Mokele

Artificial liver, not that I know of, though the liver is pretty sturdy and can regenerate quite well (either from undamaged portions or from a small transplant section).

As for artificial kidneys, yes and no. We have dialysis machines, but they're far too big to fit inside the body, and it'll be a long, long time before we can reduce their size enough to make them implantable.

There's a broad sense, yes, but also a more specific sense that the OP was talking about, namely making one particular tool, a spear.

Tool use *is* widely convergent, but there is also parsimony. If a crow and a rook can use tools, it's very likely a raven can too (since they're all corvids).

Why would they be unequal? We use more tools, but we can still use the same tools chimps do (and will, in survival situations).

The string theory folks have pretty much proven the the existance of other dimensions mathmatically and may do so experimentally with the Hadron. Black holes have never been observed directly but we were able to prove their existance mathmatically long before we were able to observe their effects on matter in space.

I'll start listening when they have empirical data, not a moment sooner. Plenty of theories with pretty math have died when the data didn't support them.

But if we make pot illegal, soon it'll be illegal to smoke and drink! Then they'll make caffeine and candy illegal! Soon they'll just ban food and we'll all starve!

You do have a point, however, I feel compelled to make a few notes:

First, no organism can ever be that well adapted, and even if it is, no environment will stay static long enough. If you want absolute stasis, you won't find it, especially at the genetic level (though morphological stasis may occur).

Secondly, you need to distinguish between species which remain unchanged (a good example being the Australian lungfish, which is found in Australian sediments dating back 100 million years with no obvious morphological changes) and *lineages* which retain the same body form (such as bats, birds, etc.)

Thirdly, what counts as "unchanged"? No genetic changes at all? Minimal enough changes that, given a time machine, a modern individual might, as it was once so eloquently put, "do the nasty in the pasty" and produce offspring? "Invisible" genetic changes but constant morphology? How constant? Scale pattern changes in crocodiles? Jaw shape changes?

Fourthly, what about descendant lineages. For instance, consider crocodiles and sharks. Modern crocodiles and reef sharks strongly resemble fossil forms far back in time, but in each case, there are numerous divergent lineages with radically different body forms (all extinct in crocodiles, some extant in sharks).

That said, it is known that under certain circumstances, species will persist unchanged for very long periods of time, often garnering the term "living fossil". I'm unaware of a specific scientific term for these taxa - I suspect most of the time they're dealt with individually in scientific texts, so a collective term has never been needed.

For whole lineages, there's a term "phylogenetic conservatism", which generally refers to a trend to remain in the ancestral state (not necessarily in terms of morphology).

Yes, the most plausible hypothesis is that the common ancestor also showed this behavior, based on parsimony (the hypothesis with the fewest evolutionary events should be preferred).

Honestly, it's not really surprising, though. What's the practical difference between a chimp using a sharpened stick to remove a prey item from a hollow tree and a Galapagos cactus finch doing the same with a cactus spine or a crow doing the same with a bit of wire?

No. I can alter someone's consciousness very easily with plain old 3-D drugs, or more permanently with a nice 3-D bone saw and scalpel.

There's no evidence higher spatial dimensions even exist, much less have any functional impact on the mundane details of neuron firing.

Again, it's all or nothing when it comes to muscle fiber contraction.

Minor technical note: this is only true for vertebrates. Invertebrate muscle fibers can respond in a graded way to levels of neural stimulation (which, in turn, allows them to get away with having very few motor units per muscle, usually less than 10, and often only 3 or so).

Blood has more than just blood cells in it - sugars, salts, lipids, proteins, amino acids, hormones, all in there. By definition, it has everything your body needs, since that's how your cells get fed.

PDF including digestive physiology of blood-sucking leeches

Long story short, they have unique colonies of symbiotic bacteria to help break down the blood, and a digestive system specialized for the consumption of protein.

Think of it like this:

You have a pump, and it moves fluid through a long tube which circles back to the pump. It does this by generating pressure to push the fluid through. But the resistance of the pipes saps that pressure. If the pipe is too long, or too narrow, there won't be enough pressure to move the fluid all the way through the system, and it'll fail. You can fix this by increasing the pressure of the pump. So when your blood vessels constrict, there's more resistance, and the heart needs to generate more pressure to overcome this resistance.

When considering forking, you're right about the path of least resistance, but you're forgetting that blood vessels are all normally relaxed. Imagine our pump system has a fork in it, both paths of which lead back to the pump. Each path has a diameter of X. If one path contracts to 1/2 X, then blood will preferentially flow through the unconstricted pipe. However, the total area available for blood flow has decreased - you used to have two pipes of diameter X, now you have one pipe of that size and one pipe of 1/2 X, so there's less total pipe space for the blood.

Long wings can work just fine in still air - look at gulls. It's just a question of being more economical vs. more nimble.

If the projected economic growth can support them, what other aspect is there? The problem in France is due to the fact that the economy cannot support them.

Narrow wings have high lift-to-drag, leading to very economical flight. However, broad wings have much higher maneuverability. That's why active aerial predators like hawks have broad wings, while long-distance seabirds have long, narrow wings.

Green - just because something changes developmentally doesn't mean "insta-cancer". If that were the case, we'd all still be hagfish.

ttyo - The pterosaurs definitely had air-sacs, but the unidirectional lung is not confirmed, and even if they had it, it may have simply evolved in the common ancestor of them and dinosaurs.

As for it evolving anew, the trick is the need to evolve extra air-sacs in the first place. Presumably these sacs did not originally serve a gas-exchange function, but were instead for lightening the animal's body to allow faster movement. How and why that occured in the first place is a bit of an open question.

You actually answered it - vision doesn't work in smooth movements. Even simply turning your head slowly is fast enough to cause a visual field to blur. For many animals, including us, the solution is called "saccades" - short, rapid eye movements which, during motion, "skip ahead", then fix, then "skip ahead" again, over and over, faster than we can detect, to minimize visual downtime.

Birds, for whatever reason, do not have saccades, and must instead perform the same motion our eyes perform with their whole heads. Several humans whose optic motor nerves have been damaged have compensated by developing this method, resulting in a very "bird-like" mannerism.

Look into supply companies for ecology and watershed management. Non-toxic colored dyes are often used to evaluate stream flow rates and watersheds.

They have very different shapes. Some bats have wing membranes that join at the ankle, others at the knee, and the aspect ratio can vary a lot - some are long and thin, others short and broad.

Actually, strontium is known to increase bone strength in animals dosed with it. It's just not used in nature because it's so much rarer that you'd never find enough to build a functional bone.

Remember, biological systems are rarely "optimal" in the broad sense. Biology does the best it can with what it has, but is often constrained by external factors, embryology, or ancestry.

Mouse is right - while we are very adaptable, we are limited by our embryology, which is why no organism has it's head in its torso, among other things.

Teeth can only develop from the outermost layer of the embryo, the ectoderm. In contrast, bones can only develop from the middle layer, the mesoderm (which forms stuff like kidneys, heart, bones, muscles, reproductive system, etc).

Another problem is functional. Bones are tremendously strong and damage resistant is large part because they're a mix of mineral matrix and woven strands of organic matter (like composite materials such as carbon fiber). Dentin has less organic matter, which makes it stiffer (not necessarily stronger), and more prone to cracking. Enamel, for all its benefits, is extremely prone to cracks and fracture, far more so than bone.

Basically, with real bone in your legs, if you run away from a tiger really fast, most times you put too much weight on the bones you'll get "micro-fractures" which will hurt later (once you've outrun the tiger) but can heal (and make bone stronger). If, however, your bones were dentin (or enamel), any time you put too much weight on them, they'd simply snap, and you'd get eaten by the tiger. Better to have lots of minor damage that doesn't impair function than a bit more strength and a much greater risk of catastrophic failure.

Embryology - teeth can only be formed from ectoderm, bones form from mesoderm.

I usually just google "Impact factor (journal name)", though that's not really how I pick outlets - the journals in my field don't have narrow defines, but you can typically read any given draft and go by "feel".

The 'low impact' journal I referred to earlier had an IF of 3.485 for 2007, which rather surprises me, since it isn't very low.

I find that a bit odd, since in my field the absolutely highest impact factor journal outside of Nature and Science is 2.98. I mean, we publish in PNAS and such, but those aren't really specific to our field.

Of course, our field is also tiny, our ratio of grad students per faculty is pretty low, and our experiments take a *long* time. On the other hand, it's rare for us to have more than 3 authors on a paper, and 2 authors is most common (Student & Adviser, Date).

However, I have to say that I recently submitted a letter to PNAS (through the normal peer reviewed route) and was really impressed with the speed. From initial submission to receipt of peer reviews and a decision (in my case corrections) was under two months. So I guess if you can fit what you want to say into a short format, and can find an appropriate journal, you don't have to wait an age to get published.

Yeah, I've heard that a lot of the higher-end journals are working on reducing their turnaround time.