The Tree of Life

“Behold, the man has become like one of us in knowing good and evil. Now, lest he reach out his hand and take also of the tree of life and eat, and live forever…”

I find it fascinating that in the bible’s story of the fall of man, the reason god gives for banishing humanity from their original home in the Garden of Eden is that they could become immortal by eating from the tree of life. This tree is first mentioned in the previous chapter, where it’s said to be in the midst of the garden with the tree of the knowledge of good and evil. However, there is no prohibition against eating from it. Adam and Eve were prohibited from obtaining knowledge of good and evil, and told that doing so would kill them. Yet even after breaking this command the possibility still existed for them to become immortal, so god had to kick them out and guard his special trees with a flaming sword in order to make his threat of death come true.

The bible’s tree of life is just an ancient story, almost certainly borrowed from some earlier mythology like most of the bible is. What I’ll be talking about this time is the real tree of life…the family tree of all life on earth.800px-phylogenetic_tree-svg

It starts with a single cell. Nobody knows where this first life came from, although there are many hypotheses. The building blocks of life are plentiful in this universe, and with innumerable molecules interacting on enormous numbers of planets in trillions of galaxies, even an extremely unlikely event may be expected to happen many times. Sheer numbers could easily make up for the unlikelihood of a specific result.

But that’s not what evolution is concerned with. The beginning of life is a separate question, one we are still trying to solve. From the first life onward, however, we know quite a lot. We know that all life on earth uses precisely the same basic coding system, that organisms are constantly-changing messes of trial and error, and that those better equipped to survive in their environment are the ones whose genes survive.

The tree of life takes root in water, where several branches of single-celled organisms diverged, taking specialized roles as they became better adapted to their environments. Some had the ability to harvest sunlight for energy, some scavenged for organic material, some grew to monstrous sizes compared to their peers and started gobbling up everybody else. In such an arms race, it should be no surprise that some organisms started banding together in colonies, to help protect each other from predators. And some of the predators gobbled organisms that they couldn’t digest, which ended up living inside them in a symbiotic relationship. These were the precursors to the cells of modern complex life we are familiar with. By teaming up, these little organisms exponentially increased their future potential, and complex life exploded across the planet.

Plants colonized the land when most life was still aquatic, and filled the atmosphere with molecular oxygen which rose to more than 150% of its modern level. This was the perfect setting for the rise of terrestrial arthropods, whose size is limited by the oxygen content of the air due to how their respiratory systems work. Ancestors of millipedes and centipedes grew bigger than humans, dragonflies the size of modern seagulls, scorpions as big as dogs. Without predators they ruled the land, until it started drying, cooling, and oxygen levels dropped.

Amphibious tetrapods crept out of the water around that time as well. Based on our understanding of geology and evolution, a team of scientists were able to pinpoint the likely location of fossils representing the transition from fish to amphibians in the Canadian arctic, and in 2004 they found tiktaalik precisely where it was expected. A lobe-finned fish with gills, it also had crocodile-like arms and wrists, strong ribs, a flexible neck, a primitive lung, and more. Tiktaalik is a fantastic example of the relationship between fish and amphibians, and the fact that evolutionary theory pinpointed exactly where we could find its fossil indicates our theories are on the right track.

The descendants of tetrapods that ventured onto land diversified into different roles. Amniotes, which laid eggs on land, diverged from the amphibians which continued laying their eggs in water. Without the need to reproduce in water, they spread far and wide over dry land, and split into two main groups called sauropsids and synapsids. Initially these two groups shared many similarities, and early synapsids superficially look very much like lizards and dinosaurs (dimetrodon is a well-known example). But after multiple mass extinctions and millions of years of evolution, what remained of the synapsid line became warm-blooded and furry, and now we call them mammals. Most of them switched to live birth rather than laying eggs.

Synapsids ruled the land early in their history, but later a group of sauropsids called diapsids took over with great success, and modern species descended from them still greatly outnumber synapsids. They are remarkably diverse, ranging from tiny lizards to monstrous dinosaurs to graceful birds. Lizards came first, and snakes descended from lizards. Crocodiles and their relatives split off later, and then came pterosaurs and dinosaurs.

The dinosaurs were far more interesting than even movies make them look. Two related suborders contain some of the most famous and recognizable dinosaurs: theropods were bipedal and mostly carnivorous, and sauropods were the largest land animals to ever live. The theropod group ranged in size from smaller than chickens to the largest land predators we know of–tyrannosaurus, gigantosaurus, and spinosaurus. Tyrannosaurs, raptors, and a few other types of theropods make up a group called coelurosauria in which most species, if not all, were covered in feathers. Some of the smaller members of this group survived the Cretaceous-Paleogene extinction event, and we call their descendants birds.

Another of the many successful predictions of evolution is that crocodiles and birds should be genetically more similar than crocodiles and lizards. After studying their genomes, it turns out this is true. Crocodiles have more DNA in common with birds than lizards because of the family tree outlined above…birds (dinosaurs) and crocodiles share a common ancestor, and that ancestor in turn shares a common ancestor with lizards and snakes. It’s like birds and crocodiles are cousins, and their shared grandfather has a cousin whose descendants are lizards and snakes.

The discovery of DNA and genes is what really made evolution undeniable, because many predictions about relationships between animals could finally be tested and found to be true. We learned that birds have inactive reptilian genes for the development of snouts, teeth, long tails, arms, etc. We learned that the gene which controls the development of hands in a fetus is the same in all vertebrates…the same genetic code guides the basic development of fins on fish, wings on birds and bats, and hands on primates. In numerous species past heritage can be seen in the fetal stage, when ancient features develop and then disappear as newer genes take over. Genetic information can also serve other purposes, like giving us an estimate of the minimum past population of a species necessary to produce the current variety among living members. For humans that number is at least several dozen to a few hundred, but our minimum population was likely closer to a few thousand during the narrowest bottleneck in our past. It is impossible for the current human population to have arisen from just one breeding pair.

To put it bluntly, if evolution is false and the life on this planet is the work of an omniscient being, he must have intentionally designed everything to perfectly match the predictions of evolutionary theory. He used inferior designs, like our poorly constructed eyeballs, that serve no purpose other than making life appear to have evolved. He planted deceitful evidence all over the planet and in our own DNA, knowing it would lead us us to these conclusions. Creationists claim DNA as evidence of god, yet he couldn’t be bothered to encode a simple message to us among the vast amounts of unused genetic material. Instead, he made it look like a haphazard mess of trial and error, as if it had been written blindly by a natural process rather than an intelligent mind. They told me to look at nature to find the fingerprints of god, but when I looked beyond their incomplete and superficial version of biology, god was nowhere to be found. I looked at my own body and found its “design” to be fundamentally unintelligent.

For the rest of this article, I’ll respond to a few comments from a creationist to address specific objections.

Quote: “On what you said about eyeballs, you’re joking right? On them being poorly designed I mean. They are literally some of the most complex parts of our bodies. There has also been no evolutionists who has adequately described eye evolution.”

Compared to brains and other organs, eyes aren’t that complex, and complex things can still be constructed poorly. For an introduction to the weirdness that is the human eye, this article lays it out pretty well. The most striking issue is that the photo-receptor cells are backward, behind other layers of supporting cells, which is obviously inferior to putting them the other way around and can contribute to retinal detachment. This is a feature we share with all vertebrates, as we are all descended from a common ancestor. It cannot be argued that eyes must be this way, because octopuses and squid evolved separately and their eyes provide a fine example of doing it the right way.

Evolution explains all of this easily, since it can only work with existing systems and can’t redesign them from scratch just because they’re less than ideal (which is also the reason our left recurrent laryngeal nerve wraps around the aorta before running back up to the larynx). Creationism, on the other hand, has to propose that a perfect and all-knowing god used a good and logical eyeball design for a few animals, and then gave all vertebrates, including his special humans, a ridiculous and illogical design that serves no purpose other than to make certain visual problems more common and reduce the efficiency of our eyes. And this barely scratches the surface; our long distance vision is dismal compared to that of many birds, our nighttime vision is very poor compared to many other mammals (such as cats), our color vision is limited, and so on. There are numerous simple improvements that would make our eyes far more impressive and useful and durable than they are. They just haven’t been made because they haven’t been strongly selected for; our powerful brains make up for our poor eyesight.

And speaking of adequately describing eye evolution, we can do that with six simple images and a few words. Every step is observable today in more primitive living animals, and every step is more useful than the previous one. Claiming that human eyes are “irreducibly complex”, as creationists often do, means ignoring the existence of a lot of other eyeballs that are quite useful despite lacking some of the special features ours have.

eyeevolution

Quote: “Also your point of bipedalism does not to further evolution being anything but a failed hypothesis but I’ll discuss it anyways. humans were designed by God to have feet. Our feet are wonderfully made by him and are actually pretty good for humans.”

That…doesn’t actually explain why he gave us feet with numerous little bones, which is still a bad idea for bipedal locomotion whether or not it works “pretty good”. Our feet are obviously re-purposed from the hand-like feet of our primate ancestors. I find this feature useful for picking up items with my toes (which I do a lot because my spine is also poorly designed for bipedalism and causes back pain), but when it comes to durability, efficiency, and effectiveness for bipedal locomotion, our feet lag far behind the well-adapted ones of other bipedal animals, such as ostriches. A few simple changes, like using fewer and larger bones, would reduce the rate of painful injuries and structural failure. Once again, evolution explains the situation just fine, whereas creationism is reduced to asserting that a perfect god gave us imperfect feet. The best their wonderfully perfect god could do was a half-assed variation on hands. Maybe when he got around to making human feet he was tired of coming up with new and reasonable designs, so he took the lazy option and just stuck some deformed hands on our legs and called it good.

Quote: “Also the different animals in layers is easily explained by many creationists. To summarize animals were at, of course, different areas.”

If the animals were in different areas, then how did their fossils get spread all over the world and stacked up in neat layers on top of each other? How did all these reorganized layers end up in the same order all around the world, and even match up across oceans? How did fossils from one layer end up in gastroliths in the stomachs of dinosaurs in another layer if they were all buried at the same time? To summarize this is, of course, a stupid argument that shows abject ignorance of the fossil record. Evolution explains the data quite well, while a global flood contradicts it.

There is no way a global catastrophe like that could produce all the finely-sorted sediment we observe, and defy physics to deposit it all on higher ground instead of at the bottom of the oceans. There is no way it could produce the perfect organization of animals into separate layers, or the geological features of ancient landscapes in those layers, which were shaped by water and drought alike over a long period of time before more layers were added. There is no way it could have buried both giant insects and mammals, since those life forms cannot exist at the same time due to requiring different atmospheric compositions to survive. There is no way it could have buried 3000 times more organic material in one year than currently exists in the planet’s entire biosphere. There is no way it could produce the millions of distinct layers of varves and ocean sediments that are comprised of particles so small they would remain suspended in moving water, and the cyclical difference in composition of the layers, and the volcanic ash from known eruptions that is embedded in the layers, and the patterns in the layers corresponding to weather changes caused by earth’s Milankovitch cycles. In addition, almost all vertebrate fossils are disarticulated, meaning their bones are jumbled. This happens because they died on the surface, decayed, and the bones got moved around before they were buried and fossilized. Fully articulated vertebrate fossils, which indicate rapid burial as predicted by the flood “hypothesis”, are quite rare.

Quote: “Actually the model Ken Ham supports (which is a biblical idea held up by science) is EXTREMELY accurate and has an amazing amount of evidence. He never said 11 new species every day. Bill Nye falsely said that about him.”

This is such a hilarious comment that I’m going to respond to it by laughing and then doing math. Hahaha! 8.7 million (a relatively low estimate of the number of species alive today) divided by 1.46 million (number of days in 4,000 years) equals about six. You need at least six new species every day over 4,000 years to produce the diversity of life we have now, if you started with the 7,000 or so different “kinds” that Ken Ham proposes were on the ark. But that’s not all, because we haven’t factored in extinct animals. So if you do the math, like Bill Nye did, you inevitably find that in order for Ken Ham’s model to be true, we absolutely would need to get an average of at least eleven new species every day. And that’s using a low estimate…there could be a whole lot more. This isn’t just a convenient attack on Ham, it is the mathematically inevitable result of his own stupid claims.

And there is no evidence for those claims. Science contradicts them at every turn, in obvious and easily understood ways. Speciation, while it has been observed, takes a long time. A particularly fast example of evolution is a case in which a single-celled yeast evolved to form multicellular colonies after two months of being subjected to an environment in which larger clumps were more likely to survive. If single-celled organisms, which reproduce very quickly, still take months to evolve one significant adaptation in a carefully controlled experiment, how are mammals and birds and reptiles and fish and insects and all the other complex animals evolving into entirely new species with extensive genetic alterations in even less time? If you’re going to accept such an unrealistically powerful form of evolution, why not accept the more reasonable full theory that’s actually supported by evidence?

That’s a rhetorical question; I know why. You don’t care about what’s true, you care about supporting your precious beliefs at any cost, which is why you will hypocritically reject a model of evolution that has been constructed from facts, while accepting a model of evolution with an impossibly short time scale that contradicts all known facts. You are destroying any shred of credibility you might have had in order to protect your false opinions from reality.

Quote: “You need to learn what a theory and law is. Theory Is a idea backed up by evidence (evolution isn’t this) a law has enough evidence to be a fact.”

You need to learn what theories and laws are. You also need to learn grammar. A theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment (source: National Academy of Sciences). A law is a descriptive generalization about how some aspect of the natural world behaves under stated circumstances (source: National Center for Science Education).

So what’s the difference? Laws don’t tell us “why” or “how”, they’re just general descriptions of the consistent and predictable phenomena we observe. Theories do not “become laws” when they’ve been backed up by “enough evidence to be a fact”, as dishonest Creationists often claim. Your statement indicates you know very little about the scientific process, and are confused about what a fact actually is. In science, a fact is something accepted as true for all practical purposes, but 100% certainty is neither possible nor attempted, so sometimes the things we accept as facts can change over time in the small chance that they’re incomplete or wrong. To illustrate how incomplete facts can still represent reality, I have often used an example of viewing a three-dimensional object from different angles. If you’re a two-dimensional being who doesn’t know about the third dimension, you might be very confused about how a rectangle and a square both represent the same object. The additional information of the third dimension can reveal a box that is square when viewed on one side and rectangular on another, so your original facts, while still accurate in a specific context, are not representative of the whole reality on their own.

Theories, on the other hand, tell us “why” and “how” using a foundation of facts. In the example above, the facts are the square and rectangle. To reconcile these different views of the same object, a hypothesis is proposed: maybe there’s a third dimension. The next step is to do experiments to test your hypothesis, which involves identifying and testing a prediction that would only be true if there are three dimensions. By confirming such a prediction, you’ve confirmed your hypothesis with observation, and it may now qualify as a theory. The fact is that different two-dimensional shapes can represent the same object. The theory is that there’s a third dimension. The theory explains the facts.

In the case of evolution, the facts are that populations of animals change over time due to mutations in their DNA, that all life on earth shares the same basic building blocks, that specific mutations are shared among similar animals whether or not they actually serve a purpose, and much more. The theory is the collection of ideas and explanations that tell us how these facts interact and are causally connected. Evolution–the process of a population of organisms changing over time–is a fact, and evolutionary theory explains how and why it happens, and how it produced all life on earth from a common ancestor.

Quote: “Actually hundreds of fossils (including dinosaurs) have been found with muscle tissue and brain cells. That Is 100% true. I’m very educated on the topic.”

I’m sorry to break it to you…but no, you’re not. You’re one of the most incredibly dense and ignorant creationists I have ever encountered, and you’re spewing dishonest arguments that were debunked decades ago and long since abandoned by any creationist with a desire to appear credible and honest (which seems to be very few of them, unfortunately).

Listening to these false and ludicrous claims is like listening to someone claim the earth is flat while staring at the planet through the window of a spaceship. It’s sad and frustrating that so many people have shut their minds to the vast and exciting realities of biology, and blinded themselves to evidence that can be found in their own eyeballs, just because they have an old book that tells them a different story.

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