Some Notes on Evolution
Posted: Sat Jul 27, 2019 2:47 pm
[People who attack evolution generally have no knowledge of it and seem embarrassingly unaware of how little they know. Dunning-Kruger, I suppose. They think evolution is just a mish-mash of half-baked ideas when actually we know quite a lot about how life evolves. So I just put this short bit into a Q and A format that discusses various aspects at work in evolution confirmed by experimentation. It's a bit harder to refute when you understand a bit more of how it actually works. Maybe I'll add more later. You can add stuff too in any format you want. I choose Q and A because its easier to read and comprehend. This serves as a kind of reference pool for knowledge of evolution.]
Q: When did the first plants form?
A: The first plant formed approximately 1.6 billion years ago. All terrestrial plants formed from a single cell consisting of a microscopic alga that had absorbed a cyanobacteria. Whether this was an attempt by the alga to eat the cyanobacteria is not known but it ended up being a symbiotic relationship. The alga carries the cyanobacteria around and so the cyanobacteria manufactures food via photosynthesis and provides that food to the host. The host provides protection to cyanobacteria. One other agency is required to pull this off and that is a group of cells that transport that food from the cyanobacteria to the alga host and these cells are actually related to chlamydia—the STD—and were actually similar to the bacteria that causes Legionnaire’s Disease. The genes of these cells are required to take food from the cyanobacteria and transmit it to the alga host. But we know other bacteria also participated in a trial-and-error basis and this enabled this tripartite organelle to harden up.
The alga involved was a type of freshwater blue-green algae, a very ancient form of algae called a glaucophyte. These glaucophytes called Cyanophora paradoxa are considered living fossils and we have studied the genome of about 70 million base pairs. All modern plants share the same exact genes required to allow the cyanobacteria to merge with the alga host. This means it happened only once a very, very long time ago and it was so successful that all plants today from tiny grasses to daffodils to dandelions to ferns to wheat to corn to apple trees to mighty oaks to huge redwoods are all the genetic descendants of this single green cell, this microscopic organelle that formed 1.6 billion years ago.
Q: How did these green cells, as you call them, become plants?
A: Hard to say for certain. We only know that they did. They banded together maybe to catch more sunlight for photosynthesis. Genesis gets it right that sea animals preceded land animals but, of course, says God made each separately on different days but we can clearly see that terrestrial animals evolved from marine animals that eventually left the water over the course of hundreds of millions of years. The oldest living creatures of all are bacteria called prokaryotes which are cells without nuclei and they came into existence perhaps as long ago as four billion years—maybe a half-million years after the earth formed which is astonishing to think about. Then cells with nuclei or what we call eukaryotes evolved from prokaryotes as long ago as 2.5 billion years. The earliest multicellular creatures were wormlike but we know nothing else about them. We call them metazoans. We don’t have any fossils of them but we have fossils of their burrows which are wormlike.
The earliest true animal we know of was either the sponge or some kind of animal similar to a comb jellyfish. Sponges came into existence about 650 million years ago but there is now good evidence that this comb jellyfish-type creature is actually significantly older and yet had a rudimentary nervous system. There are no fossils of it so we cannot put a date on how old it would be but well over 650 million years old.
Q: How do they know this?
A: We have new technologies that can handle the processing of huge amounts of genetic data and analyze where splits in earth’s life family tree occurred and the answer repeatedly came out that the comb jellyfish split off on its own evolutionary path well before the emergence of the sponge. No matter how much data they added and how much they refined it to get the most accurate picture, it always comes out with the comb jellyfish splitting off on its own evolutionary path before the sponge did. How long before the sponge, we don’t know without having fossils to analyze and we have none. Strangely, this mysterious creature is more advanced than the sponge which does not have tissues and a nervous system but that’s what the evidence shows. Animals and plants though have the same root method of originating which is endosymbiosis when one life form swallows another but instead of digesting it, incorporates it whole and the two bodies live symbiotically. The first plants and the first animals formed this way. So there is safety in numbers not only because the sheer numbers can overcome adversaries but because greater numbers introduces diversity and variation that synergetically form lifeforms of greater strength or resourcefulness or adaptability.
Q: We are all really jellyfish at our deepest core?
A: It would seem so. As strange as it is. While they have a basic nervous system and tissue, which other early animals as sponges lack. Their mouth is also their anus. That’s true of only some humans. They have a top and bottom but no front or back, no left or right. So they lack polarization. No head or brain. But somewhere deep down inside us, there they are.
Q: How does polarization work?
A: At the end of limb buds of embryos are these little patches of tissue called ZPA or Zone of Polarizing Activity. The ZPA gives us mirror image hands and feet. The ZPA causes the pinky to form on one side of the hand and the thumb to form on the other and to do it in mirror image in regards to the left and right hand. And this happens with fish, frogs, lizards, birds, bats, whales, dogs, lemurs, tigers and wombats. Any limbed animal. All of them have ZPA. How does the ZPA do this? It exudes a set of genes called “sonic hedgehog” that, when activated by retinoic acid, makes a pinky grow on one side of the hand first and, moving across the hand, a thumb on the other side as well as the fingers in between. It grows the pinky or digit 5 first and then works across the hand to the thumb and creates mirror image hands and feet with respect to left and right. If you have a ZPA on both sides of the limb bud, it will sprout digit 5 first and then work across the hand where the two hands meet in the middle. The effect would be a two mirror-image hands sprouting from one wrist.
Q: Any experiments to prove that?
A: Yes. We also have rare but sufficient examples of people born with two ZPAs on the limb bud who developed two joined mirror-image hands on one wrist.
Q: Face-hugger hand.
A: Yes. It does resemble a face-hugger.
Q: So that is a result of two ZPAs?
A: Two ZPAs on one limb bud—posterior and anterior—of the embryo, yes. If you inject a chicken egg with vitamin A, which is the main ingredient of retinoic acid, you can over-stimulate the ZPA of the embryo and get the same effect. They once isolated the sonic hedgehog of a mouse and injected it into the fin cartilage of the embryo of a skate—a shark relative. That cartilage in the fins are like long, skinny cylinders that all look pretty much the same, nearly identical in shape, size and length. They inserted a tiny bead of mouse sonic hedgehog protein in the middle of the fin between the center cartilage rods. When the skate hatched, the rods had developed like those of mammal hands. Those rods closest to the bead, each formed a digit 5 and worked outward in both directions and terminated in a thumb or digit 1 at each side of the fin making a mirror image that appeared more hand-like than fin-like. Since that time, we’ve done this type of experiment on a variety of animals and the results are the same. This means that genes that form hands or fins are really the same. That tells us that the formation of the hands of mammals did not involve the formation of new DNA but ancient DNA already present in fish.
Q: I once had a cat with six toes on all four legs. What causes that?
A: That’s called polydactyly. The extra digit is usually postaxial meaning that it happens on the pinky or digit 5 side. Sometimes, it occurs by the thumb or preaxial side and very rarely it occurs by the inner fingers or central axial area. It happens because there is a genetic mutation upstream of the shh gene or sonic hedgehog where we locate the ZPA on the posterior limb side. This mutation is cis-acting meaning that it occurs on the same DNA strand of the structural genes but basically results in an ectopic region, that is, a ZPA not in the normal spot but on the anterior side of the limb, that sends extra cells and instructions to create another thumb digit or digit 1. With an extra digit 5, the ectopic region is just offset from the ZPA on the posterior end of the limb. Anything to do with formation of the hands or feet is dependent on sonic hedgehog or shh protein.
Q: When did the first plants form?
A: The first plant formed approximately 1.6 billion years ago. All terrestrial plants formed from a single cell consisting of a microscopic alga that had absorbed a cyanobacteria. Whether this was an attempt by the alga to eat the cyanobacteria is not known but it ended up being a symbiotic relationship. The alga carries the cyanobacteria around and so the cyanobacteria manufactures food via photosynthesis and provides that food to the host. The host provides protection to cyanobacteria. One other agency is required to pull this off and that is a group of cells that transport that food from the cyanobacteria to the alga host and these cells are actually related to chlamydia—the STD—and were actually similar to the bacteria that causes Legionnaire’s Disease. The genes of these cells are required to take food from the cyanobacteria and transmit it to the alga host. But we know other bacteria also participated in a trial-and-error basis and this enabled this tripartite organelle to harden up.
The alga involved was a type of freshwater blue-green algae, a very ancient form of algae called a glaucophyte. These glaucophytes called Cyanophora paradoxa are considered living fossils and we have studied the genome of about 70 million base pairs. All modern plants share the same exact genes required to allow the cyanobacteria to merge with the alga host. This means it happened only once a very, very long time ago and it was so successful that all plants today from tiny grasses to daffodils to dandelions to ferns to wheat to corn to apple trees to mighty oaks to huge redwoods are all the genetic descendants of this single green cell, this microscopic organelle that formed 1.6 billion years ago.
Q: How did these green cells, as you call them, become plants?
A: Hard to say for certain. We only know that they did. They banded together maybe to catch more sunlight for photosynthesis. Genesis gets it right that sea animals preceded land animals but, of course, says God made each separately on different days but we can clearly see that terrestrial animals evolved from marine animals that eventually left the water over the course of hundreds of millions of years. The oldest living creatures of all are bacteria called prokaryotes which are cells without nuclei and they came into existence perhaps as long ago as four billion years—maybe a half-million years after the earth formed which is astonishing to think about. Then cells with nuclei or what we call eukaryotes evolved from prokaryotes as long ago as 2.5 billion years. The earliest multicellular creatures were wormlike but we know nothing else about them. We call them metazoans. We don’t have any fossils of them but we have fossils of their burrows which are wormlike.
The earliest true animal we know of was either the sponge or some kind of animal similar to a comb jellyfish. Sponges came into existence about 650 million years ago but there is now good evidence that this comb jellyfish-type creature is actually significantly older and yet had a rudimentary nervous system. There are no fossils of it so we cannot put a date on how old it would be but well over 650 million years old.
Q: How do they know this?
A: We have new technologies that can handle the processing of huge amounts of genetic data and analyze where splits in earth’s life family tree occurred and the answer repeatedly came out that the comb jellyfish split off on its own evolutionary path well before the emergence of the sponge. No matter how much data they added and how much they refined it to get the most accurate picture, it always comes out with the comb jellyfish splitting off on its own evolutionary path before the sponge did. How long before the sponge, we don’t know without having fossils to analyze and we have none. Strangely, this mysterious creature is more advanced than the sponge which does not have tissues and a nervous system but that’s what the evidence shows. Animals and plants though have the same root method of originating which is endosymbiosis when one life form swallows another but instead of digesting it, incorporates it whole and the two bodies live symbiotically. The first plants and the first animals formed this way. So there is safety in numbers not only because the sheer numbers can overcome adversaries but because greater numbers introduces diversity and variation that synergetically form lifeforms of greater strength or resourcefulness or adaptability.
Q: We are all really jellyfish at our deepest core?
A: It would seem so. As strange as it is. While they have a basic nervous system and tissue, which other early animals as sponges lack. Their mouth is also their anus. That’s true of only some humans. They have a top and bottom but no front or back, no left or right. So they lack polarization. No head or brain. But somewhere deep down inside us, there they are.
Q: How does polarization work?
A: At the end of limb buds of embryos are these little patches of tissue called ZPA or Zone of Polarizing Activity. The ZPA gives us mirror image hands and feet. The ZPA causes the pinky to form on one side of the hand and the thumb to form on the other and to do it in mirror image in regards to the left and right hand. And this happens with fish, frogs, lizards, birds, bats, whales, dogs, lemurs, tigers and wombats. Any limbed animal. All of them have ZPA. How does the ZPA do this? It exudes a set of genes called “sonic hedgehog” that, when activated by retinoic acid, makes a pinky grow on one side of the hand first and, moving across the hand, a thumb on the other side as well as the fingers in between. It grows the pinky or digit 5 first and then works across the hand to the thumb and creates mirror image hands and feet with respect to left and right. If you have a ZPA on both sides of the limb bud, it will sprout digit 5 first and then work across the hand where the two hands meet in the middle. The effect would be a two mirror-image hands sprouting from one wrist.
Q: Any experiments to prove that?
A: Yes. We also have rare but sufficient examples of people born with two ZPAs on the limb bud who developed two joined mirror-image hands on one wrist.
Q: Face-hugger hand.
A: Yes. It does resemble a face-hugger.
Q: So that is a result of two ZPAs?
A: Two ZPAs on one limb bud—posterior and anterior—of the embryo, yes. If you inject a chicken egg with vitamin A, which is the main ingredient of retinoic acid, you can over-stimulate the ZPA of the embryo and get the same effect. They once isolated the sonic hedgehog of a mouse and injected it into the fin cartilage of the embryo of a skate—a shark relative. That cartilage in the fins are like long, skinny cylinders that all look pretty much the same, nearly identical in shape, size and length. They inserted a tiny bead of mouse sonic hedgehog protein in the middle of the fin between the center cartilage rods. When the skate hatched, the rods had developed like those of mammal hands. Those rods closest to the bead, each formed a digit 5 and worked outward in both directions and terminated in a thumb or digit 1 at each side of the fin making a mirror image that appeared more hand-like than fin-like. Since that time, we’ve done this type of experiment on a variety of animals and the results are the same. This means that genes that form hands or fins are really the same. That tells us that the formation of the hands of mammals did not involve the formation of new DNA but ancient DNA already present in fish.
Q: I once had a cat with six toes on all four legs. What causes that?
A: That’s called polydactyly. The extra digit is usually postaxial meaning that it happens on the pinky or digit 5 side. Sometimes, it occurs by the thumb or preaxial side and very rarely it occurs by the inner fingers or central axial area. It happens because there is a genetic mutation upstream of the shh gene or sonic hedgehog where we locate the ZPA on the posterior limb side. This mutation is cis-acting meaning that it occurs on the same DNA strand of the structural genes but basically results in an ectopic region, that is, a ZPA not in the normal spot but on the anterior side of the limb, that sends extra cells and instructions to create another thumb digit or digit 1. With an extra digit 5, the ectopic region is just offset from the ZPA on the posterior end of the limb. Anything to do with formation of the hands or feet is dependent on sonic hedgehog or shh protein.