56 replies to this topic

[sam12six]

synchronomy, on 20 September 2012 - 01:20 PM, said:

Two legs might be just as efficient energy wise to four legs...but 2 legs are far slower than four so the evolution couldn't have been to outrun danger.  Most mammals as small as rabbits and cats can outrun a human easily.

Rabbits and cats can easily outrun an Ostrich too, right? It's not the number of legs, it's the proportion and length of those legs that determine speed.

OH, and humans evolved an upright gait because they were going through too many gloves and it was a survival advantage to be able to look for food instead of sitting around making new gloves all day.

[Arbitran]

synchronomy, on 20 September 2012 - 10:21 PM, said:

Where the heck did you hear that?
Humans have multiple, major musculoskeletal differences from great apes who walk on all fours.  We are specifically designed to walk upright.
If we were not designed to walk upright...why don't you try crawling around on all fours for a day.  Bet your knees couldn't make it until mid-day.

Well, to be clear, you're both right. As a matter of fact, the human vertebral column could likely be described accurately as a transitional phase between a quadrupedal spine, and a fully-erect spine. It is curved, and thus it is viable for humans to walk quadrupedally (the long legs are the biggest obstacle; but, as a bit of a side note, when I was studying chimpanzees and gorillas in Africa, I trained myself to knuckle-walk, and can do it perfectly naturally, albeit with less grace than our hairy cousins), and yet it is this same curving which causes true erect posture to result in unfortunate physiological consequences, such as back pain. It hasn't been a very long time since our ancestors forsook their quadrupedal posture; we're still in the process of becoming truly erect bipeds.

[Junior Chubb]

Arbitran, on 20 September 2012 - 11:12 PM, said:

Well, to be clear, you're both right. As a matter of fact, the human vertebral column could likely be described accurately as a transitional phase between a quadrupedal spine, and a fully-erect spine. It is curved, and thus it is viable for humans to walk quadrupedally (the long legs are the biggest obstacle; but, as a bit of a side note, when I was studying chimpanzees and gorillas in Africa, I trained myself to knuckle-walk, and can do it perfectly naturally, albeit with less grace than our hairy cousins), and yet it is this same curving which causes true erect posture to result in unfortunate physiological consequences, such as back pain. It hasn't been a very long time since our ancestors forsook their quadrupedal posture; we're still in the process of becoming truly erect bipeds.

I remember seeing an article on back pain years ago that suggested if we scampered about on all fours (as apes do) then a lot of the back pain people suffer would not have developed. Its an interesting point of view and I have considered it true since hearing it. I also wonder what role our furniture plays in back pain too, again forcing us into positions we may not be ready for. I often sit on the floor, especially to eat, at work and at home, so far so good (I haven't opted for the scampering around on all fours yet though).

Edited by Junior Chubb, 20 September 2012 - 11:27 PM.

[synchronomy]

sam12six, on 20 September 2012 - 11:11 PM, said:

Rabbits and cats can easily outrun an Ostrich too, right? It's not the number of legs, it's the proportion and length of those legs that determine speed.

OH, and humans evolved an upright gait because they were going through too many gloves and it was a survival advantage to be able to look for food instead of sitting around making new gloves all day.

and a horse can outrun an ostrich.  So can a lion.
If it's the proportion and length of the legs that count why can a cheetah run faster?
All of the great apes running on 4 legs average 25-30 mph.
The fastest humans can barely touch 23mph...and that's Olympic level sprinters.

[Junior Chubb]

synchronomy, on 21 September 2012 - 12:06 AM, said:

and a horse can outrun an ostrich.  So can a lion.
If it's the proportion and length of the legs that count why can a cheetah run faster?
All of the great apes running on 4 legs average 25-30 mph.
The fastest humans can barely touch 23mph...and that's Olympic level sprinters.

I thought Ostriches were faster than horses, and Lions wouldn't even qualify for this race as a 'wild card'.

I also thought it was more like Apes can just about reach 25mph and Olympic sprinters go past 25mph.

This is based on top speeds though, when distance comes into play things may change.

I will have to dig out my VHS of Animalympics and find out.

Edited by Junior Chubb, 21 September 2012 - 12:38 AM.

[Bildr]

Can't find many info for the moment, but i've often heard and read about the fact that we, in our sedentary lifestyle, are so much often in a sitting position in most of our life time, that it weakend our back.

---> http://www.dailymail...-hours-box.html

[synchronomy]

Bildr, on 21 September 2012 - 01:16 AM, said:

Can't find many info for the moment, but i've often heard and read about the fact that we, in our sedentary lifestyle, are so much often in a sitting position in most of our life time, that it weakend our back.

---> http://www.dailymail...-hours-box.html

Very true.  I have suffered terrible pain from sciatica many times.  It causes severe lower back pain.
Always the medical advice is the same.  Never sit for long periods.  Stand or lie flat on the back or at least in a reclined manner.
Sitting puts tremendous unatural stress on the lower back.

[Bling]

synchronomy, on 20 September 2012 - 10:29 PM, said:

That's not true either.  Great apes can walk while carrying a baby or food.  They can walk quite easily with three limbs free.
They can even scratch their butt while eating a banana.

You've misquoted me, I never said that - Troublehalf did

[synchronomy]

Bling, on 21 September 2012 - 01:57 AM, said:

You've misquoted me, I never said that - Troublehalf did

Sorry...I goofed there!

[Metal Head]

We evolved because it's easier when you're walking upright to see BOOBIES!

[IamLegend]

synchronomy, on 20 September 2012 - 01:20 PM, said:

Two legs might be just as efficient energy wise to four legs...but 2 legs are far slower than four so the evolution couldn't have been to outrun danger.  Most mammals as small as rabbits and cats can outrun a human easily.

I just found this.



This is one of the last tribes on earth to hunt like this.

[sam12six]

synchronomy, on 21 September 2012 - 12:06 AM, said:

and a horse can outrun an ostrich.  So can a lion.
If it's the proportion and length of the legs that count why can a cheetah run faster?
All of the great apes running on 4 legs average 25-30 mph.
The fastest humans can barely touch 23mph...and that's Olympic level sprinters.

As I understand it (And I'm not claiming super specific knowledge. Everything I'm saying is based on a documentary about the relationship between the way an animal's legs are made and how fast it can run), leg proportion multiplied by some factor for leg length = speed. That speed is relative to the actual size of the animal.

A rabbit has super long calves and short thighs. Scaled up, they would be much faster than cheetahs. Of course, they might not if there were actually rabbits that big because body weight would adjust their relative speed down.

A great ape's legs are proportioned similarly to ours, but they are far stronger than we are per body weight. It's like a car having an engine that produces a given amount of horsepower and a motorcycle with tires half the diameter but a stronger engine. In the case of us and big apes, it's pretty much a wash (though lazy Orangs pretty much don't run ever).

Anyway, the animal's relative theoretical speed can change up or down based on proportional body weight (fat guy runs slower than fit guy with the same leg length and proportion), gait (cats' flexible spines allow them to take a bigger stride than most other animals, so they get a speed boost), and the aforementioned muscular strength per body weight - all of which is about speed and so it's sort of off topic as the OP was about efficiency.

Addressing the OP seriously, there could have been a single factor, but I doubt it. The article linked in the OP says basically that we're not supernatural. Our walking efficiency is within the norm for mammals our size - duh, we are mammals our size. Like apes, our legs aren't proportioned for sprints, they're proportioned for efficient long distance travel and probably has very little to do with our being upright. More likely, factors like being able to reach higher, see farther, etc were the environmental advantages that made evolution in that direction happen.

[Him over there]

Has no one considered that walking upright frees the front pair of hands to hold an item, pick something up, examine by holding close and turning and I am sure too many other things to list here, none of which would be easy if we walked on all fours which would cause the front hands to be thick skinned and indelicate.

[Bling]

synchronomy, on 21 September 2012 - 03:16 AM, said:

Sorry...I goofed there!

No probs

[Abramelin]

Metal Head, on 21 September 2012 - 04:48 AM, said:

We evolved because it's easier when you're walking upright to see BOOBIES!

And she would see your 'reaction' much easier too.