Post by cjm on May 13, 2015 7:28:13 GMT
This will make Richard Dawkins shudder.
phenomena.nationalgeographic.com/2015/05/12/reversing-bird-evolution/
Scientists have long known that a single gene can have several effects on an animal. This multi-tasking is called pleiotropy. The new experiment hints that the bird beak didn’t evolve simply through a series of little steps, each having a single effect on bird heads. Instead, birds might have taken some bigger evolutionary leaps.
Scientists have long known that a single gene can have several effects on an animal. This multi-tasking is called pleiotropy. The new experiment hints that the bird beak didn’t evolve simply through a series of little steps, each having a single effect on bird heads. Instead, birds might have taken some bigger evolutionary leaps.
Richard Dawkins: The Blind Watchmaker, Norton, pp 43-49
CHAPTER 3
ACCUMULATING
SMALL CHANGE
We have seen that living things are too improbable and too beautifully
'designed' to have come into existence by chance. How, then, did they
come into existence? The answer, Darwin's answer, is by gradual, step-
by-step transformations from simple beginnings, from primordial entities
sufficiently simple to have come into existence by chance. Each success-
ive change in the gradual evolutionary process was simple enough, rela-
tive to its predecessor, to have arisen by chance. But the whole sequence
of cumulative steps constitutes anything but a chance process, when you
consider the complexity of the final end-product relative to the original
starting point. The cumulative process is directed by nonrandom
survival. The purpose of this chapter is to demonstrate the power of this
cumulative selection as a fundamentally nonrandom process.
…
There is a big difference, then, between cumulative selection (in
which each improvement, however slight, is used as a basis for future
building), and single-step selection (in which each new 'try' is a fresh
one). If evolutionary progress had had to rely on single-step selection, it
would never have got anywhere. If, however, there was any way in
which the necessary conditions for cumulative selection could have
been set up by the blind forces of nature, strange and wonderful might
have been the consequences. As a matter of fact that is exactly what
happened on this planet, and we ourselves are among the most recent,
if not the strangest and most wonderful, of those consequences.
...
CHAPTER 3
ACCUMULATING
SMALL CHANGE
We have seen that living things are too improbable and too beautifully
'designed' to have come into existence by chance. How, then, did they
come into existence? The answer, Darwin's answer, is by gradual, step-
by-step transformations from simple beginnings, from primordial entities
sufficiently simple to have come into existence by chance. Each success-
ive change in the gradual evolutionary process was simple enough, rela-
tive to its predecessor, to have arisen by chance. But the whole sequence
of cumulative steps constitutes anything but a chance process, when you
consider the complexity of the final end-product relative to the original
starting point. The cumulative process is directed by nonrandom
survival. The purpose of this chapter is to demonstrate the power of this
cumulative selection as a fundamentally nonrandom process.
…
There is a big difference, then, between cumulative selection (in
which each improvement, however slight, is used as a basis for future
building), and single-step selection (in which each new 'try' is a fresh
one). If evolutionary progress had had to rely on single-step selection, it
would never have got anywhere. If, however, there was any way in
which the necessary conditions for cumulative selection could have
been set up by the blind forces of nature, strange and wonderful might
have been the consequences. As a matter of fact that is exactly what
happened on this planet, and we ourselves are among the most recent,
if not the strangest and most wonderful, of those consequences.
...