Biogenesis, the creation of life, is nothing more than a clever chemical reaction. A chemical reaction that creates a molecule capable of copying itself. This requires a degree of "intelligence"- after all, this molecule must be smart enough to recognize other organic molecules and use them as building blocks of its offspring- DNA, RNA, and their associated enzymes and proteins developed out of this basic replicator. Far along the evolutionary tree, these simple chemical reactions became cells- cells had the ability to use membranes to selectively filter chemicals, absorbing nutrients and so on. This again, is simple chemistry. Certain molecules pass through certain gates. Some of these cells developed actual behaviors- the start of instinct/tropism. The Euglena has a light-sensitive organelle that allows it to "navigate". Amoeba can respond to chemicals in the water triggering movement and a "food seeking" behavior.
Skip a few billion iterations of the evolutionary process and move to plants. A major plant behavior is phototropism- a simple series of chemical triggers cause growth and shrinkage of cells- the end result is that the plant moves (slowly) to maximize the surface area exposed to light. This is a pretty complex series of biochemical reactions that produces a very sophisticated behavior.
Skip again to the animal kingdom. Brains begin to develop providing a behavior repository- a computer that can do far more complex processing and handle far more complex behaviors. Swimming, for example, is simple in a unicellular organism but involves incredible coordination among thousands of cells in an animal. This computational repository is still fairly deterministic- given certain stimuli, certain behaviors can be predicted. "Instincts" require no understanding of the world. Most animals have mastered the "see-food" diet- they respond to stimuli in predictable, deterministic ways to stimuli. When confronted with unfamiliar stimuli, their reality-processing bioware attempts to find the most applicable response and use that. This, for example, allows me to trigger the hunting instincts in my cats with a laser pointer.
Some animals, mostly mammals and birds, have cognitive capacities that exceed even that. They have the capacity to not simply respond in complex and deterministic ways to stimuli, but to begin to draw inferences and connect those stimuli into cognitive models- they understand the world not as a collection of experiences but as a system that can behave predictably. This is the seed of intelligence. For example, when I first caught my cat Rochester as a stray, he was still fully functional genital-wise and wanted to go outside. Alot. Not only did he connect the door with the path to outside, but by observing us using the door, he connected the knob to the act of opening the door. When he discovered that he couldn't get a good grip on the knob, he began to move a table towards the door so that he could have better leverage. This is systematic problem solving. Observations are made, conclusions are drawn and behavior is modified. Instead of following scripted responses to stimuli new behaviors are developed. These behaviors undergo a process of selection based on which ones are effective at reaching a goal. This then, is the core of intelligence, and examples of it among animals are legion.
So what makes humans different? Humans, in my mind, have reached the "singularity" of intelligence. Our capacity to observe and invent behavior has allowed us to reflexively observe our behaviors and draw conclusions about our methods of behaving. We can make inferences not just about how the world works, but about how our minds work. We can make far more complex inferences. This is not to say that we are free of the relics of our evolution- we have instincts and programmed behaviors and non-rational responses to stimuli. Evolutionary legacy is painfully clear in human behavior.
The important thing, the thing that defines humanity, is our capacity to analyze and infer. That capacity allows the tool-using nature that permits civilization to occur. What makes us human is the ability of critical thought.
The point I'm making with this long prologue is that critical thought, analysis, logic, reason, etc. are the core of what makes us human. All humans possess that capacity. But "capacity" and "achievement" are very different things. All fully-functional humans possess the capacity to run- but vanishingly few (out of the total number) run marathons. And those that attempt it just can't decide to start running one day and complete a marathon. It takes training. The body has to be conditioned. Just because we have the capacity doesn't mean that we can assume that it will develop all by itself.
Running is a valuable skill, but critical thought is crucial to our humanity. Without it, we are something less than human. We all possess the capacity, but it is something that must be nurtured and refinements to it must be taught. For example, we all instinctively will recognize patterns of behavior. We rapidly learn, for example, that politicians are untrustworthy, and modify our behavior accordingly. When presented with unfamiliar situations we will (often) make reasonable decisions in response to them and (generally) survive the encounter. We call this having "common sense".
But throughout history, we have repeatedly learned that "common sense" is often wrong. "Common sense" tells us that the Earth is stationary, therefore it must be the Sun that moves. Common sense tells us that if I'm on a train traveling at the speed of light and I walk forward, I must be going faster than the speed of light.
Because common sense has failed us, we have recognized that failure and altered our behavior accordingly (the earmarks of intelligence!). Because our senses also deceive us, we have recognized that failure and modified our behavior. The end result is the Scientific Method.
This is an amazing crowing achievement in human thought. By recognizing the fallibility of humans, we created a system that is "controllably fallible". Because science is not infallible, not by any stretch. But science starts out by assuming error. In logic, we can supply "givens", apply logical rules to those givens and draw conclusions. But, according to the GIGO principle- if our givens are flawed, so will our conclusions be (but the argument is still logical- just wrong). So science doesn't allow any givens- the only given is that the Universe is knowable and behaves according to discoverable principles (which isn't much of a given, because if it's false, it becomes impossible to know anything and everything simply turns into solipsism and nihilism).
The scientific method is an incredible advancement that allows us to make sense out of the world and to improve our understanding as our tools and experience improve. The fact that we can honestly say that Newton was wrong about gravitation isn't to disparage his achievement- because he wasn't wrong exactly- just inaccurate. In most cases, his formulae work perfectly well- but in special cases they break down and Relativity takes over. We improve our understanding. Scientific theories are nothing more than approximations that work. The famous
e=mc2is a representation of an observed phenomenon; it is not a statement about reality, it is a statement about how reality works. As Carl Sagan said, Science isn't a collection of dry facts to be learned by rote, it is a way of thinking about the world.
We teach science wrong. We teach it as facts, and occasionally, we give the kids a whiz-bang "experiment" which isn't an experiment at all- a baking-soda/vinegar volcano isn't an experiment, it's a toy. Making a diorama of the layers of the Earth or a model of the solar system out of styrofoam balls isn't science education- it's handicrafts.
Scientific thinking is a skill, and it is a skill that can be taught. Like any skill however, it's easiest to learn if you start young. We need to give children the tools to think critically and rationally at a young age, and let them develop with those tools at hand. This is why I advocate teaching children to program as soon as they're able to read and write- because it teaches them to take a structured approach to thinking about the world. Planning, problem solving, critical and scientific thinking all depend on that. Children should be given the opportunity to put the scientific method to work for them as soon as they're capable of speech. They're going to ask "why" as soon as they're able because that curiosity is a hard-wired survival trait built out of our rational thinking apparatus. Instead of putting them off or spoon-feeding them answers (or worse, lies (I'm lookin' at you stork))- let's start giving them the opportunity to experiment. Instead of just showing them or having them play with vinegar and baking soda, let's actually do an experiment- what happens when I mix vinegar and flour? What about lemon juice and banking soda? What about water and baking soda? Why does the reaction happen sometimes, and not others? Let's make a guess, and find out if that guess is right!