Name that gene

In my previous post I responded to Mr. Egnor’s assertion that he had asked me a scientific question when he asked “What is a human embryo?”, pointing out that if it was a scientific question it was a poorly worded one that required refined operational definitions if it was to be answered. Furthermore, answering the question is not a scientific proof of what is or is not ‘human’ but simply an affirmation of what does or does not meet the operational definition of ‘human’. Lastly, after coming up with a workable operational definition Mr. Egnor castigated me for attempting to clearly define what is being asked, even though I essentially agree with his answer to the above question. It really is a sight to behold; you should go back and read it.

In this post I respond to the remainder of Mr. Egnor’s assertions. But let us start with the humble car. What is a car? Well let’s try this out for for a definition.

Car - A wheeled platform structure supporting an engine with the ability to transfer energy to the wheels such that the structure can move forward.

Let’s not get caught up in particulars about what the car is made out of, etc. It is a mode of transportation; that is the function that defines it. So what happens when you park the car in the driveway? Does it cease to be a car? The car is only temporarily immobile, you might say. But then on the assembly line the raw materials are only temporarily immobile. The car in my driveway was mobile before I parked it, unlike the raw materials on the assembly line, you might assert. By that criterion the hunk of metal at the junkyard is still a car, because its past mobility, not present or future mobility, is decisive. But you might assert that past and future mobility, not present mobility, is what makes it a car. Then mobility is an odd criterion for a car if it is always irrelevant to the object in question now.

So it is clear that a car cannot be defined by it’s ability to move around, since that is only a temporary function. Now, I have used my car for many things (1), but moving around I would say is the primary function of my car. It would therefore seem ludicrous to not define a car by its ability to move around, even if it does not do so continuously. If you do not, and you define it by the raw materials that make up its parts, then the parts at the factory, the metal at the junkyard, the iron in the mine and even a recycled steel girder are all ‘cars’. But according to Mr. Egnor’s logic, this is not ludicrous at all. Here you see him using this argument:

...is our humanity diminished in sleep? … But the napping adult is only temporarily non-rational, Tantalus might assert. The gestating embryo is only temporarily non-rational, I would reply. But a napping adult was rational before the nap, unlike the gestating embryo, Tantalus might assert. I would reply that by Tantalus' criteria a corpse is fully human, because past rationality, not present or future rationality, is decisive. But Tantalus might assert that past and future rationality, not present rationality, is what makes us fully human. I would reply that rationality is an odd criterion for humanity if it is always irrelevant to humanity now.

I would love to sit in on one of Mr. Egnor's classes. If a transient function is of little use in defining an object, just how does he go about teaching his med students what defines a neuron? Does he go on and on about voltage gated sodium channels and dendritic morphology and never once say 'Oh yeah they also have this tendency to periodically fire action potentials which makes it different from just about every other type of cell in your body'?

It’s not so much that this is bad reasoning that bothers me. It is the fact that Mr. Egnor is arguing against something I didn’t even say. Here is the definition I gave for human:

Human - An individual Homo sapien with certain cerebral abilities believed to be unique to Homo sapiens including, but not limited to, abstract thought, language, and reasoning.

I must ask, when you sit down, do you lose your ability to walk? I know that you aren’t walking, but presumably if you stand up you won’t have to learn to walk all over again. It is reasonable to presume you still have muscles, central pattern generators, and a cerebellum that will allow you to walk. When I park my car, it is reasonable to assume that if I turn the key it has the ability to start again. When an adult is asleep, it is reasonable that when they wake up they will have the ability to carry on a conversation. However it is unreasonable to presume that an embryo has such an ability, just as it is unreasonable to presume a dead person retains such abilities. If I had said that an adult needs to constantly be rational to be fully human, he may have had a point, though a poorly thought out one. But I didn’t. So not only is it bad reasoning, it is a misrepresentation of my views.

Which brings me to a further point, and one on which I will give Mr. Egnor more slack. Here is my definition of human again;

Human - An individual Homo sapien with certain cerebral abilities believed to be unique to Homo sapiens including, but not limited to, abstract thought, language, and reasoning.

By using the phrase ‘including, but not limited to’ I meant ‘here are some examples, not requirements’. In rereading it, I see how one might be confused by my wording into assuming that I was giving a list of requirements. I thought I was clear but, as they say, it isn’t the reviewer's fault for being confused it is the writer’s fault for making it confusing. I have amended my previous post to make it so. So when Mr. Egnor goes on about how I might define a neuroscientist as more human than a taxi driver he is misrepresenting my assertions, but the fault was mine not his. Mea culpa. If it wasn’t clear before, then what I said in the comment section of an earlier post should make it so.

(Commenter) "At what point does a human child have enough of these abilities to be a human, and thus afforded the rights of a human?"
(Tantalus) You would be surprised by how many of these abilities children have, even at a few weeks after birth. If you are interested, I would suggest reading Gopnik et al. "The Scientist in the Crib". But, as I said, there is a lot of gray area here.

So, I’ve set a pretty low bar for the application of the term 'human' to an individual Homo sapien. I am not averse to revisiting my operational definitions if it appears they contain flaws and altering them appropriately. That is an assumed part of discourse.

Speaking of operational definitions, it is still difficult to get one from Mr. Egnor for the term 'human'(2). I offered the following one and welcomed Mr. Egnor to change it. Since he hasn't, it is all I have to go on:

Human -an individual, from the moment of fertilization on, with genomic content common to the hairless, social great ape originating on the planet Earth and endowed with certain rights by virtue of being a member of said species

Now I did raise some issues with this definition, one of which, the development of twins, Mr. Egnor responded to specifically and four of which he ignored.

Tantalus proposes several other philosophical dilemmas (genetic alterations, taking cells from frozen embryos, cloning, etc), none of which have any particular relevance to status of a human embryo as a human being. Hypothetical stories about chimeras and clones are irrelevant to the biological fact that human embryos are human beings.

This is an entirely new tack on scientific and philosophical endeavours! It is 'irrelevant' to define a term before we apply it. This will be great news to those who depend upon 'water memory' and 'qi' for their clinical practice.

Mr. Egnor may not want to think about these examples, but they get at the heart of how he defines 'human'. If his definition of 'human' is to have any utility it needs to be well defined. Also, to have utility in the taxonomic sense, it needs to apply not only within the development of the individual, but across individuals from different species. Mr. Egnor defines a human as a Homo sapien from the moment of fertilization until death and that it is abundantly clear what is and is not a Homo sapien, that is 'human'. That's all fine and good. But if I gave him a zygote from each of they great apes, how would he determine which is 'human' and which is 'not-human'?

Certainly not by morphology, they are virtually indistinguishable in that regard. Even if they are, it is conceivable to transfer nuclei and have DNA from one ape in the cell of another. Not by the number of chromosomes, unless Mr. Egnor is prepared to claim that muntjacs are human and Homo sapiens with chromosomal abnormalities are not. If he is clever, Mr. Egnor might claim the mtDNA is different and that is the marker. Then he would have to hope that scientists aren't able to transfer mitochondria between species (3). No, Mr. Egnor has made it clear that the definition of 'human' is predicated upon the union of 23 and 23 chromosomes. In his definition, genetic content defines the human.

Let's include the genetically altered zygote I discussed earlier. Mr. Egnor tries to hand wave his way out of this scenario too:

The taxonomy of ... human-mouse chimeras will be an interesting question if such science ever becomes reality (I pray that it won't ), but I point out that the mere concept of ... 'human-mouse chimera' presupposes that ... the human embryo to be fused to the mouse embryo is .. human.

I wasn't talking about chimeras (4). I was talking about altering the genes itself. So the question remains unanswered. If the genetic content itself is altered, at some point it will be so altered that the embryo can no longer be defined as being 'human'. What is that point?

Let's also say some industrial young scientist has managed to insert the Homo neanderthalensis 46 chromosome genome into a zygote. It cannot be classified as a 'human', if I am to understand Mr. Egnor's definition correctly (5). Let's say such a zygote develops into an adult, learns English, passes the Turing test, and in most ways is able to behaviourally integrate with society. How are we to treat such an individual? We certainly wouldn't think it was ethical to treat this individual as something other than 'human'. But his genetic code is different, so he must not be 'human'. So, by what metric will Mr. Egnor determine that the neanderthal is 'not-human'? He may try to hand wave again and say that the neanderthal is not endowed with 'humanity' but with 'neanderthality' which entitles him to all the same rights as an individual with 'humanity'. Essentially this argument would be there are 'human persons' and 'non-human persons'. But then we would arrive back at the same problem. What is the thing that confers 'neanderthality' on an individual H. neanderthalensis in the same sense that there is something that confers 'humanity' on an individual H. sapien? The answer, using Mr. Egnor's reasoning, is inescapable. Differences in genetic content draw a strict taxonomic demarcation between 'human' and 'not-human' (6). Now, it might be a cluster of genes, but that seems a little wishy washy as one individual might have some variants of one while another has variants of another. And one thing we know, the demarcation between 'human' and 'not-human' is concrete. So it probably comes down to one gene. All right.

Name that gene.

Either you have the gene, and you are 'human'; or you don't have the gene, and you are not (7). This will revolutionize the field of bioethics! We can simply get a cheek swab from everyone on the planet and quickly determine who is worthy of the title 'human'. Of course you have that messy problem of gene variation and single nucleotide polymorphisms, but we shouldn't let that stop us. Just take the most prevalent variant and reject the rest. After all, you must be human or not. There are no shades of grey.

Bring back some lingonberry jam from your trip.

(1) Not that. Oh, you people have dirty minds. By the way, this is where someone might argue that Mr. Egnor was talking about the 'gain of irrationality' which is different from the 'loss of rationality' and therefore the car analogy fails. Splitting hairs I think, but moot since he is arguing against something I didn't say.

(2) He may have given it elsewhere, I don't have the time to search all his articles. If he has he is certainly welcome to reiterate it.

(3) Which they have been doing for quite some time.

(4) "...if such science ever becomes reality... " Psst. I hate to tell you this Mr. Egnor, but human animal chimeras been a reality for a few decades now.

(5) It appears that Mr. Egnor is using an essentialist approach to defining a species, which certainly is novel since people haven't used that approach since ... well never.

(6) Yes, the irony that Mr. Egnor, who decries materialistic explanations, is defining 'human' in about the most materialistic manner possible is not lost on me.

(7) I do realize there are several genes that appear to be unique to our species. Some of those genes have already been inserted into the genome of mice though, and I don't think anyone is rushing to call those mice 'human' because of that.