Today in the Intro to Psychology class I went over good practices in experiments, specifically in reference to psychological experiments. Randomly assigning participants to either the experimental or control group can help insure that both groups are similar. Not telling participants which group they are in eliminates bias on their part, having both the participants and the experimenter in the dark is called a double blind study and this eliminates bias on both parts. An important thing to note about psychology is that a review board has to okay any experiments, the benefits must outweigh the risks and participants must sign informed consent. Participants must also be able to leave the study at anytime without negative consequences.
Lesson 3 starts out with an introduction into how long modern humans have been around as compared to other humans. Modern humans have existed for the last 200,000 years, before that were Neanderthals, homo-erectus and homo-habilus. Homo habilus, the first humans, lived from about 2.4 to 1.4 million years ago. Our closest relative would be the Neanderthals and we actually interbred with them before they died off around 28,000 years ago so many of us have Neanderthal DNA. Our closest living relative is the chimp, with whom we share about 98% of our DNA, the other 2% is what makes us uniquely human. These changes happened over a long period of time due to mutations and natural selection, in other words, we evolved.
The changes to our brains is probably what makes us most human. Our brains are bigger than our ancestors and the most differences between our brains and theirs is in the frontal lobe. Having a bigger brain did not come without consequences, childbirth is more painful because of larger skulls and we need more food to fuel our brains.
There is a section on DNA structure, from the nucleotides Thymine, Adenine, Guanine, Cytosine to the 23 chromosomes that make up our DNA. Also it is not the amount of DNA but the sequence that makes us more complex, in fact some amoeba's have more DNA than than anything else on earth. Only about 2% of our genome actually codes for proteins (these portions are called genes), most of the rest regulates which genes are activated, but some of this remaining 98% we're not really sure as to what its purpose is. Alleles are versions of genes, for example my dad has the allele for colorblindness where as my mom does not, so being that this allele only exists on the x chromosome (of which I have 2) I have one allele for colorblindness and one for normal vision. Luckily for me the colorblindness allele is recessive which means that I would need two in order to be colorblind. However this also means that there is a 50/50 chance my daughters will also carry the colorblindness allele and 50/50 chance that any sons I would have would be colorblind. Why? Because males have an x and a y chromosome so they only get one chance at a good allele, where as the x chromosome from my mom allows me to recognize all the colors males don't have a second x chromosome to cancel out or hide the colorblindness allele. This is why more men than women are colorblind, for a woman to be color blind her father would have to be colorblind and her mother would have to carry the colorblind allele.