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The Fundamental Difference Between Humans and Nonhuman Animals

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Jonathan Marks is a biological anthropologist who recently wrote an essay on the profound differences between human beings and apes. Paul Nelson and Ann Gauger have commented on him and his writing already (here and here). Marks’s essay has sparked some controversy, but the point he makes is valid.

Marks asserts:

The argument that “we are apes” is not a valid evolutionary one. After all, the distinguished evolutionary biologist George Gaylord Simpson wrote in a 1949 classic, “It is not a fact that man is an ape, extra tricks or no.”

Marks accepts the theory of common ancestry, and believes that we are descended from apes. He points out that evolutionary relationships are not the same thing as identities. Descent from apes does not mean we are apes. Taxonomy is not the same thing as identity. I agree.

Marks puts that this way:

Science no more says that I am an ape because my ancestors were, than it says that I am a slave because my ancestors were. The statement that you are your ancestors articulates a bio-political fact, not a biological fact.

Regardless of the strengths and weaknesses of the evolutionary argument that humans are descended from apes, the differences between humans and apes are so profound as to render the view that humans are apes abject nonsense.

It is important to understand the fundamental difference between humans and nonhuman animals. Nonhuman animals such as apes have material mental powers. By material I mean powers that are instantiated in the brain and wholly depend upon matter for their operation. These powers include sensation, perception, imagination (the ability to form mental images), memory (of perceptions and images), and appetite. Nonhuman animals have a mental capacity to perceive and respond to particulars, which are specific material objects such as other animals, food, obstacles, and predators.

Human beings have mental powers that include the material mental powers of animals but in addition entail a profoundly different kind of thinking. Human beings think abstractly, and nonhuman animals do not. Human beings have the power to contemplate universals, which are concepts that have no material instantiation. Human beings think about mathematics, literature, art, language, justice, mercy, and an endless library of abstract concepts. Human beings are rational animals.

Human rationality is not merely a highly evolved kind of animal perception. Human rationality is qualitatively different — ontologically different — from animal perception. Human rationality is different because it is immaterial. Contemplation of universals cannot have material instantiation, because universals themselves are not material and cannot be instantiated in matter.

I stress here the difference between representation and instantiation. Representation is the map of a thing. Instantiation is the thing itself. Universals can be represented in matter — the words I am writing in this post are representations of concepts — but universals cannot be instantiated in matter. I cannot put the concepts themselves on a computer screen or on a piece of paper, nor can the concepts exist physically in my brain. Concepts, which are universals, are immaterial.

Nonhuman animals are purely material beings. They have no concepts. They experience hunger and pain. They don’t contemplate the injustice of suffering.

A human being is material and immaterial — a composite being. We have material bodies, and our perceptions and imaginations and appetites are material powers, instantiated in our brains. But our intellect — our ability to think abstractly — is a wholly immaterial power, and our will that acts in accordance with our intellect is an immaterial power. Our intellect and our will depend on matter for their ordinary function, in the sense that they depend upon perception and imagination and memory, but they are not themselves made of matter. It is in our ability to think abstractly that we differ from apes. It is a radical difference — an immeasurable qualitative difference, not a quantitative difference.

We are more different from apes than apes are from viruses. Our difference is a metaphysical chasm. It is obvious and manifest in our biological nature. We are rational animals, and our rationality is all the difference. Systems of taxonomy that emphasize physical and genetic similarities and ignore the fact that human beings are partly immaterial beings who are capable of abstract thought and contemplation of moral law and eternity are pitifully inadequate to describe man.

The assertion that man is an ape is self-refuting. We could not express such a concept, misguided as it is, if we were apes and not men.

Image credit: John Vetterli (originally posted to Flickr as Sumatran Orangutan) [CC BY-SA 2.0], via Wikimedia Commons.

Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.

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