Evolution of ribcage

[Saber]

Evolution  has  mad  rib  cage  for  vertebrates for  protection of  lungs &  heart.....

 

Why  hasnt it made anything  to  protect  the  digestive system.........as   you  now  its as important  as  the  lungs and  heart........and if  damaged  the  animal  would die.......why  ahsnt  evolution  made anything to  protect  those  parts of the  body ?

 

Thanx

[Genady]

4 minutes ago, Saber said:

Evolution  has  mad  rib  cage  for  vertebrates for  protection of  lungs &  heart.....

 

Why  hasnt it made anything  to  protect  the  digestive system.........as   you  now  its as important  as  the  lungs and  heart........and if  damaged  the  animal  would die.......why  ahsnt  evolution  made anything to  protect  those  parts of the  body ?

 

Thanx

It did. Example: tortoise.

[Peterkin]

27 minutes ago, Saber said:

.why  ahsnt  evolution  made anything to  protect  those  parts of the  body ?

Economy. For animals that need to move, sometimes very fast, the weight of bones is a serious consideration. The brain gets most of the bony protection, because even a slight injury to the brain can be fatal. Then the heart and lungs - particularly from behind, where predators are most likely to attack. The gut and stomach get a fatty pad, and a layer of muscle. There a certain amount of flexibility in the abdomen; malleable soft tissue is better able to withstand blows and pressure than the delicate lungs.

[swansont]

Everything has a cost/benefit. A bigger ribcage or other protection means more weight and less flexibility. More weight means slower movement and/or more calories required. What would be the point of protecting the digestive system if you starve?

[CharonY]

Another thing to keep in mind is that evolution is not purpose-driven. I.e. things do not start to develop because they might be beneficial. Mutations are random and depending on the starting point, there are certain constraints to how much and in which direction a body plan can change without causing problems. 

[sethoflagos]

On 1/16/2023 at 12:37 AM, Saber said:

Evolution  has  mad  rib  cage  for  vertebrates for  protection of  lungs &  heart.....

 

Why  hasnt it made anything  to  protect  the  digestive system.........as   you  now  its as important  as  the  lungs and  heart........and if  damaged  the  animal  would die.......why  ahsnt  evolution  made anything to  protect  those  parts of the  body ?

It did. 

They were called gastralia and are seen commonly enough across the lineages that led to both mammals and reptiles for us to be pretty sure that our own ancestors probably had them oto 300 miilion years ago.

And slowly over time, all lineages lost them except for the tuatara and crocodilians in the present day.

And the only reason we lost them is that the return didn't repay the investment as well as alternative developments did.

Edited January 17, 2023 by sethoflagos
typo

[Peterkin]

When you have long legs and lots of clearance, your belly doesn't need as much protection as when you crawl on or close to the ground.

[Genady]

Also, most fish, I think, have many bones and/or cartilage protecting all organs. These don't cost much in the water as long as they are attached flexibly.