Controversies make it interesting in biology

 

George Williams

 

 

 

George Williams is a marine biologist and zoologist. He probably was a 'sociobiologist' long before anyone had heard of that term. In Adaptation and Natural Selection (1966), his famous final line on the theory of natural selection was: "I am con­vinced that it is the light and the way". He is now Professor Emeritus at the State Univer­sity of New York at Stony Brook, where the following interview took place on March 21, 1997.

 

Have you been a biologist all your life?

 

As a child I was very much intere­sted in different sorts of natural history and that sort of thing, so I got started in that direc­tion. One of the things I did in college was take a course in evolution by a really outstanding evolu­tionary biolo­gist, named Ledyard Stebbins, a botanist. Even more exiting than Stebbins himself was the textbook he used, "Genetics and the Origin of Species" by Dobzhansky. I found that a real revela­tion. That was the first time in my career that I got exposed to biological contro­versies. It was not just something to learn and to remem­ber, it was something to worry about, try to figure out.

Come to think of it, there was an earlier influence of that sort. In the summer of 1947 I spend several weeks with a group from the university of California digging fossils in the desert. In the evenings we would sit around the campfire and talk about evolution, and its controversies and problems. Not as any kind of formal instruction, but just as that sort of thing people were intere­sted in and that came up for discussion. I think the idea of contro­versies is what really makes it inte­resting in biology.

 

Thirty years ago you criticized some ideas in biology.

 

I think that my main criticism was directed at the general assumption that adaptation characterises populations and species, rather than simply the members of populations and species. What I did was try to establish the general rule that natural selection works at the individual level, and adaptations that are produced are adaptive for those individuals, in competition with other individuals of the same population, rather than any collective sense for the popula­tion as a whole.

 

In this perhaps even today the major misunderstanding about evolution­ary theory; the idea that something exists because it is good for the species?

 

Yes, I think that is still a rampant fallacy among those who have not been brought up in the last few decades in evolutionary biology.

 

Individual selection would mean that living organisms are not adapted to prevent the extinc­tion of their own species.

 

That is right. Lets say that there is no very impressive machine­ry there that seems to be designed to prevent extinction. Most evolving lineages, human or otherwise, when threatened with extinction, don't do anything special to avoid it. I presume that the last pair of passenger-pigeons, which was a once very abun­dant bird in North America, now extinct, reproduced the same old way. Once the species had gotten extremely rare, it did nothing new and did not take any special measures, the way an indivi­dual would if threatened with death.

On the other hand, we humans in fact have not gone extinct as yet; many of our relatives have, so I would presume that to some extent the human biology is biased in favor of attributes that are less likely to extinction. One thing I think that most people would agree on is that we retain sexual reproduction. This is a compli­cated process that is occasionally lost, maybe lost in such a way that there is no immediate disadvantage.

As a general rule, in plants and in everything else, once you have lost the sexual process, nothing apparently ever comes from that line of descent. They don't branch into several new species the way a sexual species might. So apparently a-sexual reproduc­tion exclusively in any line of descent is a dead end. If there has ever been a mammal that reproduced a-sexually, it is not around any more and has no descendants.

 

If selection works at the individual level, why don't indivi­du­als live forever; why do we grow old?

 

Well, no matter how fit you keep yourself, sooner or later something will get you by accident: a new epidemic, an attack by terrorists, or an automobile accident, whatever. Even if you had eternal youth, this would obviously not assure that you live forever. So the question is, once we attain our full youthful adulthood, why don't we just stay that way?

Suppose in fact we could do that, lets wave a magic wand, and suddenly we have eternal youth. In evolu­tion that would not be stable, because eternal youth does not abolish mortality. If half of us with this eternal youth managed to live to age one hundred, a quarter to age two-hundred, and one-eight to age three-hundred, and so on, this would mean that a mutation that would confer some slight advanta­ge in our twenties and thirties might well be favored, even if it causes us to drop dead at age three-hundred. Most people are going to spend time in their twenties and thir­ties and get the benefits of whatever that mutation does, but since only one-eight of the popula­tion is going to reach age three-hundred with this eternal youth that I have postulated, dropping dead then would be worth an advantage earlier in life. So the evaluation by natural selection of new genetic variability would be biased in favor of the earlier part of life-histories, and against the later part, until we had re-evol­ved to the kind of senescence we have now. Although maybe not as bad, because in the Stone Age human individuals probably were lucky to reach maturi­ty.

 

But I heard that sea-anemones may live forever, how is this possible?

 

The general rule is that anything that is passed on in reproduc­tion, does not undergo senescence. So things that can divide in two, and both halves go on, would ordinarily not have any deteri­orati­on with increasing age. You don't have the kind of trade-off that you have when there is something you can dis­card. We can discard our bodies, but our germ-cells are not necessarily coming to an end. We can pass them on in repro­ducti­on to people who in turn can pass them on in reproduction. So a-sexual repro­ducing organisms such as sea-anemones retain eternal youth for the same reason that our germ-cells retain eternal youth. I think it is the British biologist Tom Kirkwood who invented the term 'disposable soma'. If you have a disposable soma, that soma will undergo senescence. I you don't, it won't.

 

There are all sorts of wonderful adaptations, yet you write that natural selecti­on never designs new machinery. Why did you write this?

 

Because there is nothing in natural selection that looks ahead and plans ahead. All it can do is make use of variation that is present. Some things work better than others, and the ones that work better are the ones that tend to be preserved. And this is always preserved in relation to immediate circumstances, never preserved in order to facilitate anything in the future.

 

You also wrote that every organism shows features that are functional­ly arbitrary or even maladaptive.

 

The human body is just full of illustrations of what are really either arbitrary or in many cases quite unfortunate legacies from prior history. For instance our respiratory system. Way back half a billion years ago at least, some early vertebrate didn't have a respira­tory system, but it had a dige­stive system, that had at the front end a way of taking in water, and running it through a filter. That machinery turned out to be easily modified to facilitate respiration, to arrange some special mechanisms for exchanging gasses with the environ­ment when the organism got big enough that it actually needed that. Ever since then all descen­dent vertebrates have had the forward end of the digestive system and the forward end of the respira­tory system very much involved with each other. This manifests itself in the human body with a crossing of the two systems in the throat. So there can be, and frequently are, traffic problems there, the extreme being that you choke to death because you are trying to eat something. If you could re-design it, you would have comple­tely separated systems, or they would be connected in a way that doesn't require a crossing of the two systems.

 

Another seemingly maladaptive phenomenon: Why would a vital organ like the human male testis be outside the body, where it is quite vulner­able?

 

For some reason, sperm development has to be at a lower tempera­ture than that of the rest of the body. This is accomplis­hed by the somewhat external scrotal structure. This certainly is vulnerable, and I think an indication of this is that whenever mammals reproduce seasonally, and don't need to be producing sperm for much of the year, the testicles are retracted into the body, and only go into the scrotum during the breeding season.

 

But this sounds like an excuse: We don't know why testicles are outside the body, so it must be temperature.

 

Oh no, I think it quite obviously is temperature, because any time the testicular temperature is abnormally elevated, for instance by a high fever, sterility or defective sperm results.

 

Still, I think this sounds like making the theory irrefutable.

 

Well, if you are talking about the general theory, it is not refutable by any one study. No single observation like this is going to make users of some major theoretical set of ideas abandon these ideas. What does happen is that you use evolutiona­ry theory to make certain predicti­ons, and check on those predic­tions. More often than not they turn out not to work. So you go back to the drawing-board and try something else. You don't find the wrong ones being published in biological journals.

 

But aren't people justified in saying: Hey, there is a conspiracy going on of biologists who don't publish anything that is unfavo­rable to evolutionary theory?

 

The same bias affects engineers. They calculate that if they did something a certain way they would produce a better engine. They do it and try it out, and it turns out not to be better at all. So they go back and try something else. These are not things that get published in the engineering-journals. It is only the impro­ve­ments that get published. So I think evolutionary theory works the same way: Use it to generate expectations, and then check on them. If the expectations turn out as expected, then you have made a discovery which may in fact be something important.

Darwin based his theory on generalisations that were strict­ly empiri­cal. You can go out and see that organisms do vary, that variati­ons are inherited, and that every organism is capable of increa­sing its numbers in sufficiently favorable circumstan­ces. These are basic premises that can be checked directly.

 

Some people think that evolutionary theory and genetics are the same thing. Do you agree?

 

It is certainly not the same thing. An essential component of evolutionary theory is that there has to be such a thing as heredity; there have to be special resemblances between parents and offspring. And the mechanism that produces that resemblance is what the science of genetics works at. But if we find out how a certain structure is inherited there are many immediate ques­tions. If there are genes for ears, well then the question is: What good is having ears? Presumably we would not have these structu­res if they had not been selected for in evolution. Likewise the gene is there either because it was favored in evolution by natural selection, or at least permitted. In any case you have to explain why it is there.

 

I found in your work several references to Buddhism; do you have a special liking of Buddhism?

 

My readings on this sort of things is extremely limi­ted, but as a doctrine I think Buddhism is more compatible with the spirit of scien­tific inquiry then what you get in the Old Testa­ment. I think it is because of the explicit recognition in Buddhism that things are not naturally good. There is a lot of pain and suffe­ring in the world, and that is because that's the way the world is. And the way to overcome this is to live a certain way and have certain attitudes of to some extent resig­nation; well, resignation in the sense of don't let it bother you, don't be disappointed and discouraged when bad things happen. This as opposed to some Christian and Jewish traditions, in which everyt­hing is for the best to some extent, because it is God's will that things be this way. And if they don't seem right, well that is because we don't really understand. The Book of Job for instance, where no matter how many evils befall, you accept them and really don't admit that they are evil because they must have come from God. And opposing what God does is something that is stupid because God is so powerful. The absence of rebellion against God has nothing to do with God being good or wise or anything like that, but strict­ly because God is powerful, and you don't fight something when you are so much weaker than that which you would fight. I think the Book of Job is a really sick piece of litera­ture in that respect.

 

But didn't the conception of a powerful God enable Christians and Muslims to conquer large parts of the world? I never heard of victorious Buddhist armies. Buddhists seem so peaceful and introvert.

 

There is an outstanding example: Genghis Khan was a Bud­dhist. But I think you can always find an excuse for armed robbery or whatever it is, if you figure that the people you are robbing are undeserving and that you and your companions are the good guys; and you are good because God is on your side. Anybody can do that, and they always do.

 

Finally, are you a sociobiologist?

 

I am willing to be so labelled, but one of the problems with this sort of labelling is that the term is identified with one indivi­dual, - E.O. Wilson. And although I like him immensely and certainly admire him, I don't want to be labelled as a disciple of his. I think that calling someone a sociobiolo­gist does this to a certain extent, maybe much less so now than it would have twenty years ago. In general I think that scien­tists are not the kind of people who like to be considered anybody's disciple.

 

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