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Author Topic: Are animals left or right "handed"?  (Read 9020 times)

Offline ...lets split up...

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Are animals left or right "handed"?
« on: 18/11/2008 15:41:06 »
I was wondering if animals are orientated like we are? Do you get a right "pawed" dog? I assume the primates show the disposition towards being left and right orientated, but what about the rest?


 

Offline SquarishTriangle

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Are animals left or right "handed"?
« Reply #1 on: 19/11/2008 13:50:25 »
Yep, animals tend to be right handed just like us! Most dogs are right handed. Most horses will naturally (untrained) lead with their right foreleg.

A very cool example of 'handedness' in nature came from a paper a couple of years ago about the effect of shell morphology in marine snails. Looking at whelks and cone shells, they managed to find that left-handed snails gained a selective advantage over their much more common right-handed counterparts by deterring predation by crabs. The crabs are equipped with claws specialised for grasping and breaking open shells with a right-hand coil. When it comes to the left-handed version, the task of manipulating the snail just becomes too difficult! But it only works as an advantage if the lefties remain at a low frequency in the population. Otherwise there would be a greater selective pressure for crabs capable of handling both types of snails. That was from this paper:
Dietel, GP, Hendricks JR. Crab scars reveal survival advantage of left-handed snails. Biology Letters, 2006; 2:439-42.
but check out this if you can't get access to the full paper: http://news.bbc.co.uk/2/hi/science/nature/4831218.stm

Also stumbled across this newer report (from last week) while I was having a look around, on the effects of handedness on the reproductive behaviour of pond snails: www.sciencedaily.com/releases/2008/11/081111203507.htm (A third year undergrad student got her work published in Biology Letters! I'm so jealous!)
 

Offline ...lets split up...

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Are animals left or right "handed"?
« Reply #2 on: 20/11/2008 06:32:09 »
Thanks
 

Offline ...lets split up...

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Are animals left or right "handed"?
« Reply #3 on: 20/11/2008 06:58:04 »
On a different note, lets say you bred a whole bunch of sinistral snails together and created enough to flood an area so that the ratios of dextral to sinistral snail shells were 50/50.

Do you think you'd see a change in the crab population, and do you think we'd be able to see any physiological changes in the crabs in our lifetime?

Also, because of the physical difficulties of "left" and "right" handed snails mating, do you think it's possible for these snails to eventually form two different species?
 

Offline DoctorBeaver

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Are animals left or right "handed"?
« Reply #4 on: 20/11/2008 22:06:05 »
Polar bears are left-handed (or should that be left-pawed?)
 

Offline RD

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Are animals left or right "handed"?
« Reply #5 on: 20/11/2008 22:45:36 »
Quote
The coil of a snail shell can be either right-handed (dextral) or left-handed (sinistral), based on whether the shell spirals out clockwise or counterclockwise when viewed from above. Most species are composed entirely of individuals that are one or the other type; in exceptional cases, populations may differ in their handedness, or chirality, but within a single population, all individuals tend to be alike. This makes sense, since the mechanics of reproduction are harder between two individuals of opposite chirality (their genitalia are also reversed), reducing the likelihood that they will successfully mate and produce offspring. Over time, therefore, the rarer type will become rarer and rarer until it goes extinct.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1182695


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Despite a recurring internet meme that all polar bears are left-handed, there is no scientific evidence to support this claim.
http://en.wikipedia.org/wiki/Polar_bear
« Last Edit: 20/11/2008 22:48:37 by RD »
 

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Are animals left or right "handed"?
« Reply #6 on: 21/11/2008 06:26:36 »
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Despite a recurring internet meme that all polar bears are left-handed, there is no scientific evidence to support this claim.
http://en.wikipedia.org/wiki/Polar_bear

You could always fly to the north pole, rub yourself down with fish and approach a polar bear and see which paw he uses to strike first. You might need to do this with a couple of polar bears to produce any valid results.
 

Offline DoctorBeaver

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Are animals left or right "handed"?
« Reply #7 on: 23/11/2008 13:47:05 »
I first came across the alleged left-handedness of polar bears before the internet was even thought of, so to call it an "internet meme" is wrong.

What I thought was myth is the claim that a polar bear always strikes with its left paw. I didn't think there is much contention about the polar bear's use of its left paw, among other uses, to "tenderise" its prey before devouring it.
« Last Edit: 23/11/2008 13:52:55 by DoctorBeaver »
 

Offline ...lets split up...

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Are animals left or right "handed"?
« Reply #8 on: 23/11/2008 20:04:00 »
I wonder how and why the left handedness became dominant in polar bears? You think maybe grizzlies are lefties since they share the same ancestor or did the right handed polar bears fall victim to natural selection?
« Last Edit: 24/11/2008 06:15:01 by ...lets split up... »
 

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Are animals left or right "handed"?
« Reply #8 on: 23/11/2008 20:04:00 »

 

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