Would he have published half-baked ideas?
Darwin postulated natural selection while Lamarckism postulated that parts of our body that got used more would grow more adept, and that adeptness would be passed down to the next generation.
In his last edition, Darwin started to say that those parts which were more used would be more evolved. He could have been mistaken as getting nearer to Lamarckism, but that is hardly the case.
It is a simple case of cultural evolution working hand-in-hand with natural selection. One or two ancient giraffes with short necks found that they could get extra food by stretching their necks towards higher branches in the trees. Those around them started to follow this trend, and before you know it, everyone was doing the same.
Over generations, those with longer necks did better by getting more food, using the same strategy of trying to get food from the higher branches. So they produced more off-springs, and hence the appearance of long-necked giraffes.
Another example. In the midst of a primate colony, a baby was born with a larger head than most, and she killed her mother during child-birth because of that. This lady started using brains to get food instead of brawn. Her off-springs followed her example. Before you know it, a tribe of primates with the same survival skills had been formed. And so you get a branch of intelligent primates now knows an humans.
Friday, October 30, 2009
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5 comments:
Question: why do you post on two blogs? Are they suppose to have different purposes?
It was a funny image thinking of Darwin blogging !
Maybe blogspot is more the left-brained while the wordpress is more right-brained.
Each format / application has its pros and cons, and they inspire me to write differently!
Talk about irrational.
By the way, I've been asked this question thrice, and each time I came up with a different answer.
So maybe I don't really know why I do things this way, but I do know I like it this way.
There is a blog called "The Voyage of the Beagle" that is essentially a blog set up with the theme of Darwin blogging his journey on the Beagle. It's pretty rad.
Regarding the idea of "parts getting used more becoming more evolved", it isn't the Lamarckian sense. In animals, if an animal favors a part or appendage and future genetic change provides a beneficial change (i.e., an upgrade) to that appendage, the upgrade will flourish.
For example, early monkeys had already begun to rely more on sight than on scent by a great deal. Therefore, minor incidental upgrades to sight would have a monumentally more dramatic impact than minor upgrades to scent. The upgrades to sight would therefore flourish.
Human evolution itself is a lot more complex than simply being born with bigger brains. Early hominids had to develop strategies for reducing heat from their brain before their brain could actually start to develop and be efficient.
The current theory is bipedalism developed before brain size increase. Standing higher in the savanna gave them access to the blowing wind as a brain cooling mechanism (despite the obvious disadvantages of standing up out of the savanna grass, i.e., being a big target to predators).
The development of additional emissary veins also helped cool the brain. And, if you line up skulls from A. afarensis to H. sapiens and observe the amount of emissary veins, they increase dramatically at each step. As the brain got bigger, adaptations with more emissary veins were selected.
Ethinethin,
Thanks for all that enlightening information. Much appreciated.
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