[Petrochemicals (OP)]

Is Mankind going down a evolutionary culdisac?  The biggger you are the more likely you are to survive, not just running from lions, even today society dictates the bigger you are the less aggravation you will receive. Up until recently most work linked to survival was done by men because they where larger and stronger.

 Yet the bigger you are the square cube rule dictates that you are to the power 3 the mass. This increaced mass is unfortunately detrimental to the body because as monkeys our bodies are not designed to go around running and jumping and this size is having an unfortunate effect on ourselves through hip and knee replacements. It also means that movements are slower and electrical signals take longer. The more food you need. If you fall weighing 20kg you are less likely to injure yourself versus if you fall weighing 80kg as skin is finite in its strength and longer bones are more easily levered no matter how much thicker they are, a bone that is double the length under 4 times the stress would need to be 8 times as strong, whereas even if the bone was twice the diameter it would only be   maximum 3 times as strong.

[evan_au]

If humans were smaller, our aeroplanes, motor vehicles, houses and airconditioning would consume less energy - so I can see some economic and environmental advantages.

Since we have almost eliminated all large predators that could kill us, and domesticated many of our food animals, you could argue that physical size is not such an advantage in modern society.

A big body supports a larger brain (and, in turn, requires a larger brain to control it).
- Are you suggesting that we can get by with smaller brains?

But as long as "tall dark and handsome" are considered positive attributes, downsizing into a smaller body is unlikely.

[alancalverd]

The square cube rule does not apply. Distance runners (need to disperse chronic heat from aerobic exercise ) are a very different shape from sprinters (maximum anaerobic power/weight ratio)  weightlifters and Sumo wrestlers (optimum momentum/strength distribution within a weight class).  Boxers, swimmers and rugby backs tend to "ideal general purpose"  shape, for whom the rule may be approximately valid, but the forwards and scrum half cover a very broad spectrum.

Smaller pilots and racing drivers tend to have better g tolerance, but size and weight are an advantage in yacht racing.

Saami and northern Inuit survive better if they are short and round, but native Australians and South Americans need to lose heat, not retain it. 

There is an underlying problem in Western society. As diets improve and machines do more of the heavy lifting, males become both larger and redundant, so spend more time fighting than working.

[charles1948]

If we got smaller, our brains would get smaller. Wouldn't that make us less able to think.

I mean, thinking depends on our brains,  So if we had small brains, wouldn't we think less well, than with big brains?

[Bored chemist]

as monkeys our bodies are not designed to go around running and jumping

You might be a monkey; I'm not.

[charles1948]

Aren't we really monkeys with grossly and abnormally enlarged brains?  Far beyond what any natural evolutionary process could possibly produce.

[Kryptid]

Far beyond what any natural evolutionary process could possibly produce.

How do you know that?

[evan_au]

if we had small brains, wouldn't we think less well, than with big brains?

There is definite evidence that a large fraction of the brain is dedicated to:
- Processing sensory information, mostly from our outside surfaces (proportional to Area), but also some from internal sources (proportional to Volume)
- Controlling muscles (proportional to Volume)
- So calculations of "intelligence" vs size normally have an exponent of 2/3; the 2 is related to Area, and the 3 is related to Volume*
- So if humans were smaller, the amount of brain dedicated to sensing inputs and controlling outputs could be reduced, leaving the "thinking" part unchanged.
- We would then have the problems of how this tiny body could physically support and carry around this relatively large brain, and provide enough food and oxygen to feed this relatively large brain.
See: https://en.wikipedia.org/wiki/Encephalization_quotient#Calculation

* I am left with the sneaking suspicion that this formula was adopted with the chauvinistic motivation that it makes humans come out at the top of the list !!??
- The brains of whales and elephants are so huge than just a tiny fraction dedicated to introspective thought would far surpass human intelligence.

[Petrochemicals (OP)]

if we had small brains, wouldn't we think less well, than with big brains?

There is definite evidence that a large fraction of the brain is dedicated to:
- Processing sensory information, mostly from our outside surfaces (proportional to Area), but also some from internal sources (proportional to Volume)
- Controlling muscles (proportional to Volume)
- So calculations of "intelligence" vs size normally have an exponent of 2/3; the 2 is related to Area, and the 3 is related to Volume*
- So if humans were smaller, the amount of brain dedicated to sensing inputs and controlling outputs could be reduced, leaving the "thinking" part unchanged.
- We would then have the problems of how this tiny body could physically support and carry around this relatively large brain, and provide enough food and oxygen to feed this relatively large brain.
See: https://en.wikipedia.org/wiki/Encephalization_quotient#Calculation

* I am left with the sneaking suspicion that this formula was adopted with the chauvinistic motivation that it makes humans come out at the top of the list !!??
- The brains of whales and elephants are so huge than just a tiny fraction dedicated to introspective thought would far surpass human intelligence.

This sounds like another case of.......

https://en.m.wikipedia.org/wiki/Cortical_homunculus

[alancalverd]

A vast proportion of the human brain is occupied with walking upright and communicating matters of no importance. The bits that matter,  processing visual, auditory and olfactory information, are vastly better in birds (that stand on one or two legs by design, not learning) and dogs. 

[charles1948]

A vast proportion of the human brain is occupied with walking upright and communicating matters of no importance. The bits that matter,  processing visual, auditory and olfactory information, are vastly better in birds (that stand on one or two legs by design, not learning) and dogs.

Not sure that I follow you alan.  You refer to the "bits that matter" as the ones that involve processing "visual, auditory and olfactory information".

That's probably true, if we're only considering what helps organisms, such as birds and dogs, survive.

Birds and dogs do survive, very successfully,  And the keen eyesight of birds, and the keen sense of smell possessed by dogs, without doubt contributes to their success.  In the basics of survival -  which is finding food and avoiding predators.

But don't you think that human brains have evolved unreasonably beyond these basic natural, survival skills?
I mean, if human brains had  evolved to develop stone tools, and even spears, and bows and arrows, that might be acceptable.  Looking at it from a survival viewpoint.

But why on earth would we develop brains capable of inventing things like computers, spaceships and nuclear weapons?

Especially the nuclear weapons.  These seem more likely to bring about the end of our survival, than to help us survive.

So why would our brains facilitate their invention?.

[alancalverd]

I think you agree with me. Most of what the human brain does, apart from walking and talking, is either pointless or dangerous.

[charles1948]

I think you agree with me. Most of what the human brain does, apart from walking and talking, is either pointless or dangerous.

Yes, I agree.  Except I would add "apparently" pointless, though certainly dangerous .

So the question is is:  how, and why, did such brains ever evolve.

Just consider - there are over 7 billion of them on Earth.  Could there be so many, unless they had some kind of "point" -  if so what is it?

I think I know.. Do you?

[Petrochemicals (OP)]

The square cube rule does not apply. Distance runners (need to disperse chronic heat from aerobic exercise ) are a very different shape from sprinters (maximum anaerobic power/weight ratio)  weightlifters and Sumo wrestlers (optimum momentum/strength distribution within a weight class). 

Distance runners are usually smaller and thinner, I am against distance running for most as knee injuries are common, leaving someone unable to run at all, but people like Paula Radcliffe managed to have a career without a chronic injury. This does however add weight to the theory that Mankind is evolving against what intelligent design would recommend, how many of us look like Paula Radcliffe?

[Petrochemicals (OP)]

A vast proportion of the human brain is occupied with walking upright and communicating matters of no importance. The bits that matter,  processing visual, auditory and olfactory information, are vastly better in birds (that stand on one or two legs by design, not learning) and dogs.

Birds and dogs do survive, very successfully,  And the keen eyesight of birds, and the keen sense of smell possessed by dogs, without doubt contributes to their success.  In the basics of survival -  which is finding food and avoiding predators.

The bird brain is a very highly evolved and sophisticated organ, it has had 250  million years headstart on humans. A large brain may not be needed, rather a more developed one, but will this be achieved with current trends of stature seemingly winning out?

[evan_au]

human brains had  evolved to develop stone tools, ...
But why on earth would we develop brains capable of inventing things like ... Computers?

The problem is that all those stone tools were so heavy.
- And you had to carry them so far to kill a wild buffalo.
- Much better to have a herd of tame cows (agriculture)

That caused the problem of knowing that your neighbour (or the tribe over the hill) hadn't come in overnight, and taken a few of your cows.
- Some of the earliest examples of writing on clay tablets seem to be keeping accounts of agricultural products.
- A computer is just a glorified clay tablet

human brains had  evolved to develop stone tools, ...
But why on earth would we develop brains capable of inventing things like ... spaceships?

Humans have always boasted of their physical prowess - how far they could throw a javelin or a discus.
- A space rocket is just a way of throwing a weapon over the horizon.

human brains had  evolved to develop stone tools, ...
But why on earth would we develop brains capable of inventing things like ... nuclear weapons?

The same bits of brain that gave the idea to bash two rocks together probably also gave the idea to bash two lumps of Plutonium together.

[syhprum]

Bashing two bits of Plutonium together does not work very well they soon blow appart , you can do it with U235 but it is much more expensive to produce

[alancalverd]

So the question is is:  how, and why, did such brains ever evolve.

Survival in the ecological niche of the savannah requires good awareness of predators and prey, and the ability to collaborate in complex hunting and defensive actions. Hence upright stance and wide vocabulary. Our ancestors already possessed the chimp-like ability to bash things with stones.

Upright stance and bigger brain (thus bigger infant head) makes pregnant females and infants very vulnerable, hence the need for social organisation, division of labor, essential male aggression, etc. all of which are now unfashionable.

[charles1948]

So the question is is:  how, and why, did such brains ever evolve.

Survival in the ecological niche of the savannah requires good awareness of predators and prey, and the ability to collaborate in complex hunting and defensive actions. Hence upright stance and wide vocabulary. Our ancestors already possessed the chimp-like ability to bash things with stones.

Upright stance and bigger brain (thus bigger infant head) makes pregnant females and infants very vulnerable, hence the need for social organisation, division of labor, essential male aggression, etc. all of which are now unfashionable.

Yeah, I get all that.  What you say.  Natural evolutionary adaptations, to improve survival on the savannah.

But I find it difficult to see how these adaptations could naturally lead to us inventing things like steam-engines and nuclear-reactors  And taking an immense amount of time and trouble to send space-probes to Jupiter, Saturn, Uranus and Neptune.

And launching things like the Hubble Space Telescope, which supplies views of stars and nebulae tens of  thousands of light-years away from our solar-system.

Where's the evolutionary advantage of all that?  Unless - we are driven by something else.

[Kryptid]

Where's the evolutionary advantage of all that?

It's also allowed us to develop things like medicines, vaccines, surgery and an overabundance of food. The survival benefit of those things is pretty obvious.