Evolution at work? Craziest thing I've seen all day.

[Slimebeast]

superchunk said:

Slimebeast said:

 

You're interpreting it wrong. There is not a dramatical difference between birthing traits. Actually there are 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 secretes 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.

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.