Lecture 2: Humans are not the Pinnacle of Evolution

false

t/f

humans are the pinnacle of evolution

no (we share a common ancestor, they are our closest relatives)

are chimpanzees or Neanderthals out ancestors?

true

t/f

no living species is the ancestor of another living species

true

t/f

our closest living relative is chimpanzees, but our closest relatives are Neanderthals

• teeth need upkeep, losing your teeth can shift bones in head leading to hearing loss

• trachea and esophagus are very close together making breathing, eating, and communicating a major choking hazard

• knees and shoulder never heal the same once broken

• permanent breasts, periods

what are some examples of the “bad body” of humans

lobe-finned fishes

what were the first fishes to come to land

ray-finned fishes

what category do most fishes today fall under

• coronary artery is the only way to get blood to the heart (only 2!)

  • if there is a blockage in said arteries, we will have a heart attack (very common)

• higher blood pressure because we are always standing up against gravity

• dangerously fragile (evolved from fishy ancestors)

what are some flaws with our hearts

• places pressure on our feet, ankles, knees, and back

  • in the course of a single day, the disks in our lower back are subjected to pressures equivalent to several tons per inch

what are some risks that come with bipedal locomotion and upright posture

• retina (transmits images to the brain) can easily detach from back of eye

• blind spot where optic nerve goes through retina

  • octopus eyes are better because optic nerve goes around the eye rather than through

• protective fluid of the cornea become less transparent over time (lens thickens and yellows)

what are some flaws with our eyes

urethra prone to constriction

• the prostate becomes enlarged in one of every two males at some point in life. as it grows, it squeezes the urethra, potentially obstructing the flow of urine. total obstruction can be fatal

fix: urethra hugging outside of prostate would not be squeezed if the prostate became enlarged

what is the flaw with the male prostate and how can it be fixed

evolution, our cold blooded ancestors had them there

• it is very hot inside our bodies so testes cannot stay inside the body cavity (sperm cannot develop in such hot temperatures)

why do testes start inside the body cavity?

human pregnancy is more difficult than marsupial

• newborns are always born prematurely, but if we spent any more time in the womb, our heads would be too big and we would be unable to get out

what are some flaws associated with human pregnancy

muscles and ligaments that weaken with time

• particularly after multiple pregnancies, the muscles of the pelvic floor and the bladder, and the ligaments that support the bladder, can sag leading to incontinence

fix: stronger sphincter muscles in bladder and more durable ligaments would increase control over bladder function

what are some flaws associated with the female bladder and how can it be fixed

common upper passageway for food and air

• when food travels toward the esophagus, a flaplike tab of cartilage (the epiglottis) closes off the trachea, or windpipe. with age, a progressive loss of muscle tone decreases the tightness of the seal, raising the risk of inhaling food or drink

fix: raised trachea would help food and drink to bypass the windpipe more effectively (however would disrupt breathing and the ability to speak)

nerve called the recurrent laryngeal runs from the brain to the larynx. ir goes down into the chest, loops, and goes straight back up (unnecessary path)

what are some flaws associated with the esophagus and trachea and how could it be fixed

science

the use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through the process

theory

comprehensive explanation of some aspect of nature that is supported by a vast body of evidence

ex. theory of gravity, atomic theory, theory of plate tectonics, germ theory

there can be exceptions to these theories based on the need for further understanding

ex. things in space that don’t follow the theory of gravity

fact

an observation, measurement, or other form of evidence that can be expected to occur at the same way under similar circumstances

true (because the evidence supporting it is so strong, scientists no longer question whether biological evolution has occurred and is continuing to occur. instead, they investigate the mechanisms of evolution, how rapidly evolution can take place, and related questions)

t/f

evolution is a scientific fact

hypothesis

an answer to something (an educated guess to falsify a theory about a phenomenon)

ex. apples fall to the earth because of gravity

• can never be 100% confirmed, there could always be something that comes later on to falsify it

falsification

testing something (ex. a hypothesis) to prove it wrong (knock out everything that is false and what is left is “truth”)

true (the 2008 louisiana science education act allowed livingston parish school board to consider introducing the biblical account of creation into schools; was the motivation for an effort to block louisiana’s adoption of standard biology books)

t/f

Louisiana is the only state to have anti-evolution bill on the books

• evolution is the foundation of all subdisciplines of biology

• cant truly understand medicine, anatomy, reproduction, or any aspect of biology without acknowledging our evolutionary history

• explains the history of life on earth

• explains “where you are from”

why do we need to study evolution?

john edmonstone

one of darwin’s most important early influences was from a former enslaved man who taught taxidermy and told darwin of his wonderful tropical adventures as a naturalist. without him, perhaps darwin would have never gone on the beagle and we would never have gotten the origin of species