to contractors: even those batteries fail after several years - which my mother and her husband discovered when it started beeping - so, it would be a big help if those alarms were actually ACCESSIBLE! To get to this one required climbing a ladder placed on the landing at an alarmingly steep angle, a task most of us would rather not attempt, given our desire for the smoke alarm actually to save our lives, rather than end it. Thus, the residents had no choice but to wait two days for the services of their local fire department - who sent a fireman to make the climb and deactivate the alarm.

My mother called me shortly after the alarm had been firmly and permanently disconnected, and the haunted tone in her voice made me shudder at her recent trial. "It kept beeping..." she wailed, "Every. Twenty-six. Seconds." Though driven nearly to their wits end, their German short-hair pointer was clearly the most damaged of the three by the experience. Shortly after the beeping began he found the deepest recess of the downstairs guest room and burrowed within it, refusing to come out for anything but the quickest dash outside to relieve himself, after which he returned to his spot, trying, trying but (being a dog of very little brain) not succeeding in escaping the beeping torture. I witnessed his post-traumatic stress disorder on my next visit, when an inadvertent breaker pull caused one stray beep, and the terrified beast nearly knocked me over skidding to his designated burrow. Despite the fact that no more beeps were heard that night, the dog had to be crowbarred out of the corner of the room when I was ready to go to bed.

Really one of the stranger aspects of the low-periodicity beep torture is that it is not recognized as such by all vertebrates alike. Some friends, a family of four, invited us over for dinner once, and I noticed immediately upon crossing their threshold that they had a smoke alarm on the blink. I politely pointed it out to them, and astonishingly, the response I got was, "We know, it's been doing that for weeks now." Agog, I enquired with the grin frozen on my face, how they could stand it, and they just shrugged and said they didn't notice it after awhile. I tried to bear up under the strain, but by halfway through dinner I just couldn't keep myself from blurting out conversationally, "Wow, it's really amazing that the smoke alarm doesn't bother you." Being astute students of the subtleties of human communication, they finally got the hint, and one of them laughed as he went immediately to extract the offending battery.

I suppose that answers my question about why smoke alarms are programmed with predator-avoidance response. Those of us driven crazy by one are as likely to take a hatchet to it as a new battery (until we sigh to ourselves that maybe, just maybe it will save our lives one day), while the rest of everyone out there just can't be bothered to hunt them down (and may be selected out by unalarmed house fires). I just hope the people of Hawai`i have more success with accepting the grating chirp of the coqui than I have had with the grating chirp of a smoke alarm, because they will likely be there forever.

Labels: behavior, environment, humans, invasive species

My last post covered a paper that found brain physiological correlates of political attitudes. That paper did not address the origin of the physiological differences, i.e. whether they might be genetic or environmental. An earlier paper (Alford, J.R., C.L. Funk, and J.R. Hibbing, 2005. Are political orientations genetically transmitted? American Political Science Review, 99:153-167), though, does claim a genetic origin for particular suites of political attitudes. While authors acknowledge that on the surface this seems nonintuitive, they back up their case by citing numerous studies that other social attitudes have a genetic origin.

This is another example of a twin study being used to support genetic causes of differences among people previously assumed to be purely environmental. The survey data used were collected not as part of this study, but recycled from a previous study, and include the usual thousands of twin pairs, because these authors, like so many others, assume that more is better, when that is not in fact true. A weakness of the data set is exposed when they calculate a surprisingly high 40% heritability of educational attainment, without any mention of the demographics of the survey-takers. Could there be any correlation of socioeconomic and education level and the willingness to return an esoteric research survey? It seems likely, but there is no consideration here of the possible effect.

The authors are all political scientists whose paper, published in a political science journal, purports to teach other political scientists how genetics works. (One can't help but wonder how they would react to a bunch of biologists pontificating on a political topic in a biological journal.) It probably does not matter whether or not any biologists actually reviewed this paper; twin studies appear in plenty of biological journals as well.

All the arguments the authors make supporting their assumptions, come from other twin studies, which have the same methodological issues, stemming from the ethical impossibility of manipulating human phenotype and social environment. The most important assumption upon which the results are based is of course the one apparently made in all twin studies: correlation in survey scores between identical twins minus correlation in scores between fraternal twins equals "heritability" of the survey scores. The authors attempt to address the obvious criticism that identical twins are likely to have a more shared environment than fraternal twins by citing studies that assert this is not so. Of course, if a weak study is published, all those that rely on it are weak as well. The problem with all of these studies is that they fail to separate the effects of genotype vs. phenotype. This is the major criticism of "twins reared apart" studies - similarities between identical twins reared apart aren't automatically genetic, because they look the same (and often have similar mannerisms). Researchers seriously underestimate the importance of visual cues in affecting human interpersonal interactions. Hence, their social interactions will have a greater tendency to be similar even when they live in different environments.

In a similar vein, when the authors claim that a majority of political attitudes are genetic, do they honestly think this explains why black women are likely to be more liberal than white men? Clearly phenotype, which drives much life experience, is the important difference here, not genotype. The authors also do not address at all the fact that many peoples' political attitudes change over time, sometimes in an extreme fashion. Yet they assert with a straight face that when children have opposing political beliefs from their parents, it must be due to a genetic mutation. They actually even calculate a heritability for party affiliation at 0.14. Yes, 14% of your choice of party apparently is from those alleles for "republican" and "democrat" you have tucked away.

Oddly, considering the tone of most of the paper, the authors do manage to point out correctly (even going into some depth on the topic) that all people are a product of the interaction of their genotype with their environment. They seem to do this to bolster their point that political attitudes must be partly genetic, but the discussion shows that clearly they think genes are as important as the social scientists they are criticizing think environment is. They go so far as to express regret that the current polarizing political environment will not change because of assortative mating - those with overlapping political views are more likely to reproduce together (true), and thus the "political genes" of their offspring will make them more likely to be polarized. Then they go on to speculate about the evolution of these genes and their effect on society, as if they actually know something about how evolution works, after reading a few papers.

Looks like all of the people with Ph.D.'s in genetics and evolution just wasted their time. They could have had a different career and still published papers on the topic.

Labels: humans, politics, sociality, statistics