April 28 2023

What makes humans unique are
10,032 missing pieces of DNA
https://english.elpais.com/science-tech/2023-04-28/what-makes-humans-unique-are-10000-missing-bits-of-dna.html

Humans are missing 10,032 pieces of DNA
in certain genome regions that are present
in every other mammal, including our close
hominid relatives. This genetic information
must have disappeared in the evolution of
the species.

.... They discovered that humans have 10,032
DNA deletions that are present in every mam-
mal species, even other hominids.

The vast majority of the deletions are very
short sequences of a few base pairs (the 4
bases of DNA are adenine, cytosine, guanine,
and thymine) with unknown functions.

.... “deletions are especially enriched to func-
tion in the brain.”

.... “When thinking about innovative functions
of new phenotypic abilities in humans, many
scientists, including us, believe that our DNA
encodes new instructions with new genes.
Surprisingly, we found that deletions can also
generate something new,” said Reilly.

“The theory is that evolution is tinkering with
the fundamental building blocks & instructions
shared by all mammals to give us our unique
traits.”

Reilly says it was humbling to discover that the
huge phenotypic difference between humans
and chimpanzees is because of a few minor
changes.

“Deletion of just one or two DNA bases could
suppress a repressor sequence, leading to in-
creased gene expression, or deletion of a base
that doesn’t fit well in an activator [gene], and
leading to enhanced gene expression.

Surprisingly, we see this 30% of the time, where
a deletion increases gene activity rather than
suppressing it.”

“We tend to think of evolution as a linear process
toward a specific end, as if humans were the most
important evolutionary milestone,” said Gallego.

“But knowing that mutations and deletions both
contribute to the phenotypes that characterize the
human species adds a measure of humility to how
we view ourselves – some human traits we value
highly are a consequence of a molecular deletion!”

~~~

Phenotype meaning
https://www.google.com/search?q=phenotype+meaning

the set of observable characteristics of an individual
resulting from the interaction of its genotype with the
environment.

~~~

Genotype meaning
https://www.google.com/search?q=genotype+meaning

In a broad sense, the term "genotype" refers to the gen-
etic makeup of an organism; in other words, it describes
an organism's complete set of genes. In a more narrow
sense, the term can be used to refer to the alleles, or
variant forms of a gene, that are carried by an organism.

~~~

Genotype vs Phenotype – Definitions and Examples
https://sciencenotes.org/genotype-vs-phenotype-definitions-and-examples/

Picture: Genotype vs Phenotype
https://sciencenotes.org/wp-content/uploads/2021/11/Genotype-vs-Phenotype.png

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