Strong vs. Smart

Imagine yourself sitting with your best friend, and you attempt to lift a chair and move it to the other side of the living room, to see how it would look. And as you try to heave it up grunting, your friend says to you:
"Stop, you might hurt yourself, its too heavy, you're not strong enough, I'll help you lift it."

You'd happily accept their offer. And thank them.

Imagine however if the situation did not involve moving a heavy sofa, but was about something that requires some high mental abilities. Say wisdom or intelligence. for example: You're trying to figure out your accounting figures for your small business. Or trying to solve some mathematical equation for a statistics class. Or maybe even trying to figure out how to diplomatically work your way out of a sticky argument at work with some stubborn manager. Take any of these examples or think of one of your own, and imagine that you're failing in dealing with it, and you're telling your best friend about it, clearly in need of help. And the friend says something like:
"Stop, the way you're handling this is wrong, you're not smart enough, let me offer you some advice."

I don't know about you, but the "not smart enough" bit would very likely piss me off.

So, what's the difference between these two situations? both involve your deficiency, and both involve someone else criticizing you in that lack of ability. The first is a muscular ability, the other is a brainy ability.

But we're way more sensitive to criticism when it is directed at our intelligence than if it is towards our athletic prowess.

Lets go down to a childish level. Kids do tease each other based on physical abilities all the time.
"I can easily outrun you and run circles around you. You're SO slow! wahahahaha"

But now as grownups, if someone sneered at how slow you ran, you'd point them out to your friends and laugh at how irrelevant the comment was. "what's this crazy person on about?"

But if the remark mentions anything about how stupid or unwise we are, even if the intention of the remark was friendly and genuine, most likely we'd be very offended and defensive about our mental abilities.

We're all too willing to concede that black athletes are more proficient in speed, jumping height, strength and so on. But dare to mention any hint of academic achievement or mental ability differences between blacks and whites, and you're likely to get scornful and chastising stares from all around you. just incase, here are some references:
The g Factor: The Science of Mental Ability
Chapter 11 of The g Factor fully documents that, on average, the American Black population scores below the White population by about 1.2 standard deviations, equivalent to 18 IQ points. (This magnitude of difference gives a median overlap of less than 15%, meaning that less than 15% of the Black population exceeds the White average of 50%).

So my question is, Why?

Why are we more sensitive towards our mental capabilities, but not so much towards our physical ones?

I'm guessing one possible answer could be that in this day and age, being smart is more important for prosperity. If you're smart and handicapped, you still can get a PhD and be an overpaid consultant. If you're strong and dumb you might end up a janitor on foodstamps.

So was the situation reversed in hunter/gatherer communities 1000's of years ago?

Stone Age Muscular Joe says to his Thinker friend Archimedes : "Oh man, Archie, you're still fiddling with that round rock with the hole in the middle? why don't you get off your ass and hunt some more deer with us? I hate to be so crass and rude, but its sort of straining my family's food supply to always have to trade a deer's leg for the bone hair clasps you make. Don't get me wrong, my wife likes using them to hold up the wet laundry and even hold up her hair, but give me a break, you can't really feed them to your kids now can you. Poor baby timmy even tried and almost choked on one of them."

So what do YOU think?