Thinking may or may not require being conscious, depending on how consciousness is defined; it's a term that scientists have yet to agree on. In the past, only philosophers studied consciousness. But in recent years, neuroscientists and evolutionary biologists have entered this debate, arguing that because the mind is based in biology, consciousness must be as welland it must have evolved. "Consciousness does not belong only to humans; it belongs to probably all forms of life that have a nervous system," the distinguished neuroscientist Rodolfo Llinas commented in a 2001 interview for NOVA. He explained, "This is basically what consciousness is about putting all this relevant stuff there is outside one's head inside, making an image with it, and deciding what to do." Scientists do not yet know how consciousness emerges from the neurons and organization of the brain, but they are making good progress, gaining insights both from neurological patients who have suffered some type of altered consciousness and from monkeys and rats whose brains are scanned while they are making decisions. Several leading cognitive neuroscientists and neuroanatomists are now so confi dent about the biological basis of consciousness and the idea that other animals are conscious that they wrote a declaration on the subject at a University of Cambridge conference in 2012. It declares, in part, that "humans are not unique in possessing the neurological substrates that generate consciousness. Nonhuman animals, including all mammals and birds, and many other creatures, including octopuses also possess" theseand therefore, they must be conscious. Other mental abilities may be linked to consciousnesssuch as self-awareness, empathy, insight, and something called "theory of mind," which is the ability to attribute mental beliefs, desires, and intentions to both oneself and others. These, too, must be "evolved, emergent qualities of brains," as the evolutionary biologist Richard Dawkins has described consciousness. And, as such, it is most likely that there are degrees of each one of these abilities in various species throughout the animal kingdom, with the most advanced found in species possessing complex nervous systems and the biology for consciousness.
There is one more point to be made about animal minds and evolution. Evolution is not a progressive force. Although it was once thought that there was a scale of nature or a Great Chain of Being, with all the forms of life ascending in some orderly, preordained fashionfrom jellyfish to fish to birds to dogs and cats to usthis is not the case. We are not the culmination of all these "lesser" beings; they are not lesser and we are not the pinnacle of evolution. We are not more highly evolvedeither physically or mentally than our closest genetic ancestor, the chimpanzee.* Nor, despite the belief of many cat owners, are cats more evolved than dogs. Evolution is not linear. It is divergentwhich means that we all sit on the limbs of a bushy tree, each species as evolved as the next, the anatomical differences largely a result of ecology and behavior.
* In 1992, the leading neuroscience journal Brain, Behavior and Evolution officially announced the end of the use of the scale of nature in articles discussing the evolution of the brain. It declared that "vague, subjective descriptors such as 'higher' and 'lower' should be avoided" when referring to animal groups.
The processes of natural selection have shaped every organism on the tree of life in response to the challenges its ancestors faced. Species that haven't succeeded are no longer on the bush; they are extinct. That's why sharks, which have been on earth more than four hundred million years, are considered one of the most successful animals. In comparison, our species, Homo sapiens, has been present for only about two hundred thousand years, and it remains to be seen how long we will last. Our human brains are undeniably more complex anatomically than those of sharks. But sharks have survived throughout the ages because they have evolved brains perfectly designed for how they hunt, find mates, and reproduce in their environment.
Excerpted from Animal Wise by Virginia Morell. Copyright © 2013 by Virginia Morell. Excerpted by permission of Crown. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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