How did giraffes grow such big necks?

Just saying interesting reading and I have an entire room dedicated to the giraffe....


I'm fascinated with them also.

when referring to these mutations don't think of it as yearly time but in generations. Lets look at the Galapagos Island tortises. all of these gus started off the same general body and hard top. each isalnd of the Galapagos isdland is a unique enviorment, the terrain, the vegetation, and foods. the tortises mutated over time to what was better suited traits, some have a shell (called a carapace) that allows the neck to reach higher, another island has a tortise with thicker mouth skin so it can eat cactus. all in all there are five or six varieties of the same tortise but each is unique to only that island's habitat. the finches (Darwin's favorite) are another example. while these little birds can fly to the other isalnds they dont, why? because over the years the mutations have made them fairly specific to the isalnd thay in habit, thicker bills for some, longer bills for others. all depending on the specific changes that benefited the population. All that this is a natural method of selective breeding. regarding humans, well we have mutated as well. first of all, we are classified as Homo sapien sapien we are the mutation that derived from Homo sapien one of the big differnces and most noticeable? we are bigger, we're taller, we have a slightly bigger cranium. so you see mutations are not all bad. mutation is nothing but a variance from the norm. sometimes for the bad, sometimes for the good.

However, apparently some of us haven't quite kept up with the mutation curve. i was in penis's sporting goods last night, looking for a shirt for a normal sized 17 yo and if he had arms as long as my legs, and a torso as thick as a redwood tree, we'd have had 1,000 shirts to choose from. an entire department there should be designated "MISSING LINK" :umno:
no shirt for you-- you normal, structurally-adapted mutated teenager. sorry.

Standstill? It only seems like that, due to the length of lifespans. Plus, it's really hard to put humans under a microscope and observe them for the length of time necessary to notice mutational change over generations. :)

I'm leaving this thread if anyone decides to bring in the influence of sexual dimorphism....

Not too hard to understand. There are recorded cases in the 19th century where animal coloring changed to adapt to the environment. In England there was a type of monarch butterfly. When the industrial revolution spewed out all its coal smoke and dust, the air and buildings got darker. The butterfly slowly adapted to the darker environment by having larger amnounts of dark/black coloring on its wings.
Interestingly, a Giraffe's neck has the same amount of vertebrae that we have. Personally, if you look at the big picture, perhaps the animals main source of food was a short bush. Over the years, to survive the giraffes, it started getting taller, the giraffes' necks became taller to get to the leaves. Just one thought.

I had forgotten the Monarchs of London. as for the plants changing in Africa hat is exactly what happenned, it went from being a dense forrest/woods to the Savannah. Which is also considered the main reason early hominids started to walk upright.

Bacteria are much simpler than mammals. I think the evolutionary effect of mutations is greatly reduced when you get to the really complex lifeforms. I'm sure there are a lot of mutations in humans, but they don't show up because it's a relatively small part. Let's say for the sake of example a mutation occurs in one of every 100 bacteria. That's one percent of the organisms will have the mutation. But in people, if one percent of your cells have a mutation that lets you withstand radiation, you won't be able to withstand radiation. But that one bacterium out of 100 will because it's a fully functional organism. For a mutation to have an extensive effect on a complex organism it would have to occur very early in life at the first few cell divisions.
I'm just going off of what seems logical to me - someone let me know if I'm incorrect.
You're mostly right actually...bacteria are single-celled organisms and are extremely prolific therefore mutations can be readily seen within a short period of time.
Concerning multicellular organisms such as humans, in order for them to acquire a mutation that is inheritable and is able to be passed down successively to the next generation, the genetic change has to occur during gamete formation (sperm and egg). Therefore the offspring that arises from the union will receive the new genetic trait in their makeup and may or may not, depending on whether the change is recessive or dominant, display the mutant phenotype. Note that the change is present in all the cells in the offspring since after fertilization, the cells that divide from the zygote are copies of one another (how they differentiate into the different tissues & organs of the body is a whole other complicated story on gene regulation).
Therefore your notion on a small percent of cells in the body having a mutation is incorrect concerning inheritable (germline) mutations (all cells will have the mutation...depending on the cell type, the mutation may be expressed visibly).
A mutation that occurs in cells other than the sex cells results in cancer.
The reason why mutations are sometimes not visible is because they are 'masked' by other dominant genes...hence they are recessive.