Anthrarc 296 Day 2 Reading
Delicious Chapter 1
Mechanisms of Evolutionary Change
Pleasure vs displeasure
Lucretius (Roman poet) said that pleasure was the way that a body fulfilled its physical needs ie pleasure and displeasure is a natural phenomenon. A life minimizing displeasure and maximizing pleasure is ideal.
Criticisms of Lucretius include how it challenges Christianity (is sin pleasure?) and how it may be a threat to Western society
Caused by chemicals in the brain, reward/penalizing system for meeting needs
Stoichiometry dictates what food a creature should eat
Vocab
Deliciousness: Pleasure associated with the flavors of food
Stoichiometry: balancing chemical equations
Left side of the equation is the prey, right side is the predator. Nutrients must match energy and waste, down to the amount of chemicals
Challenging for some animals to get enough like herbivores and omnivores. They rely on pleasure and flavor
Flavor: aroma, mouthfeel, taste
The tongue has taste papillae (the bumps) which have taste receptors at the end of tentacular hairs. Neurons travel to the brain when a taste receptor is activated Cells are replaced every nine to fifteen days
When necessary nutrients are consumed it sends a dopamine rush to the brain, creates cravings, and causes a specific sensation based on what was eaten
Predictable taste system based on what ancestors needed. Taste can be hardwired
Herbivores can eat 50x more than they need to ensure they are getting enough nutrients
Two salt receptors ensure the animal is getting enough salt, one for too little and one for too much
Sometimes animals are deficient in nitrogen, calcium
or phosphorous
Kikunae Ikeda
Invented name for umami
Tested dashi to find origin of deliciousness
He confirmed glutamic acid, but other researchers added on with inosinate and guanylate
Patented the method to make MSG in 1908
Work was neglected outside Japan because it was written in Japanese and because it did not identify how the mouth tasted umami
No taste receptors for phosphorous, except for some animals like mice and cats can detect it. More research is needed for humans
Sweetness and other tastes
have changed over time because of evolution
Fat is liked a lot for its mouthfeel
Sourness and bitterness indicates danger to animals. It tastes bad to prevent animals from consuming toxic chemicals
Three types of bitter compounds: Everyone thinks its better (dangerous), some people think its bitter (might be dangerous) and no one thinks it is bitter (safe)
Throwing up is a reminder that it is bad for you while also getting rid of the toxic compounds
Evolution occurs by breaking and regaining taste receptors
Human taste receptors are similar to chimpanzees
Microevolution: changes in allele frequencies within a a single population
Natural selection: when a specific individual carries on because they are able to survive better/ have a higher reproductive rate than others, and thus reproduce
Genetic Drift: Random fluctuations in a gene, usually in a small population. Genes or alleles could even disappear completely. Not driven by the environment. The effect is larger in small populations and smaller in large populations
Bottleneck effect: Sharp an sudden decline in a population (usually from environmental factors).
Founder effect: loss of variation when a smaller population is isolated and reproduces
Mutations: Change in the DNA. Can be neutral, positive, or negative. Spontaneous or caused by outside factors
Gene mutation: Any change in the sequence of nucleotides of the genetic material
Chromosome mutation: Change in structure or arrangement of chromosomes
Genome mutations: Changes in number of chromosomes in the genome
Aneuploidy: loss or gain of chromosomes
Euploidy: variations in complete sets of chromosomes
Viruses
Antigenic drift: small changes from the flu
Gene flow: transfer of genes from the gene pool of one population to another. Can change the frequency or range of alleles. More alleles= more variation.
Horizontal gene transfer/Lateral gene transfer: getting genetic material asexually (ex pollen spreading long distances)