Transcript 3 Aspects of Humans and Evolution

3 Aspects of Humans and
Evolution
3 Aspects of Humans and
Evolution
 Sickle Cell Anemia, Malaria and Evolution
3 Aspects of Humans and
Evolution
 Sickle Cell Anemia, Malaria and Evolution
 “The Red Queen” in action
3 Aspects of Humans and
Evolution
 Sickle Cell Anemia, Malaria and Evolution
 “The Red Queen” in action
 Scars of Human Evolution
Sickle Cell Anemia
 Genetic Blood disorder
 Two forms, severe and mild
 Severe form is often fatal
Blood clumps if oxygen levels are low
Damage to organs, etc. can occur
Sickle Cell Anemia
 Sickle
cell Anemia
Various
Effects of Sickle Cell
Sickle Cell Anemia
If sickcle cell anemia is so bad, why is it
around anyway?
And why, in parts of west Africa, is the rate
of affliction so high that most people are
afflicted?
Sickle Cell Anemia
 Sickle
Cell is Explained by Evolution!
“The Red Queen”
The “Red Queen” is the idea in evolutionary
biology that we are in a race with our
predators and we have to keep evolving in
order to stay alive.
Our predators, at this time, are mostly
microbes: viruses, bacteria, fungi and
parasites.
“The Red Queen”
“The Red Queen” comes from “Through the
Looking Glass”. Alice runs as fast as she
can, but seems to go nowhere. The Red
Queen remarks:
`Now, HERE, you see, it takes all the
running YOU can do, to keep in the same
place.
The Red Queen
“The Red Queen”
Two excellent examples of how human
biology is connected with evolution and
the race against predators are…
 Tuberculosis,
 HIV
drug resistant strains
– rapidly evolving (changing) virus
The Scars of Human
Evolution
Two Types …
 Scars confined to individuals



genetic diseases
genetic deformities
genetic tendencies toward disease
 Scars
that we all have
The Quadrupedal Skeleton
The Human Skeleton
The Quadrupedal Spine
Human Spine
Lots of Problems in the Lumbar
Vertebrae
Knee and Hip Problems
Prognathism and Tooth Room
 Prognathism
decreases from
Australopithecus to Homo sapiens
 The reduction of the mouth, left less room
for the teeth.
 Being catarrhines, we inherit 32 adult
teeth.
Teeth Problems
3rd molar causes most tooth problems
 Nine out of ten people have at least one
molar that doesn’t descend
 Those that do, often cause trouble
 The
3rd Molar Impaction
Evolution in Action
 Traits
that are undergoing strong
evolutionary pressure are often quite
variable.
 Our dental situation is a case in point.
After 20 million years with 32 teeth, we
find ourselves in trouble producing so
many!
Brain Size
 Archaic
humans and Neandertals both had
brains bigger than the modern average.
Even 100,000 years ago.
 Is it possible that the long trend toward
larger brains has reached an end?
 What would put the brakes on selection for
big brains?
Difficult Birth!!!
 Other
wild mammals typically have nonstressful birth of their young.
 Humans are notorious for difficult and
dangerous births. It is part of our deepest
knowledge.
 The mythology and folklore around
childbirth indicates the point.
Human Evolution
 Mutation
and sexual reproduction
produces variation
 Natural (and cultural) selection is involved
in who leaves offspring and how many
 Each generation is genetically different
than the previous generation
 Over time, the species becomes different.