Small tweak to DNA may have given us our unique hands

September 7, 2008 10:35 AM

Fingering What Make Us Human:Did a gene enhancer humanise our thumbs?
posted by homunculus (41 comments total)

This kind of science has always made my pants tight. Thanks homunculus.
posted by ZaneJ. at 10:46 AM on September 7, 2008 [1 favorite has favorites]

This totally blows me away!
posted by Kattullus at 10:48 AM on September 7, 2008

It's what makes us such excellent hitchhikers and movie critics.


(this is cool.)
posted by louche mustachio at 10:52 AM on September 7, 2008

Primate hands are clearly very unique. But are human hands really that different from chimp hands? Looking at this they don't seem different in more than small ways.
posted by Solon and Thanks at 10:53 AM on September 7, 2008

I shall bless that gene enhancer every time I need to hold a pen, press the space bar, or hitch a ride.
posted by Cranberry at 10:53 AM on September 7, 2008

God, that makes me sound like a fox news reporter ("Is something you wear everyday trying to kill your family?") - I'm really asking why both articles and the experiment made the distinction between chimp and human hands and how exactly the human hands stand out.
posted by Solon and Thanks at 10:54 AM on September 7, 2008

My cat is nervous at the prospect of mice with thumbs escaping the lab and running amok
posted by louche mustachio at 10:56 AM on September 7, 2008

Solon: opposability?
posted by phrontist at 11:08 AM on September 7, 2008

Scientists Find Our Eyes Evolved for 'X-Ray' Vision
posted by homunculus at 11:11 AM on September 7, 2008 [3 favorites has favorites]

I just figured we had opposable thumbs since it made jerking off easier and more pleasant.
posted by jonmc at 11:20 AM on September 7, 2008 [1 favorite has favorites]

Oh, sweet!
Would that Hox-generated hand configuration allowed for hacking in opposable pinkies, too. Because that would be neato.
posted by zusty at 11:21 AM on September 7, 2008

So where is my bipedal, dexterous, talking mouse?
posted by cmoj at 11:29 AM on September 7, 2008

This is super cool! Thank you!
posted by airgirl at 11:44 AM on September 7, 2008

For this reason the banana fits right into my hand!

Kidding, what a fantastic article! Thanks for posting it.
posted by zerobyproxy at 11:44 AM on September 7, 2008 [1 favorite has favorites]

Carl Zimmer: Science Writers Need Science History

For some reason, a number of articles on the paper are using the hook that this segment of DNA was once dissed as junk. “A patch of DNA once regarded as ‘junk’ may hold the key to upright walking and opposable thumbs,” according to Wired. These reports seem to be following the language from the original press release.

The “Wow! Junk DNA is not junk after all” news hook is a tempting one, but it needs to be resisted. At the very least, science writers need to recall some history.

...

The new paper about hand evolution reports on the discovery of a special kind of DNA segment called an enhancer. An enhancer sits very far away from the gene it enhances. But if DNA is folded in on itself, the two come close together. Proteins that clamp down on the DNA can then increase the production of the gene’s protein.

So, are enhancers an amazing new kind of junk that’s not junk?

Nope. The first reports of enhancers came out in 1981, 27 years ago.

posted by delmoi at 12:13 PM on September 7, 2008 [1 favorite has favorites]

phrontist, the page you linked to shows that chimps, gorillas, and a slew of other apes/monkeys/non-primates have opposable thumbs, too.
posted by Solon and Thanks at 12:14 PM on September 7, 2008

For this reason the banana fits right into my hand!

Hah! that banana thing actually proves evolution, not ID. The plant that the banana comes from doesn't fit comfortably in your hand at all, rather constant artificial selection by human growers is the reason bananas have that shape.
posted by delmoi at 12:16 PM on September 7, 2008

By the way, if you like this kind of thing you should read Carl Zimmer's blog every day. Seriously he puts out stuff this interesting like at least once a week.
posted by delmoi at 12:19 PM on September 7, 2008

I just figured we had opposable thumbs since it made jerking off easier and more pleasant.

Would easier and more satisfying masturbation lead to greater reproductive success? I would think the opposite, but I'll defer to your expertise.
posted by homunculus at 12:36 PM on September 7, 2008 [2 favorites has favorites]

Would easier and more satisfying masturbation lead to greater reproductive success?

Well, think about it. Jerking off is like practice. The more you do it, the longer you can hold back, which makes you a better lay, which attracts more females for mating, thus more reproductive success.
posted by jonmc at 12:42 PM on September 7, 2008

Solon: my understanding is that it's all about leverage. Small tweaks in bone length and muscle insertion points make big differences in strength vs dexterity. Think about chopsticks: and whether you hold them near the end or at the middle.

People often go on about how damned strong apes are compared to humans: well reason they have better grip strength is that their hands are designed to support their weight from branches, and not for making and using tools.
posted by i_am_joe's_spleen at 12:48 PM on September 7, 2008

So if I jerk of more I'll get laid more? That's what I call an elegant hypothesis. But it needs testing. The next time I jerk off, I'll be doing it for Science!
posted by homunculus at 1:02 PM on September 7, 2008 [2 favorites has favorites]

The more you do it, the longer you can hold back, which makes you a better lay, which attracts more females for mating, thus more reproductive success.

I had read reasoning contrary to this. A shorter copulation time allows less time for the back to be exposed to competing males and other possible dangers.

Or maybe that was just the reasoning that paricular scientist used to cover to up his *ahem* "premature problems".
posted by P.o.B. at 1:03 PM on September 7, 2008

constant artificial selection by human growers

For anyone wondering, here is what a wild banana looks like.
posted by synaesthetichaze at 1:05 PM on September 7, 2008

The next time I jerk off, I'll be doing it for Science!

Talk about being Blinded with Science!
posted by jonmc at 1:05 PM on September 7, 2008 [5 favorites has favorites]

Solon and Thanks writes "But are human hands really that different from chimp hands? Looking at this they don't seem different in more than small ways."

Touch the fleshy pad of the tip of your thumb to the pad on the tip of each of your fingers on the same hand. Notice how the paired finger and thumb points out, opposite the length of your arm.

This gives you four different padded grips with which to manipulate objects. (Actually more than four, if you include grips like all four fingers opposing thumb, the grip you'd use to open a jar of mayonnaise, or middle-finger and index opposing thumb, the grip for turning a key in a lock.)

Now touch the tip of your fingers to the base of your thumb; this is approximately where the tip of the chimp's finger is.

You really can't reach your pinkie that far; you can do it with the other fingers, but now the fingers, instead of pointing away from your arm, are pointing back toward your elbow, and the grip is not as strong. You can kind of grip things, but you can't point the fingers out as you do so. Turning a key is right out, opening a mayonnaise jar is much more difficult, turning a screw-driver requires much more concentration.

The human hand allows simultaneously a precise grip (well, dozens of kinds of precise grips) and the ability to provide force or torque through that grip.
posted by orthogonality at 1:39 PM on September 7, 2008 [4 favorites has favorites]

Endless Forms Most Beautiful is a book largely about the role of enhancers in evolution. It's a good read. Written by a scientist, not one of these breathless journalist types.
posted by nowonmai at 2:19 PM on September 7, 2008

Well explained, orthogonality and i_am_joe's_spleen. Thanks.
posted by Solon and Thanks at 2:24 PM on September 7, 2008

Actually this tweaking was engineered by hair, which are old parasites/symbiotes which attached to first mammals long time ago. It seems that hair slowly designed a better, neater self-grooming growing platforms for themselves, humans. Some scientists have learned to use their 'antennas of heaven' to further the understanding of hair, humanity and the world. Having thumbs has obvious evolutionary advantage for hair as it allows for more and faster variation in ecology of hair styles. Standing position helps hair to avoid dirt.
posted by Free word order! at 3:28 PM on September 7, 2008 [1 favorite has favorites]

Wing of Bat, and Mouse's Leg: Deciphering how a paw becomes a wing confirms some of eco-devo's basic hypotheses.
posted by homunculus at 3:37 PM on September 7, 2008

Solon and Thanks's diagram confirms what I've always suspected: I am, in fact, a gorilla.
posted by Faint of Butt at 5:01 PM on September 7, 2008

Nope. The first reports of enhancers came out in 1981, 27 years ago.


1981 was 27 years ago?

[head reels]

Whoa. I remember being 27 years old.

This is blowing my mind. There's like an idea sign flashing in my head now.

And it reads, "I am older than I think I am. I am older than I think I am," over and over.

I wonder if it's true?
posted by humannaire at 6:36 PM on September 7, 2008

Also, fricking great post, homunculus! Blue clone thumb me, hoo-ah!
posted by humannaire at 6:38 PM on September 7, 2008

The next time I jerk off, I'll be doing it for Science!

paging...
posted by penduluum at 7:14 PM on September 7, 2008

First: The more you do it, the longer you can hold back, which makes you a better lay, which attracts more females for mating, thus more reproductive success.

Then: I had read reasoning contrary to this. A shorter copulation time allows less time for the back to be exposed to competing males and other possible dangers.

Evolutionary explanations without experimental tests are our Just So Stories -- there are plausible evolutionary forces to cause basically any desired outcome.
posted by jhc at 7:18 PM on September 7, 2008

I just bought the galactic edition of Spore, and it comes with a Nat Geo video about this topic, and how Will Wright's work was influenced by it. Worth a look, especially if you like smart, creative games.
posted by bashos_frog at 8:09 PM on September 7, 2008

There's an article about Spore in Seed: Will Wright’s eight-year, multimillion dollar project Spore encompasses almost every aspect of science, from star formation to biological evolution. So why does it resemble intelligent design?
posted by homunculus at 8:20 PM on September 7, 2008

Ok I kinda looked and didn't see this: This post gets.... wait for it..... wait for it... TWO THUMBS UP!!!
posted by Mastercheddaar at 6:01 AM on September 8, 2008

Before Evolution Came Prevolution, Say Biologists
posted by homunculus at 11:09 PM on September 10, 2008

Evidence of evolutionary selection found in 544 genes: By comparing the genomes of humans and five other mammals, Cornell researchers have identified 544 genes that have been shaped by positive selection over millions of years of evolution.
posted by homunculus at 9:43 AM on September 17, 2008

Getting to the bottom of evolution: Genetic study investigates the origin of the anus.
posted by homunculus at 7:24 PM on September 17, 2008