In this video Robert Sapolsky introduces his free on-line course "Human Behavioral Biology" at Stanford University.

One of the main themes in the video is the existence of free will. If our biology causes us to do things both famous and infamous, are we responsible for those behaviors? The course will explore how biology causes human behavior. Sapolsky suggests that free will is supplanted by the biological causes of human behavior. Do you agree? Does biology prove that we are just neurotransmitter hiccups hung on a skeleton clothed with protoplasm?

These are my summarizing notes for Robert Sapolsky's first video in his free on-line course "Human Behavioral Biology" at Stanford University ( which includes 25 videos totaling 36 hours 40 minutes).

What is the thing in common between the following four situations? 1) Having your period, 2) Having a brain tumor, 3) Eating a lot of junk food, 4) Taking a lot of anabolic steroids (the ones that build muscles including testosterone derivatives).

Punchline: "All of these have been used successfully in courts of law to explain the behavior of a murderer."

A major point of the course: "Sometimes the stuff going on in your body can dramatically influence what goes on in your brain."

Second key theme of the course: "Sometimes what's going on in your head will affect every single outpost in your body."

"This course is about the intertwining, the interconnections, between your physiology and your behavior, the underlying emotions, thoughts, memories, all of that, and the capacity of each to deeply influence the other under all sorts of circumstances."

It is complicated trying to make sense of human social behavior especially when it comes to grossly abnormal human behavior.

Breaking continua into categories is extremely useful. For example, the continua of colors is broken down by each language into color terms which are different in different languages. Colors that are in the center of each term's range of meaning are easier to remember than colors at the boundaries between the word-categories. "Thinking in categories makes it easier for us to remember stuff. And makes it easier for us to evaluate stuff."

Similarly different languages categorize different sounds (phonemes) differently. So that some people cannot distinguish certain sounds whereas other sounds may be crisply rememberable.

"When you are paying too much attention to categories, you can't differentiate two facts that fall within the same category."

Even though there is very little difference between a test result of a 64 versus a 66, because schools often differentiate those differences between "failing" and "passing", we see a world of difference between the two grades even though they are practically indistinguishable!

"When you pay too much attention to boundaries, you don't see the big picture. All you see are categories."

"When you think in categories, you underestimate how different two facts are when they fall in the same category. When you think in categories, you overestimate how different they are when there happens to be a boundary in between them. And when you pay attention to categorical boundaries, you don't see big pictures."

In the course, we will use categories to explain behavior, but at the same time resist falling into the problems of thinking in categories. The approach of the course will be to start with an understanding of the behavior. Then trying to understand the proximal causes of the behavior ("what happened a half second before": the "bucket" of neurology and brain science). Then we will look at what environmental factors caused that behavior. Then looking at the more distal cause of hormones which may have made the organism more or less sensitive to the environmental factors. Then looking at the early development of the organism, its genetics, population genetics, and most distally of all its species' evolutionary history.

So the categories (the "buckets" and "outposts" of explanations) are just convenient tools ("temporary platform") to describe what is really very complicated behavior. "There's no buckets. All there are are temporary platforms and each platform is simply the easiest most convenient way of describing the outcome of everything that came beforehand."

Many professional biologists have gotten it wrong:

"Give me a child at birth from any background and let me control the total environment in which he is raised and I will turn him into anything I wish him to be whether doctor, lawyer, beggar, or thief." --- John Watson in 1912, one of the founding fathers of the behaviorist school of psychology

Sapolsky says of him: "Here's a guy living pathologically in this bucket that behavior can be explained solely by understanding reward and punishment."

"Normal psychic life depends on the good functioning of brain synapses and mental disorders appear as a result of synaptic derangements. Synaptic adjustments will then modify the corresponding ideas and force them into different channels. Using this approach we obtained cures and improvements, but no failures." --- António Egas Moniz advocating frontal lobotomy as "synaptic adjustments" on accepting his Nobel prize.

"The selection for social utility must be accomplished by some social institution if mankind is not to be ruined by domestication-induced degeneracy. The racial idea as a basis of our state has already accomplished much in this respect. We may, and we must rely on the healthy instincts of the best of our people for the extermination of ailments of the population loaded with dregs." --- Konrad Lorenz, Nobel laureate

Many of the most influential scientists of the last century have been responsible for living pathologically in buckets about how to explain the whole world. We need to "resist the temptation to think inside a bucket and find the explanation."

To explore human behavior, human social behavior, and including abnormal human social behavior there are three intellectual challenges:

1. In some circumstances, there is nothing fancy about humans, "we are just like every other animal out there". "The challenge is to accept that." "Some of the time, we are just a plan old off the rack animal." For example, in all animals, including humans, ovulatory cycles are synchronized by olfaction.

2. Some of the time, we appear to be just like other animals, but we can use standard animal physiology in an unrecognizable way that no other animal could. For example, stress in human grandmaster chess or thinking about our mortality or reading about something awful that has happened to a child on the other side of the planet.

3. Some of the time, we can do things that no other animal can do anything remotely like it. For example, our language use, aspects of our sexuality (such as frequent nonreproductive sex, confusing aspects of sexuality with aggression), etc are aspects of our behavior for which animal models are largely inadequate.

Content of the course: Part 1: study the biological tools for understanding our behavior including evolutionary theory, molecular genetics, behavioral genetics, ethology, the brain and nervous system, and endocrinology; Part 2: look at specific behaviors and try to understand them in an integrated way supported by the categorical thinking of the different biological disciplines. First we will try to understand each behavior, then look at proximal (near) biological causes in our neurology and then at more and more distal (remote) causes including perinatal (around the time of birth, both pre and post) and genetic and evolutionary causes.

We are each behavioral biologists every time we serve on a jury, every time we vote, in dealing with our family members. "We are behavioral biologists all the time. So it's probably a good thing that we be informed ones."

"For 500 years we all have been using a very simple model for thinking about living systems which is if you want to understand something that is complicated you break it apart into its little pieces. And once you understand the little pieces and put it back together, you will understand the complex thing."

He recommends James Gleich's book "Chaos" which suggests that this reductionist approach doesn't work for complex biological systems. "I found this to be the most influential book in my thinking about science since college."

Much of the end of the lecture is admistrivia. You might want to watch it at a faster playback speed.