Metroblog

A one-time school project gone terribly, terribly wrong.

20 May 2009

Yet Another Transitional Fossil Found

One of the common arguments used by creationists used to be "Well, where are the transitional fossils, eh?"

And they had a point at one time. It was difficult to link, for example, birds to dinosaurs, land mammals to whales, and humans to other primates. Surely if one creature morphed into another we should see some in-between forms. But for the past thirty years in particular those transitional forms have been showing up.

Unfortunately, every time a new one turns up the usual response from creationists is "Well that was a separate species, all on its own ..." Which is true. But doesn't mean what they want it to mean.

And every time a new missing link is discovered, the gaps in evolution that have traditionally had gods forced in to account for what we don't know grow a little smaller.

And so we have Ida. Ida isn't a lemur, nor an ape. And yet she seems to be both. The magnificently-well preserved fossil may ... I say may because lo it is way sciency to try and be clear about what we don't know ... Certainty is the province of creationism ... be a link between lemurs and other primates, including us.
Researchers are unsure when and where the primate group that includes monkeys, apes, and humans split from the other group of primates that includes lemurs.

"[Ida] is one of the important branching points on the evolutionary tree," Richmond said, "but it's not the only branching point."
~From National Geographic, emphasis mine.

The question is whether the discovery of yet another transitional is likely to wring some acknowledgement of the truth of evolution out of the theory's detractors. I am unlikely to hold my breath.

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8 Comments:

At 2:02 AM, Anonymous G Eagle Esq said...

Have you any thoughts on how the Whale/s "evolved" (allegedly) from a common ancestor who (allegedly) also evolved into a hippopotamus?

Is it really true that, at a molecular level, a change in just one gene can produce :

* webs on a human hand ..... could this be how flippers ere (allegedly) "evolved" in (eg) seals

or

* the loss of legs, as (allegedly) in whales

 
At 10:22 AM, Blogger Metro said...

I'd never heard about the hippo/whale connection. The mind doesn't reel, but walks unstadily for a moment.

In fact, it's a fallacy (as I understand it) that a change in a sole gene necessarily leads to any major changes. What seems far more likely is that successive changes in organisms that survive successfully lead to major changes over time. Coupled with changes in the environment which may favour one or another modification, those lead to the major, visible changes.

It's one of the major holes in the "Oh sure we see MICROevolution, but not macro-" argument.

Consider: One grain of sand moves on a mountaintop. This is change, but has no visible effect. However, repeat this a couple of million times and you get a small slide, which may trigger something far bigger. Or may simply end without making any noticeable difference.

Forgive the analogy, but I'm not a biologist.

 
At 12:28 PM, Anonymous Anonymous said...

Penmachine has an interesting take on the missing link:

http://www.penmachine.com/2009/05/missing-link-fossil-that-isn

Barb

 
At 4:49 PM, Blogger Derek said...

G Eagle Esq seems to misunderstand genetics, developmental biology, and the relationships between organisms a bit.

There are circumstances where a changes in a single gene in a reproductive cell can generate large changes in an organism once it's born, but much more common are the interactions, mutual suppression/activation, and other complex interconnections between many genes. That's why, even though we have many organismal genomes mapped now, they're not simple "blueprints" for the organisms they come from either -- it turns out to be more complicated than that. But it also means there are many interesting pathways for natural selection to take place as well.

So, for example, various circumstances can yield webbing on hands or feet in humans, reminding us that there are many parts of our genome that are usually inactive or don't interact the way they do in other related organisms -- but they could just as easily indicate that ancestors of our had webbed digits, or that we have the potential to evolve webbed digits if selection pressures pointed us that way over many generations. Similarly, horses are sometimes born with striped legs, indicating that the common ancestor of horses and zebras was probably striped, but NOT that horses are evolving INTO zebras.

The loss of legs in whales (or snakes for that matter!) didn't happen in a single step with a single gene, with a legless sea-living whale (or snake) born from a legged mother land-dwelling proto-whale (or lizard). It took millions of years, and we have plenty of transitional fossil forms (as well as genetic and physiological evidence) to show it. Each stage was still a viable organism too, with its own adaptations to its environment. And yes, whales and hippos share common ancestors, something like 50 million years ago. You can see it in their bone structure even today, and there's an analogy there too -- both are big, fat, aquatic but air-breathing mammals. But whales developed fins, baleen, and blubber and blowholes for living in the ocean, while hippos developed big stocky legs, chunky vegetarian teeth, and top-mounted nostrils for living in rivers -- just as our monkey cousins developed prehensile tails for tree dwelling while we developed upright posture for walking in grassland.

Being related long in the past doesn't mean we have to have the same mode of life or body morphology today.

 
At 2:39 PM, Anonymous raincoaster said...

There are a lot of transitionals in my neighborhood, and some of them are old enough to be fossils. And most of them insist on being called by female names, too.

 
At 7:35 AM, Blogger Metro said...

@Anonymous
Penmachine has a point. Calling this "The Missing Link" over-emphasizes its place in the record. It's just another transitional fossil. One of a large number of such. The main reason people are excited about it is its state of preservation.

But it also generated a lot of excitement from outer wingnuttia--Mostly in terms of "It's not transitional! It's a separate species!" Which also misses the point.

@Derek:
Thanks for stopping by, and for a solid explanation of how the gene "recipe" isn't, exactly :-) However, I'd like to point out that Herr Eagle is a raptor of infinite-resource-and-sagacity and poses these questions for the enlightenment of all.

I liked a lot of PM, by the way--The Boeing tour sounds wicked and I must do it. Mme Metro may wish to remain at the hotel ...

@RC
The phrase "Speak for yourself" is being deliberately avoided here.

 
At 11:47 PM, Anonymous Anonymous said...

What? I've been demoted to "anonymous"?

How sad...

Barb

 
At 3:05 AM, Anonymous G Eagle Esq said...

Bonjour M Metro

Monsieur Derek has let us have such an interesting und enlightening Komment - hopefully he will visit this Erudite und Thought-provoking Space again

- je suis tres content qu'il n'a pas carrying out son research sur le summit de Mt St Helens quand elle a blewée sa top

BUT perhaps he should consider revising his post to omit the doubting words "seems to" from his first line

If I had £10 (err ... US $5 in 2010 Values) for everything I had misunderstood, I would be a vastly rich Eagle, well-resourced enough to buy this latest German Fossil of (perhaps) the ancestor of all you Homo pseudo pSapiens

... AND to employ you & him to make Disney Films about this tragically & prematurely departed creature, as well as managing the much desired Tree OktoPodia Park in British Columbia

Your obedient servant etc

G E

wv = concout - is this some kind of French

 

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