5 Social Organization - Biology Flashcards
How did evolution by natural selection shape modern-day skin color in humans?
Our bodies require Vitamin D. We catalyze vitamin D from ultra-violet light from the sun. Anywhere from 100,000-70,000 years ago, some of our ancestors began migrating away from sub-saharan africa. Once our ancestors started moving north, they were exposed to less ultraviolet light. Due to the tilt of our planet, regions around the equator are hit with large amounts of ultraviolet light year-round, but regions distant from the equator are hit with much less. This set the stage for natural selection to operate on skin pigmentation as lighter shades are better able to absorb ultraviolet light and produce vitamin D in environments far from the equator.
Articulate the logic of evolution by natural selection using the 3 components discussed in class.
1) Overproduction, Limited Population Growth, and Competition - populations have exponential potential to grow but typically remain stable at a certain size due to intense competition and limited resources.
2) Variation & Inheritance - Not all offspring are identical due to random chance. We all have roughly 40-50 genetic mutations that we did not inherit from our parents. Many genetic variations are heritable, meaning they are passed on to offspring. Therefore, due to random chance, some offspring will have advantages that make them more likely to survive and thus make their genes more likely to be represented in future generations.
3) Non-random Differences in Survival and Reproduction - Differences in survival and reproduction between individuals are non-random, with some traits being passed on at a higher rate than others and increasing in proportion in the population from one generation to the next
When did human and chimpanzee lineages diverge in our evolutionary timeline?
5-6 million years ago
What is a fact?
Fact - an observation that has been repeatedly confirmed and, for all practical purposes, is accepted as “true” in science. Remember, we can never be 100% sure of anything, but we behave as if facts are true until proven otherwise.
How are scientific theories and facts related?
Scientific theories incorporate facts.
Describe all of the evidence covered in class that supports the theory of evolution.
Artificial speciation experiments - we can watch the evolutionary process happen with species that produce very quickly (fruit flies, e coli, etc.).
Paleontology - we have discovered fossil remains that map out evolutionary history. Importantly, we have found transitional fossils showing creatures in the middle of large evolutionary changes, such as evolving from water to land and land to flight.
Modern human traits with specific evolutionary origins - sickle cell trait, lactose intolerance.
Genetics - human chromosome #2 is an identical copy of two chromosomes in other primates. Genetics is a language/alphabet that connects us to all other living creatures. We share roughly 50% of our DNA with a banana.
Define and distinguish between genotype and phenotype.
Genotype - our evolved genetic code; the genetic instructions for how to build an organism.
Phenotype - the expression/appearance of an organism.
What is epigenesis?
Epigenesis is the process by which genetic information (the genotype), as modified by environmental influences, is translated into the appearance and behavior of an organism (the phenotype)
Homo sapiens are less genetically diverse than apes. Why is this important when considering the impact of culture in both human history and modern societies?
The lifestyles of modern humans are much more variable than other primates. If genes were the primary driver of such variability, we would expect humans to have more variation than other primates. This is not the case. Modern primates have much more genetic variation than modern humans. Thus, it is culture and not genes that are driving modern human variation in behavior.
