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There are several kinds of speculation about the origins of play: (a) The first holds that play originates as a mutation and therefore an amelioration of dangerous adaptational conJicts. According to John Allman in Evolving Brains, this play mutation constitutes a pre-existing genetic function. (b) Some scholars claim…
Since no one has succeeded in showing me what I'm missing, we're left with the second option: I'm just incapable of understanding. I'm certainly willing to grant that it may be true, though I'm afraid I'll have to remain suspicious, for what seem good reasons. There are lots of things I don't understand -- say, the…
Now, with respect to literature, authors are frequently faced with the task of re-explaining and restating background material that has been explained well elsewhere. If you could just borrow that material, those existing good explanations, and incorporate them (with automatic credit where due), your efforts could be…
[Motoo Kimura] has been the chief advocate of the neutral theory of evolution. The neutral theory says that, through the history of life from beginning to end, random statistical fluctuations have been more important than Darwinian selection in causing species to evolve. Evolution by random statistical fluctuation is…
For evolution, which knows nothing, the steps into novelty are blindly taken by mutations, which are random copying “errors” in DNA. Most of these typographical errors are of no consequence, since nothing reads them! They are as inconsequential as the rough drafts you didn’t, or don’t, hand in to the teacher for…
Cancer, we now know, is a disease caused by the uncontrolled growth of a single cell. This growth is unleashed by mutations—changes in DNA that specifically affect genes that incite unlimited cell growth. In a normal cell, powerful genetic circuits regulate cell division and cell death. In a cancer cell, these…
The body of an animal operates as a society or ecosystem whose individual members are cells, reproducing by cell division and organized into collaborative assemblies or tissues. In our earlier discussion of the maintenance of tissues (Chapter 22), our interests were similar to those of the ecologist: cell births…
Anybody who teaches human evolution is inevitably asked: Are we still evolving? The examples of lactose tolerance and duplication of the amylase gene show that selection has certainly acted within the last few thousand years. But what about right now? It’s hard to give a good answer. Certainly many types of selection…
We can even see the origin of new, ecologically diverse bacterial species, all within a single laboratory flask. Paul Rainey and his colleagues at Oxford University placed a strain of the bacteria Pseudomonas fluorescens in a small vessel containing nutrient broth, and simply watched it. (It’s surprising but true that…
But “laboratory” adaptations can also be more complex, involving the evolution of whole new biochemical systems. Perhaps the ultimate challenge is simply to take away a gene that a microbe needs to survive in a particular environment, and see how it responds. Can it evolve a way around this problem? The answer is…
It’s important to realize, though, that there’s a real difference in what you expect to see if organisms were consciously designed rather than if they evolved by natural selection. Natural selection is not a master engineer, but a tinkerer. It doesn’t produce the absolute perfection achievable by a designer starting…
Every animal and plant genome is subject to a constant bombardment of deleterious mutations: a hailstorm of attrition. It is a bit like the moon's surface, which becomes increasingly pitted with craters due to the steady bombardment of meteorites. With rare exceptions, every time a gene concerned with an eye, for…
In recent years the geneticists have turned away from good mutations and begun to think about bad ones. Sex, they suggest, is a way of getting rid of bad mutations. This idea also has its origins in the 1960s, with Hermann Muller, one of the fathers of the Vicar of Bray theory. Muller, who spent much of his career at…
We cannot expect to find a good child-machine at the first attempt. One must experiment with teaching one such machine and see how well it learns. One can then try another and see if it is better or worse. There is an obvious connection between this process and evolution, by the identifications Structure of the…