Ancestral Magnitudes
Written by Stephen DarkSyde and Aron-Ra
My grandfather wasn't no monkey! You think we came from slime? Well, goo to you! Man, if you want to believe your great to the 100th-grandpa was a rock, be my guest . . . but it's STUPID!
Objections like these are all too familiar to those of us who defend evolutionary biology from the constant onslaught of religious opportunists who prey on their theistic victims for personal or political gain. As for a great-to-the-100th-grandfather being a rock, I assume this objection refers to a grandfather of 100 generations ago. And yes, frankly, that would be pretty stupid. Clearly, such claimants don't have an adequate grasp of the actual concept of evolutionary ancestry, nor of the significant time factors involved. I think you need a whole lot more zeros in there.
Let's do a little math. Using a minimal generational length of twenty years per generation, one hundred generations of grandfathers would equate to twenty centuries, or 2,000 years. That would make that ancestor a contemporary of rabba Yeshua bar Yossef--not quite an adequate evolutionary timescale, and certainly far from the mark when talking about the origin of life on earth. Only one hundred years ago, sixteen years per generation was more the norm as a minimal length, as it was with my grandparents and many of their ancestors. That would have put grandpa-one-hundred-generations-ago in the time of another wildly-exaggerated hero, King Arthur, in about the 5th century of the Common Era (CE).
We're going to need to go back further than that, a great deal further. Increasing the multiple by another factor of ten, an ancestor one thousand generations removed would have had even shorter generation gaps, about fourteen or fifteen years, on average. He would have been a Paleolithic nomad in about 13,000 BCE, just shortly before the foundation of the most ancient cities like Jericho and Damascus. He may have hunted mammoth, been a fisherman, or lived off Arctic seal. But no matter where he was or how he survived, he would have been 100 percent Homo sapiens.
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Mammoth Hunter, by Carl Buell, depicts a hunter around 14,000 years ago keeping tabs on a small herd of Woolly Mammoth in Berengia, the land bridge connecting Siberia to Alaska. Molecular analysis of genetic material indicates that all modern humans today descend from a tiny population that lived almost 200,000 years ago near modern day Ethiopia. You and I and everyone we know, be they light skinned or dark, regardless if they call themselves Eskimo or Aborigine, are in the end, 100 percent African and we are all family
Now, an antecedent from 10,000 generations ago would have been everyone else's great-to-the-nth-grandparent, too--everyone alive today, that is. He would still have been definitely human, and visibly different from his Neandertal neighbors. Whether he would be considered Homo sapiens or classified as a late model H. antessesor or H. heidelbergensis doesn't really matter. If you cleaned him up, dressed him in modern clothing and put him on a subway in New York, no one would notice anything different about him. Even our ancestors from that far back were still no more ape-like than any of the people in existence today.
Our grandpa or grandma from 100,000 generations ago (about 1.3 million years), on the other hand, was distinguishable from modern humans. He or she might now be called Homo ergaster or H. erectus, illustrated by artist Carl Buell on the left.
And H. erectus' remote ancestors from a million years earlier might be called Homo habilis or rudolfensis. Any or all of them would have appeared to be a bit more ape-like than the most monkey-faced modern guy, but they still would have been definitely human, especially when compared to the other fully bipedal apes that were wandering around two-and-a-half million years ago. If you were to put your ergasterine or habiline forebear on a crowded pew in your church, he would have looked like the classic ape-man. But if you saw him amongst his natural neighbors, the Australopithecines, you would see him as nothing less than a human being. The minimal length of a generation was shorter then--something like twelve or thirteen years on average.
One million grandmas back is quite a leap. A lot can happen in 900,000 generations and the world was much different ten million years ago. There were no definite humans yet, but there were proto-hominids--even though none of them could walk on two legs for very long. There were creatures similar to modern gorillas, chimpanzees and orangutans, but they were different from the ones we have today. One of the orangs, for example, stood as much as eight feet tall. This grandmother may have loosely resembled the modern bonobo shown to the right, courtesy of the Wikipedia. And the time span between generations would have been only eight to ten years, and much less as we go earlier.
At six or seven years between generations, your great to the 10,000,000th-grandma would have been barely recognizable as a primate, looking almost as much like a squirrel. She might have witnessed the demise of the dinosaurs, or he would have grown up in the harsh wasteland that was the wake of the K-T Impact for so many years.
Circa 60 million years ago; Plesiadapis on the right, one of the earliest known primates. Plesi still had claws instead of the more modern primate nails and her eyes had yet to face fully forward. Illustrations by Carl Buell
Left: A Triassic Cynodont called a Thrinaxodon. This critter lived about 220 million years ago and laid eggs, but shared many features with mammals.
Your grandmother of one hundred million generations back was a shrew-like mammal darting through the Jurassic underbrush 170 million years ago. The amniotic sacs her children were born in didn't have quite the same integrity that her own remote grandmother's birth-sacs had. Although leathery and easily torn, they would still have been considered egg shells, much like those from which some snakes hatch today. This grandma would have been mammalian, but not yet placental.
Now the generation gap really begins to close. For most of the Mesozoic era, and a long time before that, the age difference between father and son would be only about a year.
Your ancestor of a billion generations ago would have lived underwater--along with everything else, including trilobites and some really alien beasties--a few hundred million years ago and at least a couple hundred million years before the first dinosaur. The generation gap is now a monthly rather than yearly division. But for most of the last half-billion years of our genealogy, that wasn't the case. In half a billion years, your ancestors went from toothy, swimming worms like pikaia to conodonts, and on to lobe-finned crossopterygian fish, tetrapoidal amphibians, synapsid reptiles, amniotic proto-mammalian cynodonts, and finally the familiar placental mammals.
Primitive quasi-vertebrates such as the Conodont on the right, swam in strange primeval seas almost half a billion years ago. Conodonts are a strong candidate for the ancestor of all subsequent vertebrates including fish, amphibians, reptiles, birds, and mammals. Illustration by Carl Buell
Left: Tiny colonial animals which may have resembled a miniature version of this siphonophore to the left, probably first evolved around 700 million years ago. The individual polyps comprising these simple colonies may have evolved as much as one billion years in the past. Photograph courtesy of the Wikipedia (Chondrophore)
The world of your ancient grandmother ten billion generations in the past wasn't much different, although there were a lot fewer trilobites then. And she wasn't a swimming worm yet. She would have been a roundworm, if considered a worm at all. She may have looked more like a tiny jellyfish with a sense of direction. Before that, she may have been something even simpler, like a microbial sponge, but still definitely a metazoic animal. And from this point back, there are no more he's and she's; all your ancestors would have been mothers, all their offspring daughters.
Your grandma of one hundred billion generations ago would have been, at best, a microscopic colony of differentiated cells similar to the plaocozoa, the simplest animals known today. And just a few hundred million years before that, she may not have been an animal at all, but a protozoan; a sort of bacterial and viral co-op living inside a single membrane, all of which have their own individual ancestries.
The eukaryotic cell is a collection of bacterial and viral like elements that work as a single entity. The individual organelles, such as mitochondria, probably descend from even simpler, free living microbes, such as the proteobacteria bacteria on the right. Eukaryotic cells have existed for at least 2 billion years, bacteria for well over 3 billion. Illustrations courtesy Wikipedia
Your grandma of one trillion generations ago would have been all those various bacterial and viral components before they learned to cooperate in a single eukaryotic cell. And your grandmother of ten trillion generations in the past would have been bacteria, too. Your direct ancestor 100 trillion generations removed may have been an even simpler chemosynthetic protein, barely alive in the formal sense, on an inhospitable waterworld unrecognizable as Earth.
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"Lunar Dawn", by graphic artist Karen Wehrstein, was chosen for the cover of the Kosmos Kronicles. Here, Karen depicts the earth, shortly after it cooled enough for liquid water to precipitate out of toxic, reddish-yellow clouds to form the first oceans, over 4 billion years ago. From a mere 70,000 miles away, the softly glowing moon shines brightly from sunlight reflected off of a lunar atmosphere formed by outgassing as it rises quickly from the eastern horizon courtesy of a rapidly rotating earth. In the steaming primeval ocean, shown here flanked by mostly idle volcanic mountain chains and solidified pyroclastic flows, the first self-replicating organic molecules are already active: Life has arisen
The oldest sedimentary rocks we've been able to locate date from this time period, about four billion years ago, and show chemical signatures suggesting that simple replicators had already developed. Even earlier, under ideal conditions, generations could come every few minutes in the form of chemical hypercycles. Your ancestors, for lack of a better word, would have been a series of macromolecular reactions, in which the end result of a given chemical process is the constituents to fuel the next leg of the cycle, which ultimately circles back around to any one reaction. This is the earliest we can go back in terms of proto-biology, even in speculation. We are now at just over four billion years in the past, just a hundred million years or so after the earth cooled enough for liquid water to form the first oceans.
Those substances in turn came from the smaller planetoids and dust grains that formed
the Earth itself starting five billion years ago. Although the concepts of ancestors and generations no longer have meaning, our ancestral molecules can be found in volatile ices and hydrocarbon tars making up cometary bodies in the solar nebula before the earth congealed. Five to six billion years ago, much of the material that now comprises your body--the minerals, for example--would have been present in the solar nebula as just rocks.
Five to six billion years ago: Our proto sun at the center of the solar nebula from which the earth and other planets would eventually form. Illustration courtesy NASA
The material that condensed into a disk to form our solar system, including the earth, was a combination of interstellar hydrogen and heavier elements such as silicon, iron, nitrogen and oxygen. These heavier elements were cooked up inside a large star and released in a supernova, or blown off in the formation of a beautiful planetary nebula with a dense, white dwarf in the center. You are made of stardust like this:
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The Super Nova Remnant known as the Crab Nebula. All the atoms in our bodies heavier than hydrogen were cooked inside a star and released by a variety of mechanisms. The iron in our blood was cooked and released in a super nova. Photograph courtesy of the Hubble Space Telescope and NASA
The primordial elements, hydrogen and helium, which made up the first massive stars themselves, were produced shortly after the Big Bang. The helium came from an interesting process called Big Bang nucleosynthesis.
Let There Be Light: The Wilkinson Microwave Anisotropy Probe (WMAP) captures an image of the first light to bathe our infant universe over 13 billion years ago shortly after Creation. The individual specks represent the precursors to the first galaxies. Courtesy of NASA
That's quite a heritage to be proud of! And, while we know little about the trillions of individual organisms which make up the long ancestral lineage leading to each of us today, one thing we can say with certainty: they were, each and every one, survivors. It's an extraordinary story, spanning billions of years and stretching across all of space and time, back to the initial Big Bang. It's hard for humans to really get a handle on that kind of deep time, and that's understandable. We have a tendency to form opinions about what is possible and what is not based on intuition derived from everyday experience, and on emotional acumen. It makes sense to do so when confronted with the day-to-day problems and decisions we all must make. But is this methodology always useful?
Everyday experience will not help us when it comes to continental drift, traveling close to the speed of light or ice sheets marching and retreating across the landscape. We ephemeral creatures place such events not in the class of rare or time-consuming or unusual, but of never. And that's just one example of how our common sense can fail us when dealing with the most uncommon of phenomena.
Most folks who object to evolutionary biology or cosmology are doing so, not based on knowledge or reasonable inference, but on emotion. The emotional objections likely revolve around two concerns: 1) the idea of being just an animal or coming from slime and rocks. and 2) worry that science undercuts religious faith. On the latter: yes, science can undercut some tenets of faith. If the idea of a flat earth or a Sun god is a part of that faith then one either ignores the science and lives in ignorance with respect to that bit of it, or one adjusts one's theology. Those really are the only two intellectually honest choices.
The first objection is more common--many people don't like the idea of being the product of random physics and biochemistry. They feel there is no room for a Creator or their religion in such a scenario. I've always found this puzzling, as it seems to contain a hidden premise that the natural world science reveals must be in conflict with all religious faith.
And yet, even as a skeptic, I cannot imagine greater natural evidence for the brilliance of any Creator than the myriad complex processes unfolding over billions of years, through countless steps, in exquisite order, spanning the entire cosmos. The technical skill and artistic vision of such is to be admired in awe and, in that context, evolution, chemistry, astronomy and physics should be worthy of devotion, or at least respect--certainly not disdain.
Just a monkey? Just slime? Just a rock? . . . So many people speak of these things with latent fear; fear usually disguised as contempt. But a Creator is not limited to our prejudicial desires about how creation must unfold. If I were religious, I would teach my fellows to feel honored at being descended from a long line of God's wondrous creations and for sharing the amazingly complex biochemical processes those ancestral benefactors endowed us with. If I were a Sunday School teacher, I'd tell my young students that through the wisdom and creative genius of the Lord we can include cheetahs and peregrine falcons in our extended family; I think they'd eat that up! And they'd grow up secure in their faith, never having to fear that science would undermine it. Indeed, if anything, the grandeur of the natural world would only serve to strengthen their belief.
And I'd praise our evolutionary lineage and be grateful for our Linnaean ancestors, from the primates to the microbes and, yes, all they way back to the comets and the rocks and the dust. For through them God bequeathed unto us the finest natural possessions we will ever own: our body and our intellect.
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C
harles Darwin died on April 19, 1882, surrounded by family and friends in his home in Kent, England. Despite the heated debate and mixed feelings Darwin's work created in both the scientific and religious orthodoxy of the day, friend and foe alike insisted he be honored with a hero's funeral. He was laid to rest with all the pomp and circumstance of a full scale British affair of State. In death, Charles Darwin's mortal remains are in the best of company: His final resting spot is in Westminster Abbey, a scant few feet away from the graves of Sir Isaac Newton and Sir John Herschel. The inscription on his marker gives only his full name, date of birth, and date of death. A bronze memorial, with a life-sized relief bust, was erected by his family near the grave in 1888. The inscription just says simply "DARWIN".
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