Why aren't all animals becoming smarter?

Not necessarily.
It's not quite as simple as that.

Like you said, nature finds a medium.
It may well select for having 3 children that are cared for than having 15 that are not.
It may select for less offspring, if those offspring are stronger.

Sometimes having offspring can be more of a detriment than a befefit.

 

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Insanity is inherited. Parents get it from their children.

 

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And children get it from their parents. It's a vicious circle.

 

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"Why aren't all animals becoming smarter?"

Because they don't have to. Cockroaches having been doing quite well working with the low level of intelligence they have.

On the other hand it's also possible that greater intelligence doesn not always equate with a better ability to survive. It's worked OK for humans but a lot of the other primates aren't doing that well.

 

Why aren't all animals growing flippers.. ?

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"Best reproduce" doesn't nescessarily mean "have the most offspring"

 

Interestingly they are (if we define flippers very liberally as webbed feet, and all animals as tetrapods

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).

The webbing between the digits is actively removed. Having webbing between the digits is the default start. Programmed cell death mediated by BMP signaling removes the cells between the digits.

reference:
Science. 1996 May 3;272(5262):738-41. Requirement for BMP signaling in interdigital apoptosis and scale formation.

 

Spurious, I know that. I was just trying to get a point across.
What I meant was "why aren't all animals evolving towards having flippers". The answer is pretty simple, a cow (for example) doesn't need flippers. The same is true for smarts, animals that aren't evolving a higher intelligence simply don't need a higher intelligence to survive in their current environment.
The thread title suggests it was made up by someone uneducated in the workings of evolution. But the OP reveals that isn't the case.

To answer the questions in the OP:
Evolution does select for intelligence whenever it means advantage.
Human ancestors probably passed a threshold in intelligence after which it became a self-amplifying evolutionary advantage.

 

You are quite right. I just used your post as an excuse to throw in a little anecdotal piece of science.

 

Heh ok then

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It's just that it is a classical paper and although I threw it in as an anecdote it tells a lot about evolution, especially on the creation of evolutionary novelty.

It's easier to regress than to create.

Extra digits are more difficult to form than getting rid of some.

Deleting is used more than creating (although it results into novel form and not deletion of form!).

To create fingers it is easier to delete tissue in between fingers than to create fingers.

And of course you might know all this, but certainly the general public has no clue whatsoever.

I might have been arsed to go into detail in the past on these topics, but currently the atmosphere has become repressive so I stop here.

 

Yup, it's as if the embryo goes through the entire evolutionary development from one celled organism to human. Pretty cool actually.

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The BMP signaling you are talking about, does that refer to the mapping system the developing body is thought to use ?

 

Point taken.

 

hmm...dunno. There are so many levels of 'mapping' and I do not know which one you are referring too.

BMP signaling is indeed used to create positional information in many systems and is a major component of reciprocal signaling between compartments and in signaling centers in all developing tissues. In mammals it consists of a large superfamily of ligands with many different receptors, co-factors, inhibitors, activators and crosstalk between other signaling pathways involved in morphogenesis such as FGF and Wnt signaling. It's probably one of the more messy and buffered signaling pathways in existence.

We always had trouble showing the effect of individual BMPs in tissue culture in my field because of this buffering by inhibitors and activators. Recently more and more work is focussed on these inhibitors and activators.

 

I too do not know anything about BMP signalling but have for 40 years wondered why right hands always appear at the end of right arms when the arm starts out as a little "bud" on the main body. I.e. as the bud tip expands away from the body how does it know which it is (right or left) much later when it is time to differentiate tissue at the distal end and make it into a hand?

IMHO mankind is still very ignorant about what nature and the human body knows, despite having learned much. This is why I like to say: "My body is smarter than all the doctors in the world" and try to avoid letting them touch it.

Except for annual PSA and few other "checking tests," I have seen a doctor only once in last 25 years. Then I had a systemic infection / fever, which I let my body fight for about a week, but that bug had evolved stronger attack than my body had (thur it evolutionary history) developed defenses and when I conclude that, I did let doctor give me an anti-biotic perscription. I rely on my immune system, not doctors, except whenever that is obviously not winning the battle to keep me healthy. As I have done this for at least 65 years, I think I have developed a very strong immune system - bring on your bird flue - I am not afraid of it.

 

Basic patterning of the axes is done early in development. It starts with anterior-posterior and dorsoventral pattern, and the right-left asymmetry is established soon after. The limb doesn't wait till it needs to make the hand to decide what is left and right. It already knows when it starts making the limb.

 

Thanks. You or someone here has told me than before and I believe it but I still stand in awe of the little tip knowing which it is. To some extent, until we know how this information is possesed by the tip, those are just words. Like the doctor explaining how a sleeping pill works by saying: "It contains a "NARCOLEPTIC AGENT." Yes the tip knows the "anterior-posterior and dorsoventral pattern" but how? Is not the set of words "anterior-posterior and dorsoventral pattern" just renaming our ignorance in fancy words like " NARCOLEPTIC AGENT" is? Not really explaining anything?

 

No, it's quite well known in fact.

It's just that I can't be bothered to explain further because I am currently under the persecution of a member of the moderator team and that eliminates all desire to be thorough in my explanations.

The limb is a classic model for these patterning interactions. In drosophila the main body of research in developmental biology is on patterning. Well, basically patterning is a central topic in developmental biology in any organism.

 

i have thought about this alot in the past actualy, i always wondered why human babies are frail and weak for years on end. also cant even walk until they are 10-12 months old, many animals can walk as soon as they are born. i watch plenty of wildlife docs on african animals, they all seem to stand up and start running about within 30 seconds of being born. i came to the conclusion that because of local predators, they have to run straight away, or be eaten. where humans are protected from birth and dont need to run so soon.


peace.