Lecture 1: Differentiating Humans from Animals

The first topic discussed by Dr. Heine was the difference between homo sapiens and the rest of the animal kingdom. Why were chimpanzees, orangutans and other types of gorillas/monkeys stronger than we were, even though we shared the same ancestry? It is known that humans are so much weaker than our nearest primate relatives, but why? A Michael Phelps analogy was needed to drive the point home; as one of the best competitive swimmers of all time, Phelps trains extremely hard multiple times per day to be the world class competitor he is. To maintain his body weight, he has to consume 12,000 calories per day. For the average human being, this amount of exercise and food consumption is not feasible to maintain a "normal" lifestyle.

"I love Psychology THIS much."

A trade-off between traits in species becomes apparent, in this case a trade-off between muscle and brain. Two physical adaptations to bring about a bigger brain size come into play: Humans have less muscle mass and smaller intestines, which is apparently an adaptation to eating cooked food. Eating raw food apparently takes more energy, and as we are all lazy human beings, this adaptation is awesome!

Moving forward, we get to three competing theories on why primates have such big brains:

1) Many primates are fruit eaters and fruit eating is a highly intellectual practice requiring a big brain. Not only do you have to remember where the fruit trees are, but you must also remember when to come back so you get some nice ripe fruits.

2) Many primates like to eat puzzles, in which I mean foods they have to somehow manipulate to extract the good stuff inside. Examples: Termites (a fine delicacy) and nuts.

3) Many primates like to live within large social networks in which you can learn from each other (progressive learning) while having to spend a lot of time maintaining relationships.

Of course, any good theory must have some scientific evidence to back it up. This is where theory 1) and 2) fall, while theory 3) prevails. There was zero correlation between brain size and a fruit diet, and also zero correlation between brain size and a extraction required food diet. However, there is a positive correlation between brain size and the mean group size kept by the species in question. [Fun fact of the day: Humans can have relationships with approximately 150 people without losing touch. Many will disagree saying they have 900+ friends on Facebook. Facebook is like a steroid for social networks. And you really don't know everyone on your list anyways.] Conclusion: "Primate brain evolution appears to be largely driven by their highly social lifestyle."

So... Humans are ultra-social! Compared to primates, we live in larger groups, we're more interested in each other's activities and we participate in cultural learning. A study was done to compare the learning styles of a 2.5 year old human children, orangutans and chimpanzees by Herrmann et al. in 2007. When tasked with general problem-solving skills regarding the physical world, chimps and humans were nearly identical in their results, with the orangutans being slightly worst. Nevertheless, when tasked with social learning, the humans fared the best than both the other primates. Conclusion: Humans are unique in the sense that we partake in so much social learning. The ability to learn skills by observing and imitating is a key factor in our large brain evolution.

When humans learn from a model, we imitate; when chimpanzees learn from a model, they emulate. Let me XPAND: Humans tend to internalize the model's goals and behavioral strategies to solve similar problems, while chimpanzees focus on the environment and their surroundings rather than taking into account the model's intentions.

Another study (by Nagel et al. 1993) comparing chimpanzees and 2 year old human babies showed a disadvantage of imitative learning. In this study, the subject used a rake to reach an object that he/she/monkey couldn't reach without the tool. The model would demonstrate how to use it using either the teeth down (the ineffective way) or the teeth up (the effective way) approach. The babies would all imitate whichever method the model used, while the chimpanzees tried to figure it out on their own and used the teeth up approach more frequently. This disadvantage of imitative learning can be seen all the time in real life. One example: You aren't prepared for your exam and you're stuck on a particular question. You look to your right and you see a girl wearing glasses and think "that girl must know the right answer" and you copy her answer when in fact, she hasn't studied either and she copied off the jock to her right, etc. Ok, that wasn't the greatest analogy, but you get my point.

What is the key benefit of imitative learning? Cultural accumulation. "Imitative learning allows for a faithful and high fidelity reproduction of the target behavior." (Quoted that one cause its quite the aesthetically pleasing sentence). Not only can we reproduce a high quality imitation (ie. fake Gucci bags), but we can actually improve them (ie. Windows Vista vs. Windows XP... wait. Bad example) (ie. 2010 Honda Accord vs 2004 Honda Accord). We have that two word phrase (cultural accumulation) to thank for all the technology we take for granted. All of our iPhones/Blackberries/Androids, laptops, televisions, architecture, shopping malls, cities, automobiles, and hammers. That's right. Hammers. With that, I leave you with the evolution of hammers with an addition to the most modern of hammers that Dr.  Heine's image didn't include. Please feel free to comment! Share any interesting theories you guys have for why humans have bigger brains or how we evolved from our hairier counterparts.

From stone age fist rocks, to steam powered hammers to...

...MC Hammer