Endless forms most beautiful: the new science of Evo devo and the making of the animal kingdom: A review by Samantha Lee Czen Shing
Before I summarize what the book is about, have you ever wondered about the existence of life in the world? How did it first come about? How were humans created? How were animals created? The list of questions goes on and on.. Is there a difference between humans and animals? Or are we somewhat similar.
Quoting Darwin, he mentioned “The difference in mind between man and higher animals, great as it is, is one of degree and not of kind.” -Charles Darwin, The Descent of Man (1871)
To understand all that, we first start off with the origins of animal form. The aim is to expand that wonder and fascination to how form is created. Giving us new understanding of the biological processes that generate patterns and diversity in animal design. It sure is a remarkable process how they transform a tiny single cell into a large, complex, highly organized and pattern creature. The first approach to further our understanding is to sort into groups of vertebrates and arthropods. Every animal form is the product of two processes, development from an egg and evolution from its ancestors. Development is the process and evolution of form occurs through changes in development. Through this, we can conclude that Development + Evolution has an intimate connection.
In this book, the writer asks its reader to consider how slight changes, introduced at different points in the process and in different parts of the body over the course of many thousands or million generations, spanning perhaps tens of thousands to a few million years can produce different forms that are adapted to different circumstances and that possess unique capabilities.
Evolution is as natural as development which leads us to gradual evolution. It begins with a small genetic change that produces variation which is acted upon by natural selection. Forms do change and that natural selection is a force. But the question is how could we make progress on questions involving the evolution of form without a scientific understanding of how form is generated in the first place?
Tying genes and form, this evolution was marked by long periods of stasis interrupted by brief intervals of rapid change. The principle that evolution is due to changes in genes. It is proven through scientific research that most of the genes first identified as governing major aspects of fruit fly body organization were found to have exact counterparts that did the same thing in most animals, including ourselves. The discovery was followed by the revelation that the development of various body parts such as eyes, limbs, and hearts, vastly different in structure, was also governed by the same genes in different animals. This concludes that animals and humans all share a common “tool kit” of “master” genes that govern the formation and patterning of their bodies and body parts.
It now makes sense how complexity is constructed from a single cell into a whole animal. It is amazing how modifications of development increases complexity and expands diversity.
Through Evo Devo, we can trace the modifications of structures through vast periods of evolutionary time to understand how fish fins were modified into limbs in terrestrial vertebrates, how successive rounds of innovation and modification crafted mouthparts, poison claws, swimming and feeding appendages, gills and wings from a simple tubelike walking leg. Evo Devo paints a vivid picture of how animal forms are made and evolve.
These concepts are crucial for understanding how the species-specific instructions for building an animal are encoded in its DNA and how form is generated and evolves. The output of these devices found in the DNA is ultimately transformed into pieces of anatomy that make up animal forms.
“From so simple a beginning, endless forms most beautiful have been, and are being, evolved.”
The best science is an integrated product of our emotional and intellectual side. There’s a fog of events and suddenly we see a connection. It expresses a complex of human concerns that connects things that were always in us that were never put together before.
Looking into the construction of animals from building blocks, the fossils demonstrate evolution’s pervasive use of repeating parts and modular architecture in forging animal designs. Majority of the individual body parts reflect the theme of modular design. For example our limbs, each built of several pieces (thigh, calf, ankle, upper arm, forearm, wrists) and the hands and feet bear five similar digits. Although there are cases when the modular design of a structure may not at first be apparent. Take for instance, a butterfly wing whose pattern looks random at first glance, comprises repeating patterns of lines, chevrons and spots and fine details, some almost out of range of the naked eye. Such beautiful wing patterns are actually built from tiny scales on the wing. Each scale is a projection of single cells that are assembled in many rows in the wing, each having its own specification.
From just these few descriptions, we can begin to appreciate the immense task of development to build large, complex animals beginning with only a tiny single cell. Every detail counts, a small shift in an early process would have a cascade of later effects.
In considering particular groups of animals, it appeared that some of the most obvious differences between members of a group were in the number and kind of repeated structures. For example, while all vertebrae have a modularly constructed backbone made up of individual vertebrae, different vertebrates possess different numbers and kinds of vertebrae. A similar pattern applies to arthropod form and diversity. Arthropod bodies are made up of repeating segments. Groups of segments are distinguished from one another by their size and shape especially by the appendages that project from them. These two groups of animals have successfully exploited every environment on earth (water, land and air) and are the most complex animals in terms of anatomy and behavior. Both groups are constructed of repeated assemblages of similar parts. Could there be a connection between modularity of design and the success in evolutionary diversification? Perhaps. But the question is how these animals are built, beginning from just a single cell and how all sorts of variation on a body design evolve.
It is important when comparing body parts between species to know whether one is comparing the same body part that might have changed in different ways or parts in a series where the one-to-one relationship may be obscured. Take for example, the forelimbs of a salamander, mice and our arms are all homologs. They all have the same structure modified in different ways in each species which derived from a common ancestral forelimb.
Linking back to what was mentioned previously, Bateson divided abnormalities into two basic types. Those in which the number of repeated parts was altered and those in which one body part was transformed into the likeness of another. The purpose of collecting these oddities was to show that leaps in morphology can occur in nature and thus could be the basis of evolutionary change. The spectacular effects of homeotic mutants inspired what would become a revolution in embryology. Which interrelates to the power and glory of combinatorial logic. It is amazing how our immune systems cope with the enormous diversity of the potential pathogens that live within and around us by making antibody proteins that bind to the proteins, sugars and fats of these foreign invaders.
In conclusion, the first part of this book illustrates four critical ideas about animal development being the modularity of animal architecture, the genetic tool kit for building animals, the geography of the embryo and the genetic switches that determine the coordinates of tool kit gene action in the embryo. In the second half, the central idea is that animal forms evolve through changes in embryo geography. It shows how geography and form evolve by changing the way the tool kit genes are used. With all that being said, “new genes for new animals?” Sounds interesting to me. The most commonly held idea relating genes to the evolution of complex form is that new genes must evolve in order for new kinds of body designs and structures to arise. Since the form of a given species is due to its unique genetic information, then new forms require new information.
Other than genes, relating revolutionary inventions to our everyday life, how did we get to this state of overspecialization? In the sense where while having a fancy dinner, we get intimidated by the cutlery. Mixing up the use of butter knives, steak knives, cheese knives, tablespoons, soup spoons and so on. Dining etiquette was definitely simpler in the Middle Ages, but evolving. People began eating with two knives, one to cut the food and a second to spear it and bring it to the mouth. It isn’t clear when and where forks started replacing the second knife at the dining table. This little snippet of cutlery history is analogous to a broad trend in biological evolution. Namely structures (like the fork) that evolve a dedicated function (spearing food) are often derived from preexisting structure (the knife) that served more than one role (cutting and spearing). The duplication of the original structure (the practice of using two knives) enabled subdivision of labor among two distinct structures. Furthermore, selected for a new purpose, the structure can then evolve further modifications and specializations.
The history of cutlery are analogous to the evolution of animal appendages. Subsets of appendages have evolved new forms and functions that enabled species to compete in an intensely competitive natural world. Through all these, it is safe to say that our life’s are evolving constantly right before our eyes without realizing. It is a continuous drama of evolution to better cope and adapt with the ever changing environment. New structures open up new ways of living. Nature works as a tinkerer with available materials, not as an engineer does by design.
Evolution of form is very much a matter of teaching very old genes new tricks.
As you may wonder, how do we then relate all these back to the built environment? How does genes and the history of animal evolution relate to architecture? In my opinion, we must first understand the user and the environment. How it all started, how it came about. Only then we can relate better. By understanding how nature works, we can then apply it to the built environment. Nature and architecture has to come in simultaneously, they must both be incorporated together. Now we understand how evolution works in animals, it is time for us to apply the principles in the built environment. With the ever changing nature we have to design spaces/buildings in a way where it can constantly be upgraded and modified just like genes.