Growth limit

What keep plants and animals from growing out of all proportion in size.
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus? Just DNA?



--
LSMFT

I look outside this morning and everything was in 3D!

On Sep 30, 12:04*pm, LSMFT wrote:
What keep plants and animals from growing out of all proportion in size.
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus? *Just DNA?

I'd say *gravity*. They could still grow, but gravity made it a
disadvantage to be too big. The good old square-cube law.

John Savard

On Sep 30, 2:45*pm, Quadibloc wrote:
On Sep 30, 12:04*pm, LSMFT wrote:

What keep plants and animals from growing out of all proportion in size..
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus? *Just DNA?

I'd say *gravity*. They could still grow, but gravity made it a
disadvantage to be too big. The good old square-cube law.

John Savard

Also, when you get too big, the blood pressure required to pump blood
around efficiently becomes too great for a cellular structure to
handle. And nerve impulses don't travel fast enoough for, let's say,
a 20-story-high Godilla to control his body. The giant sauropod
dinosaurs that stretched over 130 feet were probably as long as any
animal can ever get.

Matt Bille

On Sep 30, 2:04*pm, LSMFT wrote:
What keep plants and animals from growing out of all proportion in size.
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus? *Just DNA?

--
LSMFT

I look outside this morning and everything was in 3D!

Growth control Is designed into their genetics.

LSMFT wrote:

What keep plants and animals from growing out of all proportion in size.
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus?

On the land it's the square-cube law. An animal twice as tall has to be
eight times as heavy. It's also why a tiny ant can carry many times its
own weight. Consider that humans with giantism keep growing and growing
until their heart can't take the hold so they die of heart failure.

Check Larry Niven novels for trees genetically engineered to grow rocket
boosters. They had to become an entire patch to be able to make a
multi-stage seed launcher.

Just DNA?

Not just, but the DNA has to reflect the limit. Grow too big to work
and you don't live long enough to have enough offspring.

Doug Freyburger wrote:
LSMFT wrote:

What keep plants and animals from growing out of all proportion in
size. Why not trees larger than the Sears tower. Animals larger that
Brontosaurus?

On the land it's the square-cube law. An animal twice as tall has to
be eight times as heavy. It's also why a tiny ant can carry many
times its own weight. Consider that humans with giantism keep
growing and growing until their heart can't take the hold so they die
of heart failure.

Check Larry Niven novels for trees genetically engineered to grow
rocket boosters. They had to become an entire patch to be able to
make a multi-stage seed launcher.

Just DNA?

Not just, but the DNA has to reflect the limit. Grow too big to work
and you don't live long enough to have enough offspring.

And it's more than just square-cube law. It's food or energy available.
There's a well known effect (island effect) that basically says the bigger
the area, the larger things will grow. Or in reverse, if you take elephants
to a small island, over time if they don't go extinct, they'll select
towards a smaller size that can feed more effectively.

So I'd say it's sort of like the chicken and the egg. The DNA won't let
things grow to large because DNA that does gets selected against.

For example with a tree, if the DNA selects for a tall redwood in an area
that has constant fires or flooding or other damage, they'll probably never
grow to maturity and hence never have offspring that can grow. So they'll
select for faster growing trees that mature faster and can have offspring
faster.

Remember, the real "goal' of life is to perpetuate the genome, not the
carrier.


--
Greg Moore
Ask me about lily, an RPI based CMC.

On Sep 30, 7:27*pm, Matt wrote:
On Sep 30, 2:45*pm, Quadibloc wrote:

On Sep 30, 12:04*pm, LSMFT wrote:

What keep plants and animals from growing out of all proportion in size.
Why not trees larger than the Sears tower. Animals larger that
Brontosaurus? *Just DNA?

I'd say *gravity*. They could still grow, but gravity made it a
disadvantage to be too big. The good old square-cube law.

John Savard

Also, when you get too big, the blood pressure required to pump blood
around efficiently becomes too great for a cellular structure to
handle. *And nerve impulses don't travel fast enoough for, let's say,
a 20-story-high Godilla to control his body. *The giant sauropod
dinosaurs that stretched over 130 feet were probably as long as any
animal can ever get.

And for endotherms, ever larger resources for cooling .. elephant
ears, frex.

/dps

Greg D. Moore (Strider) wrote:

And it's more than just square-cube law. It's food or energy available.
There's a well known effect (island effect) that basically says the bigger
the area, the larger things will grow.

Blue whales live in the oceans. Oceans are big. So are whales.

Or in reverse, if you take elephants
to a small island, over time if they don't go extinct, they'll select
towards a smaller size that can feed more effectively.

Catalina Island off Los Angeles apparently had a breed of pygmy
mastadons that took a long time to go extinct.

On 9/30/2010 6:27 PM, Matt wrote:

Also, when you get too big, the blood pressure required to pump blood
around efficiently becomes too great for a cellular structure to
handle. And nerve impulses don't travel fast enoough for, let's say,
a 20-story-high Godilla to control his body. The giant sauropod
dinosaurs that stretched over 130 feet were probably as long as any
animal can ever get.

They just found out that the dinosaurs may have had massive cartilage
between their leg joints that helped take up the impact of moving such a
great weight around:
http://www.sciencedaily.com/releases...0930171418.htm
Of course, how centralized a Sauropod's nerve system was is open to
debate; a Diplodocus was over 100 feet long, yet had a brain the size of
a kitten's.
The whole creature may have operated on almost pure instinct and
automated responses to stimuli; just like the way that you pull your
hand out of a fire without thinking about it.
The signal to do that comes from your spinal cord, not your brain.

Pat

On 10/1/2010 7:28 AM, Doug Freyburger wrote:

On the land it's the square-cube law. An animal twice as tall has to be
eight times as heavy. It's also why a tiny ant can carry many times its
own weight.

Of course that implies that the whole body is completely solid and full.
If it has an internal gas-filled void, then the creature can be quite
large and yet still have a pretty low mass (check out the book "The
Flight Of Dragons" for a really fun take on this; the reason dragons can
fly with their small wings is that they are full of hydrogen gas like
living dirigibles)
A good real-world case is the Giant Squid; although it can get up to
fifty feet long end-to-end (mostly tentacles) it only weighs around
300-400 pounds once out of the water as so much of it is the normally
water-filled hollow mantle.
I always though someone put some thought into the design of the Shadows
out of Babylon 5, as you will note that their arms and legs use detached
musculature to cut down the weight of the exoskeleton:

Pat