Homology (biology)
In the context of biology, homology is the existence of shared ancestry between a pair of structures, or genes, in different species. A common example of homologous structures in evolutionary biology are the wings of bats and the arms of primates. Evolutionary theory explains the existence of homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.
In the context of sexual differentiation—the process of development of the differences between males and females from an undifferentiated fertilized egg—the male and female organs are homologous if they develop from the same embryonic tissue. A typical example is the ovaries of female humans and the testicles of male humans.
Etymology
The word homology, coined in about 1656, derives from the Greek ὁμόλογος homologos from ὁμός homos "same" and λόγος logos "relation". In biology, two things are homologous if they bear the same relationship to one another, such as a certain bone in various forms of the "hand". The alternative term homogeny was also used in the early 1900s.
Podcasts:
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by Soundtracks (other tracks) soundtrack
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by Frank Zappa
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by Neil Diamond
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by Marianne Faithfull
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by Kate Bush
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by The Renaissance
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by Electric Light Orchestra
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by Andrew Lloyd Webber
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by Arlo Guthrie
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by Steven Curtis Chapman
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by Fat Joe
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by Mago De Oz
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by Mago De Oz
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by Ayreon
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by Manilla Road
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by Shadows Fall
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by Iron Savior
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by Septic Flesh
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by Mae
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by Opeth
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by Amon Amarth
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by Waltari
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by Arcade Fire
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by Alan Menken
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by Wizard
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by Bal-Sagoth
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by Eraserheads
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by Rilo Kiley
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by Parliament
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by My Ruin
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by Terminal Choice
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by Heimdall
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by Legend
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by Crash
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by I Killed The Prom Queen
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by Boy Sets Fire
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by Dismal Euphony
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by Capercaillie
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by Antichrisis
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by Joseph
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by Joseph
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Prologue
by: Soundtracks (other tracks) soundtrackNARRATOR
Once upon a time,
In a far away land,
A young Prince lived in a shining castle.
Although he had everything his heart desired,
the Prince was spoiled, selfish and unkind.
But then, one winter's night,
an old beggar woman came to the castle
and offered him a single rose
in return for shelter from the bitter cold.
Repulsed by her haggard appearance,
the Prince sneered at the gift,
and turned the old woman away.
But she warned him not to be deceived by appearances,
for Beauty is found within.
And when he dismissed her again,
the old woman's ugliness melted away to reveal a beautiful enchantress.
The prince tried to apologize,
but it was too late, for she had seen that there was no love in his heart.
And as punishment, she transformed him into a hideous beast
and placed a powerful spell on the castle and all who lived there.
Ashamed of his monstrous form,
the Beast concealed himself inside his castle,
with a magic mirror as his only window to the outside world.
The rose she had offered was truly an enchanted rose,
which would bloom until his twenty-first year.
If he could learn to love another,
and earn their love in return by the time the last petal fell,
Then the spell would be broken.
If not, he would be doomed to remain a beast for all time.
As the years passed,
he fell into despair and lost all hope,
For who could ever learn to love .... a beast?