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.

[ZULU]

Yeah, they do contradict a literal interpretation. Snakes evolved long before modern man appeared in the fossil record. That's a fact.

Therefore, ther reference was symbolical, allegorical and teleological, not scientific.

The "serpent" in the Garden of Eden was Satan, not a reptile. The same passage in Genesis states that Satan assumed the shape of the serpent.

[VRWC_minion]

The real reference in the Bible is to Satan,

This article seems to indicate that the change to a crawling creature happened to creatures that were formerly ground based animals and the scripture is consistant with that. That to me is interesting.

However, how do you know both things cannot be true. Couldn't God have changed snakes from having legs to crawling on their bellys at the same time he cursed Satan ?

As an aside, later in the scripture, God curses the ground which means the snake/Satan is fully exposed to the cursed ground from head to tail.

[ZULU]

Its NOT a fairy tale, there are siginificant fossil indications, as well as modern analogies with lizards. Both groups of reptiles are closely related. One preceded the other in the fossil record and the other (snakes) are an obvioous modification which appeared later.

[ZULU]

Good for you.

I can't really believe some of the idiotic statements appearing on this board in reference to this article.

[ZULU]

They don't rinse their food, but they sure as heck don't eat dust, anyone than people eat bread flavored with sweat.

Its SYMBOLIC - ALLEGORICAL. Like the Parables.

[VRWC_minion]

Like the Parables.

The parables use real events in everday life.

[ZULU]

The production of any individual fossil is a unique and unusual event - hence the gaps.

Take a walk in the woods - any woods. How many deer, squirrel, or bear skeletons have you ever found? Does that prove that they don't exist?

[ZULU]

These are all symbolical and allegorical statements.

[ZULU]

Thank you Ayatollah. Thinking like that is rampant in Islamic society. You would feel very at home there.

[ZULU]

You are correct. Why these literalists think reading everythiong in the Bible so literally makes sense or amkes them better Christians is totally beyond me.

Rabbis have told me that the Torah must be studied in order to understand what the passages actually mean. You can't literally interpret EVERYTHING in it. They should know. The Old Testament is essentially a Jewish product.

[ZULU]

Good Lord!!!

Snakes tongues pick up particles of scent suspended in the air and press them against Jacobson's organ to locate prey. It has NOTHING to do with eating dust.

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

[ZULU]

The Greek was translated from the Hebrew. What's the Hebrew word and what does THAT mean??

[ZULU]

I have kept HUNDREDS of snakes, and BELIEVE ME, they would DIE on a diet of dust!!

They eat animals - live ones or freshly killed ones!!

[Donna Lee Nardo]

LOL!

[general_re]

Primates have no INHERENT fear of snakes.

Just to expand on that a bit, it turns out that classing it as either an inherent fear or not is somewhat oversimplified. Rhesus monkeys do not start out life afraid of snakes - a monkey that has never been exposed to a snake will not show any fear when encountering one. However, if you show rhesus monkeys another monkey reacting in fear to a snake, then those monkeys will also react in fear to snakes from that point onward, even if they've never encountered a snake before for themselves.

But it's not a completely learned behavior either - if you show those same monkeys another monkey reacting fearfully to, say, a flower, the monkeys do not develop a fear of flowers thereafter. So rather than fear of snakes being a totally learned behavior, or a totally hardwired behavior, it seems to be a matter of predisposition - primates are predisposed to fear snakes, but without the cues that trigger such fear, the behavior is not evoked.

[Woodman]

Maybe she should consider purchasing a good set of Dr Bukks

[VRWC_minion]

Number 5175

TDNT:
nachash {naw-khawsh'} Word Origin:
from 5172 TDNT:
1347a Part of Speech:
Noun Masculine Usage in the KJV:
serpent 31

Total: 31Definition:

1. serpent, snake
   1. serpent
   2. image (of serpent)
   3. fleeing serpent (mythological)

TDNT - Theological Dictionary of the New Testament; TWOT - Theological Word Book of the Old Testament

[southland]

You are quoting the designer and maker.

[Southflanknorthpawsis]

My, my, my........Aren't we angry.

[ZULU]

"Couldn't God have changed snakes from having legs to crawling on their bellys at the same time he cursed Satan ?"

NO!!

Snakes appeared in the fossil record LONG before modern man did. As a matter of fact, they may have appeared before even our predecessors like the Australopithecines did. The time frames are all wrong!!

The passage has allegorical and symbolic significance wnad relate to the Hebrew perspecitve of serpents, and their worship by neighboring pagan tribes. The ancient Minoans worshipped snakes, so did the Greeks and Romans. Ever see the symbol for medicine? It has two snakes intertwined on a staff as a symbol of Aescupalius, the Ancient Roman God of medicine. Its OBVIOUSLY symbolic. We DON'T worship snakes.