This site is not maintained. Click here for the new website of Richard Dawkins.

← The Common Hand - By Carl Zimmer Illustration by Bryan Christie - National Geographic

The Common Hand - By Carl Zimmer Illustration by Bryan Christie - National Geographic - Comments

VrijVlinder's Avatar Comment 1 by VrijVlinder

Very interesting Thread Alan, I always had a fixation with hands and feet. How mine were almost identical to my fathers hands. We talked a lot about evolution and adaptations. And the one point that always came up were hands.

Extremities which are a tool. I suppose that is where ID believers would speculate as to the planning to provide organisms with built in tools to serve them in their purpose. However it need not be a design by something or someone.

People tend to look at results starting with how we ended up looking like this. That is when the mind goes into fantasy mode and ridiculous ideas are invented as to the reason for hands. In any organism who has extremities.

Evolution is a series of try and try again until the desired adaptation is completed by nature and time. If there was a "Designer" It would have to be Planet Earth. Because everything in the planet has adapted to the planet. And continues to adapt and evolve.

So Planet Earth is the catalyst for evolution and adaptation of those who ride the blue marble around the sun. It is not something planned it can't be. Everything is much too accidental to be a grand plan.

Hands and dexterity the next best thing after sight and hearing. In the Xray hands look so fragile yet are strong enough to hold our own weight as we hang perilously on a cliff's edge.

We can play musical instruments!! If we did not have hands we would have developed our feet to use as hands. People born without arms end up using their feet and they can pretty much do everything.

We are all related for sure, it should make everyone take better care of it all.

Sun, 03 Jun 2012 19:55:36 UTC | #945335

Alan4discussion's Avatar Comment 2 by Alan4discussion

@OP - Our hands began to evolve at least 380 million years ago from fins—not the flat, ridged fins of a goldfish but the muscular, stout fins of extinct relatives of today’s lungfish. Inside these lobe fins were a few chunky bones corresponding to the bones in our arms. Over time the descendants of these animals also evolved smaller bones that correspond to our wrists and fingers. The digits later emerged and became separate, allowing the animals to grip underwater vegetation as they clambered through it.

It is interesting to trace the evolution and diversity of hands, alongside the other vertebrate features which evolved though fish, amphibians reptile and mammals to their present diversity leading to modern specialist uses.

Many of the earlier evolved forms are still shown in some present day vertebrates.

Sun, 03 Jun 2012 21:32:56 UTC | #945357

CEVA34's Avatar Comment 3 by CEVA34

Re Comment 1. Vrij, you're a bit naughty talking of evolution achieving a "desired" result. Who is doing the desiring?

Every stage of evolution is a result, each stage taking the organism closer to ideal performance.

Mon, 04 Jun 2012 19:45:46 UTC | #945545

VrijVlinder's Avatar Comment 4 by VrijVlinder

@Comment 3 by CEVA34

I did use the words in a tongue in cheek way. I suppose it does make it seem as if I meant evolution was an entity. Sorry about that. I did not mean it that way. I take the heat for it nonetheless because naughty is a good thing. It means I like to go against the grain because everyone else going with the grain makes me suspicious ;)

I meant the evolution of every specific function in a living organism. The entity being the organism. The adaptations were results from evolutionary processes . The desired effect would be for example dexterity. Not all which has hands can use those hands. The vestigial leftovers of an obsolete adaptation would be limbs that don't function or extra bones without modern purpose. Every adaptation has a purpose. A reason for being. Having eyes or no eyes. Both serve a purpose.

But the desire for a certain adaptation if you will, would stem from need. Desire, not to be taken literally maybe the better word would be the goal.

Survival being goal number one and the logistics to achieve survival , evolutionary adaptation.

If it were not for fossil evidence, this sort of thing would make one think someone crafted this. What am I saying they do say that !!! Maybe the concept of how much time it takes for adaptation is hard to grasp. But it is a short period of time astronomically speaking.

Tue, 05 Jun 2012 01:40:12 UTC | #945623

All About Meme's Avatar Comment 5 by All About Meme

Carl Zimmer is one of my favorite science writers. Thank-you, Alan4Discussion, for bringing this interesting article to our attention.

(P.S. Zimmer's Parasite Rex is a fascinating read.)

Tue, 05 Jun 2012 03:04:08 UTC | #945630

HardNosedSkeptic's Avatar Comment 6 by HardNosedSkeptic

Thanks for starting this discussion Alan. I liked the article as well, and I thought those X-Ray photographs were fascinating.

I think it’s worth pointing out that our hands are pretty dexterous and versatile even compared with other great apes. The reason for that is probably because we do not have to walk on our hands, like the other great apes do.

Tue, 05 Jun 2012 22:21:03 UTC | #945772

Alan4discussion's Avatar Comment 7 by Alan4discussion

The National Geographic does some really good illustrations of evolutionary processes;

One they did earlier, was the transition of whales from land to sea with the reduction of limbs:

http://ngm.nationalgeographic.com/2010/08/egyptian-whale/whale-animation

The link below takes you to the "photogallery" where the photograph of bones of the prehistoric whale leg is the last picture in the series.

The 18-inch-long hind legs of Basilosaurus (left leg, above) were far too small to support the whale's massive 50-foot-long body. In fact, the creature never left the water. But the retention of legs is dramatic evidence that earlier whales once walked—and ran—on land. No one knows for sure how Basilosaurus used its tiny legs; paleontologist Philip Gingerich believes they may have served as stimulators or guides during copulation. - http://ngm.nationalgeographic.com/2010/08/whale-evolution/barnes-photography

Wed, 06 Jun 2012 08:44:57 UTC | #945823

Helga Vieirch's Avatar Comment 8 by Helga Vieirch

And then there is hand-eye coordination. The forward position of the eyes, making binocular vision possible, so that the hand can reach out to grasp a branch or a piece of fruit is the same system that permits us to throw a ball and catch it, or throw a rock or a spear. Yet, it was originally selected for because it made early primates better at navigating and foraging in the trees. Fruit-eating is not as simple, even in a monkey as it might first appear, and also involves hand-eye coordination. Notice that the hands are not quite used in the same way as a human hand could be used.

Much of what our hands were evolved to do was handle food, and most of the food our distant ancestors ate would have been fruit from trees. There is some evidence that they might have been seed-swallowers, like modern chimps, rather than seed spitters or seed-pickers like some species of monkeys. This has some interesting consequences for the role that apes and early hominids might have played in dispersal of valuable species of fruit trees.

Early human foragers in more open country do not just eat raw fruits and other vegetation: it is gathered and brought to a camp for processing, often by being dismembered and cooked. In the case of tubers and corms, those which are not cooked ate often dug back in to the soil for storage. Many are forgotten and left behind when the people decamp. The people leave behind a new little colony of these food plants, so, again, they aid in the dispersal of food plants useful to them.

Our hands are intimately involved in every activity towards preparing a meal: the procurement, which may involve picking, digging, and even climbing a tree to shake fruit down. It is hands that tie the skin sac together in such a way that it can hold all the gathered food and be carried back to camp, hands that sort through the resulting pile and select the ingredients for the evening meal, pull of any decayed plant material before cooking, hands that bring the firewood to the camp, and hands that manage the fire, rake back the sand and coals, and create the hot fire-pit in which the nuts, beans, and vegetables will be roasted.

Our hands are the hands of a hunter and a gatherer. That they can also hold a pen and write, become involved in tender caresses in parenting and love-making, and do so many other things is due to the tremendous diversity of activities that even the simplest human technologies demand. Hands, and the coordination between hands and eyes, probably shaped our brains!

Fri, 08 Jun 2012 07:16:19 UTC | #946279

VrijVlinder's Avatar Comment 9 by VrijVlinder

Alan: paleontologist Philip Gingerich believes they may have served as stimulators or guides during copulation.

I was thinking along the lines of vestigial limbs. It would not have occurred to me for copulation aid to be their purpose.

Helga:Our hands are the hands of a hunter and a gatherer. That they can also hold a pen and write, become involved in tender caresses in parenting and love-making, and do so many other things is due to the tremendous diversity of activities that even the simplest human technologies demand. Hands, and the coordination between hands and eyes, probably shaped our brains!

You endless romantic !! I wonder who coined the phrase "Too much time on our hands" ?

"Busy Hands"

Fri, 08 Jun 2012 07:55:13 UTC | #946281

VrijVlinder's Avatar Comment 10 by VrijVlinder

Here is something interesting, shrimp punching. Yes shrimp who punch until they penetrate a shell. Mantis Shrimp Smash!

The peacock mantis shrimp packs a powerful punch. The crustacean uses its hammerlike claws to smash through mollusk shells and even aquarium glass without getting injured. Now, a new study reveals what makes its claws so tough: a unique composition and structure that stops cracks in their tracks—one that could help engineers design lighter, stronger materials for military, medical, and other applications.

Though mantis shrimp are relatively common, a lot about them isn't. The colorful crustaceans have remarkable vision, unusually resilient armor, and the fastest punch on earth. When they strike, they swing out their dactyl clubs, armlike appendages normally held close to their bodies, at 80 kilometers per hour, accelerating faster than a .22-caliber bullet. Mantis shrimp use this mechanism to smash their often hard-shelled prey, and can do so as many as 50,000 times between molts without destroying their clubs.

Fri, 08 Jun 2012 09:53:22 UTC | #946293

Alan4discussion's Avatar Comment 11 by Alan4discussion

Comment 10 by VrijVlinder - Here is something interesting, shrimp punching.

This is a long way in evolutionary terms from vertebrate hands, but it can be interesting to look at parallels in evolutionary development of very distantly related species. The external skeleton means different constraints on the nature of the grasping structure of the claws.

Comment 9 by VrijVlinder - I was thinking along the lines of vestigial limbs. It would not have occurred to me for copulation aid to be their purpose.

As well as the other examples of specialist developments, the whale example shows limited alternative developments, with unused features being gradually reduced or lost to avoid waste of resources, as evolutionary changes progress.

Fri, 08 Jun 2012 11:51:04 UTC | #946308

VrijVlinder's Avatar Comment 12 by VrijVlinder

This is a long way in evolutionary terms from vertebrate hands,

True, what I like about it was the example of a built in tool. We come from shells . Something I read and made me think of this thread.

The design in this shrimps hands or claws is like organic kevlar. The adaptation specific to be able to penetrate mollusks . If there were only soft mollusks would you think this adaptation would change since it would not need to penetrate hard shells?

These claws are not for grasping they are for specifically punching a hole in a hard shell. With the speed and strength of a pneumatic jack hammer.

We did not get such advantage our hands are for making jack hammers. We don't seem to appreciate the hands as much as we should.

Take sci fi movies where arm canons replace arms. And steel blades come out of wolverine's knuckles. It is as if our hands are too delicate which is not a good tool for non delicate work. We must enhance what is already as it should be. It is not enough to create must also destroy with equal gusto.

whale example shows limited alternative developments, with unused features being gradually reduced or lost to avoid waste of resources, as evolutionary changes progress.

Yes being in the in-between stage of discarding no longer necessary limbs and appendages, must be confusing for the organism. "Where did you get those legs from!!??"

One tends to think everything has an evolutionary purpose but it may just be completely accidental.

Fri, 08 Jun 2012 20:07:08 UTC | #946404

VrijVlinder's Avatar Comment 13 by VrijVlinder

Erasmus Darwin is the one who said "everything comes from shells" .

Fri, 08 Jun 2012 20:25:19 UTC | #946407

Alan4discussion's Avatar Comment 14 by Alan4discussion

Comment 12 by VrijVlinder - One tends to think everything has an evolutionary purpose but it may just be completely accidental.

"Purpose" is a term beloved by IDers and creationists. I prefer to use the word "function".

Many adapted evolved features were derived from "accidental" traits in earlier features which developed further over long time periods as opportunities presented themselves.

Snake venom is highly modified saliva.[1] The venom is part of a whole: the apparatus, which is made up of venom glands that synthesize venom; and an injection system, consisting of modified fangs with which to make the venom penetrate into a prey item or a possible threat or predator.[2] The glands which secrete the zootoxins are a modification of the parotid salivary gland of other vertebrates, - http://en.wikipedia.org/wiki/Snake_venom

In humans and other vertebrates, - The pineal gland (also called the pineal body, epiphysis cerebri, epiphysis, conarium or the "third eye") is a small endocrine gland in the vertebrate brain. It produces the serotonin derivative melatonin, a hormone that affects the modulation of wake/sleep patterns and seasonal functions. - evolved from a third eye (or more accurately a primitive first eye) which became redundant as superior binocular vision evolved in a pair of new eyes.

The example at the OP is of fins, which became used for walking and climbing underwater, gradually progressing to walking on coasts and land, and then on to the specialist uses as hands or wings.

Unlike bats, the more direct independent evolution of wings from fins, can be seen in flying fish! - http://news.bbc.co.uk/earth/hi/earth_news/newsid_9232000/9232599.stm

Comment 12 by VrijVlinder - The design in this shrimps hands or claws is like organic kevlar. The adaptation specific to be able to penetrate mollusks . If there were only soft mollusks would you think this adaptation would change since it would not need to penetrate hard shells?

There are various adaptations of claws on shrimps according to their mode of feeding. eg. Harlequin shrimps feed on starfish:-

http://www.chucksaddiction.com/harlequinshrimp.html - The first Pereiopods, or feeding claws are unique with the harlequin shrimp due to their specialized use. These are what the shrimp uses to break into the starfish by nipping away small bits of the starfish's external structure (skin?) until an open wound is made large enough to insert the feeding claws. The shrimp then switches to using them to tear away small pieces of the starfish's innards and transfer them to the mouth.

Others do feed on softer food.

The ghost shrimp are scavengers in nature and eat just about any small bit of food that can find while scanning the bottom. They also swim upside down and eat food from the surface of the aquarium or pond. - http://www.buzzle.com/articles/information-on-ghost-shrimp.html

Fri, 08 Jun 2012 21:08:46 UTC | #946423

susanlatimer's Avatar Comment 15 by susanlatimer

Thank you Alan. Great article and discussion and the information in Comment 14 is fascinating.

Also thanks to All About Meme for his link to Zimmer's Parisite Rex. There's an excerpt at the link which I highly recommend. I hope to read the book some day when I get through all my other books.

Fri, 08 Jun 2012 21:53:26 UTC | #946433

Alan4discussion's Avatar Comment 16 by Alan4discussion

Comment 15 by susanlatimer

Thanks to All About Meme for his link to Zimmer's Parisite Rex and to you for the excerpt at the link.

The except is a good illustration of how evolution is driven by whole ecosystems.

I hope to read the book some day when I get through all my other books.

If you have not seen this other Nat. Geog. Zimmer article (5 pages + pictures) on Feather Evolution which I posted for discussion last year, you might like to have a look at it. - http://richarddawkins.net/articles/587327-feather-evolution

Sat, 09 Jun 2012 10:50:11 UTC | #946548

nick keighley's Avatar Comment 17 by nick keighley

Comment 3 by CEVA34 :

Re Comment 1. Vrij, you're a bit naughty talking of evolution achieving a "desired" result. Who is doing the desiring?Every stage of evolution is a result, each stage taking the organism closer to ideal performance.

not necessaily "ideal". There may be no path through evolutionary space to the "ideal" solution. Is the human knee "ideal"?

Sat, 09 Jun 2012 12:38:10 UTC | #946556

VrijVlinder's Avatar Comment 18 by VrijVlinder

Comment 17 by nick keighley not necessaily "ideal". There may be no path through evolutionary space to the "ideal" solution. Is the human knee "ideal"?

No, I do have some complaints on how our bodies are built. Bad Design if you will. Look at the oldest living creatures for good design, or at least better evolved for survival. Alligators, Tortoise ....They have not changed for millions of years so it must mean that they have evolved to fulfill all functions they need to survive long term.

Alan:"Purpose" is a term beloved by IDers and creationists. I prefer to use the word "function".

Yes you are right I will make an effort to not use the word along with evolution. I found a rather interesting article about tactile sense in robots .Robots Get A Feel For The World Almost there LOL

We've already created robots that are better at driving, cleaning, and detecting pollution than humans, so it was only a matter of time before they outpaced our sense of touch as well. The robotics masters at USC's Viterbi School of Engineering are working on tactile technology that allows robots to identify objects simply by grabbing them. Using a robotic hand modeled after that of a human, the scientists overlaid rubberized "skin" capable of gripping delicate objects without crushing them. Using feedback from the fingertips — including resistance and friction readings — the robot can be trained to identify each item based on how they feel. Currently, the bot has 117 everyday materials in its memory banks, with more on the way. The feature could be used in the future to allow robots to test consumer goods before sending them to market. Some day, a robot hand may judge the softness of your clothing, or even how ripe your vegetables are, before you ever see them in the store. via Engadget

Thu, 21 Jun 2012 22:33:17 UTC | #947952

Alan4discussion's Avatar Comment 19 by Alan4discussion

Comment 18 by VrijVlinder

Interesting links.

I suppose you have seen Asimo! - http://www.ask.com/web?l=dis&o=10148&qsrc=2873&q=Asimo%20robot%20japan

Fri, 22 Jun 2012 12:13:43 UTC | #947959

VrijVlinder's Avatar Comment 20 by VrijVlinder

Yes indeed !! I think it is quite cute but relatively useless no?

It is difficult to create a humanoid robot. The walking on two legs must be a gyroscopic nightmare to program. It would be better off with wheels like the segway. Or have more legs.

Let's admit human figures are not all terrain unless we get on all fours. Walking upright is not that advantageous , could be the reason for our back problems. I don't see a great need to canon copy a human form into a machine unless it's to become a companion. And even then having a human form would not be that necessary for conversation. ...

It can't be that hard to input sensory information into a robotic program so it could tell between surfaces and consistencies. I suppose that is how we learned how things felt as we were babies . The next time you touch something similar you associate the memory of the sensory info and compare then arrive at conclusion it is the same fabric or feel.

Of course our brain allows us to do this very fast after knowing how something feels to the hand it is only a matter of comparison with past sensations and we know what it is made from. However we did have to learn by touch. People who never touched silk may not know what it is how it feels. You would have to give them silk to touch and tell them that is how soft as silk feels.

I guess it may not be different teaching a robot what is silk by feeding it sensory information for comparison. So many materials to feel though, tedious task to program all that info.

Sat, 23 Jun 2012 08:21:20 UTC | #947971

CEVA34's Avatar Comment 21 by CEVA34

Nick Keighley - I shouldn't have used the word "ideal". In the context of evolution a better word would be "adequate". Good enough, that is, to enable the organism to survive and reproduce, but no more. Otherwise cheetahs would run at 100 mph. As for knees being ideal - mine certainly aren't. Having just had surgery for an enlarged prostate, I take a jaundiced view of the "design" of the human body!

Sat, 23 Jun 2012 15:08:28 UTC | #947975