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.

[Southflanknorthpawsis]

You might enjoy this.

Scroll down to the Eleven Principles of the Literal Method of Interpreting Scripture.

[RightWingAtheist]

Ping

[RightWingAtheist]

[PatrickHenry]

PING. [This ping list is for the evolution side of evolution threads, and sometimes for other science topics. FReepmail me to be added or dropped.]

[dozer7]

"A snake for your collection."

The collection is held by the liberals. apologies to snakes love snakes , tasty but they give me gas.

(Tilt at windmills if you must but there are times they fall on you. Sancho tell the valet to bring the burro around.)

[Verginius Rufus]

I'm wondering...did they manage to get any genes from sneaky snake?

[IncredibleHulk]

Actually, the serpent referred to in the bible is a Dragon, not a snake. The snake reference is not supported by scripture but the dragon reference is found in Sumerian cuneiform writings of 3000 BCE. The dragon is a reference to Enkei, a "god", not a talking animal.

[Verginius Rufus]

I don't know about the Hebrew text, but in the Greek Septuagint translation of Genesis 3.1-15 it uses the word ophis which is the regular Greek word for serpent or snake. (The name of the constellation Ophiuchus means "serpent holder.")

[Alamo-Girl]

Thanks for the ping!

[AdmSmith]

You must be joking!

If that is correct then man is as well a dust-eater. The corresponding organ in human to the Jacobson's organ is the Vomeronasal Organ: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10744216&dopt=Abstract

The vomeronasal organ is a chemoreceptive structure located at the base of the nasal septum with direct axonal connections to the accessory olfactory bulb in many terrestrial vertebrates. Pheromones presumably bind to the vomeronasal organ and exert behavioral or physiologic responses, thereby allowing chemical communication between animals of the same species. The presence and function of the vomeronasal organ in humans is debated. A phenotypic classification schema for the human vomeronasal organ is described and applied to 253 human subjects who underwent nasal examination. Of these subjects, only 6 percent possessed a vomeronasal organ with 64 percent unilateral and 36 percent bilateral in appearance. No difference existed in gender, age, or race between those subjects with or without a vomeronasal organ. There is no evidence supporting involutional senescence of this structure. Future investigations should use this phenotypic schema for the vomeronasal organ to allow accurate comparisons of study populations.

[protest1]

No, I am not joking. What, in your post, would lead you to that conclusion?

Snakes crawl on their belly and do eat dust. Your post, while interesting, is irrelevant.
Do we crawl around on our belly licking dust? No I think not.

[AdmSmith]

Ask any herpetologist and they will confirm that snakes do not eat dust.

You may as well ask any pediatrist and they will confirm that most small babies do "crawl around on their belly licking dust"

[VRWC_minion]

I agree with it all. However, it still leaves room to appreciate a passage on two levels. It need not be an either/or approach. Heck, even the names God chose for people were dual purpose. They forshadowed the charachter and they were their name.

We often get too tied up in the literal and we underestimate God's ability of expression in his scripture. What a masterfull God we have that can express both literal meanings for the child listening and metaphors for the adult listening.

[steve-b]

Scientists Discover Where Snakes Lived When They Evolved into Limbless Creatures

Not, one presumes, in Georgia.

[VRWC_minion]

Actually, the serpent referred to in the bible is a Dragon, not a snake.

Of course he wasn't a snake until God changed him.

The snake reference is not supported by scripture but the dragon reference is found in Sumerian cuneiform writings of 3000 BCE. The dragon is a reference to Enkei, a "god", not a talking animal.

How do you know that both stories don't have a common source and that one of them or both of them might be corrupt versions ?

[VRWC_minion]

If that is correct then man is as well a dust-eater

Real men never wash their food, only snakes do.

[rintense]

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.

Hell, we've known this for years on FR. Hillary spends most of her time on dry land.

[ZULU]

A PERFECT example of Biblicial literalists extracting a passage from Genesis as though it explains Biological facts.

A lot of the pagan cultures around Palestine worshipped snakes. Some snakes are venomous.

Human beings are primates. Primates have no INHERENT fear of snakes. HOWEVER, primates form a portion of the diet of large tropical snakes and are exposed to venomous tropical snakes. Hence, primates have been shown in behavioral tests, to have an innate capacity to DEVELOP a fear of snakes.

This passage represents more of an attmept to teleogically
explain why snakes crawl on the ground and why they are limbless and why the Jews hated them. The real reference in the Bible is to Satan, not to members of the Order Squamata. Having worked with snakes for many years, I can assure you, there is absolutelyu NOTHING Satanic about the animal. They are actually beautiful and quite interesting.

[ZULU]

Snakes and lizards are VERY closely related. They are connected EVOLUTIONARILY as this study indicates.

There are limbless burrowing lizards and their are snakes like boas which have tiny, rudimentary limbs called "spurs" located at the rear of the body. Both snakes and lizards have scales - a feature absent in Crocodilians and Turtles.
Burrowing snakes and limbless lizards have many simialr behavioral patterns and ecological requirements. Osteologically, snakes and lizards are very similar.

[ZULU]

"14 And the LORD God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:"

See my posting on the ridiculous interpretation of this passage. It is a symbolical referal to SATAN, NOT to snakes the animal.

And snakes DON'T EAT DUST. They eat small mammals, other reptiles, fish, insects, birds, and insects and sometimes eggs.

TRUST ME, I have had numerous snakes as pets and worked with them professionally. I'm a Christian and see no conflict with that and the Bible.

And every snake DOESN'T have "two spots on their belly where their legs once were". Some large constrictors have very tiny rudimentary rear limbs called "spurs" located next to the anal opening. They are remnants of legs. They evolved from lizards and this has NOTHING to do with any Biblical "curses". This evolutionary event occurred LONG BEFORE nay Modern man appeared in the fossil records.