On One Hand

January 10, 2010

What Makes Humans Distinct from Animals?

Filed under: science — ononehand @ 12:00 pm
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My fifth grade teacher once told our class that the difference between humans and animals was an elusive thing called “reason.”

Her definition of reason was basically anything other than automatic behavior. When you hit a dog, she argued, the dog would yelp in pain and run away but know nothing beyond what it shows in that action. The human, on the other hand, would ask “why?” and try to figure out why it was hit so as to avoid it in the future.

She probably wasn’t much of a pet person, because anyone who has a dog knows they definitely do learn from experience, are capable of becoming highly trained and social, and do indeed seek to avoid punishment. But another pertinent bit of information is that my teacher was an evangelical Christian, who believed that humans have souls and animals do not. And if our soul, as according to Judeo-Christian thought, contains the consciousnesss, it would indeed be logical to conclude that animals are unconscious. In that worldview, God made man and animals through two distinct acts, and that is how human societies viewed animals for thousands of years of history before Darwin.

Since the beginning of modern science we’ve recognized that humans are an animal species, not separate at all. Put a ten year old girl, a male Labrador retriever, and a pear tree in a row. All three are life forms, and Judeo-Christian philosophy would say that the human is distinct and the dog and the pear tree are similar as un-souled living things. Science would inform us otherwise, insisting that when compared to the plant, the human and the dog are very, very much alike.

Science also tells us that the center of consciousness is the brain, which our young girl and Labrador share. They not only both have brains, but very similar brains, with an enlarged, two-hemisphere cerebrum and a smaller cerebellum, a visual cortex in the rear a memory center in the in the middle. A young girl and a dog show similar instinctive ways of communicating pleasure and pain through sounds and gestures, and will entertain complex social behaviors. They both develop emotional bonds with peers and have the capability of bonding across species. They not only like to be around others, but will show a preference for certain individuals whom they can recognize, form communities, and display anxiety and sadness when they are separated from those they love. Their neurotransmitters follow the same pathways – dogs respond to the same antidepressant medications that humans do, and in the same way.

Science also tells us that the same act of creation generated dogs and humans in one fell swoop. For billions of years of Earth’s history, the species that would eventually branch into dogs and humans was the exact same lineage and creature. All placental mammals – a family that ranges from fruit bats to Wooly Mammoths – shared a common ancestor 125 million of years ago, and the order Carnivora (which contains dogs) and Primates have a common ancestor much than that. Humans and any other mammal that gives live birth has been distinct for less than 5 percent of the timeline of life on Earth.

It becomes necessary to say, not “what makes humans distinct from animals?” but rather, what makes animal species distinct from each other? A species is formally defined as a population of organisms that will not reproduce sexually with other populations in the wild, but the boundaries blur. Wolves and coyotes sometimes cross-breed in the wild, horses and donkeys breed to make mules and scientists have often found stray genetic material from one species in another species. 30,000 years ago, humans and Neanderthals may have been two distinct species that occasionally produced hybrids. There were other “species” or subspecies of human that were less likely to mate with humans, and many of them co-existed with Homo sapiens. So which of these were humans, and which were animals? It also turns out than Homo sapiens and Pan troglodytes (chimps) have more in common with each other than chimpanzees have with their next closest relative, gorillas, and there is evidence that a chimpanzee ancestor once had larger brains and then regressed for some reason. So a chimpanzee or another great ape might ask, instead, “what makes apes (including humans) distinct from the rest of the animal kingdom?”

There are obviously a few things that human beings can do that animals can’t, but any attempt to label a thought process unique to humans is going to be an attempt to socially construct a concept that has no basis in material reality. Humans can do things because their thinking abilities may work better: they communicate and share information extensively, and while animals are less prolific in their pedagogy, it would be unfair to say they don’t learn or teach each other at all. The ability to communicate through writing or pictures is probably the best example of a human-unique skill, and maybe the only near-universal (through time as well as space) human activity that no animal species besides Homo sapiens does. But we know that a list of species show the ability to recognize themselves in a mirror, we know that a list of species have a sense of “object permanence” and understand that things continue to exist even when they can’t see them, we know that a list of species has the ability to understand speech, use sign language, solve puzzles, learn from others, maintain social groups and even solve math problems.

The 1960s-80s were a time when writers and thinkers were working hard to define human against nonhuman minds, or rather, the historic beginning and the end of human consciousness. Science Fiction literature and film mediated the conversation. The Planet of the Apes featured chimpanzees, gorillas and orangutans that develop complex speech and societies while humans regressed to the wilderness, and 2001: A Space Odyssey opens with a philosophical scene, a pack of furry apes beating another to death; in that portrayal, the distinguishing moment that made man out of animals was the ability to murder for reasons other than self-defense or food. (We now recognize that many animal species do this.) That was a two-fronted discussion, as robots and thinking computers constituted another form of intelligence that could someday achieve human individuality; Blade Runner was heavy into the conversation as “replicants,” thinking robots that were illegal on Earth, went on a murdering spree against humans. The list would go on, but there is no doubt that the popularization of the theory of evolution sparked many of the questions.

And as consistent with the theory of evolution – where species arise gradually rather than suddenly – we find that animal thinking abilities lie on a continuum rather distinct contrasts of human versus nonhuman. Misconceptions about animal abilities are constantly being proven wrong, as more and more species are added to the lists of things we thought only humans did. Prarie dogs have their own languages, with different kinds of barks that mean different things and vocabularies that differ community to community. A recent study found that simple aquarium fish are more likely to thrive in groups than alone. Dolphins have been observed teaching their young how to use sponges to protect their snouts while they dig through the sea floor. When dogs playfully wrestle with each other, bigger individuals will handicap themselves to compensate for larger size or better health, have gestures to apologize for accidentally hurting another dog, and will ostracize individuals who bully or break those rules. Finally, Alex, a famous African gray parrot who died in 2007, could distinguish materials from each other, count and categorize them by substance or color and communicate that knowledge to his human trainer.

Some critics look at especially talented animals and argue that wishful thinking on the part of scientists leads to exaggeration of their senses or abilities. But from a conceptual standpoint – admitting it is not a “human” soul, but brain matter that produces intelligence, and human beings and animals share that – we should expect to find emotionality and human-like abilities in animals.

It seems that in the vast majority of cases, “wishful thinking” would downplay and reduce animal intelligence because of the inconvenience implied in thinking of them as conscious. We have been culturally conditioned through religion and by necessity to believe they do not suffer when they are slaughtered or abused or sacrificed on an altar, and we profit from using them in ways that would be difficult if we thought of them as sentient. Human societies have historically downplayed the intelligence and abilities even of other groups of humans they encountered and thought of as “uncivilized,” so have shown a track record of not seeing what is there when it benefits them. Furthermore, we know people judge each others’ intelligence by vocabulary, so the take-away impression of an animal who cannot talk would be that it is less intelligent though in reality it simply lacks the anatomy and wiring for speech.

But even this thought process may represent an anthropomorphized, and culturally limited, way of looking at the issue. Because as much as animals show typically “human” traits, we know that humans show animal traits too. We know that we use biological criteria in sexual selection and respond to pheremones, and we know that many human behaviors, such as walking and picking up language, are genetically-driven behaviors that children will develop even when you don’t teach them. And when we talk about simians or canines having social groups that resemble human families, wouldn’t it be more valid to say that human social groups resemble those of monkeys and wolves? Their species were, after all, around first.

While nonhuman animals do show “reasoning” skills, it might be more accurate to say that animals do not have http://en.wikipedia.org/wiki/Logic – reasoning that can remain confined within a set of agreed-upon rules. But that is simply an order of magnitude, not a distinct behavior that humans have and others don’t; when reasoning skills get advanced enough, and when we are given an education to boost, we learn how to use logic. We have no way of knowing if birds and cats philosophize, and inasmuch as animals do teach, we know they don’t teach things like chemistry and literature. Many species may, however, may measure up better against prehistoric humans than we normally care to admit.

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