evolutionary convergence Quotes

If you go to the octopus, and if you're not too squeamish, dissect it. You'll find that it has a camera eye which is remarkable similar to our own. And yet we know that the octopus belongs to an invertebrate group called cephalopod mulluses, evolutionarily very distant indeed from the chordates to which we belong.

I don't think an alien will be a blob. If aliens are out there they should have evolved just like us. They should have eyes and be walking on two legs. In short if there is any life out there then it is likely to be very similar to us.

The underlying reason for convergence seems to be that all organisms are under constant scrutiny of natural selection and are also subject to the constraints of the physical and chemical factors that severely limit the action of all inhabitants of the biosphere. Put simply, convergence shows that in a real world not all things are possible.

We know evolution happened not because of transitional fossils such as A. natans but because of the convergence of evidence from such diverse fields as geology, paleontology, biogeography, comparative anatomy and physiology, molecular biology, genetics, and many more.

Whenever we find, in two forms of life that are unrelated to each other, a similarity of form or of behaviour patterns which relates to more than a few minor details, we assume it to be caused by parallel adaptation to the same life-preserving function.

Once evolution gets a good basic design, it tends to throw away the variants and concentrate on the near-infinite diversity within that design.

Evolution in the biosphere is therefore a necessarily irreversible process defining a direction in time; a direction which is the same as that enjoined by the law of increasing entropy, that is to say, the second law of thermodynamics. This is far more than a mere comparison: the second law is founded upon considerations identical to those which establish the irreversibility of evolution. Indeed, it is legitimate to view the irreversibility of evolution as an expression of the second law in the biosphere.

The very large brain that humans have, plus the things that go along with it - language, art, science - seemed to have evolved only once. The eye, by contrast, independently evolved 40 times. So, if you were to 'replay' evolution, the eye would almost certainly appear again, whereas the big brain probably wouldn't.

The common ancient ancestor of mulluses and chordates could not possibly have possessed a camera eye, so quite clearly they have evolved independently. The solution has been arrived at by completely different routes.

Although elephants are far more distantly related to us than the great apes, they seem to have evolved similar social and cognitive capacities.

Humans are just barely intelligent tool users; Darwinian evolutionary selection stopped when language and tool use converged, leaving the average hairy meme carrier sadly deficient in smarts.