Category Archives: Evolution

From Simplicity to Complexity

What makes the existence of life and the universe seem so improbable? Without question, the incredible complexity of all things is at the heart of the improbability dilemma. And it requires some form of explanation. In order to properly examine improbability, we must first address complexity. How can complexity be explained?

The complexity of the universe is staggering, in some ways beyond human understanding. For many, this fact alone can’t be accounted for without a design, particularly when the only alternative considered is chance. With this comparison, design usually wins over chance, and design implies a designer. Ancient civilizations observed a universe that was much simpler—in their eyes—than the universe we know exists today. Nevertheless, it would have appeared complex enough to invoke a designer. Even a number of natural phenomena that are easily explained today were attributed to gods.

Our present understanding of the universe reveals a universe that is far more complex than the ancients could have imagined. We have the opportunity of looking back in time for answers—back to a time when the universe wasn’t nearly as complex. Through a series of scientific discoveries, simple origins were found to be the precursors of the present universe.

Darwin opened our eyes, albeit slowly, with his insights on evolution. As it pertains to life, Darwin showed us a different way of thinking about the emergence of life. His theory of evolution by natural selection broke down the complexity of life into incremental steps. He managed to shift the focus from the finished product (or the present product) to the steps that led to it. According to Darwin, and verified by other more recent discoveries, life has evolved from simple beginnings—simple relative to its present state. It all began with single cell organisms, and perhaps only one. Now we have a world full of diverse and complex life forms, some containing trillions of cells. Darwin showed that from simple origins, complexity could arise over time, and by a natural process.

Even the life that we see today starts simple, and grows in complexity. For example, a tree begins with a single seed, and grows to a complex structure of roots, branches and leaves. When I look at a seed I find it difficult to imagine that a tree can come out of it, and yet it does so naturally. Like the seed of a tree, a human being also has a simple beginning—we were all initially a single cell. You could make the argument that a cell is complex on its own, and it is, however, millions and trillions of cells working in unison is several orders of magnitude more complex. Keep in mind that what we classify as the origin of life—a single cell—is somewhat arbitrary. Even a cell has to be constructed from simpler chemical processes, which at some point we call life. Although life, especially the origin of life, is an amazing and mysterious process, we can clearly see that it moves in a direction from simplicity to complexity.

Now let’s turn our attention to the universe as a whole, and see if the same principle applies. After Darwin had provided an explanation for the evolution of life, it was not automatically assumed that the universe evolves by a similar process. In fact, the idea that the universe was eternal and unchanging was a long-held belief by the general population and scientists alike. This idea took some time to overthrow. But by the mid-twentieth century, new discoveries were pointing directly towards an evolving universe; one which had a beginning.

The big bang is analogous to a cell. Just as a single cell can be viewed as the origin of life, the big bang can be viewed as the origin of the universe. And as I mentioned earlier, a cell can also be thought of as complex, but nowhere near as complex as the life that arose from it. The universe can also be viewed in a similar light. Although the big bang was not necessarily a simple event, it was nonetheless simpler than the universe that emerged from it.

Scientists theorize that a substantial amount of activity occurred at the initial moment of creation. The basic forces of nature emerged (gravity, electromagnetism, and the strong and weak nuclear forces), as well as a host of elementary particles (such as photons, protons, neutrons and electrons). Space and time as we know it were also created.  All that and more happened in a tiny fraction of a second. On the surface, this seems to present a problem as far as a simple beginning is concerned, however, there is more to consider.

In spite of this initial creative activity, for the first 300,000 to 500,000 years the universe was nothing more than an enormous cloud of hot expanding gas. Complexity would then increase gradually over time—in a sort of cosmic natural selection. It took one billion years before stars and galaxies formed. A few more billion years before supernovae explosions (the death of stars) created and distributed the heavier elements necessary for life. Simple life on earth emerged 9.9 billion years after the big bang. And from there it would take over 3 billion years of evolution to arrive at modern humans. From this simplified timeline, we can see that the early universe was much simpler than it is now—the result of 13.7 billion years of cosmic evolution.

There is another point worth noting that relates to the discussion. The big bang theory is a theory that describes the universe a fraction of a second after the universe came into existence. The big bang theory is silent on the cause of the creation event. Although scientists speculate on what the cause may have been, the big bang represents the edge of our present ability to understand the universe, a theoretical time barrier that we have not yet crossed. I like the way Bill Bryson wraps up the discussion regarding the cause of the big bang. In  A Short History of Nearly Everything, he writes:

“… it may be that space and time had some other forms altogether before the Big Bang—forms too alien for us to imagine—and that the Big Bang represents some sort of transition phase, where the universe went from a form we can’t understand to one we almost can.”

Like a cell, which is created by more elementary processes, the big bang could have been a transition phase that was precipitated by a simpler pre-existing cosmos. Some scientists even suggest that the universe may have been created out of nothing. And by nothing, I don’t think they really mean nothing, but perhaps something very small that we don’t completely understand. Physicists now believe that you have to incorporate aspects of the quantum world in order to understand the big bang. And if you go by quantum theory, particles can spontaneously come in and out of existence from nothingness. That is the nothing that scientists are talking about. Bryson writes: “It seems impossible that you could get something from nothing, but the fact that once there was nothing and now there is a universe is evident proof that you can.” Therefore, if the universe was created from nothing or very little, you can’t get much simpler than that. And if this is even remotely correct, the principle of things moving from simplicity to complexity definitely applies to the universe as a whole.

Having said all that about complexity, let’s insert improbability into the equation. Both life and the universe evolved from simple origins, and through incremental steps, have grown in complexity. Although this does not explain how the simple origin came about, it does show that complexity can be achieved by gradual steps, even if the finished product seems improbable—improbable by means other than design. Also, an after the fact approach of looking only at the finished product can be deceiving, that is in terms of what improbability entails. If something is improbable, does it mean that it can’t happen? And because the existence of life and the universe appears improbable, does it mean that it came about by design?

Let’s begin with a simple exercise. Do you remember what you did yesterday? I mean everything you did yesterday. If you went to work, think about the route you took, and the exact location of the cars you passed. What about the people you met and the exact time you met them. Then there are the phone calls or emails you received. Where did you have lunch, what did you eat, and with whom? What tasks did you perform? And what about after work, what else happened? You get the idea. Although you may think you had an ordinary day, the fact is that the exact details of your day will never happen again. Yesterday, just as it occurred, was extremely improbable. And today, tomorrow, and every other day will unfold in a way that is also improbable.

Now let’s look at another example, something more profound than an ordinary day—your own existence. In order for you to have a life, an almost endless series of events had to occur. Think about the coupling of your parents, and their parents, and every ancestor that came before that. In order for you to exist, every combination of ancestors had to mate, and possibly at the exact time that they did. I will spare you the trouble of going any further down the evolutionary line, but the basic idea is that your life is extraordinarily improbable. And so is my life and everybody else’s. Just because something is improbable, does not mean it can’t happen. The fact is that as long as you have a universe, something has to happen, and that just about everything that happens is improbable.

Therefore, if improbable things happen all the time, does it have to come about by design? I am certain that many would say that it does. They could also argue that the existence of life seems so improbable that it implies a higher order to the universe. Although that may be true, it does not necessarily mean that life was designed. The universe’s enormous scales of time and space allows for limitless opportunities to create. Given the mind-boggling numbers that are involved, what seems improbable or impossible does not necessarily apply to the universe.

We know that the universe allows life, because we find ourselves on a planet that allows life. On the other hand, on all the planets that don’t allow life, there is no one to count the failed attempts, or whether any attempts were made—no one to contemplate why it wasn’t designed to allow life to exist, or if it was designed at all. Although we can’t definitely confirm that life exists elsewhere, we know that life is rare relative to the size of the universe. If life was plentiful, we probably would have found some elsewhere by now. This means that vast regions of the cosmos are without life. And if we could closely observe those regions, we wouldn’t think that they were anything special. We would see planets orbiting stars and swirling galaxies, but this would go on for eons, without any conscious experience. Keep in mind that the process that led to life here on earth is essentially the same process that led to the lifeless regions. Of course, there are a few exceptions. One of which is the earth’s special location.

The location of the earth is an example of something that appears improbable, and thus appears designed. The earth’s location has been called the Goldilocks Zone, taken from the fairy tale Goldilocks and the Three Bears. The obvious reason being that its location is just right (just the right distance from the sun to support life). Of all the possible locations that couldn’t support life, why here? Again you could say that it is by design. But it doesn’t have to be, simply because improbable things can happen, especially with large scales like the universe. With a universe as vast as ours, it is inevitable that some planets will be located in Goldilocks Zones. It may be that we just happen to be here. Not necessarily because it was designed that way, and not merely by chance. But rather by an evolutionary process on a cosmic scale, which moves in a direction from simplicity to complexity. It is a process that creates stars, galaxies, and planets. Sometimes when the conditions are just right, it creates life.

Goldilocks Zones are not only applicable to planets, but the same principle is also present in nature. For instance, let’s examine something that is closer to home, such as the life cycle of a tree. A mature tree can produce at least several thousand seeds in a growing season, which are eventually deposited on the ground. The vast majority of these seeds will never become trees. Usually, only a very small percentage will germinate and grow to become trees. They are seeds that fall in Goldilocks Zones. In this context, a Goldilocks Zone would include fertile soil, sufficient water, sunlight, shade, etc. The probability of any one specific seed becoming a tree is very remote; however, when all the seeds are taken into account, probabilities can be viewed in a different light. We know that some seeds will become trees, because they will benefit from conditions that are just right. What we don’t know is which seeds will be selected by this process.

There is another analogy that I have heard a few times, which deals with the improbability question. This analogy has been used in support of design, and it goes something like this: the world’s oceans, with the comings and goings of its tides and waves could never construct a sand castle. The argument being that it requires a design for something constructive to emerge, and this applies to all the complexity we see today. The problem with this view is that it evaluates design against only one other alternative—whether chance alone could construct the sand castle.

There is another way to look at this analogy, which in my opinion, better shows how seemingly improbable things emerge. I agree that the ocean could not directly construct a sand castle, but it could do so indirectly. Life emerged from the ocean, and gradually made its way on land, and over billions of years evolved into more complex forms. One of these forms, a child, walked on the beach and built a sand castle. Consequently, the sandcastle came about from a complicated natural process that can’t be broken down into simplistic explanations, such as the polar opposites of design or chance. If we could go back in time a few billion years, we would think that the likelihood of a sand castle appearing on any of the world’s beaches would be very low. And yet today, sandcastles regularly appear (and disappear). Therefore, whether we are talking about living planets, trees, or sandcastles—and even if the finished product seems improbable—it doesn’t mean it can’t happen.

 

References: Bill Bryson, A Short History of Nearly Everything (London: Black Swan, 2004), 31, 32.


 

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Evolution in a Deck of Cards

dnaFor some people the process of evolution is a difficult concept to grasp. For sure, evolution is a counter-intuitive idea. We don’t experience evolution in our daily lives. It only makes sense when we look beyond the surface of things; evolutionary concepts require a long-term view. Perhaps the biggest stumbling block towards understanding evolution is the disconnection between our lives and the evolutionary timeline. If we compared the history of the Earth to the length of a person’s arm, all of human history could be wiped out with a single stroke of a nail file.

Still, despite much scientific evidence for evolution, many people are not convinced. They may look for supernatural explanations for the existence of life, or conclude the question is beyond human understanding. How is it possible that all life evolved from single cell organisms? How did even a single cell evolve? And how did life diversify into millions of species? To get a grasp for evolution we need to shift our attention from the finished product to the process.

Evolution is indeed a process, which is ongoing. And it has no finished product in mind. Evolution can be defined as gradual changes and development over time. However, there is a mechanism that generates those changes, which Darwin called natural selection. Perhaps Darwin’s greatest insight was recognizing the power of natural selection. It is similar to an algorithm, because nature selects positive survival and reproductive traits. It also discards negative survival and reproductive traits. The process is cumulative and continuous from generation to generation. Once the process began improvements to life were inevitable, even though specific outcomes were not guaranteed.

The Card Game

deck-of-cardsAs a thought experiment we can use the analogy of a card game to show how natural selection works. The analogy is not perfect, because there are subtleties in evolution that are more complicated. The exercise is meant to provide a simple analogy for natural selection.

Although it was not known in Darwin’s time, we now understand that life is controlled by genetic information. Essentially, it is genes that are passed on through the generations. In our analogy it is more useful to view the cards as genes, and a hand of cards as a group of genes (or an individual life form). The game has 4 basic ground rules:

1) The deck of cards represents the gene pool: We need to assume multiple decks, because the same genes exist simultaneously in other individuals and are copied many times over. Each card carries information, which may or may not survive each reshuffling. For example, the 5 of spades is one gene and the 10 of harts is another gene.

2) The shuffling symbolizes the generations: Every time the cards are shuffled and handed out, it’s like a new generation. The cards are always being rearranged in different combinations.

3) The players act as natural environments: The players select which cards they want to keep. Just like nature favors different genes in different environments, each player will select different card combinations. In our game some players are playing poker, others cribbage and others bridge. For example, the poker player represents a specific environment, such as an ocean.

4) The goal of the game is to collect the best hand possible: Every player keeps the cards they want, and discards the ones they don’t want. The poker players will collect different card arrangements than the bridge players. But all the cards come from the same card pool. This selection process is done with every deal.

Stable Arrangements

For natural selection to work the process had to work in the primordial period. The creation of life on earth probably did not start in an instant of time. It is more likely that the building blocks (atoms and molecules) were assembling for a long time; nature was favoring stable patterns. Richard Dawkins points out in The Selfish Gene:

“The earliest form of natural selection was simply a selection of stable forms and a rejection of unstable ones.”

microscopic-lifeJust like today, things that last are stable arrangements of atoms (whether living or nonliving). Consequently, life began in a fuzzy period where forms were interacting and assembling. At some point the forms acquired the ability to replicate (with occasional errors). The errors are necessary for evolution; this would be like randomly adding new cards to the deck (like a 15 of diamonds). Eventually, simplicity grew into increased complexity; small patterns grew into larger patterns. This is also what happens with the game of cards.

Exact patterns would be difficult to recognize in the first few hands. Nevertheless, there would still be cards that are more desirable than others. Generally, an ace or a face card is better than a numbered card. But there are exceptions, which depends on the type of game and the combination of cards. With each reshuffling patterns will emerge, where eventually an onlooker could identify the game each player is playing. This is analogous to the time when stable patterns would be recognized and classified as organic life (that’s if someone where watching).

Reshuffling the Deck

We can now see how the process of reshuffling the deck, selecting and discarding the cards would work. It would not take too many hands to achieve almost perfection. Each player would select for their specific game, just like nature selects for its specific environment. All the hands would contain some of the same cards, but in different combinations. Nature mixes the genes in the same way.

cards-in-rowsThe power of natural selection is the continual selection and discarding process, which occurs at unfathomable timescales. Successful genes are kept from generation to generation, random gene mutations are added, and remixed in endless combinations. Only the best of the best survive the process. That is why an after-the-fact view of evolution can be deceiving. Incredible order can emerge without a design and a planned outcome.

Our card game never ends; the players are always looking to make improvements, no matter how small. Many poker players will end up with a Royal Flush (the best possible hand). Bridge hands will end up with every card of the same suit or all aces and face cards. This is where our analogy doesn’t quite measure up. In real life the environments constantly change, which drives evolution to adjust. It’s like occasionally changing some rules to each card game, which will force the players to change their hands.

I hope this thought experiment helps to conceptualize how evolution can accomplish a seemingly daunting task. The basics of natural selection are only a starting point towards understanding evolution. Evolution is a messy process of trial and error, an incalculable amount of trials and errors, which muddies the water. Yet the time involved is critical to the process (more than 3 billion years).

Knowledge of evolution is fundamental towards understanding all life on earth. The life sciences could not progress without it. Our own bodies function as a result of evolution and much of human behavior has evolutionary roots. It has been said that, “Evolution is not something you believe in; either you understand it, or you don’t.”

 

References: Richard Dawkins, The Selfish Gene (Oxford: Oxford University Press, First published 1976, Second edition 1989, 30th anniversary edition 2006).


 

Why is The Earth a Life-Sustaining Planet?

landscape-at-sunsetWhat has allowed the earth to maintain stable conditions that are favorable for life? To answer this question we need to look at our planet’s history, and ask why the earth has been habitable for almost 4 billion years. This is an extremely long time, and probably the time needed for intelligent life to evolve. Scientists have second-hand evidence to go by, like entering a crime scene after the fact. But there is plenty of evidence to reconstruct the major historical events of our planet; this comes from a wide range of scientific fields.

The earth is the home of all life that we know about, possibly the only home humans will ever have. However, given enough time, it is possible that much like ancient sailors settled new lands, spaceships will cross space to new worlds. Up until now we should consider ourselves very fortunate that our planet has maintained the conditions necessary for life. For sure, the earth has gone through dramatic changes in its lifespan, but not significant enough to snuff out life. Let us examine a number of plausible reasons why a life-friendly earth has endured for so long:

The Goldilocks Zone

The earth’s location in relation to the sun has been called the ‘Goldilocks Zone’ or ‘Habitable Zone,’ because it is just the right distance from the sun to support life. Specifically, the temperature on earth is within a range that allows for water to flow (life as we know it needs liquid water). The right location is the starting point for a living world.

It is possible that life could exist with other chemicals that are liquids at other temperatures. For example, it has been suggested the liquid methane at extremely cold temperature could support life, such as the lakes of Titan (Saturn’s largest moon). But this is speculative, and that form of life would be unfamiliar to us. Nevertheless, finding evidence for liquid water on other worlds is challenging, as Goldilocks Zones are hard to come by. Although over 2 thousands exoplanets (planets outside our solar system) have been discovered, planets in habitable zones are rare.

The Solar System

solar-system-planetsThe earth is in constant motion and in relation with other celestial bodies in the solar system. Somewhat like a mobile hanging above a baby’s crib, all the bodies have influence on the system. In addition to a habitable zone, a long-term stable system is necessary. At least, the overall effects of the celestial bodies must stabilize the movement and climate of one body (like the earth). Here are 4 earth-friendly characteristics of our solar system:

  1. Earth’s Tilt: The earth is tilted at an angle of 23.5 degrees away from the plane of the elliptical orbit. The tilt gives us our seasons, which allows a greater surface to attract heat from the sun. Without seasons, only the region around the equator would be habitable. This would have drastically changed life on the planet?
  2. The Sun: The sun is 4.5 billion years old and will live for another 5 billion years. Some stars only live for a few million years. For complex life to evolve it takes several billion years, therefore a long-lived sun is needed.
  3. The Moon: The earth-moon system seems to have attained a stable relationship. The moon is just the right size to help prevent a chaotic wobble of the earth’s axis. The moon also aids in creating larger tides, which is thought to have played a role in transitioning life from water to land. And the speed of the earth’s spin has slowed over time due to the moons presence, thus moderating climate extremes.
  4. The Gas Giants: Jupiter and Saturn are the largest of the outer planets. Their orbits outside the earth’s orbit have protected the earth from large impacts. In the early development of the solar system, there were many large moving objects. The gas giants are believed to have ejected some of the large debris out of the system, and aided the inner planets to form sooner. And who knows how many potential collisions with the earth were absorbed by the gas giants.

Climate Stability

It is remarkable that the earth has maintained a stable climate for billions of years. I mean stable in the sense that the climate has not varied enough to wipe out life. Since life has appeared the earth has gone through a number of ice ages and periods of intense warming. Average temperatures may have varied by as much as 100 degrees C. But for reasons only partially understood, the climate has always returned to moderate levels.

Factors controlling the temperature have fluctuated throughout planetary history, such as: the heat generated by the sun, the earth’s heat absorption rate, and the amount of greenhouse gases that trap heat in. Could there be a regulating effect or cancelling-out effect that has prevented a runaway process? The earth has avoided irreversible climate change, unlike our two cosmic neighbors (Venus is to hot and Mars is to cold). Currently the average global temperature is about 15 degrees C.

Moderate and Gradual Change

Changes to the climate and environment are essential for the evolution of life, provided that the changes are moderate and gradual. Evolution is a multi-generational process, in which individuals that are better suited to their environments survive longer and reproduce. Beneficial genes are passed on to future generations; however, what constitutes beneficial genes is unstable, because the earth is constantly changing.

As a result of moderate and gradual changes species evolve into other species. If the planet was unchanging, the earliest life forms would not have evolved into more complex forms. On the other hand, if the changes were too drastic life could not have adapted successfully. Earth’s history shows that environmental changes have caused some species to go extinct, while others have evolved and branched out into new species.

The Gaia Hypothesis

James Lovelock, a NASA chemist in the sixties, proposed the Gaia Hypothesis when he was searching for life on other planets. While comparing the atmospheres of Earth, Mars and Venus he noticed that the earth was chemically in a state of flux. Conversely, Mars and Venus were chemically unchanging and predominately composed of carbon dioxide. The fact that the earth’s atmosphere was an active mixture of gases and still retained its overall composition, suggested some form of planetary regulation. His conclusion was that life regulated the atmosphere by its many processes.

earthLovelock expanded the Gaia Hypothesis (also called Gaia Theory) to include the whole biosphere (climate, rocks, oceans, biology, etc.) and described the earth as a self-regulating system. In other words, the earth acted as one organism. Gaia was controversial as a scientific hypothesis when first proposed. The main objection was evolutionary theory, as organisms are not believed to act in concert with their environment (sometimes supportive and sometimes destructive). The argument against Gaia Theory was that organisms would somehow have to communicate with each other, and act altruistically towards the planet. This was impossible.

Lovelock’s counter-argument was that Gaia was not intentionally achieved, yet that natural selection was critical in shaping the regulatory patterns of the planet. Gaia did not need a controlling center; it was a consequence of natural selection. Nevertheless, loosely applied it points to life processes as being critical in creating and maintaining living conditions. Over time Lovelock’s idea gained more popularity as evidence grew for an ever more interconnected and interdependent biosphere.

It could be that natural selection allows life to adapt to whatever conditions arise, giving the impression of Gaia. Or possibly, that long-term climate and atmospheric stability is in large part due to the existence of life.

Good Luck

It could be that the earth is a rare and unique planet, which has benefited from an extraordinary amount of good luck. Evidence for planets outside our solar system is mounting. There are a number of earth-like candidates, but the odds are stacked against finding a place just like earth. This does not mean that other earths don’t exist, just that they would be extremely far away. Paradoxically, the unfathomable size of the universe could mean that life is both rare and plentiful.

Anthropic reasoning would suggest that the earth has endured through a long succession of fortunate events. Intelligent observes are the result of anthropic selection, of which other lifeless worlds have no one to observe them. If events had not worked out just right for us, we wouldn’t be here. Still, it is difficult to comprehend the many unlikely phases of earth’s evolution. For example:

  1. The emergence of life.
  2. Multi-cellular life.
  3. Atmospheric transformation from carbon dioxide rich to available oxygen.
  4. Life moving from water to land.
  5. The rise of consciousness and intelligence.

These examples are major thresholds that were crossed, yet countless other variables could have changed the course of history. Life could have taken a completely different direction, even to the point of total extinction. Obviously, this has not happened, either from cosmic events or global catastrophes. When life began there was no guarantee that it would survive for nearly 4 billion years. And the specific circumstances that led to human beings were even more tenuous. We should consider ourselves very lucky to be here, on such a special planet.

 

References: David Waltham, Lucky Planet (New York: Basic Books, 2014).

Beautiful Minds – James Lovelock – The Gaia Hypothesis / Gaia Theory, Published on Sep. 12, 2013.

Life on Earth Can Thank Its Lucky Stars for Jupiter and Saturn, By Sarah Lewin, Staff Writer | January 12, 2016 07:30 am ET, http://www.space.com/31577-earth-life-jupiter-saturn-giant-impacts.html

What Makes Earth So Perfect for Life? Dec 13, 2012 03:00 AM ET, http://news.discovery.com/human/life/life-on-earth-121019.htm.


Photosynthesis: The Breath of Life

large-leafPhotosynthesis is a chemical process, by which plants, algae and some bacteria convert solar energy into chemical energy. Basically, the organisms take in carbon dioxide and water, and use sunlight to make glucose, thus releasing oxygen as a by-product. The organisms are able to make their own food (glucose) by capturing sunlight. Other elements, such as nitrogen, phosphorous and magnesium are also needed to complete the process.

Sunlight provides the energy needed to transfer electrons from water molecules, an essential part of the process. The electrons are extracted from water molecules and passed along a chain, and finally forced onto carbon dioxide to make sugars. Photosynthetic organisms are called autotrophs. People and animals cannot photosynthesize; they are called heterotrophs. Today, plants are the most familiar form of autotrophs, but they were not the inventors of photosynthesis.

It Started Way Back

The evolution of photosynthesis is believed to have stared about 3.4 billion years ago. It was developed by primitive bacteria, first using elements such as hydrogen, sulfur and organic acids. These early bacteria manufactured food without using water, and did not produce oxygen (a process called anoxygenic photosynthesis). This was, however, an important development in the evolution of life.

algaeAround 2 billion years ago, a variant form of photosynthesis emerged. These bacteria lived in the ocean, used water as electron donors, and the release of oxygen into the atmosphere was the result (oxygenic photosynthesis). Photosynthesis was one of the most important developments in earth’s history. Learning to use sunlight to produce food took advantage of an endless supply of energy.

The introduction of free oxygen into the atmosphere was a game changer for all life. For some microbial life that existed then, oxygen was a toxin; this led to a significant extinction event. However, it opened up new opportunities for complex life to evolve, which it did. Oxygenating the atmosphere was an extremely slow process, as it took in the range of 1 billion years before complex life emerged.

How Did Plants Acquire the Ability to Photosynthesize?

Inside the cells of plants there is a separate compartment called the chloroplast. The chloroplast contains the green-colored pigment chlorophyll, which absorbs blue and red light. These are the wavelengths used in photosynthesis. The green wavelengths are deflected out, and that is why plants look green to us. In the chloroplast a number of complex interactions occur to produce food for the plant cell.

The chloroplast originated from primitive bacteria. In fact, in an earlier period chloroplast were bacteria, which eventually formed a symbiotic relationship with more complex cells. This relationship was the beginning of plant life on earth. It seems that the complex cells took advantage of the bacteria in order to get a free lunch. However, there was probably a benefit for the bacteria as well, perhaps the protection of an outer membrane or some other survival advantage.

The Ultimate Recycling Project

Photosynthetic organisms are the original source of oxygen and food for other life forms. If not for plants, there wouldn’t be any food for animals to eat. So the food chain in any ecosystem begins with photosynthesis. The food chain starts with plants, which are consumed by herbivores; the chain continues with carnivores and omnivores.

athmosphereThe earth’s atmosphere contains 20.95% oxygen and .039% carbon dioxide. The remainder is mostly nitrogen (78.09%). What concerns us here is the oxygen/carbon dioxide relationship. Most of the oxygen is provided by terrestrial green plants and microscopic phytoplankton in the ocean (they consume carbon dioxide and release oxygen). Non-photosynthetic organisms, like humans, animals and fish do the opposite (they breathe in oxygen and breathe out carbon dioxide).

Oxygen and carbon dioxide are continually recycled into the air. Life as a whole has evolved to function with the present mix of oxygen and carbon dioxide. What we don’t know is how delicate the balance is and if human carbon emissions will drastically change the balance. Scientists know that the atmosphere has changed significantly over evolutionary time; the result being the extinction of some species and the evolution of other species.

Given that life has created and maintained the atmosphere for billions of years, it will no doubt continue to do so. Life as a whole is safe. The questions for humans are: What are the long-term implications of releasing more carbon dioxide in the atmosphere? Which species will adapt successfully? And whether the atmosphere is changing in a direction that is less favorable for us?

 

References: In Our Time: Science, Photosynthesis, May 14, 2014.

livescience, What is Photosyhthesis? by Aparna Vidyasagar, July 31, 2015. http://www.livescience.com/51720-photosynthesis.html

Earth and Sky, How much do oceans add to world’s oxygen? June 8, 2015. http://earthsky.org/earth/how-much-do-oceans-add-to-worlds-oxygen


 

The Evolutionary Arms Race

Evolution is guided by an intense competition for survival. When one individual or species gains an advantage, natural selection will cause competitors to catch up. Because there is always competition, over time species are pushed to improve, and a stable balance is generally established. It would be more economical for all to keep things as is, but that’s not how it works. Evolution requires change, and change is continual. An evolutionary arms race is an unavoidable consequence of evolution. To see how this works let’s look at a few examples:

The Tree Canopy

tree canopyHave you ever wondered why mature trees in a forest are roughly the same height. Given the fact that there is tremendous diversity in nature, why not have trees of various heights. Although different species can naturally grow to different heights, they are not found in the same forest environment. The reason is due to a race upward for sunlight. All the trees in a forest are competing for solar energy.

Forests could easily have been populated by low growing trees, at an energy cost savings for all. But nature has selected the trees that gained a competitive advantage (those that grew a little taller). The other trees were forced to keep pace or be left behind. Trees have evolved to grow higher because competing trees were also reaching for sunlight. Individual trees compete with their own species and also with other species. It does not matter whether it’s an individual or an entire species, those that cannot keep pace will not be successful at passing on their genes. In The Greatest Show on Earth, Richard Dawkins writes:

“In fact, what we actually see is a forest in which each tree species evolved through natural selection favouring individual trees that out-competed rival individual trees, whether of their own or another species.”

Of course, this was a slow process that was played out over evolutionary time and at the genetic level. Genes favorable for growing tall trees were passed on, because the trees that contained them were more likely to survive and seed the next generation. This competition continued for millions of years until an optimal height was achieved. There is a limit to the amount of energy a tree can divert towards growth, and a limit to the height a tree’s structure can support. Eventually the forest settled at a maximum height, when it was no longer an evolutionary advantage to grown higher.

Running Speed of Predator and Prey

predator and preyThe relationship between predator and prey is a complicated one, with each trying to outwit the other. Both predator and prey will evolve their own skill set. Some traits are specific for catching prey, while others are specific for avoiding predators. But there is an overlap as some traits are shared. For example, let’s consider the running speed of animals, which is just one of many skills needed by both sides. Running speed is valuable for both predator and prey.

Predators like cheetahs have evolved to run faster and faster, while gazelles (their prey), have also evolved to run faster. The end result being that neither gains ground. Richard Dawkins explains:

“Natural selection drives predator species to become ever better at catching prey, and it simultaneously drives prey species to become ever better at escaping them. Predators and prey are engaged in an evolutionary arms race, run in evolutionary time.”

Running speed is important, but it is part of a delicate balance with other important traits: such as endurance, strength and eyesight. The evolutionary winners will be those that get the balance right, yet running speed will be in the mix. Although less obvious, it is just as important for an individual to outrun individuals from the same species. For instance, a gazelle which runs slightly faster than the average gazelle will escape the predator at the expense of the slower gazelles. The fastest gazelle in the herd will be favored just as much as the overall speed of the herd.

Bacteria, Viruses and Human Defenses

In the two examples listed above (the tree canopy and the running speed of predator and prey), evolution acted at the subconscious level. No conscious agent designed any particular trait. The arms race was fought by natural selection. Because of our knowledge of viruses and bacteria, another level of the arms race is added. That is, the production of vaccines and antibiotics.

The Influenza Virus and Vaccines: In 1918 the Spanish Flu was responsible for the death of about 50 million people (the worst pandemic in world history). The pandemic struck in the last year of World War 1. The world war was critical in spreading the disease as masses of soldiers moved across the globe. The poor living conditions and ill-health of the solders may also have contributed. Pandemics have reoccurred throughout history, and experts caution that it could happen again. Different strains of the flu still come around every year. Today, much progress has been made in developing vaccines, which along with sanitation is our best defense against viruses.

influenza virusViruses attack the human body by invading cells. The immune system produces antibodies that fight off the virus. Therefore, a specific virus can only infect a host body once. However, viruses evolve very fast and are inaccurate replicators. As a result they evolve into different strains that can evade the human immune system. Viruses are not trying to change; they change because of chance mutations. The ones that are resistant to antibodies populate. It may appear that viruses are attempting to outsmart the immune system, but they simply evolve through the process of natural selection in their environment.

An arms race between viruses and their host is ongoing. Each year experts predict which strains of influenza will be dominant, and they product vaccines in accordance. It is an educated guest, which sometimes they get right and sometimes they don’t. Except for particularly dangerous strains, such as the H1N1 pandemic in 2009, it is debatable whether wide-scale vaccinations for the flu are effective or necessary.

The arms race will surely continue. We have the natural competition between viruses and antibodies, and the additional armament of vaccines. The speed in which viruses replicate and evolve insures that they are here to stay. Humans are faced with every-changing viruses, which we have to keep pace.

Bacteria and Antibiotics: Common bacterial infections for today’s standards were often fatal in the past, but thanks to antibiotics are now easily treatable. Antibiotics can kill bacteria inside a human body, however it kills good bacteria as well as bad bacteria. Good and bad are subjective descriptions based on their influence on humans. Bacteria are single cell organisms that have evolved to live in symbiotic relationships with humans (bacteria cells in the body outnumber human cells). The beneficial bacteria will defend its turf against invading bacteria, and thus can be considered as part of the immune system.

bacteriaAlthough the antibiotics are engineered to target the invaders, they are not perfect and they kill some of the symbiotic bacteria. Because antibiotics have been widely used, this has changed the balance of bacteria that dwell in humans. The effects of these changes is not clear, but there is evidence it can contribute to some diseases.

When an antibiotic is used to treat an infection it does not kill all the invading bacteria. And similar to viruses, the bacteria develop resistance to the antibiotic. The surviving bacteria will multiply and evolve until that specific antibiotic becomes ineffective. New antibiotics need to be developed in order to keep up. Even though a patient is cured, surviving bacteria can still spread to other people. Once again, the battle is similar. Unwanted bacteria verses beneficial bacteria and human ingenuity. The arms race is on with no end in sight.

 

References: Richard Dawkins, The Greatest Show on Earth (New York: Free Press, 2009), 380, 381.

Big Picture Science, Skeptic Check: Evolutionary Arms Race (June 22, 2015).


 

Memes that Make the World

dnaMemes are the cultural equivalence of biological genes. The term meme was coined by Richard Dawkins in the 1976 publication of The Selfish Gene. The premise behind The Selfish Gene is that Darwinian natural selection acts at the level of genes; ultimately, it is genes that guide evolution by controlling the traits in bodies that contain the genes. In order for natural selection to work, there needs to be something like DNA and genes in which information is replicated. There also requires some copying errors so that small variations can occur from one generation to the next. Memes also fit that description.  Memes are ideas that survive in human brains, and similar to genes they can be copied and passed on.

There are many different types of memes: for example, songs, hairstyles, phrases, beliefs, words and manners. In today’s world the word meme has become popular on the internet. Whenever we here that something has “gone viral,” it is often referred to as a meme. In most cases the meme is something trivial, such as a piece of music, a surprising story or a silly video. It spreads rapidly, but usually it will not last very long. However, other memes have a far greater impact on society, and become part of cultural evolution. Or you could say that the memes guide cultural evolution, much like “the selfish genes.”

The Meme Codes

Language may be the key ingredient that allows memes to spread. Like a DNA code, language is also coded information. It comes in the form of letters and words. Speech is one variation of language, which is surely copied, but written language is even more stable as a replicating code.

We can all recall numerous instances when an event is passed from one story-teller to another. In most cases the details in the story changes until we have conflicting accounts. The information is transferred from one individual brain to another, but memories are not perfect and the copies are not exact. However, written language can exchange hands without the story being altered. The stories still have to resonate in people’s brains and the interpretations will vary, but the fidelity of the written word is higher than the spoken word.

Music is another meme that has two routes of transition. 1) Tunes are passed on by hearing the sounds and attempting to duplicate them. If a tune sounds appealing there is a higher chance it will be copied. As time passes the tune will change a bit. 2) Music can also be written in sheet music using mostly symbols. Like written language, the written music will remain close to the original form. One piano player following a sheet music may sound slightly different from another player. But as the song is played by many piano players it will not change significantly.

MathematicsMathematics is a meme of numbers, symbols and diagrams. It is more accurately copied than language, because there is less ways it can be altered. 2 plus 2 will always equal 4. There is an order in mathematics that is self-correcting, although concepts evolve over time with new applications. Language, music and mathematics are coded information that are replicated and evolve in human brains.

Marching on Through the Generations

The idea of generations is different for memes than it is for genes. A different generation for a gene is an offspring, which will carry some of the same genes. For memes, there is a double meaning for a generation. A meme can be passed on from person to person in a single day, or survive for many years. For instance, I tell you an idea, and you share it with someone else. That’s 3 generations, from me to you to someone else. In this scenario the meme could evolve like microbes, where mutations can occur in a matter of days or weeks. The idea will spread quickly, but each person could add to it or leaves something out; these would be mutations of the original idea.

There are also memes that are handed down in the traditional sense of generations, that is, from a father to a son. These memes are long-lasting and could become cultural norms or traditions. For example, holidays are memes that have survived for many years. In many cases the original customs and purposes behind the holidays are lost or changed (at least by some people). Still the celebrations continue and millions of people observe the holidays. Do we know why the colors of Christmas are red and green, or why the Easter Bunny gives out eggs, or why children get candies at Halloween?

Memes Working Together

Similar to a single gene, a single meme has a minor impact. Genes are effective when they combine with other cooperative genes. Memes also combine with compatible memes and also compete with other memes for attention in human brains. One could think of different ideas as a meme pool, which people select (consciously or subconsciously). The memes that work well together will be more likely to be copied. A meme-complex could be copied because it benefits society, but it could also be copied because it aids the propagation of itself. It is not a guarantee that humans will make the best possible choices; there are equal reasons to believe that we will choose unwisely.

football stadiumA sport is an example of a well-established meme-complex. The North American culture is fascinated with sports on a daily basis. Many play sports at local venues; many more watch sports at stadiums and on televisions. What memes could be working together? How about this list: (memes for running, throwing and catching), (memes for competing, winning and losing), (memes for watching, cheering and analyzing). Any stable and self-replicating cultural norm will consist of mutually beneficial memes.

History-Making Memes

Recorded human history is a story of culture. The ideas that populations believed in mass, whether real or imagined, has fueled the events of history. The most influential ideas (memes) have won out over other ideas. Not always because they were better ideas, but because they were more effective at spreading from brain to brain. Historian Yuval Harari writes in Sapiens: A Brief History of Humankind:

… history’s choices are not made for the benefit of humans… There is no proof that cultures that are beneficial to humans must inexorably succeed and spread, while less beneficial cultures disappear.

Religion symbolsThe cultural enterprises that have dominated human life contain large numbers of memes. Such examples are: religion, war, agriculture, kingdoms, art, music, politics, nationalism and science. No one can tell if the history-making memes (or meme-complexes) took the best course of action for humanity. Some did and others did not. Nevertheless, they had the attributes to enter human brains and to be imitated. Our modern culture is formed by memes with the same qualities as the historical memes. That is, copying fidelity, with variation, and wide-spread selection from the meme pool.

 

References: Yuval Noah Harari, Sapiens: A Brief History of Humankind (Canada: Signal Books, an imprint of McClelland & Stewart, 2014).

Richard Dawkins, The Selfish Gene (Oxford: Oxford University Press, 30th anniversary edition, 2006).

Richard Dawkins | Memes | Oxford Union, Published on Feb. 26, 2014. 

Susan Blackmore sobre memes e “temes” – TED Legendado, Published on Jul. 13, 2013.


The Rise of Homo Sapiens

From about 2 million years ago until about 10,000 years ago, the world was populated by at least 6 different human species. They evolved from a common ancestor in East Africa, a hominid called Australopithecus (Southern Ape). Over thousands of years these primitive humans migrated to regions in North Africa, Europe and Asia. It is likely that environmental changes initiated the exodus, and as time passed new opportunities opened up in other lands. The diverse environments caused humans to evolve different survival traits, eventually branching out into several species.

For many years vast distances separated each species, which allowed them to survive independently. For instance: Homo neanderthalensis (Neanderthals) occupied regions in Europe and the Middle East, and Homo denisova (Denisovans) settled in Asia. Homo erectus (Upright Man), the human species with the most longevity (around 2 million years), populated eastern Asia. And a few species, including Homo sapiens (Wise Man), continued to evolve in East Africa. How closely related to Homo sapiens these other humans were is difficult to assess. How were they genetically different? What were their mental capabilities? And how complex were their social structures?

Homo sapiensNevertheless, starting at about 70,000 years ago Homo sapiens began moving north from Africa; they spread into the Arabian Peninsula and Eurasia. This led to direct competition with other humans. It is difficult for anthropologist to piece together what actually happened in the ensuing millenniums. But the Neanderthals became extinct about 30,000 years ago, and all other humans also disappeared (except for the sapiens). The extinction of Homo floresiensis in Indonesia (13,000 years ago) ended the last of the other human species. Interestingly, Homo floresiensis were a dwarf species, which had become isolated on the island of Flores. What caused Homo sapiens to outlive all other human species?

Two Possible Theories

1) The Interbreeding Theory: When Homo sapiens encountered other humans they coexisted peacefully. The species were genetically close enough that they could have interbred. The result being that today’s human population is not pure Homo sapiens, but rather a genetic mix of humans that lived 70,000 to 30,000 years ago.

2) The Replacement Theory: In this scenario, the genetic difference between species was too great to allow for interbreeding. Or possibly the sapiens’ way of life was drastically different from the others, and they had no interest in mingling with them. Or more likely, there would have been an intense competition for resources. Homo sapiens were the winners in a battle for survival. One could entertain a number of possible ways in which the battle could have been fought and won.

New Evidence

Recent evidence has shed light on the competing theories. In 2010 Neanderthal DNA was extracted from fossil remains. Enough genetic material was still intact to map out the Neanderthal genome. A comparison with modern human DNA revealed that 1-4 % of the DNA of people from the Middle East and Europe is Neanderthal DNA.

Several months later a similar analysis was performed from another primitive human. A sample from the Denisova cave in Siberia showed that about 6% of its DNA was found in modern Melanesians and Aboriginal Australians. The Neanderthal and Denisovan findings prove that some interbreeding did occur, but the amount of DNA in modern genomes is still small. This suggests that interbreeding was not the whole story.

The species may have been at a transition phase, in which they were not completely separate species, but merging of populations was rare. The replacement theory still carries a lot of weight in explaining why about 95% of our DNA is pure Homo sapiens. The conclusion being that sapiens essentially drove the other species to extinction. But what was the crucial difference that resulted in one species dominating the landscape?

The Story of Homo Sapiens

When scientists are uncovering evidence from per-historic times there are bound to be gaps in knowledge. Therefore, a fair amount of speculation comes into play. The rise of Homo sapiens from an insignificant animal to one that claimed the globe is remarkable. Especially when you consider that other humans, as far as we know, started out with the same opportunities.

What unique attributes enabled Homo sapiens to become the only human species? Although we are so accustomed to a world with only one human species, it is the rarest of exceptions in nature. In the animal kingdom there are many species of cats, birds, turtles, and whales. Only in modern humans do we find a single unique species.

In the book, A Brief History of Humankind, historian Yuval Noah Harari identifies one critical sapiens trait that allowed our human ancestors to conquer the world. He calls it The Cognitive Revolution. According to Harari, prehistoric sapiens had evolved a rare ability to cooperate in large numbers, and to do so flexibly.

Homo sapien huntersIt was the development of complex language and social structures that set them apart from other humans. They could communicate everyday practical information, such as where and how to hunt and gather berries. In addition, myths, gods, legends and religions emerged at this time. Whether fact or fiction, storytelling allowed large groups to unite and work for a common cause. Stories also made it possible to pass on knowledge and wisdom to the next generation.

Other animals also work together in groups, but their behaviors are inflexible. In order for significant changes to come about, genetic changes have to occur through the process of evolution. This takes a long time, and that is why animal behavior remains consistent from one generation to the next. But this is not the case for modern humans. Our history reveals an unprecedented pace of change with each generation. For the first time in the history of life sapiens were able to adapt using cognitive abilities. Today, humans are the only species that can survive in all land environments and diverse climates. This is mainly due to our adaptability.

 Taking Over the World

Neanderthals

Neanderthals

When the first wave of Homo sapiens arrived in Neanderthal territory, about 100,000 years ago, the Neanderthals forced the sapiens to retreat. Evidence shows that the Neanderthals had large brains, muscular bodies, could withstand cold temperatures and lived in groups. But it is likely that they could not organize in large groups, or share knowledge in the same way sapiens did. 70,000 years ago a second wave of sapiens left Africa and overran the Neanderthals. This time there was no turning back; Homo sapiens gradually settled much of the globe, and all other human species disappeared.

As Homo sapiens discovered new lands they found an abundance of large animals. This may have been fortunate for the humans, but not for the animals. The archeological records show that roughly 1/2 of the large land mammals became extinct during this period. Climatic or environmental changes may have contributed to the extinctions, however, the human invasion is hard to ignore. In every corner of the world, from large continents to remote islands, extinctions followed humans arriving for the first time.

Large prehistoric animals, such as ground sloths, saber tooth cats and mammoths could have been victims of the sapiens success. This was the first wave of extinction caused by human activity. But they could not have known the full impact of their actions, nor could they have imagined the evolution of human civilizations that would follow. Today, our unique cognitive ability separates us from all other animals. It was developed thousands of years ago in an epic battle for world supremacy.

 

References: Yuval Noah Harari, Sapiens (Canada: Signal Books, an imprint of McClelland & Stewart, 2014)

The Nature of Things: The Great Human Odyssey, (2015).


 

A Gene Centered View of Natural Selection

Natural selection was Darwin’s term for the mechanism of evolution. In the slow process of evolution nature selects which organisms adapt to their environments successfully (that are most successful at surviving and reproducing). But what is the unit of selection? Is it the species, group, individual or gene? At what level do natural environments shape the evolution of life? Could there be a blending of different units or is one dominant? For example, do species evolve as a consequence of group selection, or do groups evolve as a result of individual selection; or do genes ultimate control the process?

Richard DawkinsThese questions have been debated by biologists and academics for a long time. Richard Dawkins, with the publication of The Selfish Gene, sided on the gene centered camp. The idea of gene selection had been proposed in scientific papers: First by Bill Hamilton in 1964 and then by others, such as John Maynard Smith and Robert Trivers in the early seventies.

Published in 1976, The Selfish Gene placed gene selection into the public sphere by getting beyond the technical aspects of the scientific papers. Dawkins’ book was accessible to a general audience, and has been influential in shaping evolutionary thinking (the 30th anniversary edition was published in 2006). It was, however, controversial as much for its implications as for the gene centered view it supported. According to Dawkins, the book was misinterpreted and used by some groups as biological justification for selfishness in humans; but his intention was to explain how natural selection works, not how people should behave. Dawkins clearly points this out in the first chapter of the book:

“I am not advocating a morality based on evolution. I am saying how things have evolved. I am not saying how we humans morally ought to behave.”

The Metaphor

The title, The Selfish Gene, is a metaphor for how genes propagate. By controlling the traits of organisms, genes influence their own survival. The genes that aid in survival and reproduction are more likely to be copied in future generations. In that sense the genes are selfish and potentially immortal (in the form of replicas), while the bodies that contain them are mortal. Dawkins writes:

“Individuals are not stable things, they are fleeting. Chromosomes too are shuffled into oblivion, like hands of cards soon after they are dealt. But the cards themselves survive the shuffling. The cards are the genes…They are the replicators and we are their survival machines. When we have served our purpose we are cast aside.

genesThe selfish gene metaphor, though powerful, has its limitations; a single gene can’t do very much. Genes interact with each other and combine in complex ways to give rise to physical traits. It is essentially groups of genes that survive (genes that work well together). Therefore, a successful gene can be defined as a portion of genetic material that survives through a number of successive generations.

 Explaining Altruism

“Survival of the fittest,” that is the popular catchphrase for evolution. But an analysis of the mechanisms of evolution requires that we ask: the fittest what? For Darwin, it was the fittest individual that would survive and reproduce. In the middle of the 21rst century, biologists were reintroducing and debating Darwinian ideas. Group selection (the idea that the fittest groups would survive) was gaining popularity. The propagation of the species was the consequence of the fittest groups. However, some biologists were pointing out that group selection was inadequate to explain altruism in animals.

Altruistic Behavior in  Animals

Dawkins is a zoologist by training, and The Selfish Gene focuses mainly on the role of genes in animal behavior. He analyses animal behavior in a variety of species, and points out the correlation between altruistic behavior and relatedness. In other words, the closer the relationship (in terms of shared genes) the more altruism we can expect to see. In this view the genes are at the core of the altruistic behavior, as they aid in the survival of copies of themselves.

zebrasWhen an animal acts altruistically, it appears that the animal is sacrificing some survival need in order to increase the chance another will survive. It does not matter how small the sacrifice is, because a number of small sacrifices can accumulate over time, and also can be reciprocated. The group selection hypothesis interprets altruism as benefiting the group, and in the long run, these groups will be more successful. However, others claimed that selfish individuals would undermine the altruistic group. The selfish individuals within the group would exploit the altruistic system, eventually winning out. The struggle for existence would favor the selfish individuals over the altruistic individuals.

Dawkins argues that seemingly altruistic behaviors can be interpreted differently from a gene centered view. From the gene point of view, the act is still selfish because it aids exact copies of itself (in the form of children, siblings, cousins and so one). Animals are sometimes altruistic because they are programed by their genes to be so. Whether to be selfish or altruistic is a delicate balancing act that is ultimately guided by the genes chances of survival. In addition to helping close relatives, individuals are also dependent on groups. Therefore some consideration for the well-being of the group would likely come into play.

The Social Insects

Perhaps no other example of altruism in animals is as evident as in social insects. This is probably the best example of which a gene centered view of natural selection is adequate. Honey bees, wasps, ants and termites are familiar social insects, and they live in large colonies. The colony functions as a highly organized unit, where each individual has a specific role. Although the roles vary, they can be broken down into two main categories: Carers and bearers. The carers are sterile workers; the bearers are the reproductive females (queens) and reproductive males (drones or kings).

In most species each individual shares in the caring and bearing roles (not necessarily equally). But with social insects it is clearly divided. The sterile workers will devote their lives to providing and protecting the reproducers, even to the point of suicidal actions. This is what we observe when a bee stings a perceived threat to the hive. The bee will almost certainly die.

With an individual selection view, we would not expect suicidal behavior to evolve, because there is nothing to gain for the individual. However, the fact that the workers cannot bear offspring of their own, self-sacrifice for the good of the colony aids in the survival of their genes (shared genes with the reproductive members of the colony). From the gene centered view, what really matters is not just reproducing offspring, but assisting the survival of one’s own genes. There are many strategies in which this can occur (usually a balance of risk and reward). The triggers for the behaviors are surely subconscious. You could say they are controlled by the genes, or call it instincts.

Are Genes Really in Control?

Although there are mountains of evidence that shows life does evolves, determining the level of selection is tricky; it seems like a matter of interpretation. It is not hard to see how each unit of selection would naturally influence the others in the same way (either positively or negatively). For example, if the fittest individual is selected, it will aid its group, species and genes to propagate. We could change the last sentence by randomly shuffling the units (individual, group, species and genes) and it would still hold true.

Maybe natural selection is a complicated process that includes several units of selection. Species, groups, individuals and genes are likely interconnected in ways that are difficult to quantify. I suspect that this issue is not completely resolved among scientists. Nevertheless, I find that the gene centered view is both fascinating and compelling. It is a somewhat counter-intuitive way of looking at evolution, and yet upon closer examination it makes so much sense. Logically, it all hangs together.

 

References: Richard Dawkins, The Selfish Gene (Oxford: Oxford University Press, 30th anniversary edition, 2006).

Beautiful Minds: Richard Dawkins, Published on April 25, 2012. BBC4 https://www.youtube.com/watch?v=C2I8f4lpBLU


 

Darwin’s Theory of Evolution: The Best Idea Ever

Charles darwinCharles Darwin’s 1859 publication, On the Origin of Species, changed the way we look at biology forever. Its central idea, evolution by means of natural selection, explains how all life evolves. No single idea has ever explained so much. It stands apart from most, if not all, scientific discoveries in its outreach and simplicity. As with most great ideas, once grasped, one is inclined to ask: “Why didn’t anyone think of this before?”

Actually, others had similar ideas before Darwin, including fellow naturalist  Alfred Russel Wallace. Wallace had figured out that species evolve through natural selection and sent Darwin his version prior to Darwin’s landmark publication. In 1858 they jointly presented their work to the Linnean Society of London. But ultimately, it was Darwin’s detailed explanation in 1859 that history would recognize.

The Idea

Organisms evolve over time by means of natural selection. Each generation is tested by its environment; the traits that aid an organism to survive and reproduce will tend to be passed on to the next generation. Not necessarily all the time, but often enough or in greater numbers. Traits that are not useful will tend to be discarded when the organism that bears them fails to survive or reproduce.

Through this process survivors are copied with slight random variations, which are then tested many times over. In other words, survivors live longer and usually reproduce more, keeping their survival traits alive in the ensuing generations. Darwin wasn’t the first to suggest that organisms evolve from previous forms, but he provided the mechanism (natural selection).

Why is This Idea so Special?

  • Outreach: Natural selection provides an explanation for how all of life evolves. It accounts for microorganisms, plants, fish, insects, birds, animals and of course humans.
  • Simplicity: As oppose to other notable scientific ideas it can easily be understood by the general public. One does not need any technical science background to grasp the basics of this simple, yet elaborate idea.
  • A confidence boost for science: Before Darwin, few could have predicted that all life on earth could be explained by natural means. Ever since Darwin, few should doubt the power of science to explain just about everything else.
  •  Philosophical implications: Darwin compelled us to take a second look at our place in the world. Long-held beliefs that humans held a privileged position, separate from the other creatures, had to be re-evaluated.
Darwin's Tree of Life

Darwin’s Tree of Life

The Controversy

Darwin delayed the publication of his theory of evolution for about 17 years, because he feared a public backlash. And he was right in assuming that controversy would follow. His chief concern, I can only speculate, was probably religious. Natural selection can easily be viewed as taking god out of the creation business. If nature is shaping all of life, what is god left to do? Despite some criticism, his book drew worldwide interest. Even today evolution still gets some people upset. Why is such a profound idea so difficult for some? Let’s look at possible reasons why:

  • Religious : Evolution contradicts the bible’s account of creation; however, many people seem to have no problem squaring evolution with the bible. They either don’t really know what the bible says or they don’t take it literally. Whereas literal interpreters of the bible clearly see what evolution means for their faith. For them evolution is akin to a fatal blow.
  • Supernatural thinking: If one is inclined to believe that there exists a dimension outside the laws of nature, then anything is possible. Life can then be guided by a supernatural force. If that is the case, evolution is no longer required as an explanation.
  • Evolution is confused with natural selection: I suspect that some people think of evolution as simply gradual change over time. In terms of the cause, they can use their imagination. However, the key insight is the means by which change happens. Evolution is the process and natural selection is the mechanism.
  • Deep time: There is nothing in everyday experience that can prepare us for the time scales involved in evolution. Simple life emerged on earth (in the ocean to be exact) 3.8 billion years ago. And from there spread to all regions of the planet. That’s 38 million centuries for life to evolve to eventually create you and me. Given enough time, minor variations in each generation can result in changes that may be hard for some to grasp.          
  • Sometimes the truth hurts: There is no plan in evolution, no final destination that has to be achieved. Furthermore, human beings don’t hold any privileged position in the tree of life. Darwin described life as a family tree, with different species spreading in all directions. Life could no longer be seen as analogues to a ladder, with humans occupying the top rung.  

A Scientific Idea

Darwin’s idea was much more than a moment of insight. It was a scientific idea, a theory that he developed based on years of experience as a naturalist. As a young man Darwin sailed across the globe on the HMS Beagle. He accompanied Captain Robert FitzRoy on a 5 year journey, where Darwin collected a multitude of natural specimens and fossils. It is on this voyage, from 1831 to 1836, that Darwin gathered extensive evidence for his theory of evolution.

Darwin collected many fossils; some were from ancient sea creatures, which he found in mountainous regions. This was clear evidence that mountains moved over time—that a high altitude had once been under water. From a geological perspective the earth had changed slowing throughout the ages. This principle of gradual change over time was extended to include life forms. If the earth changed, life could also change.

Influential to forming his ideas, Darwin collected bird specimens (finches) from the Galapagos Islands in South America. He noticed that the shape of the finch’s beaks varied depending on the island they came from. Darwin reasoned that the finches all originated from a common ancestor, and had evolved different beaks. The finches had become isolated on separate islands, thus evolving differently to meet the demands of the local food supply.

These and other similar ideas got the wheels in motion for Darwin, showing him that species were not stable, that they can change dramatically over long periods of time. Some of the fossils he unearthed were from extinct species, distant ancestors that resembled species that were still living. He also examined different mammal skeletons and noticed they were all variations of a similar bone structure. Beyond his own ideas, Darwin corresponded with other naturalist around the world through letters, thus gathering piles of information.

It would eventually culminate in the publication of On the Origin of Species. Darwin surely struggled with the implications of his theory, as it would have been radical in Victorian England. Creationism was the overwhelming belief of the time; however, it became clear to Darwin that organisms where not created in their present form. Darwin must have been apprehensive upon the publication of his book. Nevertheless, he was guided by the overwhelming evidence he observed as a scientist. He had to accept what his scientific mind was telling him, regardless of the belief of the day. Darwin’s Theory of Evolution is a great scientific idea, and that is why it still stands today.

 

References: The Genius of Charles Darwin, The Science Foundation, https://www.youtube.com/watch?v=ptV9sNezEvk, Published on Jan 12, 2011.