Neil Shubin inducted into NAS

This is satisfying:

The National Academy of Sciences today announced the election of 72 new members and 18 foreign associates from 15 countries in recognition of their distinguished and continuing achievements in original research…

Shubin, Neil H.; Robert R. Bensley Professor and associate dean, department of organismal biology and anatomy, University of Chicago, Chicago

Shubin is most famous for his evolution-utilizing research into Tiktaalik. I’m glad to see him inducted.

And congratulations to everyone else who was deemed worthy to be a member of such a prestigious institute.

Neglected point

One point I neglected about Tiktaalik is that its ability to walk on land was limited. Its limbs wouldn’t have been able to support it terribly well to do terribly much. Its life was likely spent more in the water than on land.

Coupled with the recent discovery of tetrapod footprints in a marine environment, the way to think of all this is that tetrapods did evolve at least 400 million years ago, but there were clearly still viable alternative lifestyles to go alongside fully terrestrial life (and still are). Nothing demands evolution be perfectly linear. (Neanderthals lived at the same time as our direct ancestors as recently as 30,000 years ago.) A further important fact is that while probably 90% or so of all fossils come from the ocean, they tend to be from the more settled sediments, i.e., not the shoreline, the evident habitat of these newly discovered tetrapods. That indicates a possible sampling bias. Just looking at Tiktaalik, it’s clear that its freshwater habitat lent itself to preserving fossils – aside from the area being targeted for its fossilizing properties, there were several examples extracted from the site.

More interesting fossils than Ida

Ida is a new fossil discovery that has been horribly over-hyped. It is being called “the missing link”. Following sentences usually mention humans. In other words, some articles are crafty and don’t directly say this fossil is important to Homo sapiens. Others are less crafty. All of this non-sense plays right into the hands of the lying creationists (sorry to be redundant).

Darwinius masillae, otherwise known as Ida, is a tremendously well-preserved fossil that is a primate ancestor. As with most fossils, it was probably a relatively close cousin of one of our direct ancestors. (Note, “relatively close”. Of course, all fossils we find are eventually cousins of our ancestors, if they aren’t directly our ancestors.) How close is difficult to tell – forget saying it’s a direct ancestor. It is a member of the same suborder as humans (and apes and monkeys), haplorhine, but that doesn’t mean Ida wasn’t the last member of her particular population. It can tell us some interesting things, but it in no way independently confirms evolution. Science doesn’t work that way; theories are supported by a wide body of evidence. A single find can add a little weight to a theory, but doesn’t usually completely make a theory. (Notable, if this were found in the, say, Jurassic period, it would have been a find that actually spun evolution on its head – find me a part of creationism [or its coy, dishonest, lying cousin intelligent design] that can be falsified.)

So while interesting and not simply trivial, there are more important fossils out there than Ida. What’s more, there are more interesting fossils. (Guess which claim is the author’s opinion.) Here are some.

Lucy

Lucy

Maiacetus inuus

Maiacetus inuus

Schinderhannes bartelsi

Schinderhannes bartelsi

Tiktaalik

Tiktaalik

Only in the light of evolution

Now that finals are over, I can devote more time to my dear, neglected blog. I begin with a series:

I am following a specific chapter in Jerry Coyne’s Why Evolution is True.

The fossil record: We should see fossils in a certain order if evolution is correct. They should go from simple to more complex overall, and the fossils we see in the most recent strata should resemble extant life much more than the fossils we see in old strata.

We should also see changes within lineages. We should be able to observe instances of gradual change in species that eventually leads up to either current species or at least to the time of extinction for these species.

Here’s a simple timeline of life’s history. Click it.

What the evidence shows is gradual change. First we find simple bacteria which survived off energy from the Sun, then we see more complicated cells known as eukaryotes arise. (You are a eukaryote.) Next we see a slew of multi-cellular animals arise. They’re still simple, but much more complex than the original bacteria. A few million years later more complicated life arrives. Early (and simple) plants begin to take hold. Soon the fossil record begins to show more plant complexity with low-lying shrub such as ferns, then conifers, then deciduous trees, and finally flowering plants. Gradual changes occur in the oceans and fresh waters which lead to fish and then tetrapods (Tiktaalik comes to mind).

One of my favorite fossils is trilobites. They’re extremely common due to their hard bodies. In fact, even their eyes are well-preserved because of their hard mineral make-up. I personally recall entering touristy-stores seeing countless fossils of these guys in the mid-west to the west (which, unsurprisingly, was once a shallow sea). This image shows the different lineages of this organism. Studies show that the ‘rib’ count has changed over time in each individual species, often without regard to how the other species changed. Going back further, there is less and less divergence in each species. Eventually, as evolution predicts, they all meet at a common ancestor.

So naturally the next step is to find fossils which show more significant changes. Let’s take birds and reptiles. They hold similarities between each other, both morphologically (certain shapes and structures) and phylogenetically (genetic sequence). A good hypothesis is that they came from one common ancestor. If this is true, the links between birds and its ancestors and reptiles and its ancestors should lead to the same point. They do. Dinosaurs are the ancestors of both. The links between birds and dinosaurs are so incredibly well established that I’d prefer to not go over them in detail. But for starters, some dinosaurs sported feathers and claws and had the same proteins for the feather-making process as extant birds. The links between reptiles and dinosaurs is easier just on intuition, so I’ll leave it at that for now.

Other transitional fossils include the already mentioned Tiktaalik. A view of the history of life can be see here. This shows the change in head and neck structure. Recent research on long-ago discovered Tiktaalik fossils has shown the importance in the gradual bone changes in the neck. These changes – a hallmark of evolution – were important to the ability to turn its head. This is a hallmark because natural selection only modifies what already exists. This is precisely what happened.

Going further with this example, evolution makes predictions as to how early fish evolved to survive on land. If there were lobe-finned fish 390 million years ago and obviously terrestrial organisms 360 million years ago (which is what the fossil record shows), then if scientists are to find transitional fossils, they should date in between that time frame. There should be an animal that shows both features of lobe-finned fish and terrestrial animals. Tiktaalik is that animal. It has fins, scales, and gills, but it also has a flat, salamander-like head with nostrils on top of its nose. This is a good indication that it could breathe air. Its eyes were also placed there, indicating that it swam in shallow waters. Furthermore, it was lobe-finned, but shows bones (which eventually evolved into the arm bones you used to get out of bed today) that were able to support its weight to prop itself up. And of course, it dates to 375 million years ago.

Next, evolution says the fossil record should show recent fossils being more closely related to extant species than are early fossils. This is precisely what happens. Sixty million years ago there were no whales. Fossils resembling modern whales only show up 30 million years ago. So, again, evolution makes a predication: if transitional fossils are to be found, they will be within this gap. And so it is.

We begin with Indohyus. It was an artiodactyl. This is important because extant whales have vestigial bones which indicate that they came from this order: scientists expected to find this because, again, evolution predicted it. It should be of no surprise that this fossil dates to about 48 million years ago, right in the predicted gap. From here there is a gradual evolution shown in the fossil record which leads up to modern whales.

Great New Tiktaalik Research

Details of Evolutionary Transition From Fish to Land Animals Revealed

So the jist of this new research is that Tiktaalik roseae has been vetted a bit better. Researchers viewed several Tiktaalik fossils and discovered some interesting new information on its internal anatomy. Of specific interest is the hyomandibula. Its function has changed significantly from its early arrival in fish to its current use in mammals. As it stands, this bone functions as part of the ear for mammals. It also functions as part of cranial motions for fish, namely it is very important to gill respiration. In Tiktaalik, it had a transitional function. That isn’t to say it acted as a sort of ear-gill. It didn’t. It had a function that resulted in better cranial movement, inherently giving it less importance toward gill respiration.

What’s really important here is to realize that this is the exact same bone in mammals as it is in fish. If Tiktaalik lies somewhere between fish and most land animals, we should see quite a few features lying in between. That’s precisely what we see. What’s further, this should help to demonstrate that when scientists speak of transitional features, they do not mean hybrid phenotypes like ear-gills or the silly crocoduck