hezekiah jones

I have to assume Clutch was joking, and simply omitted a third symptom: death.

KC

In regards to woodpeckers, as has been pointed out by others, many species of birds use their beaks to probe for arthropods of various kinds, both in the soil and on rotten wood. This creates competition between those different populations for the same resources. Those birds with harder beaks can exploit harder surfaces in the search for food, thus easing competition on the usual places with other species. Of course, those who have hard beaks but soft skulls can't peck at trees for long, and eventually try elsewhere. But those with harder beaks and harder skulls can ease competition by specializing on the harder wood of trees. In return, the energy usually spent competing with others can now be invested in reproductive capacity, thus tending to spread the genotypes for harder bills, harder heads, and predilection for behaving that way. This reinforces changes in morphology, which often influences mate selection, thus building reproductive isoilation from other groups, and eventually leading to species that specialize in pecking harder wood.

Cheers,

KC

Synaesthesia

Apologist,
First of all, the notion that humans do not use all of their brain is false. ( <a href="http://faculty.washington.edu/chudler/tenper.html" target="_blank">http://faculty.washington.edu/chudler/tenper.html</a> ) If a part of the brain is not used, it atrophies and dies. You make a point in that the spread of myths about our brains is an indication that we are not using their full potential!

Our picture of the brain’s evolution will always be incomplete. That is the reality of historical sciences. However, it is quite clear that it will come into clearer focus as we better understand how the brain works today in relation to a massive but still growing body of fossil evidence.

There is serious consideration given to the idea that the ability to imitate could spawn a second replicator. Given that it’s strict independence of genes (due to horizontal transmission through human populations), it’s interests often but do not always coincide with the genes’.

An independent replicator could set up an environment which creates a strong selective pressure towards not just larger brains but restructured brains capable of a high degree of plasticity. It would explain the long period of vulnerability in human babies, quite unique in the animal kingdom and seemingly undesirable genetically.

[edited by scigirl to make the link easier to follow for us lazy people! ]

[ May 30, 2002: Message edited by: scigirl ]</p>

Kosh

Christian Fundamentalism?

Clutch

Mageth, Godless, hezekiah,

I guess that's the problem with posting on a board where it's not uncommon for genuinely crazy stuff to be sincerely written. Makes it hard to know what will count as frickin' obvious satire. I woulda thought my last post managed it, though!

Mageth

I thought surely he's joking? when I first read it, but the lack of any smilie or other indication gave me pause. And you're right, I see assertions at least as wacky every day, which definitely clouded my judgment on this one.

davidH

Just like to say something here;

When talking about a woodpecker.

You mention the word adapted here - now how exactly did that adaption take place?

Maybe I am wrong but I have seen this mentioned around a lot.

It's often assumed that if a bird pecks away at harder and harder wood it's beak becomes adapted to pecking harder - that is the case, but what is also assumed in many cases is that just because that bird has a harder beak - so will its offspring...hence leading to a variety of birds that can peck harder etc.
When in actual fact it is only the genes of the parent bird that determine what the beak of the offspring will be like.
The parent bird has only obtained a beak for hard wood by pecking at the wood and its body acting accordingly - but none of it's genes have been altered in anyway, so the offspring won't just obtain the characteristic of a hard beak - that the parent has worked to obtain.

You get what i am talking about? Unless there is an actual genetic change there will be no difference.
Only here would natural selection have to come into play - and it would only take the extreme of a hard beak so far, before an actual alteration of the gene or a new allele was formed.

Cause I have heard before that it was because the early human ancestors moved out into the plains from the forests to stand up right (though there is considerable debate about this since "upright" remains seem to have been found in forest regions)

But this standing up straight will not alter the skeleton genetically in anyway - so the offspring will still be born as the parents were - there will be no change.

Just wanted to bring that up cause I have seen it assumed time and time again in discussions.
=)

Godless Dave

He meant woodpeckers as a species had adapted, not individual woodpeckers. The birds who were born with a genetic disposition towards harder beaks and the other apparatus had an advantage.

Vorkosigan

Just wanted to bring that up cause I have seen it assumed time and time again in discussions.

Well, I've been on this board a year and have never seen anyone advocating Lamarckism. Are you sure you've been reading correctly?

The poster above was referring to the fact that in the competition for insects buried in tree bark, those birds with harder beaks had a competitive advantage, and were able to nurture more and healthier offspring, who had more and healthier offspring, and so on.

Vorkosigan

Dr.GH

DavidH,

Individuals don't evolve, populations do over the course of generations. Say that there are no birds able to make deep enough holes to get at some yummy beetle. Out of a population of a few hundreds of thousands of birds, there will be a few thousand with a geneticly wired bill that is just a fraction longer than the other members of the species. Out of the few millions of beetles, there are a few thousands that are sometimes not as deep in the wood. Those birds with just a slight bill length advantage are able to eat a few more beetles than any other birds in their species, and thay can take a few more beetles to their nest for their chicks. Those chicks will do better than the chicks of the shorter billed birds. Over hunderds of generations there are birds with very long bills. Capish?