Download Genetics of Humanness

Genetics of Humanness
Blake Constant
Are we really 99% chimp?
Research tells us that the human and chimp genome
sequences are nearly 99% identical with at least 1/3 of
proteins being the same
BUT is it really that simple?
If we were to match up the human
genome sequence with the chimp
genome sequence would they mirror
each other with 99% accuracy?
Modern Synthesis/Neo-Darwinism
gene-centric view of evolution that believes that humans evolved from chimps
solely based upon random genetic mutations that produced gradual change
through the process of natural selection
4 main proponents of the original theory:
- Genetic change is random
- Genetic change is gradual
- Natural selection is solely responsible for particular gene variations
- Impossibility of inheritance of acquired characteristics
Integrative Synthesis
Molecular genetics and genome sequencing have reintroduced
physiological function and environmental interaction to the view
of evolution influencing the speed and nature of inherited change
Nobel prize winner Barbara McClintock
introduced idea that the genome is an
“organ of the cell”
Jean-Baptist Lamarck was an early
evolutionist who proposed that life forms
could acquire information from their
environment and pass it on in their genes
Epigenetics and Evolution
Evolutionary studies have shifted from simple sequence comparisons
to more in-depth analysis where gene regulation is key to
understanding the evolution of humans from chimpanzees
DNA methylation is the most prevalent chemical
modification of genomic DNA
Ape ancestor
# of unique methylated genes
HUMANS
171
CHIMPS
101
BONOBOS
101
GORILLAS
101
ORANGUTANS
450
Brain Differences
These [TSS chromatin] networks in the human
brain thought to play an important role in cognitive
processes and neurological disorders
Important to note that the epigenome is tissue-specific and
the patterns vary between the types of cells that are
studied
One key area of interest was the promoter region—the
area preceding a gene that controls its function like a
genetic switch.
Genetic change is random/gradual
Genetic change is NOT random and often not gradual
rates of epigenetic mutations, such as DNA methylation,
are much higher than rates of mutations transmitted
genetically and are easily reversed
Genetic regulation leads to genetic mutation
based on evolutionary adaptation to external
influences
Natural selection is responsible for particular
gene variations
Trans-generational epigenetic inheritance
In Modern synthesis the germ-line was believed to be isolated from any
influence by the rest of the organism and its response to the environment
epigenetic conservation in evolutionary timescale is
linked to functional conservation
epigenetic divergence between closely related species
may be related to functional specificity
Germ-line modifications
Charles Darwin proposed that there existed particles of inheritance,
called “gemmules” or “pangenes,” that carried information of
inheritance to the sexual elements and that these particles may be
modifiable by the environment
Testes show the highest quantity of transcription in the body
Where brain tissue shows the second highest rate by a large extent
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Nutrition and Epigenetics
Our health is not only determined by what we eat, but also
what our parents ate.
So if a pregnant mother's diet can affect the child's
epigenetic outcome, can dad's diet do the same?
Records show that food availability between the ages of
nine and twelve for the paternal grandfather affected the
lifespan of his grandchildren.
BUT not in the way you might think…
Why are we so different from each other if we all
share the same DNA?
WHAT MAKES US UNIQUE?
Why are we no longer covered in fur?
Why do we have different variations in skin tone?
How did our skulls change shape from our ancestors?
Why are identical twins
not identical?
Why do some people hate
the taste of certain foods?
EPIGENETICS IS THE ANSWER
Neo-Darwinism VERSUS Epigenetics
From a psychological perspective this can be view much
like the argument for nature versus nurture
The Greek prefix “epi” means “on top of” or “over”