I have mentioned before that the question of when life begins is a question of politics, not science, and today, I’d like to return briefly to this concept. Make no mistake — both an egg and a sperm are alive, and there is no time at which either stops being alive during fertilization. You and I are continuations of the same life that began several billion years ago. As “life,” we all began to exist at the same time.
Of course, this explanation is not satisfying to us when we’re discussing issues like civil rights or abortion. We want to know if a fertilized egg is a human. Typically, scientists shy away from such questions, but not for the reasons you might suspect. I’ll get to the explanation in a moment, but before I do, I want to quote one of the foremost authorities on embryology in the world, Lewis Wolpert.
“What I’m concerned with is how you develop. I know that you all think about it perpetually that you come from one single cell of a fertilized egg. I don’t want to get involved in religion but that is not a human being. I’ve spoken to these eggs many times and they make it quite clear … they are not a human being. ” — Lewis Wolpert
I am not usually fond of quoting authorities, but I feel like it’s important to let you see the context in which scientists consider such questions. As you read this quote, or watch the video on the linked page, you will note a sense of flippant dismissal. It’s as if Professor Wolpert is so tired of hearing the question that he’s dignifying it with an answer that it does not deserve.
So let’s just get this out in the open — scientifically speaking, a fertilized egg is not a human being. You have it straight from the mouth of a man who would know as well or better than anyone on the planet. I know some of you will want to object, but please save your objection until I’ve explained why this question really doesn’t matter.
We humans are very fond of dichotomies. We like things to be on or off, black or white, straight or gay, right or wrong. This predilection towards fixed boundaries is a result of the limits of our perception. We see things on a “macro” level, and we perceive time in terms of human lifespans. While it’s certainly helpful for us to see a particular collection of atoms as a tiger, it’s a bit of a hindrance when we consider abstract concepts which were not important to us in our evolutionary environment.
Yesterday, I made mention of the ring species Heron gull/Lesser black backed gull. This population of animals will make a very useful analogy for understanding the beginning of life. (Here, I am talking about the first, and only true beginning of life.) When we look at a Heron gull that is on the end of the ring, we can clearly see that it is all Heron gull, and not any part black backed gull. However, there is no line at which we can say with certainty that a heron gull has become a black backed gull. When we get to the other end of the ring, the animals we observe are most definitely black backed gulls. They are two distinct species, and they do not interbreed. The tricky part for our dichotomy-friendly brains is that there is no concrete dividing line. As we move around the ring, herons become more black-back-like, and at some point, had we not been aware of our intentional journey through “animal-space” we would say that a particular specimen “must be” a black backed gull because it doesn’t look at all like a heron gull. But this is a trick of our mind, not a function of reality.
The reality, paradoxical as it may seem, is that the entire group of heron/black backed gulls is a spectrum. In fact, perhaps visible light is a great example of this concept, since it’s something we’re all more familiar with:
We’ve all seen this, and we’ve all probably noticed that there is no clean divide between colors. If you look at the area in between orange and red, for instance, there is no point at which you are seeing red beside orange. We could draw a line exactly half-way between orange and red, and call that the “true” boundary, but the line is arbitrary. We call these colors “orange” and “red” because we like to put things in boxes. Our labels are handy for us because they allow us to speak intelligently of things like the orange wall or the red food coloring we used to make fake blood for a play. The reality, though, is that visible light is a continuous spectrum. We humans simply have no way to coherently consider it as such because we see things as discreet entities. That car is definitely green, and the sky is definitely blue.
Now that we’ve seen two examples of things that are definitely different, but lack specific dividing lines, we can get to the heart of the “origin of life.” Like light in a visible spectrum or birds in a ring species, life is a continuum, not an on/off switch. Difficult as it is for us to imagine, there was not a distinct moment when something that was previously “non-living” suddenly became “living.” If we were able to play a video of the origin of life at a superhuman speed so that we could watch a billion years pass in a matter of minutes, we would see the precursors of DNA (whatever they were — perhaps clay crystals) gradually changing in much the same way that heron gulls gradually change into black backed gulls. At some point in the film, we would realize that we were looking at “life,” but no matter how many times we rewound and replayed the film, we would never discover the exact moment that life began, anymore than we could discover the exact dividing line between herons and black backs. It’s true that life had a beginning, but it is not true that there was a moment at which life did not exist, and the next moment, life did exist. Like gulls or light, life has fuzzy edges. At some point, we must say that things are alive, but as we move backwards through time, all we can say is that things are less like life, until eventually, it becomes obvious that there is no life.
This concept extends to species, as well. As much as we might like to believe that mice, dolphins, E coli, and puppies are all distinct “kinds” of animals, the reality is that they, too, are part of a continuum. The difference, in most cases, is that all of the intermediate creatures are no longer alive. There is a continuous line of DNA stretching from humans to monkeys, but because of the process of natural selection, large chunks of it no longer exist. If you can imagine compressing time into a single plane, upon which we could lay out every single organism that has ever lived, there would be no gaps. Every species would meld into every other, and there would be no borders — only fuzzy edges of “between-ness.”*
Once we have grasped this concept of fuzzy borders, we can see why scientists typically refuse to answer the question of humanity. It’s not that the answer makes them uncomfortable or threatens their research. Instead, it’s because there is no hard, fast answer, and it’s very difficult to explain this to people who don’t understand science and want a dichotomy.
- Embryonic Development
Hopefully, you can see that the scientific answer to the question of humanity is that there is no answer to the question of humanity. We can look at a fully formed adult Homo sapienand say that it is a human, and we can look at a zygote and say that it is not a human, but like life itself, there is no unequivocable line before which a mass of cells is “non-human” and afterwards is “human.”
What impact does this have on the abortion debate? A lot, and none. It certainly puts some arguments against abortion rights on shaky footing, but anyone attempting to argue against abortion on scientific grounds is clearly not very familiar with science. Abortion rights are a question of politics, not of science, and no self-respecting scientist would take a hard position on when a fetus becomes human.
I began this entry with a quote from an authority, and I think it fitting to end it with one as well. I was inspired today by an entry in Pharyngula, so I will quote P.Z. Myers in the hopes that between my explanation and the words of two of the most qualified scientists on the planet, I will have laid this argument to rest at least in the minds of a few readers.
I’m saying that it is absurd to talk about a life beginning at conception because it didn’t begin then: the precursors to the zygote were also alive. The only “beginning” of life that we could talk about occurred a few billion years ago, and even that wasn’t discrete, but the product of a gradual progression from chemical replicator to functioning cell, a cline upon which there was no point where one could say that everything before was dead, and everything after was alive. Life is a very fuzzy concept. PZ Myers
* To be fair, there are such things as macro-mutations, like frogs with eyes in their mouths, and we cannot rule out the possibility that some speciation events were saltations, but it has been well argued that even if there have been odds-defying successful saltations in evolutionary history, they must have been incredibly unlikely anomalies, and would not be considered significant in any workable theory of natural selection.
Note: This post was originally written in March of 2009. So if you’re reading it thinking, “Hmmm… deja vu…” you’re not crazy. I’ve got hundreds of new subscribers and readers since then, and I think it’s important enough to repost from time to time. -HD