Download biology of myths and monsters

The Biology of Monsters
• Many of the creatures found in myths and fairy tales
have some basis in biological facts. Our forebears may
have extrapolated and expanded on what they saw and
heard about, but there was usually a kernel of truth
underlying the myth.
• Here I have presented some biological information about
several such phenomena: dwarves, cyclopses,
werewolves, vampires, two-headed monsters, humananimal hybrids.
• Please be aware that some of the images presented
here are quite graphic.
• Also, please be a bit sensitive to the people born with
various genetic conditions. They may appear strange,
but they ar no less human than we are.
Dwarves
• “Dwarfs” is the more
accepted spelling. JRR
Tolkein has resurrected
the plural form from Old
English.
• A race of short people,
perhaps miners and
warriors. Similar to
humans, equals of
humans, but not really
“us”.
Dwarf Images
• Or perhaps figures of
fun: circus freaks, the
Munchkins of The
Wizard of Oz, the
Oompa-Loompas of
Willy Wonka and the
Chocolate Factory.
• Good book: The
Munchkins of Oz, by
Stephen Cox, about
the little people who
played the
Munchkins.
Achondroplasia
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Achondroplasia is the most common
form of dwarfism, 70% of all cases.
Symptoms include a torso of normal
length, with disproportionately short
arms and legs. Other features are a
large head with a high forehead, and a
small, often turned-up nose.
Achondroplasia is recognizable at
birth. In many cases, the legs bow
outward.
The major medical problem with
dwarfism is “spinal stenosis”, in which
the channel in the vertebrae that holds
the spinal cord is too small. This
results in compression of the nerves,
with numbness and paralysis possible.
The bad fit between large head and
small spinal column also causes
hydrocephalus (spinal fluid buildup
crushing the brain) in some cases.
Biochemistry of Dwarfism
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Achondroplasia is caused by a gene
mutation.
The gene is involved makes the protein
“fibroblast growth factor receptor-3”.
Fibroblasts are the cells that make skin,
bones, and other connective tissues;
fibroblasts make and secrete collagen, the
protein that gives these tissues their
structure.
A “growth factor” is a small molecule (a
small protein) secreted by one cell that
causes the cells around it to grow and
multiply.
The growth factor receptor is a protein on
the surface of the fibroblast cells that acts as
an antenna: it attracts and binds the
matching growth factor molecules that
approach it, then passes a signal along to
the inside of the cell, telling it to grow and
divide.
There are at least 22 different fibroblast
growth factors in humans, with matching
receptors. Different cell types use different
signals.
The achondroplasia gene just happens to
be very sensitive to mutation at one
particular spot, for unknown reasons.
Genetics of Dwarfism
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Inherited as a dominant trait: those with 1
mutant (dwarf) gene and 1 normal gene
show the condition. If both copies of the
gene are mutant, the child invariably dies
around the time of birth.
Most dwarves are born to normal parents: a
random mutation occurred in one of the
parents.
If a dwarf mates with a normal sized person,
½ of their children will be dwarf, ½ normal.
If 2 dwarves mate, ¼ will be normal, ½ will
be dwarf, and ¼ will be “double dominants”
who die at a very young age.
Because dwarves are heterozygotes: they
have 1 normal copy of the gene and one
mutant copy—the condition does not breed
true. It is impossible to create a race of
dwarves because they will inevitably have a
significant number of normal size children
born.
Cyclops
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The one-eyed monster of the
Odyssey, who ate human
flesh. The Cyclopes were a
race of beings, children of
Uranus and Gaea, brothers of
Chronos (Saturn, Zeus’s
father). In the Odyssey, the
Cyclops Polyphemus lives a
barbaric life in a cave, herding
sheep, killing passers-by. The
resourceful Odysseus gets
him drunk on wine, then puts
out his eye and escapes tied
under a sheep. Also discussed
in the play The Cyclops, by
Euripedes, and in Hesiod.
Holoprosencephaly
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Holoprosencephaly: failure of the
forebrain to divide into 2 lobes during
embryonic development. Many
degrees of expression and severity,
but the cyclopia form includes
development of a single orbit where
the nose normally is, and a nose that
is either missing or present as a
proboscis above the eye.
Sometimes there is no eyeball,
sometimes one, and sometimes two.
Usually a single optic nerve leading to
the undivided brain.
Affects about 1 in 16,000 live births,
but only rarely survive to birth, usually
aborted in embryonic life (before 3
months gestation time). Survivors are
severely mentally deficient.
Less severe cases have two eyes, but
a single nostril and a flat nose. Even
less severe: cleft lip.
Trisomy-13 (Patau Syndrome)
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Normal humans have 2 copies of each
chromosome, one from each parent.
Sometimes, there is an extra or
missing chromosome. Three copies of
a chromosome is called “trisomy”. The
most common form of trisomy is
trisomy-21, or Down Syndrome.
Patau Syndrome, 3 copies of
chromosome 13, is quite rare: about 1
in 10,000 live births.
The standard symptoms of Patau
syndrome include extreme cleft lip and
palate, extra fingers and toes, and
severe mental retardation. Average
survival time after birth is less than 3
days. Oldest known case lived to age
21. The cyclops condition is an
occasional symptom.
Cause of Patau Syndrome
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The presence of an extra chromosome is
due to “non-disjunction”, the failure of
chromosomes to properly separate during
the formation of the sperm and egg cells.
Our body cells are all diploid: 2 copies of
each chromosome. The gametes, the
sperm and egg cells, must be haploid, one
copy of each chromosome, so that when the
sperm fertilizes the egg, the diploid condition
is restored.
The special cell division process to convert a
diploid body cell into a haploid gamete is
called “meiosis”. During meiosis, the pairs of
chromosomes line up in the center of the
cell, then each pair gets separated into
different cells. Non-disjunction occurs when
both members of a pair go into the same
cell.
The rate of non-disjunction is greatly
affected by the mother’s age.
Most embryos with extra or missing
chromosomes are spontaneously aborted.
Down and Patau syndromes are unusually
viable.
Werewolves
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Lycanthropy, the belief that one is a
wolf (or other wild animal) is a form of
psychosis. Few scientists believe that
it is actually possible to physically
change from a human into a wolf.
King Nebuchadnezzar of Babylon,
described in the Book of Daniel in the
Bible, apparently had this belief. It is
found in culture throughout the world,
associated with the local carnivores:
were-crocodiles, tigers, bears, and
sharks have all been described.
Accidental ingestion of hallucinogenic
substances, such as ergot mold (on
infected rye) may have contributed to
some of these beliefs. More recent
cases often involve more recent drugs.
Psychosis is another major cause.
Lycanthropy
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A case in 1977 described in the American
Journal of Psychiatry (volume 134 number
10). Here is part of that description: “A 49year-old married woman presented on an
urgent basis for psychiatric evaluation
because of delusions of being a wolf and
"feeling like an animal with claws." She
suffered from extreme apprehension and felt
that she was no longer in control of her own
fate: she said, "A voice was coming out of
me." Throughout her 20-year marriage she
experienced compulsive urges towards
bestiality, lesbianism, and adultery.”
A Google search easily finds numerous
people who feel that they are werewolves, or
at least animal trapped in human form.
There is a whole movement called “furries”,
in which the participants dress in animal
costumes and do odd things.
Hypertrichosis
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Hypertrichosis univeralis: hair everywhere.
People with this condition at least look like
werewolves ought to look.
Peter Gonzales, born in 1556 in the Canary
Islands, lived in the court of Henry II of
France. His 3 children (2 daughters and a
son) and grandchild) also had
hypertrichosis. They lived at Ambras castle
in Austria; one form of hypertrichosis is
called “Ambras syndrome”.
Stephan Bibrowsky, born in Poland in 18,
exhibited as “Lionel the Lion-faced Man”.
He worked for the Barnum and Bailey circus,
using the story that when she was pregnant,
his mother was attacked by a lion. He wore
good clothes and held intelligent literary
discussions with the people who came to
see him, demonstrating that underneath the
hair he was a normal man.
There are several forms, and a lot of
variation between individuals.
Some geneticists consider this an example
of an “atavism”, an ancestral trait that is no
longer expressed in most people, but lies
dormant in our genome.
Vampires
They drink your blood,
fear the sunlight, and
associate with bats.
Count Dracula from
Transylvania is the
prototype.
The Real Dracula
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Dracula means “son of Dracul” in Romanian.
Vlad, son of Dracul (Dracul means
“dragon”), was a ruler in Transylvania, in
Romania during the 1400’s. At that time,
Romania was ruled by the Ottoman Turks.
Vlad spent most of his time fighting the
Turks and the Hungarians.
Vlad get his nickname “the Impaler” from his
habit of impaling hundreds of victims on
stakes, a very unpleasant and slow way to
die. He occasionally ate bread that had
been soaked in his victims’ blood.
Dracula had a modern counterpart in
Nicolae Ceausescu, the Communist ruler of
Romania from 1967 to 1989. Ceausescu
was a paranoid who ran a very unpleasant
Soviet-style country: no freedom of
expression, starvation due to the export of
most food, birth control forbidden, and a
personality cult revolving around himself and
his wife. In 1989 Ceausescu and his wife
faced a firing squad.
Vampire Bats
• Vampire bats, which drink
the blood from cattle and
other large animals, are
found in Central and
South America. They are
small: 8 inch wingspan.
Their saliva contains an
enzyme that inhibits
blood clotting and also
acts as an anaesthetic.
They make several small
cuts in their victim’s skin,
then lap up the blood.
• Vampire loonies:
Johnny Blood ran
for Parliament in
Banbury,England
on the Monster
Raving Loony
Party ticket. He
campaigned as a
vampire, with the
promise that he
would eat his
constituents last.
He got 9 votes.
Porphyria
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Porphyria is a group of 8 metabolic diseases
that stem from a buildup of precursors for
heme. Heme is the small molecule that
holds the iron atoms in hemoglobin.
Hemoglobin is a protein that carries oxygen
in the blood, and it is red due to its iron
atoms. Heme must be synthesized in the
liver, building up the molecule from
precursors in a series of steps.
In some forms of porphyria the skin burns
and blisters on exposure to sunlight. The
excess heme precursors are excreted in the
urine, which often turns red or dark on
exposure to the air.
Lack of heme means pale skin due to
anemia. Drinking blood was considered to
be a cure in olden times. Modern treatment
includes injection of heme directly into the
blood.
Psychosis and dementia are also common
symptoms.
Porphyria Genetics
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Most types are inherited as recessive mutations. This
means that only those who inherit two bad copies of the
gene, one from each parent, will get it. Because this is a
relatively rare disease, the easiest way to inherit two
mutant genes is through inbreeding, the mating of close
blood relatives.
For example, first cousins have one set of common
grandparents. If one of these grandparents carries a
porphyria gene, each cousin has a ¼ chance of also
carrying that gene. Then, their children have a ¼
chance of inheriting the porphyria gene from both
parents and getting the disease. Recessive genetic
diseases are fairly common in small inbred populations,
such as royal families.
King George III (and his grandmother Mary Queen of
Scots) had this disease. The resulting psychosis may
well have affected the course of the American
Revolution. Movie:”The Madness of King George”.
Cerberus and Two-Headed
Monsters
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Cerberus—the 3 headed
dog who guarded the road
to the Underworld, not
allowing the inhabitants to
return to Earth. Hercules
“borrowed” him for a while
as one of his twelve labors,
and the great singer
Orpheus escaped from the
Underworld with his wife
Eurydice by lulling Cerberus
to sleep with a song.
Unfortunately, Orpheus
looked back at his wife
before reaching the Earth,
and she was forced to stay
in the Underworld.
Janus, the 2-faced god of
doors and beginnings.
Fearsome monsters with 2
heads coming from one
body.
Twinning
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All such creatures are the result of twin
conceptions and births.
Two basic types of twins: fraternal (or dizygotic)
and identical (of monozygotic).
Fraternal twins are the result of 2 eggs
fertilized by 2 sperm: siblings who just happen
to share a womb. They are often of opposite
sexes. Sometimes they even have different
fathers.
In most cases, human females release only a
single egg, but occasionally 2 or more are
released, giving rise to fraternal twins. Higher
multiple births, especially under the influence of
fertility drugs, are usually fraternal. “Dizygotic”
means 2 zygotes (fertilized eggs).
The fetus is surrounded by 2 membranes, the
chorion and the amnion. In fraternal twins,
both membranes are separate. Sometimes the
placentas fuse.
Identical Twins
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Identical twins (monozygotic) are the result of 1 egg
fertilized by 1 sperm. After fertilization, the fertilized
egg (zygote) divides into 2 cells, then 4, then 8, etc.
For unknown reasons, sometimes embryos split
into 2 or more pieces. These become identical
twins. “Monozygotic” means that they started with
1 fertilized egg.
If the split is early enough (before 4 days), the twins
develop within separate outer and inner
membranes (chorion and amnion). This is the
usual situation.
A somewhat later split, between 4 and 8 days,
results in twins that develop within a single chorion,
but separate amnions. A still later split, between 8
and 12 days, causes development within a single
inner membrane. Because they share a blood
supply, sometimes one twin will get too much blood
and the other not enough: this is “twin to twin
transfusion syndrome”, and it can kill either or both
of the twins.
Still later splits, after 12 days, result in conjoined
twins.
Limits on Twinning
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The single cell of the fertilized egg
develops into every cell in the
body. It is “totipotent”.
This works up to the 4 cell stage in
humans: each cell in a 4 cell
embryo can develop into an entire
human being. The Dionne
quintuplets (born 1934) were
apparently identical, so this works
even slightly beyond the 4 cell
stage.
However, cells that become
separated after the 4 cell stage
embryo are unable to develop into
complete individuals. They have
lost the property of “totipotency”,
the ability to develop into any type
of cell.
Conjoined Twins
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If embryonic cells become partially detached
from each other, conjoined twins can result.
Used to be called “Siamese twins”, after Chang
and Eng Bunker, who were born in Thailand
(called Siam in those days) in 1811. Their
parents were Chinese, and in Siam they were
known as the “Chinese twins”. They were
discovered by an English merchant who got
permission from their mother and the Siamese
government to exhibit them. Later they toured
with P.T. Barnum’s circus. Eventually they left
show business, and settled down as farmers in
North Carolina, married 2 sisters and had
several children apiece. None of the children
were twins of any sort, although 2 of their
granddaughters produced twins. They died
within a few hours of each other at age 63.
They were joined by a thick ligament at the
abdomen, and they could easily have been
separated during their lives.
More Conjoined Twins
• There are wide variations
in the degree of shared
tissue and the point of
attachment, all based on
when, where, and how
completely the embryonic
cells separated.
• Most common form:
joined at the thorax with a
shared heart.
• 75% of such cases are
stillborn or die within 24
hours of birth.
Asymmetric Conjoined Twins
• In most cases the two
individuals are
symmetrical, but
sometimes one is only
partially formed and the
other is complete. This is
called “parasitic twins”; in
many cases the parastiic
twin lacks a brain and a
heart, conditions
incompatible with life.
Sometimes one twin
inside the other (often
incomplete: called fetus in
fetu.
Two-headed Conjoined Twins
• The “dicephalous”
type of conjoined
twins: 2 heads and
necks on a single
body—is very rare.
• A Google search
turned up pictures of
a 2 headed moose,
several two-headed
snakes, squirrel,
tortoise, and toad.
Chimera, Sphinx, and Manticore
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Chimera—foreparts of a lion, hindparts of a goat,
tail of serpent, breathed fire. Killed by Bellerophon
with the aid of the winged horse Pegasus. In one
version of the myth, Bellerophon thrust a block of
lead at the Chimera, and her fiery breath melted the
lead, which smothered her.
The Sphinx had the head of a human female, body
of a lion, and wings of an eagle. The most famous
Sphinx figures in the myth of Oedipus. The Sphinx
lived near Thebes, and devoured all who couldn’t
answer her riddle, “What goes on 4 legs in the
morning, 2 legs in midday, and 3 legs in the
evening?” Oedipus answered that Man crawls on
all fours as a baby, walks on 2 legs as an adult, and
then hobbles with a staff in old age. The Sphinx
became distraught at this answer and threw herself
off a cliff. Oedipus was made king of Thebes, were
he unknowingly killed his father and married his
mother. This event lead to a great deal of
unpleasantness in Oedipus’ subsequent life.
Manticore: face of a man, body of a lion, tail of a
scorpion.
Interspecies Hybrids
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Why can’t different species produce
offspring? Some sterile offspring among
close species: mule = horse x donkey, also
lion x tiger, zebra x horse, zebra x donkey,
cow x buffalo, coyote x wolf, plus many
others. Sheep x goat usually results in
stillborn, but occasionally born alive.
But this gets down to the definition of a
species; inability to produce a fertile
offspring. And, in evolutionary terms, when
mating between two creatures results in no
offspring or infertile offspring, “reproductive
isolation”, various mechanisms evolve to
prevent further mating. Some mechanisms
are behavioral or appearance: not attractive
to one another. Others involve fertilization:
the sperm of one species don’t recognize
the eggs of another species. Or embryonic
development may not occur properly:
signals between cells not sent or received
properly, or genes don’t interact smoothly.
Or the hybrid creature might be rejected by
its mother by not smelling or looking right.
Many possibilities. The division between
species is very fundamental.
Human Mosaics and Chimeras
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A “mosaic” is a person having cells with two different genetic constitutions. Normally, all the cells
in our bodies have the same genetic makeup: the same genes and chromosomes. What makes a
liver cell different from a muscle cell, for instance, is difference in which genes are being
expressed and not expressed. Many genes only function in one type of cell.
Mosaics occur when a chromosome is lost or gained during an aberrant cell division. Extra or
missing chromosomes is usually lethal for the cell, but there are exceptions.
Conjoined twins are nearly always the same sex, but on rare occasions, one X chromosome is
lost from one twin in an XY (male) embryo, giving one normal male twin and the other twin a
female with Turner syndrome. People with Turner’s have only one X chromosome and no other
sex chromosomes. The absence of a Y makes them female, but they lack ovaries and are thus
sterile.
Mosaic Down syndrome occurs in about 3% of Down syndrome cases. In mosaic Down’s, some
cells are normal, and other cells have 3 copies of chromosome 21, the Down’s condition. Such a
person’s appearance and mental condition are dependent on which cells are which. There is a
case of a British admiral from the late 1700’s ( the height of the British navy—Horatio Hornblower
days) whose portrait clearly showed he had Down syndrome, but who nevertheless was a brilliant
admiral. (Unfortunately, I have been unable to track the details of this particular factoid down.)
A related phenomenon: the human chimera. Starts out as fraternal twins, where the 2 embryos
implant side by side in the uterus. This can result in the 2 embryos growing together, or one
embryo incorporating the other within itself. Usually seen as a person with 2 different blood or
tissue types, occasionally as a partially formed body within the person or disorganized hair, bone,
teeth within the body. But could possibly result in different sex conjoined twins.
Interspecies Chimeras
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Human-mouse chimeras.
One method (not too controversial). Start with a mouse that
has SCID: severe combined immuno-deficiency). This mouse
has no functioning immune system and can’t detect or destroy
invading organisms. Inject human lymph node cells, which
develop into the immune system. The mouse develops an
immune system consisting of human cells. This technique has
been patented as the “scid-hu” mouse. It can be used to study
the development of the immune system and to test drug
toxicity in a system that is more similar to humans than the
mouse immune system, but much less bound by ethical
considerations than studies in humans.
More controversial: mix cells from human embryos and mouse
embryos to form a chimeric embryo. Part of the debate on
using human stem cells for research and medical therapy.
Embryonic cells are much less restricted in what cell types
they can develop into than adult cells. How does this creature
develop? Mouse gestation time = 20 days vs. 9 months for
human. Human sperm in a mouse? Etc.
The “geep”, a goat-sheep chimera, was created by mixing
embryonic cells of a goat and a sheep, then implanting the
chimeric embryo into a surrogate mother. The resulting
animals had patches of wool and goat fur, with various other
intermediate structures.
Various other chimeras have been made by similar means:
quail-chicken, for example.
Frankenstein
• A man made from
parts of others, reanimated by an
electric current.
• Why can’t we freely
transplant body parts
from one person to
another?
Tissue Types
• Every cell has molecules on its
surface that do a variety of
jobs: attach to other cells, act
as hormone receptors,
transport materials in and out
of the cell.
• Some of these proteins are
involved in identifying the cell
as a legitimate part of the
body. These identification
proteins are called “tissue type
antigens” or histocompatibility
antigens. They are the main
cause for rejection of
transplants.
Tissue Grafts
• Grafting within a person,
or between genetically
identical twins, is easy: all
cells have the same cell
surface proteins.
• Allografts: between
different people, and
xenografts: across
species lines, don’t
generally work because
the cells have different
surface proteins.
Histocompatibility Genes
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Most of the cell surface proteins that
cause differences between individuals
are made by a set of genes called the
“major histocompatiblity genes”, or
MHC. There are hundreds of variants
to these genes.
Since we each have 2 copies of every
gene, the number of unique
combinations of these genes is very
large, ensuring that most people have
different tissue types.
The person most likely to have the
same tissue type as you is one of your
siblings: a ¼ chance of having the
same MHC genes as you do.
Other genes besides the MHC also
control tissue type, making perfect
matches between people very unlikely.
The Immune Response
• What happens when a tissue transplant occurs?
• The immune system has a group of cells called “killer T cells” that
roam the body looking for foreign cells.
• Each killer T cell has a unique protein on its surface that will react
with one specific matching protein. There are very many different
types of T cell receptors, enough to detect almost any foreign body.
• Once a foreign object is recognized, the killer T cells either swallow
it or bore holes in its membrane to kill it.
• Your own cells don’t get attacked because around the time of birth,
all T cells that recognize anything in the body are killed: this is how
“self” is distinguished from “non-self”
• Autoimmune diseases start when T cells start recognizing some of
your body cells as “non-self”. The T cells then kill your own body
cells.
• Graft vs. host disease: when the T cells in the host’s body recognize
the foreign graft and start to kill it.
Cyclosporin
• The first trick to successful
grafts is to match tissue types
as best as possible. This cuts
down the number of T cell
incompatibilites.
• The drug cyclosporin
suppressed the immune
response, making it possilbe
for many transplants to occur
• The bad side of cyclosporin:
the body has a permanently
weakened immune system.
Abominable Snowman
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Human-like creature covered with fur who lives in
remote parts of the world: the Himalayas in Asia,
the US Pacific Northwest, the Ozark Mountains,
various places in Canada, Iran, Africa, Australia.
“yeti” means “rock-living animal” in Tibetan.
Westerners first spotted the yeti during mountain
climbing expeditions in the 1920’s. The name
“abominable snowman” is also a translation of a
Tibetan term. One man even claimed to have been
nursed back to health by a nine foot tall yeti.
Photographs of 13 to 18 inch long footprints exist.
Sir Edmund Hillary and Tenzing Norgay saw giant
footprints during their ascent of Mt. Everest in 1953.
In 1960, Hillary led a well-equipped, 11 month
expedition to find the yeti. They never saw the
animal, and the 3 skins they collected turned out to
be from other animals. Hillary then decided that the
yeti was mythical.
Bigfoot, or Sasquatch, has bee around since the
late 1800’s. Numerous spottings and footprints, but
no dead ones. Some movies have been made, but
some are known fakes.
More Yeti
Bigfoot Story
• In 1924 a Canadian lumberjack named Albert
Ostman was prospecting near the coast of
British Columbia when he was captured by a
family of Bigfoots. The father and daughter
guarded him while the mother and son prepared
the meals. The family was vegetarian and ate
roots, grass and spruce tips. After about a week
Ostman was able to slip away. He didn't tell his
story to anyone till 1957, fearing people would
think he was insane. -
Neanderthals
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In August 1856 workers in a limestone quarry in the
Neander valley in Germany came across some
bones that were undeniably human, but very odd
looking, especially in the skull. Scientists held two
differing views: they were either the bones of a
modern human distorted by disease (a Cossack
soldier fleeing Napolean’s army was a popular
theory), or they were the bones of an human
ancestor. Darwin’s Origin of Species was published
in 1859, considerably adding to the controversy.
“Neanderthal” means “Neander Valley”. Often
spelled without the h (Neandertal” to match the
German pronunciation.
As time went on, more similar skeletons were found
throughout Europe, and it became clear that the
bones were quite ancient.
In 1864 Irish anatomist WIlliam King decided they
represented a new species, christened “Homo
neanderthalensis”. They were considered to be the
ancestors of modern humans.
Neanderthal bones have been found across Europe
and the Middle East, but not in Africa or eastern
Asia. Neanderthals lived from approximately
200,000 years ago until about 30,000 years ago.
There are no human remains in the Americas older
than about 30,000 years.
What did Neanderthals Look Like?
More Neanderthal Appearance
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Physical description: short, stocky, heavy build, large
head, protruding brow ridges and a large nose. Their
brain was as large or larger than ours. The oldest
known was 40 years old when he died, and nearly all
Neanderthal skeletons show signs of injury: healed
bones.
Were they hairy like apes or smooth-skinned like us?
When fist discovered, Neanderthals were thought to
have been extremely primitive, closer to the apes than
to us. We now know that there were many other
human-like species that came between us and our
common ancestor with the apes. In recent times
Neanderthals have been thought to be very human-like
in appearance and behavior. Certainly living in cold
climates it seems likely that they wore clothing—animal
skins, probably, although no direct evidence for such
clothing exists.
A recent study of human lice bears on this subject.
Head lice live in the hair, and they have been with us
since long before we became human. Body lice, on
the other hand, live in clothing. Body lice are a subspecies of head lice. By examining the DNA of the 2
types, and comparing them to chimpanzee lice, it is
clear that they diverged from each other fairly recently,
about 70,000 years ago. This implies that early
humans and Neanderthals may not have worn clothing.
Neanderthals may have been hairy beasts after all. The
evidence is pretty indirect and does rely on a number
of assumptions.
Alternate Views
Neanderthal Behavior
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Could they talk? It’s a little late for a conversation!
An argument has been made that the structure of the
base of the skull would not have allowed the larynx
(voicebox) to produce the range of sounds that
modern humans have. Another contribution to this
controversy: in one skeleton, the hyoid bone in the
throat (connects the tongue to the lower jaw) has
been found. It is shaped like a modern human hyoid,
and not like the hyoid bone in gorillas and chimps.
Evidence for human-like behavior. Neanderthal
bones are sometimes found in what look like funeral
burials, arranged in a comfortable position. Some
evidence that flowers were used to cover one of
them. This evidence is controversial, however. In
one case, Shanidar (named after the site), the person
had had severe injuries, including destruction of an
eye socket. These wounds were healed, and they
were severe enough so that he wouldn’t have
survived without assistance.
A fragment of a flute has been found from
Neanderthal times (50 000 years ago) It is bone, with
holes spaced in a way that allows several modernstyle notes on it.
They definitely made stone tools and used fire.
What happened to the
Neanderthals?
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About 35,000 years ago, modern humans came into their
territory in western Europe. The modern humans are
sometimes called “Cro-magnon”, based on the first
archeological site they were found at. Although there is no
obvious evidence of conflict, after several thousand years of
co-existence, the Neanderthals apparently died out.
Two competing theories. 1. The Neanderthals were the same
species as modern humans, and the distinctive Neanderthal
type disappeared by interbreeding. This implies that people of
today carry Neanderthal genes. 2. Alternatively, the
Neanderthals may have been an entirely different species,
unable to produce fertile hybrids with modern humans. This
implies that people today carry no Neanderthal genes.
Theories are tied up in a larger context. The older theory ,
called the “Multi-regional hypothesis”, says that all of the
human-like creatures that lived in the past two million years or
more (including Homo erectus, generally considered to be our
ancestral species) are part of the same species, Homo
sapiens, and that they evolved worldwide from the primitive
forms into the forms we see today. The mechanism for the
spread of new genes was a slow process of interbreeding
between neighboring groups. This theory suggests that many
of today’s populations have lived in the same area of the world
for a very long time: the Chinese evolved in China, the
Africans evolved in Africa, etc.
The newer theory, called “Out of Africa” says that there have
been many different species of human-like creatures, with
Neanderthals just one of these species. Modern humans
evolved in Africa about 100,000 years ago, then spread out
from there. All other human species were eliminated.
Evidence
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The main evidence for the multiregional hypothesis comes from fossil bones.
Anthropologists of this school claim to see the same regional differences in ancient
bones as are present among the current inhabitants. Also, some skeletons are
claimed to show intermediate characteristics between modern humans and
Neanderthals. The out of Africa adherents say that bones are subject to
deformation, and that the differences are too subtle to be real. I can’t judge these
arguments.
The multi-regional hypothesis is currently losing ground due to DNA evidence.
The DNA from 3 different Neanderthals has been examined, and the variant forms
there are far outside the range of modern human DNA—at least twice as far from
any modern human type as any two modern types are from each other. This
implies that Neanderthals and modern humans last had a common ancestor
450,000 years ago, long before the encounters in western Europe.
Another aspect of DNA evidence is that modern human DNA is not very variable:
there is more genetic variation among the chimpanzees in the Gombe Stream
Reserve in Tanzania than there is among all human populations. This implies that
somewhere around 100,000 years ago the human population went through a
bottleneck—it was reduced to a very small number, from whom we are all
descended. Most of the human DNA variation is found in Africa, and modern
human remains have been found there of an appropriate age.
The DNA evidence mostly comes form the mitochondrial DNA, a small circle of
DNA found outside the nucleus, in the mitochondria, the organelle that provides
most of the energy to run the cell. This DNA is found in large amounts than
nuclear DNA, and it is tougher—as a circle it has no free ends to attack.
Mitochondrial DNA is inherited strictly through the mother, so it doesn’t give
complete information about inheritence patterns in the species. For instance, if
Neanderthal-human hybrids were only fertile with a modern mother and a
Neanderthal father, we could have Neanderthal genes in us now, but not
Neanderthal mitochondrial DNA. This type of situation; fertility in one direction but
not the other—is very common in crosses between closely related species.
Human Evolution
Human Evolution
• At some point our lineage
split with that of the Great
Apes (gorilla,
chimpanzee, bonobo,
orangutuan). All
creatures on the lineage
after this spilt are called
“hominids”. This split is
thought to have occurred
about 5.5 million years
ago. After that time there
have been a number of
species of hominid,
mostly living in Africa.
Hominid Evolution
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The largest group of pre-human species was
Australopithecus. Shortly after the
ape/homnid split the species Autralopithecus
afarensis lived. The best known example is
the skeleton “Lucy”, which is almost
complete. These creatures were 4 feet tall or
less, but fully bipedal (walked on 2 legs all
the time, unlike chimps and gorillas). They
had large jaws and fairly small brains.
The hominid line split into 2 main branches
after this time. One branch led to the
modern humans, and the species on this
line are in the genus Homo: Homo habilis,
Homo erectus, Homo sapiens.
The other branch contains several species
that are called Paranthropus or continue to
be called Australopithecus, or the “robust”
Australopithicines. This branch developed
very large jaws along with the sagital crest
(on top of the skull) to support the jaw
muscles. Big jaws, small brains—they seem
to have been vegetarians. All species on
this line died out more than 1 million years
ago.
Our direct ancestral species was Homo
erectus.
Homo erectus
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learned to create stone tools as long as
2 million years ago. Use of fire is more
controversial. Some think fire use (if not
the ability to make fire) came quite early,
and that the gradual decrease in jaw
size is a response to the use of fire to
cook food. Others hold that fire use is a
very late development, Homo sapiens
only.
H. erectus did one other interesting
thing: walked out of Africa and populated
most of the Old World. This happened
perhaps 1.8 million years ago. The “Out
of Africa” theory really means Out of
Africa Twice: once by Homo erectus,
and them again by modern humans. The
multiregionalists also believe that Homo
erectus migrated out of Africa to the rest
of the world (although they consider H.
erectus to be primitive Homo sapiens
and not a separate species).
Could Homo erectus talk? The only real
evidence against it is that the spinal
column in the thorax in the best
preserved skeleton is quite narrow. It
has been argued that this implies an
inability to control breathing well enough
for speech.
Loch Ness Monster
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Many large lakes seem to have resident sea
monsters, and certainly the ocean is full of them.
Lake Champlain in New York has “Champ”, and
lakes Okanagan and Manitoba in Canada have
Ogopogo and Manipogo.
The oldest story about he Loch Ness monster
comes from 556 A.D., when St. Columba saved a
swimmer from the monster by shouting at it.
Since roads first reached Loch Ness in 1937,
Nessie has been spotted many times, and several
pictures have been taken. The best picture has
withstood a considerable amount of scientific
analysis.
Unfortunately, this picture has been revealed to be a
hoax, made of some plastic and a toy submarine.
This hoax was created in response to yet another
hoax. In 1939 the Daily Mail hired George
Wetherall, a big game hunter, to find Nessie. He
found some tracks and made plaster casts. When
examined by a museum, the tracks proved to be
those of a baby hippo, probably from someone’s
umbrella stand. The Daily Mail was mad at
Wetherall for having been hoaxed, and in revenge
Wetherall came up with the plastic-enhanced toy
submarine picture.
Loch Ness is large,deep, and full of peat—very hard
to see into. Several expeditions have looked, but
ambiguous photos have been the only results.
Realize that just 1 monster isn’t enough—you need
a breeding population of them. No remains have
ever been found.
Pleiosaurs
• The most popular candidate for
Nessie and the other lake
monsters is a dinosaur, the
pleiosaur. Like all dinosaurs,
pleiosaurs were reptiles,
although the current belief is
that they were warm blooded,
like birds.
• Pleiosaurs had long legs, fat
bodies, and flippers. They
were carnivores. Like seals
and whales, they evolved on
the land, then took to the water
later and had their limbs
modified to flippers.
Extinction of the Dinosaurs
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All dinosaurs are thought to have become extinct 65 million
years ago, when a large object collided with the Earth. It left a
crater in the Yucatan peninsula in Mexico, with an iridium-rich
layer of ash and clay deposited over the entire world. The
collision threw enough dust into the atmosphere to block
sunlight for several years, leading to the collapse of food
chains and the deaths of most large animals. Apparently no
animal lager than about 50 pounds survived.
This theory was proposed by Berkeley physicist Luis Alvarez
and his son Walter, in 1980, and it was once very
controversial. Older theories had the dinosaurs dying of
“genetic exhaustion” or climatic shift, or predation by
mammals. The older theories were not very satisfying—lots of
hand waving and no very clear explanation for the sudden
disappearance.
The meteor theory has gained a lot by finding the iridium-rich
clay layer everywhere on Earth that rocks of the proper age
are exposed. Also, the Chixulub crater in Mexico is 100 miles
in diameter and of the proper age.
The idea that dust blocks photosynthesis comes from volcanic
eruptions, such as Krakatoa in 1883 and Tambora in 1815.
The latter caused “the year without a summer”, 1816, in New
England—frosts as late as July, and the growing season cut in
half. The global average temperature dropped by about 5
degrees Fahrenheit.
More on the Extinction
More!