In the history of humans in the 12th
century, Japan was ruled by a clan of
warriors called the Heike.
The nominal leader of the Heike, the Emperor of
Japan was a seven-year-old boy named Antoku.
His guardian was his grandmother,
the lady Nii.
The Heike a were engaged in a long and
bloody war with another Samurai clan
the Genji.
Each asserted a superior ancestral claim
to the imperial throne.
Their decisive encounter occurred at Dan-no-Ura
in the Japanese Inland Sea on April 24th
in the year 1185.
The Heike were badly outnumbered and
outmaneuvered. With their cause clearly
lost, the surviving Heike warriors threw
themselves into the sea and drowned.
The Emperor's grandmother the, lady Nii,
resolved that they would not be captured
by the enemy
what happened next is related in the
tale of the Heike. The young Emperor
asked the lady Nii, "Where are you to take
me?" She turned to the youthful sovereign
with tears streaming down her cheeks
and comforted him.
Blinded with tears, the child
sovereign put his beautiful small
hands together.
He turned first to the east,
to say farewell to the god of Ise
and then to the west to recite the
nembutsu, a prayer to the Amida Buddha.
The lady Nii, took him in her arms and with the words,
"In the depths of the ocean is
our capital, " sank with him at last
beneath the waves.
The destruction of the Heike battle fleets
at Dan-no-Ura
marked the end of the clans 30-year rule.
The Heike, all but vanished from history.
Only 43 Heike survived. All women. 
These former ladies-in-waiting of the imperial
court were reduced to selling flowers,
and other favors, to the fishermen near
the scene of the battle. 
These women and their offspring by the fisher folk
established a festival to commemorate
the battle.
To this day every year on the
24th of April, their descendants
proceed to the Akama shrine which
contains the mausoleum of the drowned
7 year old emperor, Antoku.
They conduct the ceremony of remembrance
for the life and death of the Heike warriors.
But there's a strange postscript to this story.
The fishermen say that the key samurai
wander the bottom of the Inland Sea
still, in the form of crabs. There are
crabs to be found here, which have
curious markings on their backs. 
Patterns which resemble a human face with the
aggressive scowl of a Samurai warrior
from medieval Japan
These Heike crabs, when caught, are not eaten
they're thrown back into the sea, in
commemoration of the doleful events of
the Battle of Dan-no-Ura.
This legend raises a lovely problem.
how does it come about that the face of
a warrior is cut on the carapace of a
Japanese crab how could it be the answer
seems to be that humans made this face
what happened
like many other features the patterns on
the back or carapace of this crab are
inherited but among Krabs as among
humans there are many different
hereditary lines now suppose purely by
chance
among the distant ancestors of this crab
they came to be one which looked just a
little bit like a human face long before
the battle fishermen may have been
reluctant to eat a crab with a human
face in throwing it back into the sea
they were setting into motion a process
of selection if you're a crab and your
carapace is just ordinary humans are
going to eat you but if it looks a
little bit like a face he'll throw you
back and you'll be able to have lots of
nice little baby crabs that all look
just like you as many generations past
of crabs and fisher folk alike the crabs
with patterns that would most like a
samurai face preferentially survived
until eventually it was produced not
just a human face not just a Japanese
face but the face of a samurai warrior
all this has nothing to do with what the
crabs might want selection is imposed
from the outside the more you look like
a samurai the better your chances of
survival
eventually there are a lot of crabs that
look like samurai warriors
this process is called artificial
selection in the case of the Heike crab
was affected more or less unconscious
with a fisherman and certainly without
in the serious contemplation by the
crabs humans for thousands of years have
deliberately selected which plants and
animals shall live
we're surrounded with farm and domestic
animals fruits vegetables
where did that come from where they once
free living in the present form in the
wild and then induced to adopt some less
strenuous life on the farm
no they are almost all of them made by
us
