GEOFFREY West: Everything scales in a predictable way, but they also scale in a non-linear way. This theory, which we have developed with great precision, states that the universal mathematical and physical properties that all networks possess that allow an organism to grow and develop are what these scaling laws reflect. It's one the most remarkable characteristics of life. Take mammals as an example. The whale, the largest mammal in terms of measurable quantity, is actually a scaled-up version of the shrew, the smallest mammal. They are both scaled versions of each other. This theory of scaling laws allows you to determine the parameters and the knobs you could turn to alter the lifespan. It's a tremendous effect and a huge one.You can have the theory of networks underpinning these scaling laws. Then you ask yourself, "Is there a scaling law that increases lifespan?" You would expect that if you double the size an organism, it would result in a doubled amount of metabolic energy needed to keep it alive. You don't actually need twice the amount of metabolic energy. You only need 75% of the energy systematically. This is a 25% systematic savings. The metabolic rate is simply how much energy an animal needs to survive each day. It's roughly 2000 calories per day for a human being. This is an extremely complex process that scales very easily. These quarter power scaling laws also increase life span.These flows are the limitations that determine how large these quantities can be scaled. These flows are called dissipative. This simply means that they cause wear and tear. They must be repaired just as traffic is moving back and forth across the roads. As it turns out, traffic through the multiple networks causes damage. A large animal will live longer than a smaller one due to the fact that the metabolic rate per unit of mass, or per cell, becomes systematically lower the larger the animal, corresponding with these quarter power scaling laws. The larger the animal, the less damage that is done to its cells. The system becomes unviable if it sustains more than a certain amount of unrepaired damage. This gives you an estimate of your maximum life expectancy. This is the maximum lifespan you can expect for a given mammal size if you do your best. If you do this, you will be able to understand roughly where the hundred-year lifespan of a human being comes. What could you do to increase that number from 100 to 200? There are two options. One, you can decrease wear and tear, or increase repair. You can reduce the amount of food you eat to decrease the damage caused by metabolism. Although it may not be the most pleasant thing for your lifestyle, this would mean that you will live longer. Some controversial monkey experiments have not had the same effect. This is why it's still very much work in process.You can also reduce your metabolism in another way. It's not easy for us. Surprisingly, it's very simple for most organisms on the planet. This is because we are homeotherms, which means that we maintain the same temperature. When they are cold, insects can't move. To warm up, they have to wait until the sun rises before they can fly around and move around. This is true for almost everything around them. It's impossible to resist that, and it's been incredibly powerful for us. It separates us from the outside temperature, the environment temperature. All other things are subject to the temperature of their surroundings. It matters because metabolism is determined from chemical reactions. Chemical reactions are dependent exponentially on the temperature in which they operate. A small temperature change can have a significant impact. A small temperature change, or a small temperature increase, can exponentially increase your metabolic rate. This means that you could live longer if you took drugs that would lower your body temperature.A tangential observation to all of this, and a crucial one in our time, is about global warming. Many people are puzzled by the fact that a mere two degrees of temperature change can make a significant difference. My temperature changes 40 degrees each night where I live. Temperature changes can have an exponential effect on things such as growth and death rates. The whole ecosystem, the biosphere, is extremely sensitive to temperature fluctuations. One to two degrees of temperature change can have an exponential effect. Some may be very deleterious, while others may be beneficial. This is an important point, and I fear my colleagues in global warming are not able to convey it well.
