BBC Focus Magazine

[Bio v2.0]

This might sound like a silly question, but... Why did we evolve separate ribs rather than just one big, erm... chest-skull kinda thing? Because I think that as long as it could still move enough to alter the pressure in the chest cavity to allow breathing then it would work just as well, and it would do a better job of protecting our organs.

[The Beige Avenger]

Arguably, it would be better... another point for unintelligent-design!

I don't know what a big chest skull kinda thing is, but from what I imagine, the mineral resources it would need would be very high i.e. a lot of calcium and our diets don't include such levels of minerals.

[Shadowwolf]

The current rib set up does its job, to have evolved a solid plate would have required pressures that would make such an arrangement more advantageous, and so those with plate cages would have been more likely to live and procreate. As they are they provide sufficient support and protection, more would require as noted above a different diet and a heavier load on the body; perhaps making it less useful by slowing a person down.

Basically there needs to be some reason to drive such a development and we did not have it apparently.

[M Paul Lloyd]

Its more flexible than a skull like plate and lighter and technically some parts of the skull are far more vulnerable to injury than the rib cage.