ffrom the December 17, 2013 eNews issue
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Mitochondria. Little power houses for the cell. They spit out the ATP necessary for the energy we need to drive in crazy traffic and to stay warm in sub-freezing temperatures. Mitochondria are unique among the citizens of the cell for a wide variety of reasons, including the marvel that they have their very own DNA that is different than the DNA that gets reproduced in the cell nucleus. That mtDNA is only passed on by the mother, answering questions about certain genetic diseases, and has been used in recent years to trace lineages from daughter-to-mother straight back thousands of years.
Most recently in the question of human ancestry, Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany has sequenced the mtDNA of ancient Spanish humans. Remains of long-dead people were found in the cave Sima de los Huesos (the “bone pit”) in Northern Spain and their mitochondrial DNA almost entirely sequenced. The mtDNA has been determined to be related to that of the Denisovans in ancient Asia, which in turn are related to the Neanderthals. And Neanderthals… well, they were just thick-boned human beings after all.
“The fact that the mtDNA of the Sima de los Huesos hominin shares a common ancestor with Denisovan rather than Neandertal mtDNAs is unexpected since its skeletal remains carry Neandertal-derived features,” says Matthias Meyer, team leader of the Max Planck group that did the DNA research.
Neanderthals used to be considered half-ape knuckle draggers, but recent research has proved them to be fully human with brains larger on average than today’s Homo sapiens. The world is filled with the remains of ancient humans of all sorts, large and small. We shouldn’t be surprised by this; according to Genesis, all descendants of Adam were killed—and all their genetic variations—with the exception of Noah and his family. One sliver of the genetic heritage of humanity was preserved while the rest got wiped out in one massive flood that destroyed everything that had breath in its lungs.
MtDNA offers us the ability to connect ancient humans to a common ancestor. Scientists have used mtDNA in other theories that involve our ultimate history, though, ones that generate a bit more controversy.
Mitochondria and Endosymbiotic Theory
Lynn Margulis, the once wife of Carl Sagan, made popular the importance of symbiosis in a bit of mutiny against the by-tooth-and-claw survival of the fittest of Neo-Darwinism. She saw that the earth and creatures in their environments exist in a whole-world symbiotic relationship, and was considered a rebel by the scientists of her time. Yet, her work has been valued by those who appreciate her lack of satisfaction with standard biological explanations.
Dr. Margulis was best known for promoting the endosymbiotic theory, a now popular answer to the evolutionist’s dilemma of how prokaryotes
first became eukaryotes. Prokaryotes, namely bacteria, are distinctive in that they have no nucleus to hold their DNA. Eukaryotes like us have a nucleus in our cells, along with a host of organelles that do all the work that goes on inside a cell. Margulis argued that mitochondria in animals and chloroplasts in plants were once free-living bacteria that were swallowed up by other prokaryotic cells. Rather than being digested, the proto-mitochondria and chloroplasts became part of the cell, contributing their DNA to the newly developing cell nucleus.
There are a few facts that microbiologists use to support this theory. Both mitochondria and plastids divide by binary fission and have their own DNA, which is organized as a circular chromosome like that of bacteria. The organelles also have a cell wall composed of peptidoglycan, typical of bacteria. Mitochondria and bacteria have some similar enzymes and transport systems, and mitochondria and plastids and bacteria are all about the same size. Many microbiologists now believe that early mitochondria are related to rickettsia bacteria, obligate intracellular parasites, and that chloroplasts are closely related to the single-celled photosynthetic cyanobacteria (blue-green algae).
The endosymbiotic theory appears on the outside to be reasonable, but it does raise a great many questions. For instance, both mitochondria and chloroplasts need a variety of proteins to function; when and how were the protein transport pathways built? There are at least five pathways that bring proteins into mitochondria, which would need to be in place in order to maintain these little organelles inside the cell, else they would stop functioning after they had transferred their DNA to the nucleus as the theory describes. What series of mutations could haveproduced those pathways, or could have matured the proto-mitochondrion into its current productive purpose? Are there any intermediates that show how the proto-mitochondria or chloroplasts might have survived in the meanwhile? Is there any evidence for eukaryotes that have existed without mitochondria?
Tim Martin Embley and William Martin stated in Nature in March 2006, “The idea that some eukaryotes primitively lacked mitochondria and were true intermediates in the prokaryote-to-eukaryote transition was an exciting prospect… But the evolutionary gap between prokaryotes and eukaryotes is now deeper, and the nature of the host that acquired the mitochondrion more obscure, than ever before.”
Our purpose here is not to pick on Dr. Margulis. She was an honest scientist who made a heroic effort to answer one of the more profoundquestions that evolutionary biologists face. It’s proved to be an exceptionally difficult question to answer, of course, but Dr. Margulis offered an idea that has gained wide acceptance in biological circles.
Dr. Margulis herself, however, had a serious problem with the idea that natural selection acting on mutations could create anything new. She didn’t apply it to the problem of the protein pathways in the cell, but she did recognize the lack of evidence of beneficial mutations. In her 2003 book co-written with Dorion Sagan, Acquiring Genomes: A Theory of the Origins of the Species, Dr. Margulis notes:
Although random mutations influenced the course of evolution, their influence was mainly by loss, alteration, and refinement. One mutation confers resistance to malaria but also makes happy blood cells into the deficient oxygen carriers of sickle cell anemics. Another converts a gorgeous newborn into a cystic fibrosis patient or a victim of early onset diabetes. One mutation causes a flighty red-eyed fruit fly to fail to take wing. Never, however, did that one mutation make a wing, a fruit, a woody stem, or a claw appear.
Mutations, in summary, tend to induce sickness, death, or deficiencies. No evidence in the vast literature of heredity changes shows unambiguous evidence that random mutation itself, even with geographical isolation of populations, leads to speciation. Then how do new species come into being?
Her honesty earned her the criticism of eminent materialists like Richard Dawkins, even though Margulis herself was a materialist and a supporter of microbes-to-man evolution. She simply recognized that the mechanisms scientists were offering were terribly insufficient to explain the evolution of the earth’s species. She did an excellent job of pointing out the subjectivity of the phylogenic tree models as well as the shortcomings of natural selection. She told Discover magazine in 2011, “This is the issue I have with neo-Darwinists… Natural selection eliminates and maybe maintains, but it doesn’t create.” She went on, “…[T]he laws of genetics showed stasis, not change. Mendel showed that the grandparent flowers and the offspring flowers could be identical to each other. There was no change through time.”
Mutation and natural selection were insufficient to explain how anything new was made, Dr. Margulis said. Her answer was symbiogenesis—that new structures that were built from the cooperation of several organisms. She saw symbiosis taking place everywhere in nature. “Life did not take over the globe by combat, but by networking,” she said in 1986.
In many ways, she was right. The plant and animal worlds do work together in a million ways to maintain life and health. She has the same problem as the Neo-Darwinists in the long run, because she doesn’t answer where the functioning cooperative pieces came from in the first place. What formed the proto-mitochondria or cyanobacteria that she believed invaded the cell for good? Still, Margulis recognized that the nature of the world is one in which harmony wants to dominate, even in the death that cuts through it.
According to Moses, in the beginning, God made everything “good”. Down to our mitochondria, we were fearfully and wonderfully made. The entrance of sin and death marred what started as excellent, yet the longing for perfection remains in all of us. The Apostle Paul described the conflict in Romans, saying:
“Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God. For we know that the whole creation groaneth and travaileth in pain together until now. And not only they, but ourselves also, which have the first fruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body.” -- Romans 8:21–23
We appreciate scientists like Lynn Margulis for their independent thinking, and we look forward to the day when the “good” that God created is once again realized, with no more destructive mutation and no more death—all creation living in harmony with Him.
Notes
Oldest Hominin DNA Sequenced: Mitochondrial Genome of a 400,000-Year-Old Hominin from Spain Decoded
— Science Daily
Neanderthal Cave Paintings Found in Spain
— K-House eNews
Neanderthal: 99.5 Percent Human
— Live Science
Lynn Margulis
— Discover
Eukaryotic Evolution, Changes And Challenges
— Nature
‘Non-Evolution’ Of the Appearance Of Mitochondria…
— Answers In Genesis
The Serial Endosymbiosis Theory of Eukaryotic Evolution
— PBWorks
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