this could just be a survival trait built into their DNA.

So what are the mechanics to explain how the trait got into the DNA to begin with?

For the love of God man, are you really incapable of expanding on the ideas presented in the article?

The article says there is ONE species of skinks with TWO dramatically different birthing traits.

Southern population lays eggs like other reptiles. It later says that animals that lay eggs (which would by default include these southern skinks) provide calcium to the embryo via the thick shell.

The article then clearly says that the northern population give LIVE BIRTH, with a picture even. It later says that animals that give birth use a placenta to provide nutrients like calcium and that without a thick egg they would presume these skinks would potentially have defects. They then realized in these skinks that the mother has traits of an early placenta and give the embryo calcium directly to make up for the lack of a thick shell.

How are you missing this relationship in the article? The author assumes that its readers can grasp the bigger connections here between the egg laying and live birth skinks to the general idea of the difference between eggs and placenta.

ok slimebeast (if that is your real name) here are direct quotes without all the other hubbub to help you see it more clearly.

Starts off with...

"Along the warm coastal lowlands of New South Wales (map), the yellow-bellied three-toed skink lays eggs to reproduce. But individuals of the same species living in the state's higher, colder mountains are almost all giving birth to live young."

Then the article continues with other reptile species and some history notes.

Then...

"One of the mysteries of how reptiles switch from eggs to live babies is how the young get their nourishment before birth."

Generalization, but still distict to each population; those that have eggs and those that have live babies. Then it discusses how a placenta helps mammals and how eggs give calcium.

"In mammals a highly specialized placenta connects the fetus to the ovary wall, allowing the baby to take up oxygen and nutrients from the mother's blood and pass back waste.

In egg-laying species, the embryo gets nourishment from the yolk, but calcium absorbed from the porous shell is also an important nutrient source."

Then it discusses in general terms how a thin shell (or no shell with live birthing skinks) could have a nourishment issue. Then it moves on to the scientists studying these northern skinks...

"Stewart and colleagues, who have studied skinks for years, decided to look for clues to the nutrient problem in the structure and chemistry of the yellow-bellied three-toed skink's uterus."

The conclusion for these specific southern skinks is....

" 'Now we can see that the uterus secretes calcium that becomes incorporated into the embryo—it's basically the early stages of the evolution of a placenta in reptiles,' Stewart explained."

Then it concludes with the answer to 'why' would this transition happen, thus why would they evolve to an entirely different birthing platform.

You're interpreting it wrong. There is not a dramatical difference between birthing traits. Actually there is no difference at all between traits. The only difference is that the guys in the northern cold retain the eggs longer, because it's cold, not because they're different than the southern guys. They explain the reason why it's possible (in this snake and in others), namely that the uterus is able to secrete calcium to the thin eggs.  But the guys in the south can do this too, it's just that there is no cold weather there to trigger the prolonged egg retainment.

You do realize that mammals technically do the same thing right. Ever watch a dog have puppies? They come out in clear sacs, i.e. final remnants of what once were eggs.

The article is showing that these skinks are evolving to that same point. They started to keep eggs inside, over time eggs don't thicken up, to combat nutrient loss, the mom begins secreating calcium on her own... over time this will continue to not have yolk at all as the placenta fully develops. Its just the path to take for live birth similar to mammals. All the article is demonstrating is the beginning of that path. A path you seem to think is simply choice, not a slower change in the species. Unfortunately, neither of us will be around long enough to see the proof in concept.

However, the idea of evolution is stupid to argue against. We have evolved hundreds of animals and plants through forced selection (as opposed to natural selection). Why is it so hard to see its already happened. Just research the history of corn if you need further proof. Used to be tiny and only found in the America's. Now its massive (delicious) and grown in many places around the world. Compare cows in the US to those that have almost not selective breeding in India. Compare wild dog races to those of domesticated, big differences. Since they can still breed with eachother, its obvious they are nto different species, just races, yet they have very different capabilities due solely to human manipulation that is proof in concept for evolution.

It's a demonstration of one possible step, but it doesn't show any proof of links between steps. Proof would be to show some more examples of further steps in the same evolutionary path. Since you also seem to believe this article demonstrates evolution right here, right now - and that it's also happened several times in other species, from lizards to mammals - it's only logical that there should be living examples of steps that are closer to the live birth of mammals. Or else you need to ask yourself why there are several examples of lizards that retain their eggs until they dissolve and give live birth, but no example of an evolutionary step further down the line towards mammalian full live birth where the embryo gets full nutrition from a placenta without having a shelled egg at any point in embryonal development.

Ever study the birthing a platypus? Its a mammal that lays eggs.

Point is there are animals all accross the spectrum, but her is the same species that utilizes two distinct paths. In the long run one version will become the sole path as the other is far more fuitful. i.e. evolution by natural selection.

More food for thought.

http://ncse.com/creationism/analysis/mammal-eggs-reptile-placentas

"The marsupial mammals have a rudimentary and short-lived placenta which is, in most marsupials, structurally and functionally different from the typical eutherian placenta. Placental nourishment of marsupial young is negligible compared to nourishment from the milk obtained in the pouch. Furthermore, there are mammals which lay eggs and have no placenta. These creatures, the monotremes, share with other mammals the characteristics of fur and the ability to lactate, but they lay eggs with leathery shells, which the females then incubate in a pouch."

and

"Some reptiles (e.g. garter snakes) are viviparous and develop a rudimentary placenta (see Stewart, JR, American Zoologist 1992 32(2):303-312, "Placental Structure and Nutritional Provision to Embryos in Predominantly Lecithotrophic Viviparous Reptiles" for a not-so-recent discussion of these facts)."

Also, http://icb.oxfordjournals.org/content/32/2/303.short has more info on placenta having reptiles.

Basically, the info is there if you actually look. Reptiles appear to be evolving (obviously very slowly and based on environmental conditions, typically cold weather) to live birth as its better for the survival of the species.

Those that are better at producing the hormones in cold weather are more likely to produce offspring which share that ability, seems like a perfect example of natural selection to me.

(Also, I don't think this is a step towards mammalian birth, I think this maybe something new, you've just assumed that position of me). - After some reading I retract this statement.

But yet again you've avoided my question. My question is concerning the fact that these animals can pass on their traits, and the strong survive to do so. That is exactly what this is. All you've got to do is prove to me that either the most fit don't survive or that genetic traits are not passed on from one generation to the next. Yet you've avoided this question twice now!

Your postulation that this is not evolution rests on the notion that the fit members of a population do not have the ability to pass on their genes. Please, show this to me; the burden of proof is one you. In fact I think every biology department of every top university in the world would be interested in this.

Sorry boss. I like skepticism when skepticism is due, but I can't help myself when I think it isn't.