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We can make an educated guess though, right? They didn't evolve them quick enough, so were out competed by the giraffes, for example. I know you were making a m

We can make an educated guess though, right? They didn't evolve them quick enough, so were out competed by the giraffes, for example. I know you were making a more general point, but I just wanted to throw that in.

snovv_crash 5y ago
What about all the places where there aren't giraffes?
- Akronymus 5y ago
  Much faster conversion to savanahs, which resulted in not being able to adapt fast enough; no evolutionary pressures to evolve to be that tall; evolutionary pressures exists/ed but there were stronger pressures to not evolve to be tall, and similar reasons are what come to my mind.
z3t4 5y ago
Or giraffes find long necks (and other body parts) very attractive.
- Smaug123 5y ago
  That is a glib answer which misses the point entirely. Why do they find long necks attractive? The answer to that sort of question usually turns out to be "because animals who randomly happened to be a little more attracted to long necks were more likely to breed with the long-necked animals, so their genes became better represented in the gene pool thanks to the long-necked animals' better survival power".
  - gpm 5y ago
    Why do peacocks (or really peahens) find giant feather displays attractive? I think the answer is usually actually "because it is indicative of a healthy mate". If you need to be well fed and healthy to grow tall, or to maintain a giant set of ridiculous feathers, then it will probably be an attractive trait a few generations later, since it will predict success.
inglor_cz 5y ago
On the other hand, plenty of species developed fins and did not give up only because they were outcompeted by someone else. But the ocean is a big place. Tree tops in the savannah may not be as important resource.
gpm 5y ago
Moreover just glancing at Giraffe physiology shows us all the compromises that a long neck entails. For instance it's long neck traps a lot of air in it's breathing cycle, requiring larger lungs for the same oxygen capacity. It has twice the blood pressure of a human to enable pumping up the long distance, and as such a giant heart. It has a complex circulatory system to control the change of blood pressure at it's brain when it bends over, and handle the high blood pressure in it's legs. And so on and so forth.
im3w1l 5y ago
Adding to that. There used to be ~150k giraffes (recently their numbers are declining) divided amongst 4 giraffe species. So while the strategy of using a long neck to eat the high leaves is viable, it's not crazy successful. It's not "everything should get in on this".

snovv_crash 5y ago

What about all the places where there aren't giraffes?

Akronymus 5y ago
Much faster conversion to savanahs, which resulted in not being able to adapt fast enough; no evolutionary pressures to evolve to be that tall; evolutionary pressures exists/ed but there were stronger pressures to not evolve to be tall, and similar reasons are what come to my mind.

z3t4 5y ago

Or giraffes find long necks (and other body parts) very attractive.

Smaug123 5y ago
That is a glib answer which misses the point entirely. Why do they find long necks attractive? The answer to that sort of question usually turns out to be "because animals who randomly happened to be a little more attracted to long necks were more likely to breed with the long-necked animals, so their genes became better represented in the gene pool thanks to the long-necked animals' better survival power".
- gpm 5y ago
  Why do peacocks (or really peahens) find giant feather displays attractive? I think the answer is usually actually "because it is indicative of a healthy mate". If you need to be well fed and healthy to grow tall, or to maintain a giant set of ridiculous feathers, then it will probably be an attractive trait a few generations later, since it will predict success.

inglor_cz 5y ago

On the other hand, plenty of species developed fins and did not give up only because they were outcompeted by someone else. But the ocean is a big place. Tree tops in the savannah may not be as important resource.

gpm 5y ago

Moreover just glancing at Giraffe physiology shows us all the compromises that a long neck entails. For instance it's long neck traps a lot of air in it's breathing cycle, requiring larger lungs for the same oxygen capacity. It has twice the blood pressure of a human to enable pumping up the long distance, and as such a giant heart. It has a complex circulatory system to control the change of blood pressure at it's brain when it bends over, and handle the high blood pressure in it's legs. And so on and so forth.

im3w1l 5y ago

Adding to that. There used to be ~150k giraffes (recently their numbers are declining) divided amongst 4 giraffe species. So while the strategy of using a long neck to eat the high leaves is viable, it's not crazy successful. It's not "everything should get in on this".