We Humans love to think we are different from the "lesser" animals. Yup, we go on and on about "soul" and "symbolic manipulation" and "tools" and "language".
What is interesting, however, is that I have yet to see any study that shows any real difference between us and the other species.
There are gradations, of course. We use tools WAY better than any other animal. We use a more complex language (but other animals _do_ communicate, and even lie). Hard to say if animals use symbols in any way like we do, but bees perform interesting abstract dances to represent flight paths (so I hear). As for soul? Well, as soon as someone devises a test for this, let me know.
Animals have feelings, both emotional and physical (of course). They remember (and in the case of Parrots, they can keep a grudge for _ages_). The look forward to the future.
Heck, some animals both communicate better and have a richer mental and emotional life than do tiny humans!
So really, what does it mean to be human?
And then, take your garden variety human and... take away part of their mind. Put a railroad spike through their brain. Or give them a stroke. Take away a part of their body... remove their hands in a war, lop off their legs. Still human?
In some ways, who we are is an accumulation of our memories and experiences; our identity based on a continuous chain of existence, recorded in our minds. Damage a piece of your brain and this chain is snapped; nothing new gets added. What are you then?
Take a child who is just four cells big. What is this? It is a small speck of potential! But what if it grows into a baby with no brain? Or a person who is genetically scrambled, making them behave or function far below the mean?
Human?
Or, the person who is brilliant, who soars above the rest of the madding crowd to achievements that most of us can only imagine? Still human? Are all of these "humans" the "same"?
We are very attached to our humanity, and defend it vigorously. But to what end? Does it serve us well to set ourselves high on this pedestal and to look down all all other creatures as inferior? Then, we can enslave them, breed them, torture them in animal fights or for "sport", eat them, do whatever we like to them without it impinging on our conscience.
In fact, history has shown us repeatedly that groups of people can easily consider other groups of people to be inferior, to be "just animals" or "the enemy", based on any slight trick of the moment; their color, their tribe, their religion, anything. And from this trick of the mind, they can justify any type of abuse.
Some cultures or subgroups have moved in a direction to treating animals as equals. Others still consume the tasty critters but do so in ways that honor them and minimize their suffering.
I eat animals, and I love to do so. I have killed chickens with my own hands, and have contracted to have a cow slaughtered in our driveway (in a trailer, it turns out, and not in the open), so that my step-kids at the time would realize that meat comes from life. We should be aware of this. I also did these things so that I would know, deep down, that yes, I am a predator and that these foods I buy and eat so lightly from the store carry a heavy price to the creatures providing them.
In spite of my predatory nature I would not slaughter and eat another person. Nor a monkey. Nor a dolphin. Perhaps it is hypocritical, but I prefer not to consume anything that is "close to me" in terms of its internal life.
Pigs are known as vicious, filthy animals. And yet, I've had pot-belly pigs and they are amazing creatures with fascinating personalities. Big pigs, the kind we eat? I have no idea, but I do know someone who won't eat them because she feels they are too smart to be treated as food.
Maybe it is this ability to reflect on things, to consider things in the abstract, to _identify_ with all manner of entities, that makes us human. I doubt a cat feels badly when it is torturing a mouse to death; but I know that I would feel very badly if I were to hunt and wound some creature so that it suffered badly before it could be killed. But how do _I_ feel when my cat is torturing am mouse? I try not to think about it.
I used a glue trap once, and caught a mouse. I will never do so again.
Some say that our ability to look into the future, and to reconstruct the past in symbols, is a gift from our background as hunters. We must be able to look at marks in the environment and deduce what has already happened, so that we can predict the future so we can kill and then eat. To hunt, we must predict; to predict, we must identify with our prey, and we must invent "time" so as to simulate this prey's actions into the future.
We use our minds to build up these pictures, these stories and progressions, so that we can hunt. We _have_ to use our minds, because our other senses are so poor; our smell, our vision, our hearing, even our limbs are slow and weak compared to many animals.
What came first, the ability to use our minds to make our lives easier hence providing a gateway for our other aspects to fade, or the loss of our skills necessitating the growth of our minds to compensate?
Take a human as they are now and go back in time 2,000 years. Yup, still human. We haven't changed much, really, in that span. 10,000, to the dawn of agriculture? Probably not a huge difference there either. Heck, Chinese written history covers a significant chunk of that. How far back do you go before we think "monkey" rather than "person"?
My favorite definition of humanity comes from Frank Herbert's book, "Dune", and the test of Gom Jabber. There are different interpretations out there but mine is that a Human has Choice and can choose to suffer in order to achieve a greater goal. An Animal is ruled by the moment, by reflex, and will respond in kind.
By this rule, how many of us are Human, and how many are just animals wearing a human shape? Just because we are born with potential and powerful tools of thought, doesn't mean we use them. In the neglect of these tools, do we also forfeit our humanity?
How do you fill _your_ life? How do you make your decisions? To what extent do the emotions of the present drive your actions?
Are you human? Or just wearing a human shape?
I don't think that most of us are really human. But then again, I'm not entirely convinced that "human" is such a great special club to be in, given our track record. I think we can do better.
To the religiously fundamental, all of this introspection is set aside with a simple "to be human is to have a soul," and much of their thinking can be replaced by rules handed down through history. When pondering the great patterns of nature and life, the miracles and the horrors, it all comes down to "such is the mysterious way of God".
This is passing the buck and answers nothing; it simply pushes the problem back one step (who made God? Why does God behave in these specific ways? Was God drunk when many of these creatures were made, or does God just have a creepy sense of humor?) to a point beyond which we are not allowed to ask questions. Because to question God is a sin. Because, umm, some guy said so. Right. So move along, son, nothing to see here, don't mind that man behind the curtain.
Further reading:
http://www.sheldoncomics.com/archive/030429.html
"The Lucifer Effect: Understanding How Good People Turn Evil " by Philip Zombardo
"Phantoms in the Brain: Probing the Mysteries of the Human Mind" by V.S. Ramachandran
"I Am a Strange Loop" by Douglas R. Hofstadter
"Ishmael" by Daniel Quinn
"Dune" by Frank Herbert
"Family Evaluation: An Approach Based on Bowen Theory" by Michael E. Kerr and Murray Bowen
"Stranger in a Strange Land" by Frank Herbert