The Origin of Human Races and the Antiquity of Man Deduced from Natural Selection

and the question we have to determine is: what will change one kind of biological mechanism into another? In the body of a greyhound, there is not a single particle that remains in the same relationship as in the body of a wolf; and yet, each one is an example of the most admirable mechanism. That is one point at issue.

Then, again, in causation there are two essential ideas—the fitness of the instrument and the adequate power to work it. Now, it is perfectly unphilosophical to assign causation where you are unable to show fitness, unless you can prove causation as a matter of fact by other means. No one has attempted to do that; no one can do it. No one can show that the random influences of climate, food, and so on, can produce coordinated changes in any case whatsoever. That has not been proven as a fact, and you have no right to assume it.

For instance, when food is taken into the stomach, it is converted into blood and sent as blood to all parts of the system. That is a general process; but can you see anything in food that will lengthen a man's leg, shorten his waist, or vice versa, or that will give him a small head or a large one relative to his body? Is there anything in food or climate that can do that? Why, we have not yet been able to prove that climate changes the color of races, except temporarily by producing vesicles vesicles: small fluid-filled blisters or skin eruptions, here referring to temporary skin changes like tanning or heat rash, etc. That is the second objection, therefore: that in this theory, there is no conceivable fitness in the assigned cause to produce the assigned effect.

Next, I maintain that it is absolutely impossible for these causes to produce such effects. The fundamental law of the universe is the law of causation. That law states that there is an inevitable relationship between the cause and the effect; as causes vary, so must effects vary. If, then, you want to discover the unknown cause of a specific effect, all you have to do is find the known cause of some analogous and similar effect; then you know that there is a corresponding difference between the causes as there is between the effects, as well as a corresponding resemblance.

Now, then, here is the cause of mechanism. All mechanism is one in principle, whether it is living mechanism or the mechanism produced by man. All imply the correlation of parts and functions—the adaptation of means to ends. Now, then, do we know of any cause that is capable of producing such things? We do. Intelligence is capable; we see human intelligence doing such things. No cause in the universe except intelligence, then, can produce effects anything like those of intelligence. Surely non-intelligence cannot do it. Surely a non-intelligent cause cannot produce an intelligent effect. And not only so, but intelligence can never act without producing such things. Man never acts intelligently without adapting means to ends.

Here, then, we have a case in which mechanism and all the wonders of mechanism are producible by a known cause; consequently, all the mechanism of the universe is, logically, the result of intelligence. If, then, we want to know how species originated, we must look to those parts of nature where everything is regulated by a determined plan. I will tell you of a case in which you may change types very easily—in a single generation; you do not need infinite time. This is the simple crossing of types. The crossing of races produces intermediate...