672 lines
34 KiB
Plaintext
672 lines
34 KiB
Plaintext
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THE MAKING OF THE CAT
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R. Roger Breton
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Nancy J Creek
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------------------------------
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Soup or Sandwich
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IN THE VERY BEGINNING, about 4.6 billion years ago (give or take a few
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years), a small ball of rock, water and gas had come to be and immedi-
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ately set about the process of combining its atoms into more and more
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complex arrangements. Thus began that most wondrous story, the evolu-
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tion of life on Earth.
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For the first 2.1 billion years of the Earth's existence, the Archeo-
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zoic Era, life very slowly evolved. The Earth's crust was still in
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flux and covered for the most part by shallow seas. The atmosphere
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was composed primarily of methane, ammonia, carbon dioxide and water
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vapor. From these primitive chemicals life evolved. There are two
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primary schools of thought on the processes involved: the "soup"
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theory and the "sandwich" theory.
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According to the more-popular soup theory, chemical evolution first
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took place in the upper atmosphere, where ultraviolet radiation from
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the sun could generate an assortment of simple and complex organic
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(carbon-based) molecules out of the basic components of the atmos-
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phere. As these molecules slowly rained into the early oceans, a kind
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of primordial soup was created. Via the ultraviolet radiation, light-
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ning, volcanic action, and other forms of heat and energy, this soup
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was able to slowly combine the organic molecules into ever more com-
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plex forms: first simple amino acids, then organic macromolecules,
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then single-strand RNA molecules, and finally simple viruses.
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The only trouble with the soup theory is that is almost definitely
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wrong! The time required for it to work is statistically greater than
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the lifetime of the Earth. The time is only statistically greater,
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however, and anything is possible...
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Various explanations have been put forth to account for this time
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discrepancy. The most popular of these is the seeding of the early
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seas by organic molecules from space. This seeding could have been
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either through organic molecules present in the original formation of
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the Earth, or from later bombardment by meteors or more likely comets
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containing the organic compounds (a cosmic soup mix). None of the
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compensatory theories put forth are very likely, however.
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This brings us to the sandwich theory. The sandwich theory states
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that complex organic molecules formed on the surface of undersea
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crystalline rocks, such as those surrounding volcanic vents. The name
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"sandwich theory" comes about because the active area is sandwiched
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between the sea and the rock. Besides, what scientist could resist
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the "soup and sandwich" pun!
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The Making of the Cat Page 1
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Free-floating molecules in the water tend to cling to smooth surfaces.
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This surface effect allows various molecules to gather in one place.
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Ultraviolet energy from the sun or, more likely, heat from volcanic
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vents, would allow this gathering of simple molecules to combine into
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more complex organic molecules rather easily. Some of the simplest
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organic molecules are scums, easily formed on flat surfaces, which
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themselves are sticky and gather more simple molecules.
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Within these scums, ever more complex molecules are easily formed.
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These more complex molecules tend to be three-dimensional, and bulge
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outward from the rock surfaces. This allows them to be easily washed
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away by the sea, forming a primordial soup not of basic simple mole-
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cules, but of the far more complex and already evolved RNA macromole-
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cules and possibly even viruses.
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Viruses are fundamentally RNA and amino-acid conglomerates with many
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life-like properties. Although it is open to debate as to whether or
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not they are themselves alive, viruses are definitely right on the
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edge: simpler things are clearly not alive, while more complex things
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clearly are.
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One aspect of the sandwich theory is that at undersea volcanic vents
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today life may still be evolving from basic components! This exciting
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possibility is being carefully investigated and holds great promise
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for the future.
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The Great Pollution
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After the virus, life was off and running. During the next 500 mil-
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lion or so years, viruses evolved into simple prokaryotes, single-
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celled living beings without a cellular nucleus. In this case, blue-
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green algae, the first plants. This marked the beginning of the
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Proterozoic Era, about 2.5 billion years ago. Blue-green algae
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are blue-green because they possess that truly wondrous molecule,
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chlorophyll. It is chlorophyll which makes possible the production of
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food directly from sunlight and the carbon dioxide in the atmosphere.
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This is the process of photosynthesis.
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A side-effect of photosynthesis is the generation of free oxygen as a
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waste product. Free oxygen combined with itself and the methane and
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ammonia in the atmosphere to form ozone, water, free nitrogen, and
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more carbon dioxide. Over the next billion years, blue-green algae
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polluted the Earth with enough free oxygen to completely change the
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entire chemistry of the world. Gone was the pristine methane, ammo-
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nia, and carbon-dioxide early atmosphere, to be replaced by a corro-
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sive mixture of free nitrogen and free oxygen, surrounded by a thin
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layer of ozone.
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It is this corrosive nitrogen/oxygen atmosphere that allowed the
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evolution, about 1.5 billion years ago, of chlorophyll-less creatures
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such as bacteria and protozoans. These creatures were active, like
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the oxygen they consumed. They preyed on the algae (and each other)
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for food, and were the first animals: very early proto-cats.
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The Making of the Cat Page 2
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The production of free oxygen also altered the structure of the very
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rocks themselves, causing a slow but radical geologic change.
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Blueprints
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Protozoans are eukaryotes (cells with a central nucleus). The secret
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of all but the simplest lifeforms is locked in that nucleus: the
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chromosome.
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Virtually all living things have several different chromosomes in each
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cell. These chromosomes comprise a set, which is itself a blueprint.
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In a multi-celled creature, each cell contains an identical set of
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chromosomes. A cat, for example, has 38 chromosomes per set, with an
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identical set in each and every cell, except sex cells. Each cell of
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a cat contains within itself the code for the complete cat.
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A chromosome is itself composed primarily of a thin protein membrane
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enclosing a bit of water and a single molecule of DNA (deoxyribonu-
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cleic acid). The DNA molecule is composed of two long strands wound
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around each other in a double helix (like two intertwined springs),
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with each component of a strand connected to the opposite strand by a
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crossbar or rung. If the double helix were laid flat, DNA would be
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ladder-like in appearance.
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The evolution and concept of DNA is awesome in its potential, and awe-
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inspiring in its simplicity and beauty. There are only six simple
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compounds that go together to make up DNA, phosphate and deoxyribose
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alternate to form the helixes while four amino acids make up the
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rungs.
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It is not the number of differing compounds that provide the secret of
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DNA's success, but rather the number of rungs in the ladder (uncounted
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millions) and the order of the amino acids that make up the rungs.
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The four different amino acids are arranged in groups of three, form-
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ing a 64-letter alphabet. This alphabet is used to compose words of
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varying length, each of which is a gene (one particular letter is
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always used to indicate the start of a gene). Each gene controls the
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development of a specific characteristic of the lifeform. There is an
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all-but-infinite number of possible genes. As a result, the DNA of a
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lifeform contains its blueprint, no two alike, and the variety and
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numbers of possible lifeforms has even today barely begun.
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Sex
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There was a small problem with evolution up to this time: it was
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asexual. A cell multiplies by dividing! That is, once it has accumu-
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lated enough material to make another cell, it does--by dividing in
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half. This process is called mitosis.
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In highly simplified form, when a cell undergoes mitosis, its chromo-
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somes duplicate, move to opposite sides, and the cell divides in two.
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Each daughter cell is an exact copy of the parent cell, barring muta-
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tions.
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The Making of the Cat Page 3
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Since evolution depends upon change, asexual evolution is wholly
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dependent upon random mutation, and thus very slow. It took almost 4
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billion years, about 85% of the Earth's existence so far, to evolve up
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to the complexity of protozoans. What was needed was a means of
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speeding up the process. What was needed was sex!
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At first, sex had nothing to do with reproduction, not directly,
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anyway. The protozoans would get together, merge, swap a few genes,
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the separate and go their ways. This chromosome-swapping allowed them
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to pass around and share an advantageous characteristic.
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In order for the sexual merge to occur efficiently, the concept of a
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double chromosome evolved. In this form, chromosomes are doubled and
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paired. This gives each lifeform two of each chromosome (so far), and
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hence two of each gene. Thus, after a sexual encounter, a protozoan
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had two of any given gene. They may both be the genes it originally
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possessed, both be the genes the other protozoan possessed, or one of
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each. If, due to a mutation somewhere along the line, one of a pair
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of genes had a slightly different code than the other, the protozoan
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would assume the characteristics of the dominant gene (unless they are
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identical, one gene is always dominant over the other). It would,
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however, keep the recessive gene, and may pass it on (or not) at its
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next encounter. The tendency is then for dominant genes to quickly
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spread through a community.
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This effect was clearly demonstrated in a recent experiment wherein a
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small group of a penicillin-resistant strain of the bacterium gonococ-
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cus was merged with a much larger group of normal gonococci. After a
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short while, all bacteria in the test were penicillin-resistant. The
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bacteria had sexually interfaced and shared the genes that contributed
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to penicillin resistance.
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After the discovery of sex, the protozoans would occasionally merge
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and share protoplasm. They would then separate and go their individu-
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al ways, reproducing asexually.
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At some point in time, a mutation occurred in which a cell would
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divide not into two daughter cells, but into four half-cells, or
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gametes. Each of these gametes contained half of each pair of chromo-
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somes, comprising a half-set. The urge to merge was all powerful, and
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quickly carried out. The mutation, however, was dominant. As a
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result, so a whole colony of protozoans was dividing into gametes, a
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process call meiosis, and quickly merging in a mix and match fashion.
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Sexes
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Over the next 200 million years, the protozoans evolved into cellular
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colonies, the porifera. Porifera, such as today's sponges, are truly
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colonies, with each cell essentially the same as every other. No
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cellular specialization took place.
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Eventually, some cells started specializing in locomotion while others
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specialized in food gathering, and so forth. This lead to the evolu-
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tion of the coelenterates, with different cells performing different
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The Making of the Cat Page 4
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tasks. Today's jellyfish are coelenterates.
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With this complexity, there could no longer be a simple random merg-
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ing. All this specialization required that some cells spend their
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time reproducing not themselves, but the creature as a whole. These
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cells must, then, carry the genetic code for the entire creature.
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Since the new creature produced by a division and merging would start
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as the merger of two gametes, hence a single cell, it follows then
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that all cells in a creature must contain the entire genetic code for
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the creature. This is indeed the case.
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Those cells that specialized in reproduction must produce gametes that
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attract each other. If all were identical, there would be minimal
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attraction, so the concept of opposites arose. The gametes became
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divided into two groups: sperm (male), and eggs (female).
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If there are opposite gametes, there are opposite reproductive organs
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to produce them. Voila, male and female creatures. This proved
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to be so efficient at mixing the gene pool that it became a survival
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characteristic. Those species had the greatest urge to merge sur-
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vived, and elaborate and downright peculiar means have evolved to
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ensure the urge to merge. Sexual reproduction has been the norm for
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virtually all species more sophisticated than a bacterium ever since.
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In the Sea
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Since the great pollution, everything ate everything. Except the
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algae, who were (and still are) the bottom of the food chain: every-
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thing ate algae, directly or indirectly.
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About 570 million years ago, some critters became tired of being
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eaten, and decided (so to speak) to do something about it. Hard parts
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evolved, most noticeably shells, and the Paleozoic era began.
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The first things to evolve shells were, not surprisingly, mollusks.
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They shared the oceans of their day with a grand assortment of cepha-
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lopods (head-footed creatures, such as squid and octopi), arthropods
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(jointed-footed creatures, such as lobsters), annelids (worms), and
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echinoderms (spiny-skinned creatures, such as starfish). All of these
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forms survive today, though specific creatures don't.
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The evolution of the annelids and echinoderms was soon followed by the
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first primitive chordates (creatures with a central nervous system).
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The central nervous system allowed co-ordination between the various
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parts of the body by channeling their neurological signals through a
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central organ, the brain.
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By 500 million years ago, the early chordates had become vertebrates
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(creatures with skeletons, although of cartilage and not bone) had
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evolved. Primitive jawless fish swam the seas. Current examples of
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jawless fish include the lamprey.
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Cartilage evolved into bone, and led to the evolution of osteichthyes,
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the first bony fish. Most of today's fish are bony, though there are
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The Making of the Cat Page 5
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still some cartilaginous fish around, such as sharks.
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Some 405 million years ago, two significant events occurred. The
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obvious event was a sudden proliferation in the number of fish--fish
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became the dominant lifeform in the sea. A more significant but
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quieter revolution was also taking place: the plants were invading
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land, rapidly changing rock and sand into topsoil, and laying the
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paths the animals would later follow.
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Ferns evolved shortly thereafter, and were present to greet the ani-
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mals as they left the sea. These animals were arthropods: scorpions,
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spiders, and bugs. Arthropods still outnumber all other species of
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land animal life except the microscopic.
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Of concern to us at this time is the evolution 370 million years ago
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of rhipidistan, the first lungfish, which were the direct ancestors of
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all higher forms of life: amphibians, reptiles, birds, and mammals.
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These early lungfish lived in the coastal bogs and estuaries, occa-
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sionally venturing onto land for brief periods.
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On the Land
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By 345 million years ago, rhipidistan had evolved into eogyrinus, the
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first amphibian and a true land animal. The vertebrates had invaded
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the land. Amphibians were still tied to the water, however. Their
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eggs had no shells, and had to be laid underwater. The young were
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(and still are) born with gills, which they lost as they reached
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adulthood.
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About 290 million years ago, a creature called eosuchian learned the
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trick of enclosing its eggs in a calcium shell: the first reptile had
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evolved. Unlike amphibians, young reptiles did not have gills and did
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not require standing water. They soon developed scales to preserve
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body moisture as well.
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The Paleozoic era came to an abrupt end some 230 million years ago.
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Most of the marine invertebrates, fish, amphibians, early reptiles,
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and everything else vanished. The first Great Dying had occurred.
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Great Dyings
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The history of the Earth is punctuated with many Dyings and two (maybe
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three) Great Dyings. In a Dying, vast numbers of species vanish
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suddenly (geologically speaking) over a wide area. In a Great Dying,
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this area is world wide. Such an occurrence leaves uncounted ecologi-
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cal niches empty: those species that do survive the Dying are then
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presented with an opportunity to undergo rapid radial evolution, a
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phenomenon wherein each surviving species quickly evolves to fill as
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many ecological niches as possible.
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The reasons behind the Dyings are not clearly understood. Possibili-
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ties include asteroid impact, climatological change, volcanic activi-
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ty, and disease. Whatever the causes, their occurrence is clearly
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established.
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The Making of the Cat Page 6
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Two (three) Great Dyings occurred in Earth's history. The Permian
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Great Dying, 230 million years ago, terminated the Permian period and
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the Paleozoic era. The Cretacious Great Dying, 65 million years ago,
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terminated the Cretacious period and the Mesozoic era, and brought
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about the demise of the dinosaurs. Both these Great Dyings are gener-
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ally believed to be the result of asteroid impact, though other expla-
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nations are possible. The argumentative Quaternary Great Dying is
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currently underway, and promises to destroy the greatest number of
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species of any Great Dying. Its cause is man.
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Reptiles
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The Mesozoic era had begun. The surviving eosucians evolved into the
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anapsids.
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The early anapsids had an interesting problem to face: body heat.
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Coincident with the Permian Great Dying (possibly caused by the same
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event) the climate became cooler. Being cold blooded, the anapsids
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would assume a body temperature about the same as that of the sur-
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rounding air. This meant that they simply couldn't get their motors
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turning over on a cold morning. They solved this problem through
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solar power.
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By evolving huge fins on their backs, they could position themselves
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broadside to the sun on a cold day and absorb large quantities of
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solar energy. Once they were warm enough, they could then face to-
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wards or away from the sun. One can see several drawbacks to this
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scheme: cloudy days, strong winds, etc. These sail-backed reptiles
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are often depicted in grade-B monster movies by gluing a fan to the
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back of an iguana.
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As a dominant group, the anapsids were short-lived, surviving today
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only as the turtles and tortoises. They evolved into four other
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reptile groups: the diapsids, which became the dinosaurs, pterosaurs,
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lizards, snakes, tuatara, crocodiles, /alligators, and birds; the
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euryapsids, which became the plesiosaurs; the parapsids, which became
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the ichthyosaurs; and the synapsids. The dinosaurs, pterosaurs,
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plesiosaurs, and ichthyosaurs are all extinct (except for Nessie, the
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Loch-Ness Monster, a lone surviving plesiosaur [if you are a believer,
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that is]). The lizards, snakes, tuatara, crocodiles, alligators, and
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birds are still with us.
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Mammals
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The final group of Mesozoic reptiles, the synapsids, would not normal-
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ly have attracted attention. They were small inconspicuous quadrupeds
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with only one claim to fame: they developed mammalian characteris-
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tics. One group, the theriodonts, became the ancestor of all mammals.
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As reptiles, the synapsids became extinct 170 million years ago.
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About 225 million years ago, the theriodonts evolved into the panto-
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theres, the first monotremes. The first monotremes were small, insec-
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tivorous, shrew-like creatures about 6 inches long.
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The Making of the Cat Page 7
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Monotremes are mammals, but barely so, and survive today only as the
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platypus and the echidna found in Australia and New Guinea. They have
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very poor internal temperature control, being only somewhat warmblood-
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ed, are the only mammals to produce venom, are the only mammals to lay
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eggs, and, though milk-producing, are the only mammals without teats
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the milk is secreted directly though the skin and lapped by the
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young).
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About 200 million years ago, the pantotheres evolved into metatheres,
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the first marsupials. Unlike a monotreme, which lays eggs, a marsupi-
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al gives birth to live young. These young are very premature, and
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must crawl into a marsupium (pouch) where they attach themselves to
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teats and receive nourishment while they continue to develop towards
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self-sufficiency. The kangaroo and opossum, among others, are today's
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surviving marsupials. The first marsupials were not much different in
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appearance from their monotreme forebears, being shrew-like in appear-
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ance and about 6-8 inches long.
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With marsupialism, a mother no longer had to provide all the early
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nourishment for her young in the yolk of an egg, but could nourish her
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young as she herself was nourished--sort of child-bearing on time
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payments. The young also had the advantage of being able to flee
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danger, via mom's legs, whereas an egg is easy prey.
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Good as marsupialism is, it still exposes the young to the world when
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they are most vulnerable: a new-born marsupial is little more than an
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embryo, (a newborn opossum is about the size of a bee, a kangaroo a
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little over an inch long). This problem was corrected by the evolu-
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tion of the metatheres into eutheres, the placentals, about 100-80
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million years ago, in the northern hemisphere.
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|
||
The placenta is a complex organ allowing nutrients in the mother's
|
||
bloodstream to be passed to the fetus' bloodstream, with waste
|
||
products passed in the reverse direction, while not allowing a direct
|
||
connection between the bloodstreams. The placenta of a marsupial is
|
||
very primitive and inefficient, hence the premature birth, whereas
|
||
that of the placentals is a truly wondrous organ. The young could now
|
||
remain within the mother's womb, receiving nourishment directly from
|
||
her, until relatively well developed and more ready to face life.
|
||
|
||
The marsupials and placentals were both drastic improvements over the
|
||
monotremes, and seemed to have divided the planet between them: for a
|
||
while marsupials dominated the southern hemisphere while placentals
|
||
dominated the northern. As the placentals grew more numerous they
|
||
gradually forced out the less-efficient marsupials: Today, the only
|
||
significant marsupials left worldwide are the opossums, which survive
|
||
because they are so fecund.
|
||
|
||
The dominance of placentals is firmly established except in Australia
|
||
and a few surrounding islands, which had broken from the Asian conti-
|
||
nent after the marsupials had dominated the south but before the
|
||
placentals had spread down from the north. In pre-colonial Australia
|
||
marsupials were to be found in all the mammalian ecological niches
|
||
|
||
|
||
----------------------------------------------------------------------
|
||
The Making of the Cat Page 8
|
||
|
||
|
||
|
||
|
||
(there is even a marsupial "cat") except for the aborigines (who
|
||
arrived by boat), the dingos (wild dogs, which arrived with the abo-
|
||
rigines), the bats (which flew in), and the surviving monotremes
|
||
(which defy logic all around). Modern man has introduced many other
|
||
species of placental, most notably the rabbit and the mongoose, and
|
||
the long-delayed marsupial/placental struggle is now taking place in
|
||
Australia, with the marsupials losing.
|
||
|
||
Near Cats
|
||
|
||
The Cretaceous Period and the Mesozoic era came to an abrupt halt with
|
||
the Cretaceous Great Dying, 65 million years ago. Suddenly, the Earth
|
||
finds itself with virtually all of its dominant species wiped out: no
|
||
more dinosaurs, pterosaurs, or plesiosaurs [Nessie?], and very little
|
||
of anything else. The Cenozoic era had arrived.
|
||
|
||
Of those few creatures which survived the Cretaceous Great Dying, one
|
||
was a small, active, adaptable, shrew-like euthere, about 7-8 inches
|
||
long, who then experienced rapid radial evolution. By 60 million
|
||
years ago one of its many newly-evolved descendants was miacis, who
|
||
ate flesh and was among the first truly carnivorous mammals.
|
||
|
||
Miacis was somewhat martin-like in appearance. His distinguishing
|
||
characteristic was his teeth, which set the basis for all modern
|
||
carnivores. He had a dental plan with incisors, canines, premolars,
|
||
carnassials, and molars in each jaw. The carnassials were a new
|
||
invention, being designed specifically for the cutting of flesh in a
|
||
scissor-like action. Modern cats and dogs have carnassials, humans do
|
||
not. These advanced teeth were fundamental in the demise of other
|
||
predators, allowing him to make more kills and to better digest his
|
||
prey, both of which meant more and larger miacids and fewer others.
|
||
|
||
Miacis was a short-term creature, quickly evolving under the pressure
|
||
of competition into several different miacids, each of which went on
|
||
to become a differing type of carnivore. By 45 million years ago, one
|
||
of these differing creatures was profelis, the forerunner of all cats.
|
||
|
||
By 40 million years ago profelis had evolved into hoplophoneus and
|
||
dinictis. The primary differences between hoplophoneus and dinictis
|
||
were in jaw structure. In hoplophoneus the upper canines increased
|
||
drastically in length to become stabbing weapons, with corresponding
|
||
changes in the jaw hinge to allow the mouth to open extra widely. In
|
||
dinictis the upper and lower canines became more balanced and the jaw
|
||
hinge developed more muscle. Both were halfway between a cat and a
|
||
civit in appearance, long in the body and tail, short in the legs;
|
||
both had definitely cat-like heads; and both were plantigrade: modern
|
||
cats are digitigrade and walk on their toes, good for running, while
|
||
people are plantigrade and walk upon their whole foot, good for stand-
|
||
ing.
|
||
|
||
About 25 million years ago, hoplophoneus had evolved into smilodon,
|
||
the famous saber-toothed tiger. Smilodon was definitely a cat in
|
||
appearance, walking upon his toes and all, but had a somewhat flat-
|
||
tened head with a small brain pan (he wasn't very bright). Smilodon
|
||
|
||
|
||
----------------------------------------------------------------------
|
||
The Making of the Cat Page 9
|
||
|
||
|
||
|
||
|
||
was the end of his line, and vanished some 12,000 years ago.
|
||
The exaggerated tooth structure of the hoplophoneans and especially
|
||
smilodon was a response to the evolution of the titanotheres, the
|
||
giant mammals of the early Cenozoic. These animals were huge, with
|
||
correspondingly thick and/or shaggy coats, which the dagger-like
|
||
canines of the saber-toothed tiger could pierce to deliver a killing
|
||
blow. The largest of the titanotheres, and the largest land mammal
|
||
ever, was the ground sloth baluchitherium, which stood 18 feet at the
|
||
shoulder (the height of a tall giraffe), and whose head reached 26
|
||
feet off the ground.
|
||
|
||
Real Cats
|
||
|
||
While hoplophoneus was evolving into smilodon, dinictis was also
|
||
evolving. Dinictis itself had one seemingly trivial, but really very
|
||
fundamental characteristic: it had three eyelids. Modern cats, and
|
||
many related species, have three eyelids, the third being the haw, or
|
||
nictitating membrane.
|
||
|
||
Dinictis evolved into pseudailurus, which was definitely a cat in
|
||
appearance, not too different from some of the more extreme species of
|
||
modern cats. Its teeth were identical in structure to those of the
|
||
modern cat and it was digitigrade, walking on its toes (though not
|
||
quite as well as the modern cat), but it still had a small brain pan.
|
||
|
||
Some 18 million years ago, the oldest of the modern genera of cats
|
||
evolved from pseudailurus: acinonyx. The modern cheetah is the only
|
||
species of acinonyx surviving today and is actually little changed
|
||
from its early ancestors. Some 12 million years ago, pseudailurus
|
||
had evolved into felis, the modern lesser cats. Two of the first
|
||
modern cats to appear were felis lunensis, Martelli's cat, and felis
|
||
manul, Pallas' cat. These cats had larger brains, surprisingly human-
|
||
like in structure, and were in all ways true modern cats. Martelli's
|
||
Cat has become extinct, but Pallas' Cat is still very much with us,
|
||
the oldest living species of genus felis.
|
||
|
||
By 3 million years ago, the last of the modern genera of cats evolved,
|
||
panthera, the greater or roaring cats, to which the tigers, lions,
|
||
leopards and their kin belong.
|
||
|
||
Somewhere between the First and Second Ice Ages, 900,000 to 600,000
|
||
years ago, a very special cat, felis sylvestris, made its appearance,
|
||
and is still with us as the European Wildcat. During the Second Ice
|
||
Age, the glaciers moved down from the north, driving him southward.
|
||
At the same time, the Mediterranean and Black Seas were greatly re-
|
||
duced in size, providing many land bridges to the south into Africa
|
||
and to the east around the foot of the Urals into Asia, allowing him
|
||
to extend his domain into those regions.
|
||
|
||
As the ice receded the seas rose and the climates changed, the immi-
|
||
grant species became isolated from each other by water, deserts, and
|
||
mountains. Over time, those species of wildcat isolated in Africa
|
||
became the Sand Cat, the African Wildcat, the Forest Cat, and the
|
||
Black-Footed Cat, while the Asian version became the Chinese Desert
|
||
|
||
|
||
----------------------------------------------------------------------
|
||
The Making of the Cat Page 10
|
||
|
||
|
||
|
||
|
||
Cat. There were, of course, several other subspecies that, for one
|
||
reason or another, didn't survive the changing landscape and climate.
|
||
|
||
One of felis sylvestris' many offshoots was felis lybica, the African
|
||
Wildcat. He is still with us, but, more importantly, he is the imme-
|
||
diate and primary ancestor of all domestic cats.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
----------------------------------------------------------------------
|
||
The Making of the Cat Page 11
|
||
|
||
|
||
|