Take the 2-minute tour ×
Skeptics Stack Exchange is a question and answer site for scientific skepticism. It's 100% free, no registration required.

enter image description here

I've encountered this one many times over the years, mostly in those "useless facts" books and sites such as the one here.

In fact, it's been one of those bits of trivia I seem to have unconsciously taken for granted as true, probably due to the sheer number of times I've heard it. It occurred to me though that while I've often heard the claim stated, I've never seen it proven.

Has it been scientifically proven that ants are capable of lifting 50 times their weight?

For the pedants:

  1. It doesn't matter what kind of ant
  2. We are assuming an otherwise healthy and normal ant (of any kind).
share|improve this question
5  
    
It does seem rather unusual, when you consider that the center of gravity would shift about and cause the ant to greatly destabilise. –  Chris Dennett May 21 '11 at 2:59
    
I thought it was 300x... –  muntoo May 21 '11 at 4:57
    
@belisarius I never knew it was unsafe to lift three biscuits at once! –  Andrew Grimm Apr 1 '12 at 4:08
add comment

2 Answers 2

up vote 31 down vote accepted

Ant Source

Rex Kerr's answer has linked to photographic evidence of an Asian Weaver ant lifting 100 times its bodyweight (no, it's not the one above).

The picture won first prize in the first Biotechnology and Biological Sciences Research Council science photo competition.

To me the amazing thing is that the ant is actually clinging upside-down to a smooth surface while lifting that 500mg weight:

ant - 500mg Source


But,

ants are actually not stronger than humans.


The reason why ants can lift so much is due to scaling, meaning it has to do with math, not muscles.


Strength:

The strength of a muscle scales with the cross-sectional area. (Exercise makes a muscle bigger, but not longer)

muscle Source

This means, the strength of an organism increases as the square of the scale factor.


Mass:

The mass of an object depends on its volume.

spider small spider Source

The spider on the right is 3x the size of the small spider, but it weighs 27x as much.

The weight of an object increases as the cube of the scale factor (33=27)


Mass increases faster than strength.

Scale Source

So, if an ant would be human size it wouldn't be able to lift 100x its bodyweight anymore.

Or going the other way, playing "Honey I Shrunk the Kids":

Shrunk Source

ant size humans would be as strong as ants.


Sources:

share|improve this answer
3  
Nice answer, JBS Haldane wrote an essay on size/scaling in animals, with the great line "You can drop a mouse down a thousand-yard mine shaft; and [it]... walks way. A rat is killed, a man is broken, a horse splashes." irl.cs.ucla.edu/papers/right-size.html –  david w May 21 '11 at 11:33
    
I guess the next question is why the scaling happens? I can think (warning: pure speculation) that the effect of atomic attractions on smaller structures are much larger than on larger structures (i.e. the same reason why smaller molecules tends to be more stable than complex molecules); but would it account for alll the difference? Are the structure of human muscles and ant muscles similar enough for such a direct comparison? Or is it possible that the structure of ant's muscle is more advanced than human's? Spider silk has a much stronger structure than other similar-volume silk. –  Lie Ryan May 21 '11 at 12:03
1  
+1 for explaining scaling. –  starblue May 21 '11 at 12:34
    
@Lie Ryan If you do the math w.r.t. scaling then humans are in the same league as ants, about 300 times larger and 100000 times stronger. –  starblue May 21 '11 at 12:38
    
What about a colony of ants with the same mass as a human? Would they be stronger? –  muntoo Dec 15 '11 at 4:24
add comment

Fifty? Pah! Try one hundred.

These sorts of feats of strength are not very useful, though, even if they are possible, just like humans don't routinely lift the kinds of weights that champion weightlifters do.

Leafcutter ants, who specialize in cutting leaves and carrying the loads back to their nest are probably the most heavily studied load-carriers; they will tend to carry only a few times their body weight. For example, see Roces and Hölldobler, "Leaf density and a trade-off between load-size selection and recruitment behavior in the ant Atta cephalotes". Oecologia Volume 97, Number 1, pp. 1-8 (1994), Figure 2A, where the 4 mg ants cutting 0.22 mg/mm2 leaves cut about 60 mm2, which gives about 13 mg for a 4 mg ant (3x body weight).

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.