Why We Need To Understand Evolution (and why we need a natural history museum)
With all that has been going on in the world and all the important societal problems, I have been despairing that my desire to push for a natural history museum and more evolution education seemed not as important. But it struck me today that it is perhaps one of the most important things we need to do. There are a lot of misunderstandings about evolution, even among people who accept it, that hinder our ability to get along in the world. Understanding two important truths of evolution will go a long way towards healing our societal divides. What are those truths? 1. We are all the same, and that is a good thing. 2. We are all different, and that is also a good thing. These may seem contradictory, but if you understand how they are meant, they make perfect sense.
- We are all the same, and that is a good thing.
When you start really studying life on this planet, it quickly becomes inescapable that we are all connected. We are all part of the same family. Strip off the skin from humans and we see essentially the same underneath. We all share the same skeletons, our muscles and organs are the same, there are no important differences in our brains. Sure, there are differences, but no matter what way we try to divide humans, especially by skin color or nationality, we find that the differences within the groups are greater than the differences between groups. What this means is that the dividing lines are arbitrary and have no biological basis.
When we go beyond humans and look at all vertebrates, we see the same thing. If we compare skeletons, we see the same bones over and over again. Every animal that has four limbs shares the same bone structure. They may look different, but the bones are all the same. All of our front limbs have a humerus, an ulna, and a radius. We all have the same number of fingers and toes. They may look different, they may lose some as they grow from fetus to adult, but they are all there. As we get farther and farther away from direct ancestry and relationships, the superficial differences start piling up, but the core is always the same.
Going even farther, we all share the same base code. We all use essentially the same DNA and RNA. The sequences may be different, but just as all computer programs are different, they all share the same underlying coding language. We all share metabolic pathways, from bacteria to humans.
Why do we see all these similarities? Because we all share an ancestor. Somewhere down the line, we are all related. We are one family. It may be a very extended family, but we are all together. All life on Earth is connected. Through that life, we are all connected to the very rock upon which we stand. Life has shaped the surface of the Earth. It has shaped the air we breath. We all sprang from the same roots. When you look at someone from a different culture, someone with a different skin color, you are not seeing an other, you are seeing a long separated family member. Embrace that connectedness. Now, I know that no one can get more under your skin and angry than a close family member, but at the end of the day, we don’t generally let that tear us apart. No matter how much we may disagree with our family, we still recognize they are family. Just take that feeling and extend it to recognize that every living thing on Earth is also part of your family.
2. We are all different, and that is a good thing.
So if we are all essentially the same, how can we all be different? No matter how closely we are related to someone, there are always differences. Even identical twins are not completely identical. Our DNA and life experiences mean that each and every one of us is different in some way from everyone else. While we all share the same basic body plan and organization, there are always some differences.
Those differences are important. Ask any agricultural scientist and they will tell you that one of, if not the biggest danger in our food supply is the monoculture crops we grow. When everything is the same, that means they also share all the same limitations and vulnerabilities. Monocultures only work when there is no change. But they do not handle change well. And if there is one thing we know about life, it is that change is inevitable. These days, we are pushing change faster than ever before, so this vulnerability to change is deadly.
Purity is the death of a species. We need diversity to weather changes. As new diseases crop up, as weather becomes more unpredictable and changeable, we will need the diversity to be able to handle whatever is thrown at us. The more diverse the population, the more changes we can tolerate. In a diverse population, there will always be some fraction of the population that is prepared for anything that happens. Those people will make sure that we continue. Moreover, they will help those of us unprepared for the changes make it through. When a new disease appears, those that are naturally immune will be key to developing medicines that will allow the rest of us to survive. Those that can handle climatic changes will be the ones to build the structures and infrastructure that will allow the rest of us to weather the storms. We need diversity. If we try to homogenize our culture and our people, we will die.
We need evolution education and a natural history museum.
So how do we get people to understand this? First of all, on a broad scale, we need to teach people a proper understanding of evolution and evolutionary theory. But we have to do it in a way that exemplifies its importance in our everyday lives. We need to get people to understand why they need to understand it. Evolutionary theory affects us every day. People need to understand how.
We need natural history museums for a multitude of reasons, but two very important ones apply here. First, they will stand as storage houses of information. They are a public recording of the changes that have taken place and are taking place. Secondly, they are a way to teach people who are not in school. Even if they don’t pay that much attention to the details in the museum, they will see a record of the changes. Museums can be designed to showcase the importance of evolution, the advantages of diversity, and the dangers of reducing that diversity. Museums are one of the most trusted sources of information. We need to leverage that to showcase both the interconnectedness of life on Earth and its diversity and why that has allowed its continued existence. It also can showcase what happens when that diversity is not there.
One may argue that history museums would be better at this. The advantage of history museums is that it makes it personal and easy to make it easy for people to relate to it. The disadvantage is that it makes it personal and easy for people to get defensive about it. Natural history museums can teach these lessons on a canvas that people can view and learn from more dispassionately, without it feeling like a personal assault upon their culture that can often happen in history museums.
To be sure, many people will feel that any mention of evolution is an assault upon their worldview, so I am not advocating the idea the natural history museums are inherently better. Instead, I am advocating the view that all types of museums work better when there is a diversity of museums that can tell the stories from different angles. Without a natural history museum, we lack an important viewpoint in the public arena. By building a museum network, we can spread the ideas much more effectively. A natural history museum will not hurt other local museums. It will help all of them. We don’t need just a natural history museum. We need a natural history museum, a local history museum, an international history and cultural museum, an art museum, and other museums. In Arkansas, we have some of the history, art, and culture, but we do not have a natural history museum. As such, we lack that long and broad view that can only come from an understanding of natural history.
What’s wrong with bunny hands on dinosaurs?
I was reading a post by Brian Switek on his blog Laelops—which by the way, if you aren’t reading it, you should—about interpreting injuries on dinosaur bones. It’s an interesting read, but what caught my eye was a problem that I have seen in more places than I can count. He included this picture in his post. Take at look at the front limbs.
Plateosaurus. Credit: Brian Switek
The “hands” are pointed inwards. To get in this position, the elbows have to be turned outwards, using a rotation in the shoulders. But it also requires the hands to be pronated. To get what I mean by that, hold your hands forward with the palms up. When you do this, the two bones in your forearms—the ulna and the radius—are positioned side by side.
This position is called supination. Pronation requires the radius to rotate so that it crosses over the ulna. This can be done because of the construction of the elbow. The ulna is essentially the entire elbow joint, making it a hinge type joint. The radius is, for the most part, just along for the ride at the elbow. The head—the part at the elbow—is round, with a shallow indentation, which is surrounded by what is called the annular ligament. That ligament wraps around the radius, attaching it to the ulna, but never actually attaching to the radius itself, allowing the head to spin in the sling. It is that shape of the radius and the annular ligament that allows it to rotate freely, which makes our level of pronation possible.
Importantly, all tetrapods have the same bones. It was set in place from the first fish that developed bones to support their fins and remains that way all through the hundreds of millions of years to us today. However, not all animals have the same shape of the radial head. Some animals appear to not have both bones, but in reality, they do. They have just fused the bones together. But that fusion has consequences, just like altering the shape of the radial head.
Before we move on to dinosaurs and those consequences, it would be reasonable to ask about other animals to see if they show the same pattern. Let’s take a look at proboscideans, the family of elephants. They are large animals that have their palms facing downward.
This is an elephant skeleton on display at the Manchester Museum. They have a radius and ulna, just like humans. Theirs, however, do not swivel. Nevertheless, it is rotated so that the bones are not in parallel, but the two ends are twisted so that the radius is twisted over the ulna. Their forelimbs are in permanent pronation.
So what about dinosaurs? Let’s look at Dreadnaughtus, the giant sauropod.
This is Figure 2 from Lacovara et al. 2014. The radius and ulna are massive, as befits a giant quadruped. They are also incapable of rotating to pronate the foot. It has been said by some that some degree of pronation is required for efficient quadrupedal locomotion, but that is not really accurate. It does mean though, that the first digit, what would be our thumb, is going to face forward or at most slightly inward while the remaining digits will be angled outward (anterolaterally). They will not be situated directly forward without shifting the arms at the shoulder. As an example, here is a figure showing a sauropod trackway. Note the direction of the toes.
This is a figure from Falkingham, et al. 2010. As can be seen, the toes are not forward, but pointing outward. The level of pronation is minor and can be achieved with only rotation at the shoulder and a minimal shift or the forelimb. VanBuren and Bonnan (2013) found this was true in all quadrupedal dinosaurs.
This is a best case for pronation in dinosaurs and they can’t do the full pronation needed for bunny hands, much less the bizarre inward facing hands of the Plateosaurus above. So let’s look at theropods, where we see bunny hands all the time. For instance, in Jurassic Park pretty much all the dinosaurs have bunny hands.
The palms are downward with the arms close in, requiring a full pronation to achieve that position. So could they do it? To the bones. This is the radius of Neuquenraptor, as published by Novas and Pol in 2005. It is an unenlagiin, in the family Dromaeosauridae, along with Velociraptor, Deinonychus, and all those other raptor dinosaurs.
These radius is fairly straight, and if you look at the head, it is not the shallowly indented round cup we see in mammals. It is more angular, which is typical of theropods. That relative angularity would prevent the radius from rotating as ours do, in effect locking it into a small range of motion, preventing them from placing their hands palm down.
In point of fact, VanBuren and Bonnan didn’t just look at sauropods. They looked at all types of dinosaurs. They found that no dinosaur had the ability to cross the radius over the ulna, which means that at best, they had very limited ability to pronate their forearms. That means no known dinosaur could have characteristically held their arms close in with their palms facing downward, aka bunny hands.
It is a little more complicated than this. Studies have shown that if the arm is fully extended, the hands can be more pronated, by using the entire length of the arm to rotate, but even that is not going to be fully pronated like we can, or bunnies can. And if you think about the living dinosaurs, the birds, when was the last time you saw a bird put its wings flat on the ground in front of them? They can clap, but they can’t type or play basketball.
Of course, the wrist bones of the maniraptors—those dinosaurs leading up to birds—did have what is called a semilunate carpal bone, allowing them to move their hands to insane degrees side to side, which is what allowed them to develop the ability to fold their wings like they do, and they can flex and extend their hands to a remarkable degree. But they cannot rotate their wrist. Try it yourself. See what movements you can make with your hand without moving your forearm, just your hand. However far you can move your hand that way, these dinosaurs have you beat in spades. But once you move that forearm, you have a serious advantage over them.
paleoaerie 