We conduct direct experiments to discover how structures, systems or the whole animal works. We subject animals to a variety of performance events that involve some aspect of locomotor performance. We measure the performance of an animal under a controlled condition and then vary one parameter and make another measurement. For example, we have measured the cost of locomotion and endurance for animals that run continuously and compare them to running intermittently at twice the speed, but resting half the time. We then speculate on the mechanism resulting in performance differences.
Comparative approach. We use the comparative method to seek general architectural principles for species which have evolved vastly different solutions to the problems of terrestrial locomotion. These “novel” biological designs can be used as natural experiments to probe for basic themes synthesizing the relationships between morphology, physiology and performance.
Our goal is to understand how animals work. Any feature we study could be: 1) an adaptation to a unique environment, 2) a general principle that can be applied broadly, 3) historical accident and constraint, or 4) some combination of 1-3. We use phylogenetic comparative methods to tease apart these possibilities. Adding a phylogenetic control for natural experiments (comparisons among species) allows for stronger mechanistic explanations and enhances statistical inference by preventing pseudoreplication of closely related species. Phylogenetic methods can also aid in choosing the best species for a traditionally controlled laboratory experiment.
We contend at least two complementary approaches are required to address the complexity of the musculo-skeletal system. Direct measurements of select musculo-skeletal parameters are essential and irreplaceable. Equally as important, however, is the creation of a musculo-skeletal simulation or model. A model can serve several purposes. First, the model can operate as a hypothesis generator for direct experimentation. Second, the model can guide direct experimentation by the use of sensitivity analyses to identify the parameters to be measured that will most likely have the greatest effect on performance. Third, the model can allow estimation of parameter values that are simply too difficult to measure directly.
By the creation of a three dimensional musculo-skeletal model of an insect leg using software program (SIMM, Musculographics Inc.) and a whole body dynamic model (Boston Dynamics Inc.), we are attempting a first step in integrating the mechanics, neural control and musculo-skeletal function in arthropod terrestrial locomotion.
We are in the Department of Integrative Biology where we attempt to integrate across:
1. Levels of organization (molecules to eco-systems)
2. Organisms (plants, invertebrates and vertebrates)
3. Time (evolution)
In our laboratory, we also attempt to integrate Nature with Computer Science and Engineering by collaborations with experts in these other fields. We benefit from these collaborations in that we can learn more of the quantitative analyses used by engineers in answering questions about how animals work. We can use the techniques of computer science to test ideas that are too difficult to test on the animals. At the same time we can give the engineers and computer scientists Biological Inspiration, new design ideas for control strategies and mechanics. We both benefit. We call this Biological Inspiration (We don’t like the term Biomimetics because it implies that we should design man-made constructions to mimic nature. Nature is spectacular, but remember evolution works on the just-good-enough principle. Many animals are constrained by their history and development. It’s like building a car. Humans could start from scratch and use different designs and materials. Animals must make small changes in what their ancestors left them, like trying to modify a used car. In many cases humans can do better than nature. However, what nature does supply are amazing design ideas that can be transferred to computer science and engineering, Biological Inspiration).