Scientists Discover Where Snakes Lived When They Evolved into Limbless Creatures

Penn State ^ | 30 January 2004 | press release

[AdmSmith]

The mystery of where Earth's first snakes lived as they were evolving into limbless creatures from their lizard ancestors has intrigued scientists for centuries. Now, the first study ever to analyze genes from all the living families of lizards has revealed that snakes made their debut on the land, not in the ocean. The discovery resolves a long-smoldering debate among biologists about whether snakes had a terrestrial or a marine origin roughly 150 million years ago--a debate rekindled recently by controversial research in favor of the marine hypothesis.

In a paper to be published in the 7 May 2004 issue of the Royal Society journal Biology Letters, Nicolas Vidal, a postdoctoral fellow, and S. Blair Hedges, a professor of biology at Penn State, describe how they put the two theories to the test. They collected the largest genetic data set for snakes and lizards ever used to address this question. Their collection includes two genes from 64 species representing all 19 families of living lizards and 17 of the 25 families of living snakes.

Genetic material from some of the lizards was difficult to obtain because some species live only on certain small islands or in remote parts of the world. "We felt it was important to analyze genes from all the lizard groups because almost every lizard family has been suggested as being the one most closely related to snakes. If we had failed to include genes from even one of the lizard families, we could have missed getting the right answer," Hedges explains.

"For the marine hypothesis to be correct, snakes must be the closest relative of the only lizards known to have lived in the ocean when snakes evolved--the giant, extinct mosasaur lizards," Vidal says. "While we can't analyze the genes of the extinct mosasaurs, we can use the genes of their closest living cousins, monitor lizards like the giant Komodo Dragon," he explains.

The team analyzed gene sequences from each of the species, using several statistical methods to determine how the species are related. "Although these genes have the same function in each species--and so, by definition, are the same gene--their structure in each species is slightly different because of mutations that have developed over time," Vidal explains. When the genetic comparisons were complete, Vidal and Hedges had a family tree showing the relationships of the species.

"Our results show clearly that snakes are not closely related to monitor lizards like the giant Komodo Dragon, which are the closest living relatives of the mosasaurs--the only known marine lizard living at the time that snakes evolved," Vidal says. "Because all the other lizards at that time lived on the land, our study provides strong evidence that snakes evolved on the land, not in the ocean."

The research suggests an answer to another long-debated question: why snakes lost their limbs. Their land-based lifestyle, including burrowing underground at least some of the time, may be the reason. "Having limbs is a real problem if you need to fit through small openings underground, as anybody who has tried exploring in caves knows," Hedges says. "Your body could fit through much smaller openings if you did not have the wide shoulders and pelvis that support your limbs." The researchers note that the burrowing lifestyle of many other species, including legless lizards, is correlated with the complete loss of limbs or the evolution of very small limbs.

This research was supported by the National Aeronautics and Space Administration Astrobiology Institute and the National Science Foundation.

[CyberCowboy777]

What is your understanding of reality? Do you know all? See all?

How do you know what you do not know?

To be so arrogant as to think you have any real understanding of reality is sad. No discovery for you.

Should we bow now or wait till you are crowned as god?

How hard you would have fought those who claimed the earth was flat.

[CyberCowboy777]

Reparations for snakes.

Your understanding of the passage is fairly weak.

You seem like an intelligent fellow - you could investigate the passage and get back to us OR you could accept that you have a limited understanding and hold a opinion base upon that fact.

We are discussing a time and a place that held loose to our understanding of reality. You can choose to believe that the time and place did not exist, but you cannot then apply your arbitrary rules to it.

[js1138]

We are discussing a time and a place that held loose to our understanding of reality.

I accept that. In fact I see little change over the centuries. Fortunately for the survival of our species it doesn't take much understanding of science to lift a fork to one's mouth.

[Dimensio]

A little informaion is dnagerous in the hands of a Biblical Literalist.

Apparently it is "close enough" for hardcore literalists. Similar reasoning has been used to "prove" that rabbits chew cud.

[Modernman]

The short answer is the Bible. See post #171 and tell me where there is any doubt.

Then, under a literal reading, the Bible is wrong.

[Modernman]

What is your understanding of reality? Do you know all? See all?

Nope. Maybe God does. Assuming he exists, which I'm not all that sure of.

[Southflanknorthpawsis]

the Bible is wrong.

Believe what you will, but some day you will face God and then you will know.

Laugh, fret, argue.......do whatever you choose, but you will finally come to meet Truth and all your doubt and theory will have not been time well spent. I hope that things change for you, but it doesn't seem likely at this point.

[Dimensio]

You can't have it both ways. You can disagree because it works for settling it in your mind, but it doesn't make it right.

You seem to know exactly how the Bible is to be interpreted. Tell me, have you been imparted with divine knowledge, or are you just incredibly arrogant?

[Dimensio]

Why are we spending hard-earned taxpayer money on this nonsense?

I'm curious. Could you be specific as to the exact nature of your disagreement with this research -- specifically, why you dismiss it as "nonsense"?

[js1138]

Help me out here, Zulu. Is this God's idea of a trick? Do you believe that God would inspire the very first book of the Bible to be one of fairy tales or confusion?

Do you have trouble distinguishing between metaphors and falsehoods? How about parables? Are they literally true?

[CyberCowboy777]

which I'm not all that sure of.

Is that all that surprising considering the lack of understanding any of us have of the world around us?

Only a foolish man would seek understanding only to reject paths still unexplored.

[Michael_Michaelangelo]

[CyberCowboy777]

Then, under a literal reading, the Bible is wrong.

How do you know that? Because it is beyond your understanding?

[Southflanknorthpawsis]

Arrogance has nothing to do with it. The Bible is the inspired TRUTH of God and His plan for man's salvation. I know in my heart and soul that is so.

I'm sorry if you don't know this. I sincerely am sorry.

I can't relate to that emptiness because from as far back as I can remember I have known that God created me and I am content and solid with that knowledge.

Again, you express such an anger. What's with that anyway? Why?

I'm not angry that you don't believe. I wish everyone did, but I'm not angry that they don't; just sad.

[shaggy eel]

,,, shagadelic teef? I'm lost for words.

[js1138]

Only a foolish man would seek understanding only to reject paths still unexplored.

Excellent advice. I recommend it to you. Rejecting evidence out of fear of punishment is the greatest foolishment of all. If fyour mind is not free to follow the evidence without fear, then you have no free will at all.

[whattajoke]

I am always amazed at the depth of anger in you antiGod types. If it's all so silly, why do you care so passionately? It's amusing.

You misinterpreted my post then. I have no anger in me at all regarding God. I have no feelings in me regarding God. I am, however, passionate about science and evolution and education. That's why I'm here. I couldn't care less if you think snakes talked and eat dust... I'm just trying to explain why that particular bible story is impossible.

As for you, M_M, I can assure you, I think the world is limitless in it's beauty and wonder. This is why I try to learn as much about it as possible; That is, I'm curious about it beyond simply saying, "what a lovely world. God created it. Done."

[Dimensio]

Again, you express such an anger. What's with that anyway? Why?

I don't recall expressing anger. I don't feel angry at all. I am actually somewhat fascinated by those who seem to think that they have acquired ultimate, unquestionable knowledge and dismiss out-of-hand any competing ideas.

[Southflanknorthpawsis]

Do you have trouble distinguishing between metaphors and falsehoods? How about parables? Are they literally true?

Parables are, by definition, not literal. They are used to illustrate a concept for the benefit of man's understanding.

For the umpteenth time........when something is not to be interpreted literally, the inspired writer makes it very clear.

Creation and its description is neither parable nor metaphor.

[VRWC_minion]

That doesn't mean the window dressing around that basic concept is necessarily true and I don't beleive it is.

What window dressing ? The rest of the creation ? God created man and woman and all the rest was here by accident ?