"For Science!"

Lest anyone ever be deceived by the convincing and omnipotent power of textbooks, science is a perpetually changing field, both in that new branches of study emerge from the main "trunk" of scientific disciplines and that our previous hypotheses and theories can be (and often are) eliminated by new findings.

I recall sitting as a child, peering through my dad's old dinosaur books that depicted Brachiosaurus feeding while mostly submerged in water.

Heck, even Disney's Fantasia depicted Diplodicus feeding in quagmires, the illustrators only depicting what scientists believed to be true at the time.

Now I'm not studying paleontology, but I know all of this was built under the premise that sauropods (more colloquially known as "long-necks" thanks to the infinite series The Land Before Time) could not possibly have lived on land. Good heavens, the size of their femur is larger than my 8-year-old nephew! Can you imagine the forces on that bone from gravity? The rationalization is actually not that illogical--the largest animal to ever live on the Earth is the Blue Whale (Balaenoptera musculus), reaching lengths around 100 ft and on average weighing in at an astronomical 190 tons. The only way such an organism can reach such values is by having a buoyancy force to counter a large percentage of the weight. If that's true for the Blue Whale, then is it so irrational to believe that sauropods (deemed as the largest terrestrial organisms to ever live on the Earth--gotta love those superlatives) would have the same limitation? What's an interesting thought about this, however, is the forces acting on a standing Brachiosaurus in the water. If a Brachiosaurus eats vegetation around 30 ft. high, then let's imagine that it's heart is located roughly 12 ft. from the ground. Fluid statics says that the differential pressure changes solely with the change in height in the fluid, i.e. pressure increases only as one changes depth. With the heart at about 17 ft. deep (~5.2 m), the pressure is about 22.1 psi, where the average erect giraffe systolic heart pressure is about 2.3 psi (Citters et al., Comp. Biochem. and Phys., 1968). There is a specific point to make about this. Depending on the circumstance having that pressure could actually be fine, but it could also lead to a potential problem because the heart might not be able to generate the pressure needed to ascend up the neck of the sauropod (near the surface where pressure is lower) or down to the appendages (at the base where the pressure is even greater). So although we have some logical idea about size/mass being a limitation as to where a sauropod can actually live, we now also have to take into account the physiological consequences of this proposal and realize that it may also be problematic for the theory.

 Here's what is irrefutable: there are sauropod tracks preserved in stone that were from terrestrial habitats, usually deduced by the nature of the rock in which the tracks are preserved.

Similarly, the wear and tear on the teeth of sauropods indicates that they fed on foliage that was tough and significantly more challenging to masticate ("chew") than if all they fed on were algae or other aquatic vegetation. So in retrospect, it seems ridiculous that people once thought that sauropods could only live in water. But it's only easy to say that in retrospect. There are similar changes that have occurred with dinosaurs. Look at the transition of our view of dinosaurs as cold-blooded, lethargic animals to possibly warm-blooded, highly active creatures.

1950s depiction of Corythosaurus--notice the dull colors, slouched body, and dragging tail

Contemporary image of Corythosaurus--notice the bright colors, erect tail, and heightened stature

The facts of the matter are that science is perpetually evolving from one year to the next, and it may be evolving in the exact wrong direction for decades or even centuries. If you don't believe me on that, talk to any computer scientist or molecular biologist, both of which are scientific fields where the information from only a year or two ago is considered antiquated. In fact, genetics and molecular biology combined advance so quickly that the federal government can't keep up with the legal and ethical issues that come about with each major discovery or technological advancement. 

As another example, Charles Darwin himself used to believe in particles he called "gemmules" that would permeate throughout the body, but somehow aggregate together in the reproductive organs of organisms. When an egg and sperm merged together, the gemmules inside would merge together, making the offspring a blend of the two parents, although some of those gemmules may remain latent until future generations. Unbeknownst to Darwin, Gregor Mendel was performing his iconic pea experiments, yielding some of the same conclusions as Darwin (albeit more accurate) but building the pathway toward understanding the idea of a "gene" in inheritance. It was assumed that of the four major groups of biomolecules (carbohydrates, lipids, proteins, and nucleic acids) that proteins were the most likely candidates for inheritance. Through a series of ingenious experiments, however, we learned that inheritance was dependent on nucleic acids. And with the discovery of the structure of DNA by Watson and Crick in the 1953, a whole new avenue of understanding inheritance began.

Ultimately the objective here is to make this quite clear: science is not stagnant. Through one of the most powerful techniques ever conceived by the intellect of man (the scientific method), science has made leaps and bounds in its knowledge about the Universe and everything in it. Theories come and go. Questioning and modeling help smooth rough edges. Ingenuity and intrigue pave new paths to follow. In all, science presents one of the most exciting, fascinating and complex disciplines that any person could choose to study. The objective of this blog is to post about recent studies in scientific fields as they are published in the literature. I take an approach that strives to see a scientific study from its undergirding theories, historical foundations, and basic assumptions. Why are these studies useful or interesting? What does it build upon or reveal? How has our opinion on this study changed over the years? With each study posted, hopefully both you and I gain a greater appreciation for the research going on and for the beautiful and magnificent world that surrounds us.